Notices
C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

Front Coil Spring = Rear Ride Height?

 
Old 06-09-2019, 03:42 PM
  #1  
sunflower 1972
CF Senior Member
Thread Starter
 
sunflower 1972's Avatar
 
Member Since: Sep 2016
Location: Wauconda IL
Posts: 449
Received 70 Likes on 60 Posts
Default Front Coil Spring = Rear Ride Height?


Could this?

Cause this?
First photo is RH front coil spring sight hole. It appears I have the end of the spring about a 1/4" past the sight hole. In other words , NOT indexed correctly. Could that be the cause of the RH rear wheel opening so high? Floor to w/o measurement are R front 27 1/2", R rear 29 1/4", L front 26/ 3/4", L rear 28".
sunflower 1972 is offline  
Old 06-09-2019, 06:02 PM
  #2  
Kid Vette
CF Senior Member
 
Kid Vette's Avatar
 
Member Since: Jun 2003
Location: Niles, MI
Posts: 2,655
Received 154 Likes on 96 Posts
Default

Your front spring is indexed close enough and the front height would have negligible effect on the rear height. Your rear height problem is caused by the rear spring or how it is mounted. Could you post a picture similar to the one below of your setup on the rear?



Last edited by Kid Vette; 06-09-2019 at 06:25 PM. Reason: Add picture
Kid Vette is offline  
Old 06-09-2019, 06:34 PM
  #3  
resdoggie
1976 Blue-Green L-82 4-sp
Support Corvetteforum!
 
resdoggie's Avatar
 
Member Since: Mar 2011
Location: Some days your the dog and some days your the hydrant.
Posts: 3,135
Received 361 Likes on 330 Posts
Default

The rear spring bolts are threaded to allow ride height adjustment. To lower ride height, install 8" spring bolts in place of the stock 6" bolts.
resdoggie is offline  
Old 06-09-2019, 07:12 PM
  #4  
sunflower 1972
CF Senior Member
Thread Starter
 
sunflower 1972's Avatar
 
Member Since: Sep 2016
Location: Wauconda IL
Posts: 449
Received 70 Likes on 60 Posts
Default

Originally Posted by Kid Vette View Post
Your front spring is indexed close enough and the front height would have negligible effect on the rear height. Your rear height problem is caused by the rear spring or how it is mounted. Could you post a picture similar to the one below of your setup on the rear?

sunflower 1972 is offline  
Old 06-09-2019, 09:05 PM
  #5  
resdoggie
1976 Blue-Green L-82 4-sp
Support Corvetteforum!
 
resdoggie's Avatar
 
Member Since: Mar 2011
Location: Some days your the dog and some days your the hydrant.
Posts: 3,135
Received 361 Likes on 330 Posts
Default

That's the stock 6" bolt. Replace with an 8" bolt to lower your rear.
resdoggie is offline  
The following users liked this post:
Kid Vette (06-09-2019)
Old 06-09-2019, 10:41 PM
  #6  
Dodosmike
CF Senior Member
 
Dodosmike's Avatar
 
Member Since: Apr 2008
Location: Powassan ON
Posts: 5,323
Received 67 Likes on 59 Posts
Default

Lets say the rear spring is a fiberglass 330lb spring
Let's say the bolt is swapped out, 6" for 8".
lets assume that each nut is threaded on until the nut is flush with the end of the bolt.

how much will that lower the ride height? The full 2"? Or something less?

Last edited by Dodosmike; 06-09-2019 at 10:42 PM.
Dodosmike is offline  
Old 06-10-2019, 12:27 AM
  #7  
revitup
CF Senior Member
 
revitup's Avatar
 
Member Since: Dec 2005
Location: Pawleys Island, SC
Posts: 841
Received 121 Likes on 115 Posts
Default

Much less. Maybe 3/4" in my experience.
revitup is offline  
Old 06-10-2019, 06:14 AM
  #8  
Kid Vette
CF Senior Member
 
Kid Vette's Avatar
 
Member Since: Jun 2003
Location: Niles, MI
Posts: 2,655
Received 154 Likes on 96 Posts
Default

Originally Posted by revitup View Post
Much less. Maybe 3/4" in my experience.
I disagree. It would lower it the full 2 inches. Please explain why it wouldn't.
Kid Vette is offline  
Old 06-10-2019, 12:12 PM
  #9  
sunflower 1972
CF Senior Member
Thread Starter
 
sunflower 1972's Avatar
 
Member Since: Sep 2016
Location: Wauconda IL
Posts: 449
Received 70 Likes on 60 Posts
Default

