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Tech Talk

 

 

If you are not sure how to do the job right have your Pedders Dealer do the installation.
 
If you need advice or instructions contact your Pedders Dealer for proper installation instructions. You ill find them to be an invaluable resource as you modify your GTO.
 
When installing new suspension parts always verify the vehicle alignment and clearances to insure proper operation. Check your wheel clearances carefully. The proper installation and operation of your vehicle is your responsibility. If you are unsure of how to properly complete the installation of these parts have them installed by a qualified professional.
 
Only a qualified GTO Specialist has the proper cradle alignment knowledge and tools to set the cradles before a Wheel Alignment. This is mission critical for those of you with GTOs and rear tires and wheels larger than OEM. Pedders dealers have the tools and knowledge to get your GTO on track. Do it right. Do it once. PEDDERISE!

As the GTO ages in years and miles we find more issues during the 28Point Inspections. Typical items we find during a 28 Point Inspectionare:

Cars with detached front or rear endlinks
Cars with severely cracked drag radial sidewalls
Cars with bald inner shoulders
Cars with dry radius rod bushes
Cars with Strut Rub
Cars with failed Strut Mounts

This is a video of the worst case scenario failed radius bushes andfront struts.


This is a radius rod bush test done at 5 MPH with the brake pedalpushed to the floor as it would be in a panic stop. The bobble headinside the car belongs to yours truly. This is the worst case scenariofor a GTO owner: failed struts and failed radius rod bushes. [B]A Panicstop at 35 MPH, IMO would be uncontrollable with a car in thiscondition. The video was taken by a guest. Thank YOU Hummina !!!

It shows a GTO at 5 MPH with ONLY 7,500 miles on the odometer leakingstruts and bad radius rod bushes. This is a radius rod bush test doneat 5 MPH with the brake pedal pushed to the floor as it would be in apanic stop. The bobble head inside the car belongs to yours truly. Thisis the single worst car we have tested. If you don't have a PeddersDealer find a service technician that you trust and have them check outyour car. If you do your own work, make sure you routinely check everynut and bolt under your car. A very high percentage of the forummembers drag, autocross, road course or drive their GTO faster than theposted speed limit. That number is probably 99.9%. Your car is heavy.Your car accelerates fast. Your GTO stops faster. Your GTO requiresmore maintenance than a Miata because it is heavier and faster. Baldtires, exposed tire sidewall cords, missing bolts, leaking struts,leaking shocks, bad bushes, tire tread wear patterns and more can onlybe evaluated when you take the time to inspect it as a DIY or have itdone by a qualified professional. If you drive like a race car driverperform maintenance like a race car crew chief.

This isn't a thread to bash GM for bad parts or design. It has nothingto do with the owner's being bad guys who don't perform propermaintenance. It isn't a thread to sell more Pedders bits, though itprobably will. It is a reminder that even though you checked it a fewweeks ago, looked at it while you changed the oil or whatever, to checkit again. The only way to know that the suspension and tires have beencorrectly checked is to use a checklist just like a pilot forpre-flight. Parts break. Parts have manufacturing flaws and fail. Boltscome loose. Perdieu put up a great post a long time ago about loosebolts. http://www.ls1gto.com/forums/showthr...ighlight=bolts Your job and our job is to make sure less of it happens. We will neverbe perfect, but if we try we should be safe.

All GTOs should have come from the factory with Castor AdjustableUrethane Radius Rod Bushes, upgraded rear sub-frame bushes and adifferential insert. The inherent deficiencies in these bushes causethe car to feel loose and sloppy. A GTO with these three foundationalbushes upgraded starts better, stops better and steers better. It is anentirely different car and there is virtually no change in the ridequality. A GM Vehicle Dynamics Engineer upgraded his GTO with thesebushes. Using the OE bushes as the perfect 10 standard for NVH he ratedthe Pedders bushes as 9.5.

EP9166 Castor Adjustable Radius Rod Bushes
EP1145 Rear Sub-Frame Connector Bushes
EP1157 Differential Insert

While these three bushes dramatically improve the vehicle they donothing to control the pitch and roll of the GTO which is caused bybeing under sprung and under damped. Correcting this requires changingthe coils and dampers. Changing coils and dampers will alter the ridequality. Most find the GSRs, which are relatively high on the CriticalDamping Scale, to be OE like for a performance vehicle. Some find theGSR to be overly firm. A GSR is very German in feel much like a BMW MSeries or a Mercedes AMG. Both the M and AMG would be too firm for manydrivers. More drivers would be comfortable with a standard German rideas found in the BMW or Mercedes range. That is where our Comfort Gasdampers fit in feel and on the Critical Damping Scale.

