Ride Height: How low possible on stock suspension?
09-20-2010, 08:22 PM
#41
Pro
I currently run with 25mm in the front and 97mm in the rear. I'm running Penske 8760's with coilovers and my car only weighs about 2850#'s with me in it.
You should maintain a rake at 72mm difference front to rear.
T1 setup is about 14mm front and 86mm rear.
Front measurement is from the center of the front pivot bolt of the front lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the D dimension.
Rear measurement is also from the center of the front pivot bolt of the rear lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the Z dimension.
You should maintain a rake at 72mm difference front to rear.
T1 setup is about 14mm front and 86mm rear.
Front measurement is from the center of the front pivot bolt of the front lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the D dimension.
Rear measurement is also from the center of the front pivot bolt of the rear lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the Z dimension.
Or am I the one who is backwards.....
As the others have said, thanks a bunch for this info. I think it will be very useful.
09-20-2010, 08:36 PM
#43
Drifting
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Is something backwards here? In the table if the front is dimension D, then the factory height is 120 mm to 122 mm (without tolerance). Yet you say you are running 25 mm in the front. Conversely, if the rear is dimension Z, then the factory specifies 45 mm to 46 mm yet you are running 97 mm in the rear. So the factory recommends a larger number in the front yet you have a larger number in the rear.
Or am I the one who is backwards.....
As the others have said, thanks a bunch for this info. I think it will be very useful.
Or am I the one who is backwards.....
As the others have said, thanks a bunch for this info. I think it will be very useful.
Z is front and D is rear.
09-21-2010, 11:34 PM
#44
Melting Slicks
Here are some good pics of my car with coilovers and a low ride height in the middle of a high G turn:
http://www.headonphotos.net/gallery/...s/image16.html
http://www.headonphotos.net/gallery/...s/image18.html
http://www.headonphotos.net/gallery/...s/image27.html
And here are some pictures of my friend JRL in his TTA car with a pretty much stock ride height:
http://www.headonphotos.net/gallery/...s/image18.html
http://www.headonphotos.net/gallery/...s/image19.html
http://www.headonphotos.net/gallery/...es/image8.html
Kind of interesting to see how during full lateral grip the heights are pretty similar, except in one where his rear end is up and front end down due to the stock springs/shocks.
http://www.headonphotos.net/gallery/...s/image16.html
http://www.headonphotos.net/gallery/...s/image18.html
http://www.headonphotos.net/gallery/...s/image27.html
And here are some pictures of my friend JRL in his TTA car with a pretty much stock ride height:
http://www.headonphotos.net/gallery/...s/image18.html
http://www.headonphotos.net/gallery/...s/image19.html
http://www.headonphotos.net/gallery/...es/image8.html
Kind of interesting to see how during full lateral grip the heights are pretty similar, except in one where his rear end is up and front end down due to the stock springs/shocks.
09-22-2010, 07:37 AM
#45
Safety Car
Thread Starter
09-22-2010, 09:19 AM
#46
Drifting
Member Since: Dec 2005
Location: Dayton, OH
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I personnaly have drivers weight and about 3 gallons of gas.
Trim Height Adjustment for Front
Tools Required
J 42743 Trim Height Adjustment Tool
J 42854 Trim Height Measurement Gauge
Important
When adjusting either the right or left front trim height the opposite side trim height will be affected.
Trim height should be measured with a full tank of gas and no passengers or cargo.
An alignment hoist should be checked periodically to assure that both runners are the same height off the ground, side-to-side and front-to-rear.
Place vehicle on an alignment rack.
Set the tire air pressure to the proper pressure.
Manually lift the front of the vehicle up approximately 38 mm (1½ in) then, gently remove hands and let the vehicle settle.
Repeat the above step two more times for a total of three times.
Use J 42854 to measure the distance between the lowest point of the ball joint (2) and the center of the front side of the lower control arm mounting bolt (1).
Manually push the rear of the vehicle down approximately 38 mm (1½ in) then, gently remove hands and let the vehicle settle.
Repeat the above step two more times for a total of three times.
Measure both the right and left sides of the vehicle.
The true Z trim height on each side is the average of the high and low measurements. Refer to Trim Height Specifications in Suspension General Diagnosis.
Important
When adjusting the spring adjuster bolt, J 42854 must be used in order to prevent damage to the rubber shear pad on the end of the bolt.
One complete turn of the spring adjuster bolt is equal to 2 mm (5/64 in).
Using J 42854 , adjust the Z trim height by turning the spring adjuster bolt.
Lower the transverse spring back onto the lower control arm and remove J 42854 .
