C4 Rear end height
Thread Starter
Burning Brakes
Joined: Nov 2014
Posts: 920
Likes: 190
From: Stoneham, MA
C4 Rear end height
I'm in the market for a C4. In the past few weeks I've seen my share of some beautiful cars. A few of the C4's looked like the rear was a little more off the ground than others. It was noticeable by the space from the top of the tire to the top of the wheel well opening. The tire size was the correct factory specs as all of them. Can the height be adjusted the same as a C5????
Race Director
Joined: Oct 2005
Posts: 11,773
Likes: 178
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
I'm in the market for a C4. In the past few weeks I've seen my share of some beautiful cars. A few of the C4's looked like the rear was a little more off the ground than others. It was noticeable by the space from the top of the tire to the top of the wheel well opening. The tire size was the correct factory specs as all of them. Can the height be adjusted the same as a C5????
Team Owner
Joined: Sep 2003
Posts: 25,406
Likes: 2,744
On a "stock" car the bolts at the ends of the springs are something very near 9" long. To "LOWER" the car you lengthen those bolts, it's customary not to exceed 11" I believe. Size matters, the OE are M14 and most use a more readily available 9/16 SAE thread and a comparable castellated nut or a ny-lock.
Last edited by WVZR-1; Apr 10, 2016 at 05:13 PM.
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Race Director
Joined: Oct 2005
Posts: 11,773
Likes: 178
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Melting Slicks
Joined: Jul 2011
Posts: 2,606
Likes: 202
From: Trinity FL
Team Owner
Joined: Feb 2006
Posts: 23,237
Likes: 117
From: San Antonio Texas
I lowered the rear of mine a little with longer spring bolts to get my car to sit more level. It had the added benefit of levering the nose off the ground a little so I don't drag the air dam in the driveway now. 
Race Director
Joined: Oct 2005
Posts: 11,773
Likes: 178
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
That is all that I have done also.
Replaced the factory bolts in the rear with longer ones.
Similar to these.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
I think the rear ride height also depends on the spring rate.
Stiffer springs increase their rate more quickly as they compress, and will support the same weight over a shorter suspension travel distance, if that makes sense. So, stiffer springs allow a car to sit lower without issues. Same goes when tuning suspension -- you don't want to lower the suspension too much without stiffening the springs or your chassis may scrape the ground or tires will rub the wheel wells, or other issues.
The same car with softer springs will ride a little higher, this extra distance allows them to reach the same spring rate over a longer distance, because they are softer.
Maybe I'm not explaining this right, but I think someone will pick up what I'm laying down.
Stiffer springs increase their rate more quickly as they compress, and will support the same weight over a shorter suspension travel distance, if that makes sense. So, stiffer springs allow a car to sit lower without issues. Same goes when tuning suspension -- you don't want to lower the suspension too much without stiffening the springs or your chassis may scrape the ground or tires will rub the wheel wells, or other issues.
The same car with softer springs will ride a little higher, this extra distance allows them to reach the same spring rate over a longer distance, because they are softer.
Maybe I'm not explaining this right, but I think someone will pick up what I'm laying down.
Thread Starter
Burning Brakes
Joined: Nov 2014
Posts: 920
Likes: 190
From: Stoneham, MA
I think the rear ride height also depends on the spring rate.
Stiffer springs increase their rate more quickly as they compress, and will support the same weight over a shorter suspension travel distance, if that makes sense. So, stiffer springs allow a car to sit lower without issues. Same goes when tuning suspension -- you don't want to lower the suspension too much without stiffening the springs or your chassis may scrape the ground or tires will rub the wheel wells, or other issues.
The same car with softer springs will ride a little higher, this extra distance allows them to reach the same spring rate over a longer distance, because they are softer.
Maybe I'm not explaining this right, but I think someone will pick up what I'm laying down.
Stiffer springs increase their rate more quickly as they compress, and will support the same weight over a shorter suspension travel distance, if that makes sense. So, stiffer springs allow a car to sit lower without issues. Same goes when tuning suspension -- you don't want to lower the suspension too much without stiffening the springs or your chassis may scrape the ground or tires will rub the wheel wells, or other issues.
The same car with softer springs will ride a little higher, this extra distance allows them to reach the same spring rate over a longer distance, because they are softer.
Maybe I'm not explaining this right, but I think someone will pick up what I'm laying down.