The GTO leaves the factory with mis-matched dampers. The front strutsare oil and air. The rear shocks are oil and nitrogen. The rear coilsare installed in a 2 to 1 motion ratio / suspension geometry while thefront coils are linear motion with a ratio of 1 to 1. The rear coilsare highly progressive to maintain ride quality. They are soprogressive in the top and bottom coil and a half that they fatiguerapidly causing high negative rear wheel cambers. The rear coils andfront struts are the next weakest links in the GTO suspension.

For improved control with minimal change in OE ride quality we can do ahybrid installation. We replace the rear shocks and front struts withCG units. We retain the front coils and replace the rear coils with7643 OE Height T2 Legal coils. These coils will bring the GTO to theoriginal factory ride height of 608mm, dramatically decrease vehiclesquat under acceleration and roll in turns with a very high level ofRide comfort.

On the front end we install new heavy duty strut mounts to address thelast remaining weak point from the factory. The Pedders HD 5851 strutmount does not alter the ride quality and improves function because theupper mounting point of the strut is moving less. Using the OE coil upfront maintains a higher level of ride quality for the driver moreconcerned about ride than control. A Pedders 2142 would be superior inhandling but would tighten up the feel of the vehicle.

Because of age and miles most GTOs will be in need of Strut Mountsalong with front and rear Radius Bushes. These three bushes locate thestrut in the GTO. These three bushes control the stability of the frontsuspension. There is an inner front control arm bush, but it is a steeljacketed robust bush good for many years and miles of street driving.When the Strut Mounts along with front and rear Radius Bushes are ingood condition a GTO performs well. When they are tired or failed theylead to strut rub and sloppy handling. A GTO can be brought to betterthan new handling on a minimalist budget replacing only what isabsolutely necessary.

5030 Strut Bearings
5851 HD Strut Mounts
7643 Rear Coils
8081 Comfort Gas Rear Shocks
8995L/R Comfort Gas Front Struts
EP9019
EP9166

We can increase control a bit further by replacing the OE rubbermounting sway bar bushes and sway bar endlinks with urethane bits. Theurethane upgrade to these bushes will increase the efficiency of the OEbars by approximately 20%. As you snug up the suspension the ride willchange. The increase in the control makes driving into a corner or overa bump far more controlled. The control works to offset the increase inoverall tightness in the suspension. More control improves the ride inthe sense that there is less drama in the reaction of the vehicle.

EPC27 Front D Bush
EP3451 Front Sway Bar Endlink Bushes
EP513 Rear Sway Bar Endlink Bushes
EP613/17 Rear Sway Bar D Bush

The GTO uses a number of TTY bolts. for the work discussed here youwill need to replace the 2 x member and four differential carrier TTYBolts. Pedders and GM use the same part numbers for these bits. Theyare not as available as they once were from GM. If you have to re-usethe TTY bolts because they are not available extra care should betaken. Clean the threads with a wire brush. Use fresh LocTite. Followthe GM torque specifications.

92038482 Sub Frame / X Member TTY Bolt
92138390 Differential Carrier TTY Bolt

A GTO that is Pedderised in this combination will feel like a BMW onthe road. It will be smooth and composed. Full suspension travel isretained. None of the bushes that would alter the ride quality havebeen replaced. What we have is a very well mannered GTO with andexcellent ride quality that stops, starts, drives and turns better thana stock GTO with a minimum of 95% of the OE ride quality.

Each of the weak suspension components listed in this thread getsweaker with use and accumulated wear. As more miles accumulate on yourGTO and maintenance is required this is going to become a more popularPedderised option. At 40K or more installing these bits as amaintenance items will result in a GTO that drives better with 40K ormore than it did when it left the dealership brand new.

As the strut mounts, front and rear radius bushes wear they requirereplacement with either new OE bits or aftermarket components. This isa long term fix as Pedders EP9166 and EP9019s radius rod bushes willprobably last the lifetime of the Goat. Strut mounts regardless ofmaterial will still wear. That is a function of the design. The frontstruts require articulation. If you put in enough rubber or urethane toprevent wear there is insufficient articulation. It is Pedders opinionthat our 5851 is the the optimal blend of durability, long life andarticulation.


Leaking Strut, worn out strut mount, cut bumpstop, cracked strut cap





The shiny spot on the spring perch is the result of spirited driving orlow inflation. This is NOT strut rub. The shiny spot on the weld ISstrut rub. It is dangerous and can cut so deeply into the side wallthat it causes failure.



This shows the tire sidewall in contact with the spring perch to strutweld know as Strut Rub.



This shows the damage caused by the spring perch to strut weld contactin the form of a groove into the sidewall.



Worn out strut mount side by side with a Pedders 5851



Cracked and torn rubber on an OE strut mount.