Perform the jounce procedure again and remeasure the Z trim height.
Important
Do not exceed the maximum difference between the right and left spring adjuster bolt gaps.
Measure and adjust the front spring adjuster bolt gaps (1) to 2 to 24 mm (0.078 to 0.944 in). Refer to General Specifications .
Trim Height Adjustment for the Rear
Tools Required
J 42854 Trim Height Measurement Gauge
Important
When adjusting either the right or left rear trim height the opposite side trim height will be effected.
Trim height should be measured with a full tank of gas and zero passengers or cargo.
An alignment hoist should be checked periodically to assure that both runners are the same height off the ground, side-to-side and front-to-rear.
Place the vehicle on an alignment rack.
Set the tire air pressure to the proper pressure.
Manually lift the rear of the vehicle up approximately 38 mm (1½ in), gently remove hands and let the vehicle settle.
Repeat the above step two more times for a total of three times.
Use J 42854 to measure the distance between the lowest point of the ball joint (2) and the center of the front side of the lower control arm mounting bolt (1).
Manually push the rear of the vehicle down approximately 38 mm (1½ in), gently remove hands and let the vehicle settle.
Repeat the above step two more times for a total of three times.
Measure both the right and left sides of the vehicle.
The true D trim height is the average of the high and low measurements. Refer to Trim Height Specifications in Suspension General Diagnosis.
Important
One complete turn of the adjustment bolt is equal to 2 mm (5/64 in).
Remove the retainers (1) on the top of the spring bolts (2).
Adjust the D trim height by turning the spring bolt.
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Perform the jounce procedures again and measure the D trim height.
Important
Do not exceed the maximum difference between the right and left rear spring stud heights.
Measure the rear spring stud heights (1). Refer to General Specifications .
Install the retainers to the bolts.
Lower the vehicle.
11-27-2010, 12:37 PM
#47
Racer
The absolute easiest way to check ride height is at the top of the fender. Its so long now that I forget what those dimensions should be. Something like 25" rings a bell.
Can some of you guys with really good handling, take the dimension and taht would be a ball park starting point.
Mine is lowered by the way and handling is really poor
Lessons learned
John
Can some of you guys with really good handling, take the dimension and taht would be a ball park starting point.
Mine is lowered by the way and handling is really poor
Lessons learned
John
11-27-2010, 01:25 PM
#48
Former Vendor
Member Since: Aug 2005
Location: Lewisville TX
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
Couple things...
Generally speaking you don't want to go much past the factory adjustments if you have stock shocks on the car. Reason being is that you will start to run out of bump travel on the shock and end up with the car riding on the bump stops. Sure it lowers the car and looks cool, but for track cars, it pretty much makes the shocks pointless.
Now going to a coil over shock, at least one that is done correctly, you will have more bump travel in the shock so they can not bottom out. One of the reason's all of our shocks are short like they are is so you can get away with lowering the car more than the factory adjustments let you go and you still have a working shock.
Generally speaking about 1" lower than stock is about all you want to go, or yes you do start to run into some funny things going on with camber gain, bump steer and other geometry issues with the car. For those wanting to go that low, we did our Drop Spindles. This will allow you to start off 1" lower with no changes to the control arms, and no loss in shock travel. So for those classes that require a stock leaf spring and shock combo you could drop the car with a spindle and not run into rule issues
.
Checking heights. You should check it either at the ball joint or at the frame of the car as close to the axle center lines as possible. We have a series of snap gauges and blocks to go to. When we build the cars there are plates at each location around the car for quick checks as well. Doing tape at the fender isn't a bad way for a quick check. If your trying to do a quick spring or shock change and don't have time to get the car on the scale before the next session you can mark it before and after and get the car close enough to see what it would do for practice. Of course you need to go back on the pad after.
Generally speaking you don't want to go much past the factory adjustments if you have stock shocks on the car. Reason being is that you will start to run out of bump travel on the shock and end up with the car riding on the bump stops. Sure it lowers the car and looks cool, but for track cars, it pretty much makes the shocks pointless.
Now going to a coil over shock, at least one that is done correctly, you will have more bump travel in the shock so they can not bottom out. One of the reason's all of our shocks are short like they are is so you can get away with lowering the car more than the factory adjustments let you go and you still have a working shock.