Hey guys, I've been screwing around with suspension issues for almost 2 years now. The reason I asked about a incorrectly indexed front spring causing rear ride height problems is I seem to recall reading a couple of threads during one of my many searches regarding front springs that an incorrectly indexed front spring could indeed cause a higher ride height in the rear. I was hoping for a quick confirmation of that. Oh well, I'll just do some more searches. Thanks everyone.
sunflower 1972 is offline  
Old 06-10-2019, 12:24 PM
  #10  
revitup
CF Senior Member
 
revitup's Avatar
 
Member Since: Dec 2005
Location: Pawleys Island, SC
Posts: 841
Received 121 Likes on 115 Posts
Default

Originally Posted by Kid Vette View Post
I disagree. It would lower it the full 2 inches. Please explain why it wouldn't.
Wish I could. Has to do with spring/suspension geometry somehow. I said 'in my experience'. I swapped from 6" to 8" and it lowered the rear about 3/4".
revitup is offline  
Old 06-10-2019, 01:38 PM
  #11  
sunflower 1972
CF Senior Member
Thread Starter
 
sunflower 1972's Avatar
 
Member Since: Sep 2016
Location: Wauconda IL
Posts: 449
Received 70 Likes on 60 Posts
Default

Originally Posted by Kid Vette View Post
I disagree. It would lower it the full 2 inches. Please explain why it wouldn't.
Originally Posted by revitup View Post
Wish I could. Has to do with spring/suspension geometry somehow. I said 'in my experience'. I swapped from 6" to 8" and it lowered the rear about 3/4".
Alan 71
CF Senior Member



Member Since: Sep 2006
Location: Westminster Maryland
Posts: 30,366
Likes: 0
Received 2,733 Likes on 2,412 Posts





Hi,
I believe because of the geometry used in the rear suspension design lengthening the spring to t-arm bolt DECREASES the ride height dimension by about HALF the INCREASE in bolt LENGTH.
I.E. A 2" LONGER bolt decreases the ride height about 1".

This may be why you see folks trying to use 10" long bolts to get the decrease they need.

Regards,
Alan

Post #26: https://www.corvetteforum.com/forums...cked-up-2.html
sunflower 1972 is offline  
Old 06-10-2019, 01:46 PM
  #12  
mortgageguy
CF Senior Member
 
Member Since: Mar 2006
Location: Spartanburg SC
Posts: 799
Received 115 Likes on 102 Posts
Default

R front and L rear are very close to factory spec.
High R rear and low L front are not coincidental.
If you jacked the L front under the ca one inch I believe the R rear would lower by one inch. Something is off on your L front. Spring, shock, bushings.
mortgageguy is offline  
Old 06-10-2019, 02:50 PM
  #13  
resdoggie
1976 Blue-Green L-82 4-sp
Support Corvetteforum!
 
resdoggie's Avatar
 
Member Since: Mar 2011
Location: Some days your the dog and some days your the hydrant.
Posts: 3,135
Received 361 Likes on 330 Posts
Default

Originally Posted by sunflower 1972 View Post
First photo is RH front coil spring sight hole. It appears I have the end of the spring about a 1/4" past the sight hole. In other words , NOT indexed correctly. Could that be the cause of the RH rear wheel opening so high? Floor to w/o measurement are R front 27 1/2", R rear 29 1/4", L front 26/ 3/4", L rear 28".
No. A 1/4" off from a fully seated front spring in the upper pocket will not affect ride height. Kid Vet already pointed this out.
resdoggie is offline  
Old 06-10-2019, 05:07 PM
  #14  
sunflower 1972
CF Senior Member
Thread Starter
 
sunflower 1972's Avatar
 
Member Since: Sep 2016
Location: Wauconda IL
Posts: 449
Received 70 Likes on 60 Posts
Default

Originally Posted by mortgageguy View Post
R front and L rear are very close to factory spec.
High R rear and low L front are not coincidental.
If you jacked the L front under the ca one inch I believe the R rear would lower by one inch. Something is off on your L front. Spring, shock, bushings.

Left sight hole. Spring indexed correctly.

Thanks for the reply, mortgageguy. That makes sense to me. So, if I index the right front coil spring correctly, that will RAISE the left rear wheel opening. Correct? Would it raise it an inch to even out the rear ride height?
sunflower 1972 is offline  
Old 06-10-2019, 05:31 PM
  #15  
sstocker31
CF Senior Member
 
sstocker31's Avatar
 
Member Since: Jul 2006
Location: Edmonton Alberta
Posts: 1,512
Received 109 Likes on 96 Posts
Default

I have 8" bolts and a 330 LB spring and mine looks like this.....
It also settles about an inch or so when I'm in the car.




Last edited by sstocker31; 06-10-2019 at 05:33 PM.
sstocker31 is offline  
Old 06-10-2019, 09:06 PM
  #16  
Kid Vette
CF Senior Member
 
Kid Vette's Avatar
 
Member Since: Jun 2003
Location: Niles, MI
Posts: 2,655
Received 154 Likes on 96 Posts
Default

Originally Posted by sunflower 1972 View Post
Alan 71
CF Senior Member



Member Since: Sep 2006
Location: Westminster Maryland
Posts: 30,366
Likes: 0
Received 2,733 Likes on 2,412 Posts





Hi,
I believe because of the geometry used in the rear suspension design lengthening the spring to t-arm bolt DECREASES the ride height dimension by about HALF the INCREASE in bolt LENGTH.
I.E. A 2" LONGER bolt decreases the ride height about 1".