Cut Bumpstop



Failed OE Radius Bushes



There are four separate elements in the alignment process for a PontiacGTO.

1. Front Cradle
2. Rear Cradle
3. Transmission
4. All Wheel Alignment

These individual alignments work together to bring the entiredrive-line and all four wheels on to the center-line of the monocoquestructure. You can and will feel the difference.

1. Improved tracking under all conditions
2. Reduction in drive-line vibrations
3. Even tire wear
4. Reduction in rear wheel tramp
5. Balanced wheel well clearance
6. Correction of Strut Rub


First, we’ll discuss Front Cradle Alignment. The front fixture isessentially a large dial indicator.



This is a factory specified procedure and there is the factory stampedalignment mark covered by the skid plate.

 


The fixture needle should align perfectly with factory stamped mark.


 

 


Much like our rear cradles the front on this vehicle (Brad and Amanda’s2004 GTO with about 5, 000 miles at Waukegan Tire Saturday, September16, 2006 10:00 a.m.) are well out of spec. Alignments are tight andwithin tenths of a degree. This front cradle is out by ¼” according tothe observations of the owner. Correction is accomplished by manuallyadjusting the front sub-frame and replacing the four TTY bolts so thatthe needle is directly aligned with the factory mark.

Why has this procedure not been available in the USA until now? Whilewe were aware of the procedure and the need the tool was not available.The tools are now available at your local Pedders Dealer. With theirexpertise and the right tools your GTO will drive better-than-new.

How many front cradle alignments using a fixture have performed inNorth America? Two Amanda and Brad’s and my car. The question is whowill be next?

When can I have this done on my car? The tools have been shipped or arebeing shipped to your local Pedders Dealer. All the Pedders Dealersshould have this tool before October 1st. You should be calling toschedule your appointment now.

Will this tool be available at the Pontiac Dealer or my local alignmentshop? Only if they can find another source for the tool. This issomething we have been working on for a very long time. It is anotherreason we believe there is no substitute for visiting a Pedders Shop.They are suspension and in this case GTO Specialists who invest thetime in education, tools and parts to service their customers.

Can a shop align my font and rear cradles without fixtures? Maybe -there are certainly experienced race car techs working out of dirtfloor garages that can align almost anything with wheels using stringsand levels. Using a fixture is Holden’s solution to the most costeffective, accurate and repeatable sub-frame alignment process. If yoursub-frames have been aligned using anything other than fixture, theymay or may not be right. If they were aligned with a fixture they aredead nuts spot on.

Next is the rear cradle alignment and that requires the replacement oftwo TTY bolts in the sub-frame and four differential carrier TTY bolts.While this process is in progress it would be an ideal time to replaceyou sub-frame connectors. The triangulated plate is off, the TTY bolthas been broken loose so why not pry out a major source of rear wheelhop? Sorry for the digression. The rear sub-frame alignment differs inthat there is no indicator. This is a four datum point fit fixture thatcan only be inserted into all four holes when the cradle is in fullalignment. Once the fixture is in place the bolts are tightened. Thisprocess brings the rear sub-frame and differential into alignment withthe center-line of the vehicle.

The third phase is the alignment of the transmission cross-member. Withthe front and rear cradles aligned by fixture the transmissioncross-member can be properly centralized. This third step in alignmentbrings other elements of the drive-line on center with the relatedvehicle components.

The fourth phase is to centralize the differential mount. The objectiveis a vehicle that performs with incredible precision and minimalvibration. We are dealing with a four thousand pound load that has aminimum of 350 HP.

The final step is the four-wheel alignment. This step can only beproperly completed if the cradle previous three steps have beenfollowed and all the related suspension components are within OE orbetter yet Pedders specification. Ride height, strut mounts, tie rodends, ball joints, radius rod bushes, and so on must be in excellentcondition. There is no reason to perfectly align a vehicle with wornsuspension parts. The alignment will not hold under operationalconditions because there will be excessive travel in the geometry. YourPedders professional will walk through each suspension component andexplain the condition to you with the car in the air. In Australia, wecall this a 28 Point Check. There are actually more than 28 points butthat is another story. The stock GTO does not have front castor or rearcamber adjustment. These adjustments will require the addition ofPedders Alignment Bushes EP9166 and 5403. Your GTO can now be alignedto the factory specs or tweaked for a more aggressive spec using thePedders Alignment Specifications.

Link to the Original Holden Procedure:

Will you be able to tell the difference in your GTO? Only if you arebreathing when you return from your test ride!

Medical Warning: People with high blood pressure and heart conditionsshould use Pedders parts with extreme caution. Pedderised GTOs havebeen know to result in extreme SEGs. If your SEG persists for more than4 hours consult a doctor immediately. Severely dilated pupils mayresult from the adrenaline rush on your first drive of a PedderisedGTO. These medical side effects will last for years.