Generally speaking about 1" lower than stock is about all you want to go, or yes you do start to run into some funny things going on with camber gain, bump steer and other geometry issues with the car. For those wanting to go that low, we did our Drop Spindles. This will allow you to start off 1" lower with no changes to the control arms, and no loss in shock travel. So for those classes that require a stock leaf spring and shock combo you could drop the car with a spindle and not run into rule issues
.Checking heights. You should check it either at the ball joint or at the frame of the car as close to the axle center lines as possible. We have a series of snap gauges and blocks to go to. When we build the cars there are plates at each location around the car for quick checks as well. Doing tape at the fender isn't a bad way for a quick check. If your trying to do a quick spring or shock change and don't have time to get the car on the scale before the next session you can mark it before and after and get the car close enough to see what it would do for practice. Of course you need to go back on the pad after.
11-28-2010, 04:10 AM
#51
Racer
i'll start again
My car is a 2007 C6Z06. I lowered the car last year and cannot recall what the stock ride height was as measured from the ground to the wheel arch. I believe it to be around 26" front and maybe 26.5" at the rear
Could someone please advise as I wish to reset.
regards
John
My car is a 2007 C6Z06. I lowered the car last year and cannot recall what the stock ride height was as measured from the ground to the wheel arch. I believe it to be around 26" front and maybe 26.5" at the rear
Could someone please advise as I wish to reset.
regards
John
11-29-2010, 03:44 PM
#52
Former Vendor
Member Since: Aug 2005
Location: Lewisville TX
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
i'll start again
My car is a 2007 C6Z06. I lowered the car last year and cannot recall what the stock ride height was as measured from the ground to the wheel arch. I believe it to be around 26" front and maybe 26.5" at the rear
Could someone please advise as I wish to reset.
regards
John
My car is a 2007 C6Z06. I lowered the car last year and cannot recall what the stock ride height was as measured from the ground to the wheel arch. I believe it to be around 26" front and maybe 26.5" at the rear
Could someone please advise as I wish to reset.
regards
John
Anthony
11-29-2010, 07:19 PM
#53
Le Mans Master
04-28-2011, 09:08 PM
#55
Melting Slicks
Here's how to measure ride height the correct and most accurate way.
This is also how Phoenix Racing does it when they setup their cars and cars for customers.
The first diagram is the factory settings with tolerances. These are at curb weight.
I currently run with 25mm in the front and 97mm in the rear. I'm running Penske 8760's with coilovers and my car only weighs about 2850#'s with me in it.
You should maintain a rake at 72mm difference front to rear.
T1 setup is about 14mm front and 86mm rear.
Front measurement is from the center of the front pivot bolt of the front lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the Z dimension.
Rear measurement is also from the center of the front pivot bolt of the rear lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the D dimension.
These are the factory specs
This is the Front measuring location "Z Trim Height"
This is the rear measuring location "D Trim Height"
I put the socket over the nut, then stick the magnet on the bottom of the ball joint. Then I turn the nut on the threaded rod until the 1/2" angled aluminum piece is level then I measure the height along the threaded rod subtract 1/2 the diameter of the socket and the angle + the magnet and I have my number. This is easier on a 4 post lift but I do it on the ramps in my garage.
Here's a link to the GM tool.
http://www.costplustools.com/Kent-Mo...ge_p_9541.html
Hope this helps clear up all the questions that always come up around this subject. The primary reason you don't want to get your ride height too low is because these cars have camber gain built into the suspension and if they are too low the gain will be too fast and actually cause the tire to break loose. There is also the issue of bump steer but that can be corrected.
The T1 settings will work because the springs are so stiff. If you aren't using T1 springs those setting won't work properly!
.
This is also how Phoenix Racing does it when they setup their cars and cars for customers.
The first diagram is the factory settings with tolerances. These are at curb weight.
I currently run with 25mm in the front and 97mm in the rear. I'm running Penske 8760's with coilovers and my car only weighs about 2850#'s with me in it.
You should maintain a rake at 72mm difference front to rear.
T1 setup is about 14mm front and 86mm rear.
Front measurement is from the center of the front pivot bolt of the front lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the Z dimension.
Rear measurement is also from the center of the front pivot bolt of the rear lower control arm to the bottom of the lower ball joint. This is the 1 and 2 measurment of the D dimension.
These are the factory specs
This is the Front measuring location "Z Trim Height"
This is the rear measuring location "D Trim Height"
I put the socket over the nut, then stick the magnet on the bottom of the ball joint. Then I turn the nut on the threaded rod until the 1/2" angled aluminum piece is level then I measure the height along the threaded rod subtract 1/2 the diameter of the socket and the angle + the magnet and I have my number. This is easier on a 4 post lift but I do it on the ramps in my garage.
