Big difference in perch ring turns on one side of adjustable coilovers

[Blue96GTS]

Me again, another coilover suspension question. Thought I'd start a new thread on this one, may or may not pertain to my other thread in close proximity. Thanks for your input - a few fillers before my questions:

After numerous emails, posts read, adjustments and measurements, I believe I have settled on a ride height and look that might balance performance, looks and scraping the front-end.

The car is adjusted with a full tank of gas, and the tire pressure is equal across all 4 tires. Measurements have been taken on several "flat" concrete surfaces for comparison. No ballast has been added for my 190 lb. ass. The car has yet to be aligned. I have not corner weighted the car.

As recommended, my measurements are taken at the frame (to ground) between the front and rear wheels - basically between the control arms, or a consistent place. As recommended, there should be at least a 3/4 inch rake front-to-rear. I'm currently set at 4" in the front, and 5.25" in the rear, as measured at the frame points mentioned. I'm also taking wheel arch measurements at a consistent point just to make sure I don't end up with a crazy look. Front and rear wheel arch gap is even all the way around.

Instead of measuring shock body height, I've been counting spring perch turns to make my adjustments. I first determined there were about 18 full turns of the spring perch to get 1" of shock body adjustment. I've been religiously keeping notes on how many turns I've made to get to my adjusted height.

I'm at 30 perch-ring-turns in the front to get my desired ride height. I'm at 30 perch-ring-turns at the drivers rear shock to get the desired ride height. The passenger ride height is correct with only 18 perch-ring-turns, however - a lot less than the other side(s) This equates to about 5/8 difference in shock tube height to get the same measurement - a lot lower perch height on the passenger side rear.

SO, now that you're filled in, and before I go pulling wheels and swapping stuff, on to my questions:

Is this "normal" to have one side set this much higher/lower than the other?? (a post in the Gen3/4 section had a similar yet opposite problem)

Something I did differently in the adjustment of the spring perhaps?? (nothing is binding or unusual on any side)

Something I need to worry about, or should I just move on?

Am I right to assume the spring (and it's relative perch adjustment) is the only thing holding the car up in this position, and nothing to do with the shock?

Assuming everyone has their own tastes and pain threshold levels of scraping, any compliments or objections to this ride height:

31687

[Blue96GTS]

Here's a pic of each side.

1" on Passenger Rear
1 3/4" on Drivers Rear

With this setup it adds up to a level car.......

Pondering this a bit, I'm wondering what might happen if I just crank up the passenger side another 12 turns. Perhaps the passenger rear end is just goofing off a bit, actually using the other 3 wheels as a resting point - along for the ride so to speak... Seems the easiest thing to try without taking everything apart... It'll either make a difference or it won't. Hoping for won't.?

Thanks for any thoughts you might have.

31691


31692

[Blue96GTS]

Realizing the last thought might not have made much sense - I'd not yet tried raising the rear passenger shock to see if there was any extra pre-load that needed taken up, that the other stiff springs were simply masking.

So, raised the shock perches just a couple of turns on the rear passenger, and it raised the rear end, just like it's supposed to do. Thought for a second that I might be onto a duh moment, but 'twas not to be.

Still hoping for a duh moment from someone who might have had a similar experience. Perhaps I'm shooting trouble where no trouble exists...

I've got a spare 800 spring that I'll swap out tomorrow to see if that makes a difference.

[mjorgensen]

Realizing the last thought might not have made much sense - I'd not yet tried raising the rear passenger shock to see if there was any extra pre-load that needed taken up, that the other stiff springs were simply masking.

So, raised the shock perches just a couple of turns on the rear passenger, and it raised the rear end, just like it's supposed to do. Thought for a second that I might be onto a duh moment, but 'twas not to be.

Still hoping for a duh moment from someone who might have had a similar experience. Perhaps I'm shooting trouble where no trouble exists...

I've got a spare 800 spring that I'll swap out tomorrow to see if that makes a difference.

Are the main springs in the rear the same free length? I believe you were sent 2 new rear springs, did you change both out or just the one? Also if you already did swap both you could lower the tall side and raise the short side to even them out so that they are supporting similar weight, the ride height should remain constant as the Viper frame is very stiff.

[Blue96GTS]

I tried to even them all out initially - according to my notes:

Initial setup 22 turns front, 18 rear - even turns on each side. Everything sits too low, esp. front. Drivers rear is lower than passengers rear at this point.

Added 8 turns in front both sides for 30, only added 3 turns to drivers rear to (what I suspected should have) even things out (now at 21 for drivers rear, still 18 for passenger).