How much will this cost? This is not a $79.99 Sunday Paper Special. Thecost will vary from coast to coast. We have shops with hourly rates aslow as $65 and as high as $140. The cost of real estate and local wagerates are the major factors in hourly rates. The service you receivefrom any Pedders Dealer will be the same - excellent. If you have aPedders issue that cannot be resolved to your satisfaction with thedealer call or PM me. This is an hourly breakdown.

Front Cradle 1 Hours
Rear Cradle 1 Hours
Transmission .5 Hour
Four Wheel Alignment 1.5 Hour

 

As the GTO ages in years and miles we find more issues during the 28Point Inspections. Typical items we find during a 28 Point Inspectionare:

Cars with detached front or rear endlinks
Cars with severely cracked drag radial sidewalls
Cars with bald inner shoulders
Cars with dry radius rod bushes
Cars with Strut Rub
Cars with failed Strut Mounts

This is a video of the worst case scenario failed radius bushes andfront struts.


This is a radius rod bush test done at 5 MPH with the brake pedalpushed to the floor as it would be in a panic stop. The bobble headinside the car belongs to yours truly. This is the worst case scenariofor a GTO owner: failed struts and failed radius rod bushes. [B]A Panicstop at 35 MPH, IMO would be uncontrollable with a car in thiscondition. The video was taken by a guest. Thank YOU Hummina !!!

It shows a GTO at 5 MPH with ONLY 7,500 miles on the odometer leakingstruts and bad radius rod bushes. This is a radius rod bush test doneat 5 MPH with the brake pedal pushed to the floor as it would be in apanic stop. The bobble head inside the car belongs to yours truly. Thisis the single worst car we have tested. If you don't have a PeddersDealer find a service technician that you trust and have them check outyour car. If you do your own work, make sure you routinely check everynut and bolt under your car. A very high percentage of the forummembers drag, autocross, road course or drive their GTO faster than theposted speed limit. That number is probably 99.9%. Your car is heavy.Your car accelerates fast. Your GTO stops faster. Your GTO requiresmore maintenance than a Miata because it is heavier and faster. Baldtires, exposed tire sidewall cords, missing bolts, leaking struts,leaking shocks, bad bushes, tire tread wear patterns and more can onlybe evaluated when you take the time to inspect it as a DIY or have itdone by a qualified professional. If you drive like a race car driverperform maintenance like a race car crew chief.

This isn't a thread to bash GM for bad parts or design. It has nothingto do with the owner's being bad guys who don't perform propermaintenance. It isn't a thread to sell more Pedders bits, though itprobably will. It is a reminder that even though you checked it a fewweeks ago, looked at it while you changed the oil or whatever, to checkit again. The only way to know that the suspension and tires have beencorrectly checked is to use a checklist just like a pilot forpre-flight. Parts break. Parts have manufacturing flaws and fail. Boltscome loose. Perdieu put up a great post a long time ago about loosebolts. http://www.ls1gto.com/forums/showthr...ighlight=bolts Your job and our job is to make sure less of it happens. We will neverbe perfect, but if we try we should be safe.

All GTOs should have come from the factory with Castor AdjustableUrethane Radius Rod Bushes, upgraded rear sub-frame bushes and adifferential insert. The inherent deficiencies in these bushes causethe car to feel loose and sloppy. A GTO with these three foundationalbushes upgraded starts better, stops better and steers better. It is anentirely different car and there is virtually no change in the ridequality. A GM Vehicle Dynamics Engineer upgraded his GTO with thesebushes. Using the OE bushes as the perfect 10 standard for NVH he ratedthe Pedders bushes as 9.5.

EP9166 Castor Adjustable Radius Rod Bushes
EP1145 Rear Sub-Frame Connector Bushes
EP1157 Differential Insert

While these three bushes dramatically improve the vehicle they donothing to control the pitch and roll of the GTO which is caused bybeing under sprung and under damped. Correcting this requires changingthe coils and dampers. Changing coils and dampers will alter the ridequality. Most find the GSRs, which are relatively high on the CriticalDamping Scale, to be OE like for a performance vehicle. Some find theGSR to be overly firm. A GSR is very German in feel much like a BMW MSeries or a Mercedes AMG. Both the M and AMG would be too firm for manydrivers. More drivers would be comfortable with a standard German rideas found in the BMW or Mercedes range. That is where our Comfort Gasdampers fit in feel and on the Critical Damping Scale.

