Sliding all over the road - rear end
05-24-2019, 02:00 PM
#21
Just wanted to let you know, after some recent mods (17” conversion, Wavetrac diff) I too am floating all over the road at high speeds. It’s dangerous and scary above 100mph.
The car did get an alignment and everything on the report shows in-spec, however while they list Front Caster, there is no row for Rear Caster on my alignment sheet. Not sure why that would be but I know absolutely nothing about alignments.
The car is going to the dealer in the morning for an oil change and to check out the rear caster as well as inspect anything else in the suspension that might be causing the floating on the road. Will let you guys know what they come back with.
The car did get an alignment and everything on the report shows in-spec, however while they list Front Caster, there is no row for Rear Caster on my alignment sheet. Not sure why that would be but I know absolutely nothing about alignments.
The car is going to the dealer in the morning for an oil change and to check out the rear caster as well as inspect anything else in the suspension that might be causing the floating on the road. Will let you guys know what they come back with.
05-25-2019, 12:36 AM
#22
So... Just got back from the dealer. Was told that these cars don't really have an adjustable rear caster and if it was off at all, the car would be shaking violently, not feeling floaty like I was experiencing. The manager who explained it to me wasn't knowledgeable on alignments and was repeating what the tech told him. Now, I trust the more knowledgable guys on here much more than my dealer, but I didn't know much myself and didn't want to stand there arguing that "The internet says its this". Anyways, the dealer did a full alignment to factory specs and I took the car out for a road test and tried a couple 60-130 pulls. The car did feel a fair bit better after I picked it up and I was able to get it to above 130 safely without fearing for my life like before. The true test will be the 1/2 mile event I have coming up in 2 weeks.
As for height, I am fully lowered on stock bolts, I'm not sure if the 17" conversion spindles drop the rear anymore, but the car was perfectly fine last year at speeds when lowered.
As for height, I am fully lowered on stock bolts, I'm not sure if the 17" conversion spindles drop the rear anymore, but the car was perfectly fine last year at speeds when lowered.
05-25-2019, 08:36 AM
#23
Le Mans Master
So... Just got back from the dealer. Was told that these cars don't really have an adjustable rear caster and if it was off at all, the car would be shaking violently, not feeling floaty like I was experiencing. The manager who explained it to me wasn't knowledgeable on alignments and was repeating what the tech told him. Now, I trust the more knowledgable guys on here much more than my dealer, but I didn't know much myself and didn't want to stand there arguing that "The internet says its this". Anyways, the dealer did a full alignment to factory specs and I took the car out for a road test and tried a couple 60-130 pulls. The car did feel a fair bit better after I picked it up and I was able to get it to above 130 safely without fearing for my life like before. The true test will be the 1/2 mile event I have coming up in 2 weeks.
As for height, I am fully lowered on stock bolts, I'm not sure if the 17" conversion spindles drop the rear anymore, but the car was perfectly fine last year at speeds when lowered.
As for height, I am fully lowered on stock bolts, I'm not sure if the 17" conversion spindles drop the rear anymore, but the car was perfectly fine last year at speeds when lowered.
z51vett
Doug
Last edited by z51vett; 05-25-2019 at 08:38 AM.
05-25-2019, 09:59 AM
#24
I had to actually take my alignment gage to my dealer to do a proper alignment. Both the tech and manager argued with me about NO REAR caster like I was an idiot!!! Had to get the service manual and read the very easy step by step instructions to them and hand them my machine shop made(very simple) gage with digital protractor. Left they’re shop with a completely different well handling car and 2 pissed off grown men that instead of not admitting they were wrong stood there like 2 school girls waiting for there lunch break . We are getting worse and worse as a society whom are very incompetent and are watching other countries move ahead of us leaps and bounds. Sooo embarrassing. Gary
05-25-2019, 12:45 PM
#25
Sr.Random input generator
I don't get it. I do own the OEM rear caster measurement tool, and it cost me $180. There's nothing fancy and no special tool needed for the adjustment. It's done using the eccentric bolts on the lower control arms.
05-25-2019, 12:50 PM
#26
No dealership in DFW does this. Only 1 shop I've found that agreed to check and correct was RAC performance. A Porsche shop. I've had my car aligned there for 3 years.
A track shop lied and said they could then when I asked about it afterwards. "Oh yeah we don't do that". At least they refunded me a lot. The alignment was great on paper but the car rode like **** over ondulations because the rear caster got so far off.
A track shop lied and said they could then when I asked about it afterwards. "Oh yeah we don't do that". At least they refunded me a lot. The alignment was great on paper but the car rode like **** over ondulations because the rear caster got so far off.
Last edited by BrunoTheMellow; 05-25-2019 at 12:51 PM.
05-29-2019, 11:36 AM
#27
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That is why LG sells modified knuckles to lower a car. The shock travel isn't limited since the axle mounting point is raised on the knuckle while leaving all of the other suspension relationships unchanged.
Bill
05-29-2019, 12:23 PM
#28
The lack of suspension travel has nothing to do with the springs. The problem is the shock absorbers. Once you lower the car the shock has less available travel during compression and it bottoms out on the bump stop located inside the shock. This means when the shock runs into its bump stop you go from some spring rate of 100s of lbs/in to an infinite spring rate instantly. That changes how the car responds since it now acts like a kid's pull along wagon. And as most of us know from our childhood those things bounced back and forth when going over a rough surface.
That is why LG sells modified knuckles to lower a car. The shock travel isn't limited since the axle mounting point is raised on the knuckle while leaving all of the other suspension relationships unchanged.
Bill
That is why LG sells modified knuckles to lower a car. The shock travel isn't limited since the axle mounting point is raised on the knuckle while leaving all of the other suspension relationships unchanged.
Bill
I don't condone doing LG drop spindles as these cars rub the fender spats at stock height. A 1/2" drop on the z07s to match z06 height won't kill the shocks.
Last edited by BrunoTheMellow; 05-29-2019 at 12:24 PM.