One side ride height issue...need some ideas please!

SpyderMike · 06-02-2022, 08:56 AM

Okay, so I replaced the swing arm bushings a while ago. I used soapy water to get them in. Buttoned everything up and too it for an alignment. Drove the car off an on for months.

My next service was to get the left rear bearing replaced. Shortly after getting the car back, I noticed that the left side of the car is higher than the right. I measure and it is about 0.5" higher measured at front and rear top of the wheel arches. Hmmm. It has been bugging me for months. Now I feel like taking it on.

I want to tackle it, but I am not sure what to tackle. When I installed the spring plates, the angles matched. Now with car level on jacks and wheels removed, the spring plates are within 0.3 degrees of eachother. The left side is slightly higher by this 0.3 degree, but my math says that only accounts for .09" difference.

Distance from center of torsion bars to center of wheel are a match. Distance from floor to center of both of those is a match.

Other than starting all over, is there something obvious that I am missing...like the rubber bushing rotating on one side, a shock relaxing too much, etc.?

Ideas please! Thanks

Discseven · Discseven's Garage

Mike... based on your mentioning the height difference was noticed after the car was not in your hands for the rear bearing replacement, I'm immediately thinking something possibly took place while the car was being serviced. Might be the best mechanic in the world was attending your Porsche but never know... sh** happens even under the best circumstances. Perhaps you've already had a chat with the service place... but I'd start there (if you haven't already.) Of course any shop admitting something "happened" is only remotely possible but perhaps you can glean something from the conversation. Or, there may be no "fault" and they know exactly what it is and it's a no brainer to deal with. Surely you've already checked tire pressure.

911obgyn · 911obgyn's Garage

The body may not be symmetrical, ride height should be and sounds like from your post even, measured from center of torsion bar to center of wheel.

SpyderMike · 06-02-2022, 10:43 AM

Thanks for your input Discseven and 911obgyn. Unfortunately, the last person to touch the car, for the rear bearing, was some time ago. He has worked on the car when I was using Hergesheimer for many years (I have owned the car for 32+ years). This is on me.

The car has been hit a couple of times in my ownership - rear ended both. I did not notice the issue until after the backdate and after the alignment. It doesn't mean it wasn't there...I just didn't notice. Now that is what I see.

When the car is on the jacks, and the body is level side to side, every measurement front and back and side to side is the same - floor to wheel arches, floor to center of wheels, floor to center of torsion bars. It is just when the car is on its tires that the difference is noted. To me that means torsion bars, bushings, shocks and anything else that would affect suspension travel.

For example, I have read several differing opinions on lubricating the outside of the spring plate bushings. If one were dry and one lubed, could that cause it? To me the bushing is to suspend the torsion bar and keep it centered and not impart rotational resistance, but what do I know?

Literally, we are talking about a 0.8 degree difference in loaded angle of the springplate here. That is not much.

My shocks and torsion bars are original, could one be more tired than the other and cause it?

David Inc. · 06-02-2022, 11:23 AM

What's the spring plate angle with the car resting on the wheels after going for a drive? If it's different there then it's bushing or torsion bar. Maaaaaaaaaaaaybe shock but I wouldn't expect a half inch difference unless one were toast and the other were a brand new bilstein sport.

If the angles are the same then your body is twisted or your new bushing failed.

Edit: No if the center of the spring plate to the center of the arch matches up side to side with the body on jacks then the chassis should be all right.

You don't have an extra 20psi in the tires do you?

Discseven · Discseven's Garage

Quote:

Originally Posted by SpyderMike

...
When the car is on the jacks, and the body is level side to side, every measurement front and back and side to side is the same - floor to wheel arches, floor to center of wheels, floor to center of torsion bars. It is just when the car is on its tires that the difference is noted. To me that means torsion bars, bushings, shocks and anything else that would affect suspension travel.
...

I agree with your thinking Mike. Curious mystery. Am wondering if it makes sense---on a level floor with the car level---to put a scale on one corner of the car at a time and lower the car to a set distance and see what the weight reading is... same is done at each corner. Corner with issue would be revealed. My take is at least one of the right side corners would weigh less than either of the left corners.

Trackrash · Trackrash's Garage

Quote:

Originally Posted by SpyderMike

For example, I have read several differing opinions on lubricating the outside of the spring plate bushings. If one were dry and one lubed, could that cause it? To me the bushing is to suspend the torsion bar and keep it centered and not impart rotational resistance, but what do I know?