The GTO leaves the factory with mis-matched dampers. The front strutsare oil and air. The rear shocks are oil and nitrogen. The rear coilsare installed in a 2 to 1 motion ratio / suspension geometry while thefront coils are linear motion with a ratio of 1 to 1. The rear coilsare highly progressive to maintain ride quality. They are soprogressive in the top and bottom coil and a half that they fatiguerapidly causing high negative rear wheel cambers. The rear coils andfront struts are the next weakest links in the GTO suspension.

For improved control with minimal change in OE ride quality we can do ahybrid installation. We replace the rear shocks and front struts withCG units. We retain the front coils and replace the rear coils with7643 OE Height T2 Legal coils. These coils will bring the GTO to theoriginal factory ride height of 608mm, dramatically decrease vehiclesquat under acceleration and roll in turns with a very high level ofRide comfort.

On the front end we install new heavy duty strut mounts to address thelast remaining weak point from the factory. The Pedders HD 5851 strutmount does not alter the ride quality and improves function because theupper mounting point of the strut is moving less. Using the OE coil upfront maintains a higher level of ride quality for the driver moreconcerned about ride than control. A Pedders 2142 would be superior inhandling but would tighten up the feel of the vehicle.

Because of age and miles most GTOs will be in need of Strut Mountsalong with front and rear Radius Bushes. These three bushes locate thestrut in the GTO. These three bushes control the stability of the frontsuspension. There is an inner front control arm bush, but it is a steeljacketed robust bush good for many years and miles of street driving.When the Strut Mounts along with front and rear Radius Bushes are ingood condition a GTO performs well. When they are tired or failed theylead to strut rub and sloppy handling. A GTO can be brought to betterthan new handling on a minimalist budget replacing only what isabsolutely necessary.

5030 Strut Bearings
5851 HD Strut Mounts
7643 Rear Coils
8081 Comfort Gas Rear Shocks
8995L/R Comfort Gas Front Struts
EP9019
EP9166

We can increase control a bit further by replacing the OE rubbermounting sway bar bushes and sway bar endlinks with urethane bits. Theurethane upgrade to these bushes will increase the efficiency of the OEbars by approximately 20%. As you snug up the suspension the ride willchange. The increase in the control makes driving into a corner or overa bump far more controlled. The control works to offset the increase inoverall tightness in the suspension. More control improves the ride inthe sense that there is less drama in the reaction of the vehicle.

EPC27 Front D Bush
EP3451 Front Sway Bar Endlink Bushes
EP513 Rear Sway Bar Endlink Bushes
EP613/17 Rear Sway Bar D Bush

The GTO uses a number of TTY bolts. for the work discussed here youwill need to replace the 2 x member and four differential carrier TTYBolts. Pedders and GM use the same part numbers for these bits. Theyare not as available as they once were from GM. If you have to re-usethe TTY bolts because they are not available extra care should betaken. Clean the threads with a wire brush. Use fresh LocTite. Followthe GM torque specifications.

92038482 Sub Frame / X Member TTY Bolt
92138390 Differential Carrier TTY Bolt

A GTO that is Pedderised in this combination will feel like a BMW onthe road. It will be smooth and composed. Full suspension travel isretained. None of the bushes that would alter the ride quality havebeen replaced. What we have is a very well mannered GTO with andexcellent ride quality that stops, starts, drives and turns better thana stock GTO with a minimum of 95% of the OE ride quality.

Each of the weak suspension components listed in this thread getsweaker with use and accumulated wear. As more miles accumulate on yourGTO and maintenance is required this is going to become a more popularPedderised option. At 40K or more installing these bits as amaintenance items will result in a GTO that drives better with 40K ormore than it did when it left the dealership brand new.

As the strut mounts, front and rear radius bushes wear they requirereplacement with either new OE bits or aftermarket components. This isa long term fix as Pedders EP9166 and EP9019s radius rod bushes willprobably last the lifetime of the Goat. Strut mounts regardless ofmaterial will still wear. That is a function of the design. The frontstruts require articulation. If you put in enough rubber or urethane toprevent wear there is insufficient articulation. It is Pedders opinionthat our 5851 is the the optimal blend of durability, long life andarticulation.


Leaking Strut, worn out strut mount, cut bumpstop, cracked strut cap





The shiny spot on the spring perch is the result of spirited driving orlow inflation. This is NOT strut rub. The shiny spot on the weld ISstrut rub. It is dangerous and can cut so deeply into the side wallthat it causes failure.



This shows the tire sidewall in contact with the spring perch to strutweld know as Strut Rub.



This shows the damage caused by the spring perch to strut weld contactin the form of a groove into the sidewall.



Worn out strut mount side by side with a Pedders 5851



Cracked and torn rubber on an OE strut mount.





Cut Bumpstop



Failed OE Radius Bushes



There are four separate elements in the alignment process for a PontiacGTO.

