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Here are some pics of the spring perches.
Left front...
Right front...
Left rear...
Right rear...
To get comparable ride heights up front with my weight in the driver's seat, I had to set the left front spring perch lower than the right front. That can't be normal.
Are you measuring ride heights while on a boat ramp? Those perches should be pretty close, even when corner weighted. Get a proper setup on a leveled surface. And check ride heights with a sway bar end link disconnected. The sways are probably responsible for your semi even ride heights right now.
I've been doing my own alignments for quite some time. It's always been good enough for HPDE. My garage is flat, and I did disconnected the sway bars, and loosened all the bolts, including the long upper control arm bolts, when I installed the ELBJs (I pretty much had to since I was replacing most everything) and did the initial, post-crash setup and alignment. Then the young man at Quantum redid my alignment, but did not mess with ride heights. I did not loosen the long bolts or disconnect the sways when I went back to the OEM ball joints and realigned her. With my weight in the driver's seat, the sways have no preload.
I could start over, but I can't get my brain around it. For example, if I want 4.5" ride height with my weight in the car, I can't understand how there can be multiple combinations of perch settings that would give me that. I'm not talking corner weighting, just ride height.
BUT... I also don't understand how the car could be bent if most of the body seams look good, and the doors and windows and hood open and close fine. The only bad fit is where the left fender meets the bumper cover. The frame loop that goes around the inner headlight assembly there was badly tweaked where the fender bolts to it. I spent a lot of time massaging it, but it was not perfect when I finally gave up.
It could certainly be my fault with the setup. I just raised the right rear a few turns, to see if it made any difference. I'll take her out shortly. If that helped, then I may raise the left front a bit. I brought my toe plates and tape measures, but not my camber gauge. I believe she needs to go onto a frame machine for diagnosis.
I’m with curly, your spring perches are all at wildly different heights, seems they vary by inches when they should vary by a few millimeters. I’d say reset them in pairs to even distances, either X millimeters from the shock eye or X millimeters down from the top of the shock body, and see how car sits.
I do think the chassis probably has some deformation, even if there is no visible evidence. If a shock mount on the body was shifted by even 1cm, which would be basically impossible to see by eye over a ~3M long chassis, that could account for a several hundred pound weight difference per corner, which could definitely explain your right rear having basically no weight whatsoever when pulling out of a right hand turn.
Set the perches all the same level, no driver, and see if the chassis is obviously cocked to one side. I’m guessing the right rear pinch weld will be ~1/2” high.
If there are any rubber bushings in the arms, were the corresponding bolts all tightened at ride height?
The corner weights may be way off from trying to get the ride heights “perfect.” If this process is done without scales and without the right process, this can easily result in tons of wedge in a straight car. That’s why 949 offers the following recommendation for setting ride heights when corner weights aren’t set:
Do not attempt to exactly match pinch weld heights on your car if it involves drastically different preload left to right. It’s better to carefully measure the physical height of the preload collars and shock length and match them left to right. Even though the car will often sit lower on LR than RR, it will handle more predictably with equal preload.
It looks like you’ve taken a ton of weight out of one cross. This might not be a symptom of a bent car, but it might just reflect an attempt to hone in on exactly even ride heights. It’s better to match collar turns side-to-side and average L/R ride height when skipping cross weighting.
I put in four turns on the right rear and it was much, much better. The ride height did not seem to change at all. I was able to put two turn in the left front without using a tool. The ride height did not change hardly at all, but I have not taken her out again yet to see what that did.
I put in four turns on the right rear and it was much, much better. The ride height did not seem to change at all. I was able to put two turn in the left front without using a tool. The ride height did not change hardly at all, but I have not taken her out again yet to see what that did.
I'll start over again when I get her home.
This is a great illustration of the importance of cornerweighting, even for "just" an HPDE car. Hope it improves!
Would my ineptitude at setting the spring perches also explain locking up the left front, especially with a passenger in the right seat?
I honestly had the least fun track event ever. Read on if interested...
-Arrive VIR at 1730. Can't get down to the paddock until 1830.