Literally, we are talking about a 0.8 degree difference in loaded angle of the springplate here. That is not much.

My shocks and torsion bars are original, could one be more tired than the other and cause it?

Put the car on a PERFECTLY level surface. Use plywood shims if needed.

Measure the angle of the rear torsion arms. Jack up the front making sure you are dead center with the jack in the front, so it is balanced on the jack.

Measure the rear torsion arm angles again. If they are the same as before jacking the front, use another jack or friend to level the car and measure the torsion arm angles again.

I am betting that that .8* difference in the rear torsion arms is your problem. If not then you need a corner balance and maybe bushings.

Dpmulvan · 06-02-2022, 01:20 PM

Quote:

Originally Posted by SpyderMike

Okay, so I replaced the swing arm bushings a while ago. I used soapy water to get them in. Buttoned everything up and too it for an alignment. Drove the car off an on for months.

My next service was to get the left rear bearing replaced. Shortly after getting the car back, I noticed that the left side of the car is higher than the right. I measure and it is about 0.5" higher measured at front and rear top of the wheel arches. Hmmm. It has been bugging me for months. Now I feel like taking it on.

I want to tackle it, but I am not sure what to tackle. When I installed the spring plates, the angles matched. Now with car level on jacks and wheels removed, the spring plates are within 0.3 degrees of eachother. The left side is slightly higher by this 0.3 degree, but my math says that only accounts for .09" difference.

Distance from center of torsion bars to center of wheel are a match. Distance from floor to center of both of those is a match.

Other than starting all over, is there something obvious that I am missing...like the rubber bushing rotating on one side, a shock relaxing too much, etc.?

Ideas please! Thanks

A dead or dying shock can cause this issue especially if it was up on a lift for a bit. When was the last time you had them changed/rebuilt?

SpyderMike · 06-02-2022, 04:43 PM

To clarify, my angle difference of the swing arms on jacks with wheels off is less than 0.3*. I was expressing that 0.8* (to see a 0.5" ride height difference side to side) is a small angular difference thinking it wouldn't take much to get there. My issues could be additive with more than one source.

I will check tire pressure and take additional measurements tomorrow. The shocks are all original...250,000 fun filled miles. I guess I could measure the shock length when the car is back on the ground to see if they are different.

Thanks all for your inputs!

gled49 · 06-02-2022, 05:59 PM

Spyder, I always set the drivers side high so it levels out with the driver. Sit in the car and have someone make the same measurement.

SpyderMike · 06-02-2022, 07:02 PM

Wilco, that could be one of the factors, agreed! I used to be svelte, but...

SpyderMike · 03:56 PM

Okay, here is an update:

Tire pressures measured and within 0.5psi of each other.

Spring plate angles identical when wheels reinstalled and car taken off the jack stands; height of car identical side to side too.

Raised the nose in the center until fronts were off the ground. Rear spring plate angles identical side to side. Heights identical.

Need to drive it again to see how it settles in. I think I will try to mark the bushings relative to the cover to see if I can tell any movement when I come back.

SpyderMike · 06-03-2022, 01:34 PM

Drove the car a few miles and came back. On the ground, the angles of the spring plates are off about 1.6 degrees side to side. The higher angled side (Driver's) sits half an inch higher than the other - both front and rear. I was able to mark the bushings and they don't appear to have moved, but then again, 1.6 degrees isn't much visually.

SpyderMike · 04:26 PM

So diving deeper into this, I run across this thread:

Can torsion bars go soft ?

with this post from Tyson Schmidt:

You should take a look at your left front.

When corner balancing, weight can only be moved diagonally. So the opposite corners have an affect on each other.

"To eliminate that variable, try place floor jack centered under the front crossmember in the exact center with some sort of black or half pipe to act as a pivot. Then raise the jack until the front wheels are just off the ground.
Now your rear heights will be more accurate. This will tell you if there really is a torsion bar issue in the right rear."

He solved the issue with a 1/2 turn of the front opposite adjuster...very interesting.

Looking at my front adjusters I see that the shop that did the alignment really took them down.

Driver's side:

Passenger's side:

It looks to me like the Driver's side is a bit different from the Passenger's in terms of the threads change during his alignment. The front torsion bar adjuster is closer to the stop on the Passenger's side.

So with the car back from the drive and sitting uneven, I put the jack under the center of the front and lifted the wheels off the ground and rechecked spring plate angles and height difference...still off.

I think I might F with the front left adjust - 1/2 to one turn and see the affect. I can always turn it back to the initial spot. For another day...