1. Front Cradle
2. Rear Cradle
3. Transmission
4. All Wheel Alignment

These individual alignments work together to bring the entiredrive-line and all four wheels on to the center-line of the monocoquestructure. You can and will feel the difference.

1. Improved tracking under all conditions
2. Reduction in drive-line vibrations
3. Even tire wear
4. Reduction in rear wheel tramp
5. Balanced wheel well clearance
6. Correction of Strut Rub


First, we’ll discuss Front Cradle Alignment. The front fixture isessentially a large dial indicator.



This is a factory specified procedure and there is the factory stampedalignment mark covered by the skid plate.

 


The fixture needle should align perfectly with factory stamped mark.


 

 


Much like our rear cradles the front on this vehicle (Brad and Amanda’s2004 GTO with about 5, 000 miles at Waukegan Tire Saturday, September16, 2006 10:00 a.m.) are well out of spec. Alignments are tight andwithin tenths of a degree. This front cradle is out by ¼” according tothe observations of the owner. Correction is accomplished by manuallyadjusting the front sub-frame and replacing the four TTY bolts so thatthe needle is directly aligned with the factory mark.

Why has this procedure not been available in the USA until now? Whilewe were aware of the procedure and the need the tool was not available.The tools are now available at your local Pedders Dealer. With theirexpertise and the right tools your GTO will drive better-than-new.

How many front cradle alignments using a fixture have performed inNorth America? Two Amanda and Brad’s and my car. The question is whowill be next?

When can I have this done on my car? The tools have been shipped or arebeing shipped to your local Pedders Dealer. All the Pedders Dealersshould have this tool before October 1st. You should be calling toschedule your appointment now.

Will this tool be available at the Pontiac Dealer or my local alignmentshop? Only if they can find another source for the tool. This issomething we have been working on for a very long time. It is anotherreason we believe there is no substitute for visiting a Pedders Shop.They are suspension and in this case GTO Specialists who invest thetime in education, tools and parts to service their customers.

Can a shop align my font and rear cradles without fixtures? Maybe -there are certainly experienced race car techs working out of dirtfloor garages that can align almost anything with wheels using stringsand levels. Using a fixture is Holden’s solution to the most costeffective, accurate and repeatable sub-frame alignment process. If yoursub-frames have been aligned using anything other than fixture, theymay or may not be right. If they were aligned with a fixture they aredead nuts spot on.

Next is the rear cradle alignment and that requires the replacement oftwo TTY bolts in the sub-frame and four differential carrier TTY bolts.While this process is in progress it would be an ideal time to replaceyou sub-frame connectors. The triangulated plate is off, the TTY bolthas been broken loose so why not pry out a major source of rear wheelhop? Sorry for the digression. The rear sub-frame alignment differs inthat there is no indicator. This is a four datum point fit fixture thatcan only be inserted into all four holes when the cradle is in fullalignment. Once the fixture is in place the bolts are tightened. Thisprocess brings the rear sub-frame and differential into alignment withthe center-line of the vehicle.

The third phase is the alignment of the transmission cross-member. Withthe front and rear cradles aligned by fixture the transmissioncross-member can be properly centralized. This third step in alignmentbrings other elements of the drive-line on center with the relatedvehicle components.

The fourth phase is to centralize the differential mount. The objectiveis a vehicle that performs with incredible precision and minimalvibration. We are dealing with a four thousand pound load that has aminimum of 350 HP.

The final step is the four-wheel alignment. This step can only beproperly completed if the cradle previous three steps have beenfollowed and all the related suspension components are within OE orbetter yet Pedders specification. Ride height, strut mounts, tie rodends, ball joints, radius rod bushes, and so on must be in excellentcondition. There is no reason to perfectly align a vehicle with wornsuspension parts. The alignment will not hold under operationalconditions because there will be excessive travel in the geometry. YourPedders professional will walk through each suspension component andexplain the condition to you with the car in the air. In Australia, wecall this a 28 Point Check. There are actually more than 28 points butthat is another story. The stock GTO does not have front castor or rearcamber adjustment. These adjustments will require the addition ofPedders Alignment Bushes EP9166 and 5403. Your GTO can now be alignedto the factory specs or tweaked for a more aggressive spec using thePedders Alignment Specifications.

Link to the Original Holden Procedure:

Will you be able to tell the difference in your GTO? Only if you arebreathing when you return from your test ride!

Medical Warning: People with high blood pressure and heart conditionsshould use Pedders parts with extreme caution. Pedderised GTOs havebeen know to result in extreme SEGs. If your SEG persists for more than4 hours consult a doctor immediately. Severely dilated pupils mayresult from the adrenaline rush on your first drive of a PedderisedGTO. These medical side effects will last for years.