-When I finally get to my newly renovated room I find no microwave. Drove
over to the admin building. I was told they did that on purpose. They
didn't think people wanted microwaves. Ate cold chicken leftover from lunch
and cheese puffs.
-There's a small workspace area with a desk lamp for a laptop or writing a
letter, but there's no chair in the room. The renovated rooms have two
queen beds, but no place to eat or sit down other than the beds.
-The left button of my wireless mouse stopped working.
-No hot water Monday morning.
-Shadow Dash not working on my newer tablet. It crashes instantly after
opening. Tried old, backup tablet. Pop-up message says I need to buy the
app again. It can't connect to the website, I suspect because it is running
Android 4.4.2.
-She's still lifting the right rear on right handers even with the OEM ball
joints. Still feels generally not right.
-I had a good student, but he was doing odd things and asking odd questions.
It finally dawned on me to ask him if this was a car he drove often. he
said "No. It's not my car".
-One of the guys paddocked next to me to the west is someone I see at the
track often. He was interested in my attempts to fix the wheelspin. We
chatted off and on. Monday late afternoon he asked if I was still anti-vax.
I told him there's no way they're putting that **** in me. He said he
understood but I couldn't come to dinner with them.
-I locked up the left front and went off track with my student in the car.
-I got bit by a dog. The couple paddocked next to me to the east in a huge
RV had two pit bull/grizzly bear mixed eight month old puppies that were big
enough to carry weapons. I was walking back to my truck and walked past the
front of their RV and turned towards my parking area when the two dogs came
at me from underneath the RV. One ran out of lead. The other bit me behind
my knee.
- I talked to the owners for a bit--nice folks--but I excused myself so I
could go check the damage. I knew I was bleeding. I sat down on the corner
of the bed to take off my driving shoes. The new mattresses don't have a
strong wire edging and I fell off the bed.
-Later I was getting the car ready to put on the trailer and the guys I
couldn't go to dinner with started playing Michael Jackson's "Billie Jean".
When I thought it couldn't get any worse, they turned it up.
-One of the guys at the track who had provided some good advice for fixing
the wheelspin is friends with the dog owners and was over at their RV. I
went over to thank him, mentioned getting bit, told everyone the story about
falling off the bed, and that I would probably have to go into therapy since
I just had to listen to Michael Jackson after everything else that had
happened. I shook hands, wished everyone well, and went back to my truck.
A few minutes later Michael Jackson's "The Man in the Mirror" started
playing out of the RV's external speakers. No one was outside. When it was
over, there was no more music. I suspect it was a message.
-After I got cleaned up I set about making dinner. I had purchased a cheap
microwave and had a non-frozen microwave dinner with noodles and four
packages--seasoning, cheese, breadcrumbs, and bacon bits. The bacon bits
package had expanded to near bursting. I decided not to open it.
-Thankfully, I had an uneventful trip home...
The front left being prone to lockup and the rear right wheelspin really reinforces my suspicions that the chassis is bent along a diagonal axis. Imagine it like a Pringle; front right and rear left are the low edges, and thus heavier, and front left/rear right are higher and carrying way less weight. I’d say it’s time to find a donor tub or a competent shop with a good frame jig
The front left being prone to lockup and the rear right wheelspin really reinforces my suspicions that the chassis is bent along a diagonal axis. Imagine it like a Pringle; front right and rear left are the low edges, and thus heavier, and front left/rear right are higher and carrying way less weight. I’d say it’s time to find a donor tub or a competent shop with a good frame jig
One diagonal axis having more grip or notably different response is literally the main symptom of wedge in the car. It sounds like the perches are just all messed up in search of “perfect” ride heights (which is not the goal of a good setup), leaving it like a stool with a short leg.
Level the perches side-to-side and get average F/R heights correct. Get a good baseline with a decent setup before corner weighting or writing off the car.
Every time I have a bad track day from now on, I’m going to think of this post haha. I think I could handle most of that except for being forced to listen to Billie Jean on blast.