Here's a link to the GM tool.
http://www.costplustools.com/Kent-Mo...ge_p_9541.html
Hope this helps clear up all the questions that always come up around this subject. The primary reason you don't want to get your ride height too low is because these cars have camber gain built into the suspension and if they are too low the gain will be too fast and actually cause the tire to break loose. There is also the issue of bump steer but that can be corrected.
The T1 settings will work because the springs are so stiff. If you aren't using T1 springs those setting won't work properly!
.
thanks,
Steve A.
05-01-2011, 09:49 PM
#56
Safety Car
Thread Starter
My setup is 12mm front, 57mm rear. That looks to low according to this formula. My car is level at the jacking pucks. No rake at all. LG G2 coilover. #600 front spring. #550 rear. #2740 car weight. Hoosiers A6. I only use this car for autocross. Will that make any difference in the setup, compared to road racing? The cars pretty ba--lanced right now. Some understeer in the 30-40 mph corners. More neutral in the higher speed corners.
thanks,
Steve A.
thanks,
Steve A.
I think the rake is mostly for high speed stability (not needed in low speed auto-x) and to avoid bottoming out the rear shocks (stock--your coil overs should not be an issue). What you have might be fine IMHO.
05-01-2011, 10:16 PM
#57
Supporting Vendor
I have a c5Z w/ T1 springs/shocks and pfadt bars.
I have an alignment rack and the ride height tool. We did our best to get the ride height at this spec but a few things happened.
First - lots of jouncing is required.
Second - the GM tool does not 'fit' well - I'll get a few pics up on that. A few round magnets help that though.
Third - T1 springs are different - you don't need to worry about the rubber pad.
I'll edit w/ our alignment sheets - I def. wanted to subscribe here for correct alignment info.
-Ken
05-02-2011, 12:36 AM
#58
I would not lower it much at all, the geometry gets all screwed up, if you study such things it starts to make a ton of sense, glad I have some great books like the one from Herb Adams.
If you lower the car to much you put a great deal of leverage on the outside tires basically making the car a two tired vehicle(extreme example but pretty accurate way to describe it)
Some misunderstand the idea of the control arms, stock they point down from the mounting points on the chassis towards the outside, wheels, etc...if lowered to much they point up, bad news.
But, the actual angle from pivot point to pivot point is what matters, not the arm angle, I have seen cars setup wrong because they misunderstood where to measure from.
I normally draw it all out in full scale and do very setup to ensure I am getting it right.
Of course I know and use all the terms, just keeping it basic here, my car has just about every suspension mod I can do for handling and it is not lowered much at all (ok, bushings instead of monoball pickup points, mid size not massive sway bars, single not dual, etc coilovers, but it has the DRM rack bushing and a camber kit, etc.....and a very very good alignment)
Low looks cool but is not, unless you want to spend the money on the LG uprights, $$$$$$$ but dang sweet!
Rick
If you lower the car to much you put a great deal of leverage on the outside tires basically making the car a two tired vehicle(extreme example but pretty accurate way to describe it)
Some misunderstand the idea of the control arms, stock they point down from the mounting points on the chassis towards the outside, wheels, etc...if lowered to much they point up, bad news.
But, the actual angle from pivot point to pivot point is what matters, not the arm angle, I have seen cars setup wrong because they misunderstood where to measure from.
I normally draw it all out in full scale and do very setup to ensure I am getting it right.
Of course I know and use all the terms, just keeping it basic here, my car has just about every suspension mod I can do for handling and it is not lowered much at all
(ok, bushings instead of monoball pickup points, mid size not massive sway bars, single not dual, etc coilovers, but it has the DRM rack bushing and a camber kit, etc.....and a very very good alignment)Low looks cool but is not, unless you want to spend the money on the LG uprights, $$$$$$$ but dang sweet!
Rick
05-02-2011, 12:44 PM
#59
Instructor
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I have all stock suspension parts on my 03 C5Z except for the west coast lowering bolt kit front/rear and tires are Kuhmo Escta XS's. The car is down pretty low in the rear. I went up to Pocono last year to do a High Speed Driving School and the car did feel like it was dancing a bit from the rear on the bowl(Pocono North Course). Here this weekend I will be raising the suspension up somewhat.
05-04-2011, 10:29 AM
#60
Drifting
Member Since: Dec 2005
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First - lots of jouncing is required. AGREED! You get one heck of a workout!
Second - the GM tool does not 'fit' well - I'll get a few pics up on that. A few round magnets help that though.
This is the reason I made my own, as well as being poor.
Third - T1 springs are different - you don't need to worry about the rubber pad.
Correct, they have the nylon pad instead of rubber but it still requires a good bit of grease under it to keep it moving freely. If you don't grease it you will have issues.
-Ken