How much will this cost? This is not a $79.99 Sunday Paper Special. Thecost will vary from coast to coast. We have shops with hourly rates aslow as $65 and as high as $140. The cost of real estate and local wagerates are the major factors in hourly rates. The service you receivefrom any Pedders Dealer will be the same - excellent. If you have aPedders issue that cannot be resolved to your satisfaction with thedealer call or PM me. This is an hourly breakdown.

Front Cradle 1 Hours
Rear Cradle 1 Hours
Transmission .5 Hour
Four Wheel Alignment 1.5 Hour

 


Pedders is the leading suspension provider in Australia . Sports Ryder parts have been tested on the roads of Australia in the Holden / HSV / GTO for years. Pedders is not learning how to get the most out of your GTO by trial and error with your money? Pedders knows how to get the maximum results from your GTO upgrade budget and ... NO BULL!
  As the premier Monaro / GTO vendor in the world, Pedders is proud to offer the widest range of spring to suit your specific application. The industry standard for variance in spring height is 15mm / 5/8". Pedders Springs are manufactured to the highest standard; our own of 2mm or less than 1/8". Each spring undergoes a full scrag and is measured to insure long life and consistency.  
The GTO has an average ride height of 604mm as measured from the bottom of the rim (OE 17" Wheel) up through the wheel center and to the fender lip all around. Ride height is measured with a quarter tank of fuel on a level surface. An alignment rack is best suited for this. Using this information, you will be able to determine which Pedders coil is best for your GTO.

 
Your GTO delivered from the Holden factory in OZ arrived with NG dampers ? NO Gas. Upgrading your dampers to Pedders Comfort Gas (CG), Pedders Gas SportsRyder (GSR) or Pedders eXtreme (height adjustable front Coilovers) are designed top optimize your new Pedders SR coils.

  The foundational bushes required to elevate the performance of your GTO are Castor Adjustable Radius Rod Bushes (EP9166), rear sub-frame / x-member bushes (EP1145) and a differential insert filling the factory voids (EP1157). These three bush kits create a stable foundation to support all other modifications. Adding more power ? add these foundational bushes first. Replacing the factory rubber with stickier tires ? install the foundational bush kit to get the most out of your tires. Build you GTO just like you build a solid building. Start with the foundation!

 
Only a qualified GTO Specialist has the proper cradle alignment knowledge and tools to set the cradles before a Wheel Alignment. This is mission critical for those of you with GTOs and rear tires and wheels larger than OEM. Pedders Dealers have the tools and knowledge to get your GTO on track.
Pedders believes that Sway Bars are the final tuning element for any vehicle. The better balanced, sprung, damped and bushed the more benefits will be derived from larger adjustable bars. Many in the suspension industry believe that sway bars are the first step in improving an OEM suspension. They are wrong. The GTO requires sub-frame bushes, radius rod bushes, castor adjustment, rear coils higher in rate, nitrogen charged struts and higher critical damping rates at all four wheels BEFORE sway bars. Installing any brand aftermarket sway bars on a GTO before these foundational components are addressed is like putting lipstick on a pig.
 
While we are on the subject of sway bars, we should talk about the Rube Goldberg designed GTO front sway bar endlinks. The OEM endlinks are inefficient at best and prone to bending. Pedders HD 424209 Endlinks are more robust than OEM and use urethane bushes to increase the efficiency and effective rate of the OE bar.
 
The best possible result is achieved when you use Pedders 9433 GSR Struts with Pedders 424210 / 424211 Double-Ball Joint endlinks. No matter what bar you have, OE Pedders or Brand X the bar will function best with this combination of engineering excellence.
 
Once the foundational components are in place you will find Pedders GTO Adjustable Sway Bars to be a significant improvement to your OEM bars. The center adjustment position delivers 30mm front bar and 18mm rear bar performance. Each position you move toward the firmer setting, toward the sway bar mounting D bush will increase the sway bar rate 1mm. The same is true moving away from the D bush toward the softest setting. These bars allow you to adjust in the amount of oversteer or understeer you desire for the street or track.
 
Sway Bar Conversion Table
 
The GTO comes from the factory with a series of bushes biased toward comfort. A Pedderised GTO replaces the factory bushes with urethane bushes that unlike the factory bushes provide 360 degrees of stability control.
 
Pedders urethane products are made of a moderate durometer urethane using shape and void technology to maintain a high degree of OE ride quality. The GTO is an under tired, under sprung, under damped and under bushed vehicle from the factory. Upgrading the foundational GTO bushes (EP1145 X Member, EP9166 Radius Rod, EP1157 Differential Insert and worn or compressed 5851 Strut Mounts) will alter the vehicle character. The difference between a brand new GTO and a brand new GTO with Pedders Foundational Bushes is the difference in handling and stability between a BMW and a BMW M. These bushes provide a greater return than any other modification you can make to your GTO. Aside form launching better, steering better and stopping better you'll barely notice the difference.
 