I’m dealing with something similar in my car. The right front wheel always locks up a little before the left. It’s minor but fully repeatable. No wheelspin concerns. I’ve never made an attempt to corner weight my car (all I did was set ride heights when I got my BC coilovers) but figured I’d have a professional do it sometime in the future.
Are there different scenarios while corner balancing where one should be adjusting via preload vs ride height? Or if I want to try and tune out that imbalance, should I be adjusting ride height only.
Probably worth noting, my car was in a parking lot fender bender and probably has a little bit of frame tweakage.
That sounds like a frustrating weekend, but at least you came home safe and the car is in one piece.
At this point, I'd suggest taking a breath and stopping for a moment. In my humble opinion, you're flailing around the problem, throwing solutions at it rather than stepping back and looking at things holistically. I don't always follow this advice myself, but try, try, try to change only one thing at a time. I'd suggest focusing on the corner weights.
I can't tell from the narrative how the car was set up for your most recent track experience. The advice was to set the spring perches to nearly the same height L and R. I see that you made some kind of change here, but I don't see you saying that you for-sure set them to match. Where were the spring perches during this last outing?
It sounds like you're saying your next move is to take the car to a frame machine, but everyone else is saying to look at corner weights first. IMHO, it doesn't matter that you can't wrap your head around the relationship between ride height and perch settings. You're in deep and looking for help. If you can beg, borrow, steal, or just pay for some time on corner weight scales, do it. The results will be helpful. Otherwise, absolutely make sure your perches are matched side-to-side. I believe you should do this with the sway bars disconnected, but someone else can tell me if that is important. While you're at it, loosen every single suspension bolt that goes through a bushing. Bounce the car like hell or carefully drive it around the block. Focus on ensuring that when you move the spring perches, the weight of the car has somewhere to go. With that as a baseline, the far-smarter-than-me folks here can look at the results and give more advice.
edited to add: I see some others have jumped in here while I was composing my missive. To clarify my position - obtaining the current corner weights would be informative. Lacking that input, it's essential to know where the perches were for your last outing. If they were not matched side-to-side, you need to do that.
Level the perches side-to-side and get average F/R heights correct. Get a good baseline with a decent setup before corner weighting or writing off the car.
I can't believe I screwed that up so badly. I averaged the perches side-to-side and loosened everything up, dropped her back on the ground and she's basically at the same ride height as before. I didn't have my weight in the car, so there's still work to do, but I believe I'm on the right path.
With my weight in the seat, without any adjustment of the perches...
Front left 4 3/16". Front right 4 5/16".
Rear left 4 1/8". Rear right 4 7/16".
Shooting for 4 3/8" up front and 4 1/2" out back. How many turns or inches different side to side is too many? I believe the left front needs to come up three turns and the right one turn. Is two turns difference too much? The left rear needs to come up six turns, and the right just one. Is five too many? Should I instead make the right rear 4 9/16 or 4 5/8" or more?
I wouldn't mind making the right a little higher to compensate for when I've got student.
I did three turns all around before seeing Curly's post.
Front left 4 7/16". Front right 4 7/16".
Rear left 4 3/8". Rear right 4 1/2".
The perches are still equal, side-to-side. I plan to take out one turn up front on both sides and add one turn on both sides in back and remeasure. Researching corner weighting, but I'm not confident it will get done before my next event (if at all). Those proposed changes should get me three corners where I want her, with a little extra on the right rear, which I'm good with.
I took thebeerbarron's advice and went back to the track after only changing one thing, the perch heights, although I did loosen all the bolts with bushings and redid the alignment before tightening everything up. After some tweaking, with the perches even side to side and my weight in the car,
Front left 4 3/8". Front right 4 3/8" (which I found interesting)
Rear left 4 7/16". Rear right 4 1/2".
She's back to her old self. HOWEVER, with the Mazda sourced ball joints, I was only able to get -2.0* of camber in the left front (-2.3 on the right). I don't remember where the ball joints came from that were on the car when I had the unplanned wall intrusion, but they did give me about half a degree more camber and were not ELBJs. Can I assume it was all my fault screwing up the perch heights and I could probably put the ELBJs back in without causing any issues?
03-21-2023, 07:10 AM
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