Notes indicate I'm raising and ultimately lowering the front end a couple of times, pondering looks and the scrape factor. Along the way, I've added another 4 turns to the drivers rear in hopes it will rise to the same height as the passenger. I'm up to 25 turns in the drivers rear, still at 18 on passenger rear.

After our email to discuss front ride height with aftermarket wheels, I'm back to 30 turns in the front, but have had to raise the drivers rear another 5 full turns (total 30 to get the same frame height as the passenger rear).

Yesterday I raised the passenger rear 5 turns, and the whole rear end raised by at least 1/2 inch. Almost like that spring on the passenger rear is a super-spring, or still something wonky on drivers side. For the record, the part numbers on all the rear springs match each other.

I only changed one of the springs that were sent - drivers rear where the weirdness took place. Headed out tonight to replace the passenger rear spring. Perhaps both initial springs were wonky - we'll find out. If that doesn't show anything, I'll swap shocks/springs side-to-side, or put the other original spring in place of the replacement. Keeping confusion aside, I'm not out of things to attempt. Plus, it's better than TV.

Thanks,
Mike

[Blue96GTS]

As threatened, I replaced the rear passenger spring and put everything back together. Optimistically, I ran the spring perch rings up 30 turns, equal to the other side.

This endeavor did not seem to help anything. Rear height is now way over 6". I haven't the time to mess more tonight, but I suspect if I were to lower the rings back to 18 turns, I'd be back even and at my desired height - but the drivers side would still be at 30 turns. Remember, lowering the drivers side seems to put me in the "car is uneven" pickle.

Interesting that it took me 12 turns of the drivers side to chase about 3/8", but an equivalent number of turns on the passenger side raises the car > 1".

Does the spring hold the car up 100%, or does the shock have a part at all in this equation? I think the answer is A. Is there a way to easily check the pressure in these shocks?? Would that tell me anything? Do I need to corner weigh the car to tell me something? I did measure the shock I worked on while it was removed, so I guess I'll try the recently removed spring from the passenger side on the drivers side, or I'll swap shocks (PITA). Still half wondering if I'm just chasing a normal condition, or if I'm on crack somehow?? Pretty sure I'm not on crack, but I am up late. I'll ponder this in my sleep, hoping magical light will be shed tomorrow.

[mjorgensen]

As threatened, I replaced the rear passenger spring and put everything back together. Optimistically, I ran the spring perch rings up 30 turns, equal to the other side.

This endeavor did not seem to help anything. Rear height is now way over 6". I haven't the time to mess more tonight, but I suspect if I were to lower the rings back to 18 turns, I'd be back even and at my desired height - but the drivers side would still be at 30 turns. Remember, lowering the drivers side seems to put me in the "car is uneven" pickle.

Interesting that it took me 12 turns of the drivers side to chase about 3/8", but an equivalent number of turns on the passenger side raises the car > 1".

Does the spring hold the car up 100%, or does the shock have a part at all in this equation? I think the answer is A. Is there a way to easily check the pressure in these shocks?? Would that tell me anything? Do I need to corner weigh the car to tell me something? I did measure the shock I worked on while it was removed, so I guess I'll try the recently removed spring from the passenger side on the drivers side, or I'll swap shocks (PITA). Still half wondering if I'm just chasing a normal condition, or if I'm on crack somehow?? Pretty sure I'm not on crack, but I am up late. I'll ponder this in my sleep, hoping magical light will be shed tomorrow.

If you have access to scales I would corner weigh it to be sure you are not seeing something else going on. All of the perches should not be the same if you corner weigh the car, but making small adjustment at each corner should get you closer than you are if the car is straight or unless there is something in the car making it unbalanced.

There is more to this than just evening the perch height, I cannot talk right now, but if you want to call me after 9am central I'll walk through a couple things that may help it to make sense.

[GTS Dean]

My first comment is that you run about 1/4" more rake than I do. I never run lower than about 4.125" front frame clearance and run about 0.5" rake.

If your springs are the same free height, then your upper shock eyes may not be installed to the same dimension. You can most easily check distance from the shock body cap to center of upper bearing.

I agree with Mark that you can often balance things out by adjusting diagonally instead of straight across the car.

A couple of other considerations for you to think about:
Try setting your bump and rebound to zero when adjusting ride height. Be sure and jounce the car aggressively after adjustments and before measuring ride height.
You're probably doing it already, but be sure to use slip plates under the tires, or roll the car a couple of feet each way between measurements so the tire treads aren't bound up and holding the car higher.
You might have a bent sway bar (or frame) preloading the car. You can try loosening the frame - bushing bolts until you have your ride heights dialed in. See if tightening them up changes it.