Before you add horse power, before you buy wheels, before you get a tune; address the Foundational Bushes and get maximum return form every other modification. Many GTO owners would describe the ride in a fully urethane bushed GTO as an improvement to the OE ride quality. The Pictures and notes will provide more detail.
 
As the premier Monaro/GTO suspension parts vendor in the world, Pedders Suspension is proud to offer the widest range of springs to suit your specific application. The industry standard for variance in spring height is 15mm/5/8". Pedders Springs are manufactured to the highest standard in fact our own tolerance is 2mm or less than 1/8". Each spring undergoes a full scrag and is load height tested to insure long life and consistency.

All Springs are Not Created Equal

Pedders USA Suspension Camaro
Video: Birth of a Lowering Spring: Inside Pedders Suspension May 2, 2012 by Carter Jung


Pedders Suspension is a brand that might be familiar to enthusiasts of the domestic aftermarket. For more than six years, Pedders has offered suspension components for Chevy Camaros, Ford Mustangs and Pontiac GTOs. What most don’t know is that the company is far from an upstart in the chassis game. Pedders Suspension has been in business in their home country of Australia for over 60 years, starting back in the mid-1950s rebuilding shock absorbers.

Headquartered in Keysborough, just outside of Melbourne in the state of Victoria, Pedders Suspension has a unique business model for their domestic market. Their products are distributed solely through franchised Pedders Suspension retailers, of which there are over 130 in Australia. Think Jiffy Lube, but for suspension needs that range from the inspection and alignment all the way to polyurethane bushings and coilover swaps.

Here in the U.S., Pedders’ business model is completely different, utilizing a more traditional distribution route. In their short time in the American market, Pedders’ products have been used by GM, Lingenfelter and Saleen. Pedders sells the gamut of chassis components, including coilovers, polyurethane bushings and CV shafts, but their core product is springs. In fact, Pedders likes to refer to their manufacturing facility as the “World’s Best Spring Plant.” While that’s up for interpretation, having witnessed the birth of a spring, firsthand, we can attest that quality is very much at the core of their values.

Here’s how Pedders Suspension springs are made:


Step 1: Pedders’ springs begin life as steel from BlueScope Steel, an Aussie company headquartered in Melbourne. Instead of sourcing cheaper materials from China or India, Pedders insists upon using steel that is ISO accredited.
Pedders USA Suspension Camaro

Step 2: For heating of the metal rods, Pedders relies on gas instead of electricity. With the latter, dips and irregularity in power can cause inconsistencies in the metal. Each rod is baked close to 980 degrees C.
Pedders USA Suspension Camaro

Step 3: After the steel is heated up to temperature, the glowing rod is then coiled around a mandrel. The solid steel mandrel does not flex or bow with repetitive use. Pedders has more than 100 different steel mandrels in varying shapes and sizes for varying applications.
Pedders USA Suspension Camaro

Step 4: The next stage in the spring production is quenching, a process in which the hot coiled steel is cooled by oil. The spring is still soft at this point, lacking any memory.
Pedders USA Suspension Camaro

Step 5: Once the spring is cooled, it goes back into the tempering furnace where the coils are cured. Temperatures are adjusted to suit the gauge of the wire—the thicker, the hotter.
Pedders USA Suspension Camaro

Step 6: After another cooling phase, each spring is ground to appropriate size and fitment.
Pedders USA Suspension Camaro

Step 7: For the final step in strengthening the steel, each spring is shot peened with military grade shot.
Pedders USA Suspension Camaro

Step 8: Pedders scrags 100 percent of their springs. Scragging is a quality-control process where each spring is fully compressed, testing its load for up to 2 mm in variance.
Pedders USA Suspension Camaro

Step 9: Before they are boxed and shipped around the world, the springs are powder coated. Powder coating gives a spring its brand-distinctive color and protects it from the elements.
Pedders USA Suspension Camaro

Posted with the permission of R & T


 
 


The GTO has an average ride height of 600mm as measured from the bottom of the rim (OE 17" Wheel) up through the wheel center and to the fender lip all around. The standard variation would be a low of 590mm to a high of 605mm. This 10mm (5/16") variance is measured with a quarter tank of fuel. Your results will vary based on your baseline measurement.
 
 
Please note:
Pedders considers the spring rate to be proprietary and confidential information. The rate at full compression is only an approximation to be used as a general guideline.
 
 
   
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  1. Setting up Xa Coilovers for Installation - GTO

    Setting up Xa Coilovers for Installation - GTO

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