This may be why you see folks trying to use 10" long bolts to get the decrease they need.

Regards,
Alan

Post #26: https://www.corvetteforum.com/forums...cked-up-2.html
Well I guess I'll have to crank the nuts up as far they go and see what happens. But looking at the rear suspension, I see no reason for the change to not be 1:1.
Kid Vette is offline  
Old 06-11-2019, 04:27 PM
  #17  
Dodosmike
CF Senior Member
 
Dodosmike's Avatar
 
Member Since: Apr 2008
Location: Powassan ON
Posts: 5,323
Received 67 Likes on 59 Posts
Default

Originally Posted by sunflower 1972 View Post
Hey guys, I've been screwing around with suspension issues for almost 2 years now. The reason I asked about a incorrectly indexed front spring causing rear ride height problems is I seem to recall reading a couple of threads during one of my many searches regarding front springs that an incorrectly indexed front spring could indeed cause a higher ride height in the rear. I was hoping for a quick confirmation of that. Oh well, I'll just do some more searches. Thanks everyone.

Are the front springs stockers or aftermarket ones? Correct for the car? (BB springs in a SB car or viceversa)

Some threads I've read say the 550 sport springs (gymkhana?) will provide a stock like ride, just shorter (lower) to the ground than regular OEM (stock) springs. I have no idea if thats true or not, just what I've read online (here).

I think if the spring isn't indexed correctly, yes it'll affect the car (think like a 4 legged table, with one leg 1" shorter). Now one thing would be HOW MUCH improperly indexed would it affect the rear (the opposite table leg in my example)? 1/4" off, like not much difference, 1/2 a round or 3/4 of a round out is a whole other ballgame, IMO.

The reason I'm curious is Im thinking or dropping the car 1" to 2", but by using new shorter springs (as opposed to heating and relaxing or cutting the coils) and using 8" (as opposed to 6") bolts in the rear.
Dodosmike is offline  
Old 06-11-2019, 05:45 PM
  #18  
leigh1322
CF Senior Member
 
leigh1322's Avatar
 
Member Since: Dec 2017
Location: Marlton NJ
Posts: 332
Received 53 Likes on 40 Posts
Default

The rear trailing arm has a Motion Ratio between the T/A bushing and the wheel hub and the spring bolt. My measurements give:
Rear Motion Ratio
Spring to t-arm pivot (a) 20.0
Hub to t-arm pivot (b) 16.8
Motion Ratio 1.136
Because it is reversed compared to a normal front coil spring setup, the spring moves more than the wheel.
So if the bolt moves the spring down 2 inches, the car should lower less or 2/(1.136)^2 or 1.55 inches.
leigh1322 is offline  
Old 06-11-2019, 08:16 PM
  #19  
'75
CF Senior Member
 
'75's Avatar
 
Member Since: Dec 2007
Location: McHenry Illinois
Posts: 5,838
Received 347 Likes on 332 Posts
Default

When all else fails, using a shorter spacer on one side of the front sway bar will level it out.
'75 is offline  
Old 06-12-2019, 12:23 PM
  #20  
sunflower 1972
CF Senior Member
Thread Starter
 
sunflower 1972's Avatar
 
Member Since: Sep 2016
Location: Wauconda IL
Posts: 449
Received 70 Likes on 60 Posts
Default

Originally Posted by Dodosmike View Post
Are the front springs stockers or aftermarket ones? Correct for the car? (BB springs in a SB car or viceversa)

Some threads I've read say the 550 sport springs (gymkhana?) will provide a stock like ride, just shorter (lower) to the ground than regular OEM (stock) springs. I have no idea if thats true or not, just what I've read online (here).

I think if the spring isn't indexed correctly, yes it'll affect the car (think like a 4 legged table, with one leg 1" shorter). Now one thing would be HOW MUCH improperly indexed would it affect the rear (the opposite table leg in my example)? 1/4" off, like not much difference, 1/2 a round or 3/4 of a round out is a whole other ballgame, IMO.

The reason I'm curious is Im thinking or dropping the car 1" to 2", but by using new shorter springs (as opposed to heating and relaxing or cutting the coils) and using 8" (as opposed to 6") bolts in the rear.
Moog 5758 (474 lb.). Engine's a SB. I cut a half a coil because of the aluminum heads and intake manifold.
sunflower 1972 is offline  

Thread Tools
Search this Thread
Quick Reply: Front Coil Spring = Rear Ride Height?


Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: