If it's bottoming out in that trans, you'll see it in the rear sun gear thrust washer when the planets are inspected. I had a set of new 1.80's and low and behold, all the pin nuts were loose when i did a bench on it. Thicker nylon nuts.

how about pinion angle being out ?

How much clearance do you have to driveshaft bottoming out?


I have two shortys sitting here that are 1 1/4 different in length.

Based on the order you described maybe by the time you put the old trans case back in you had changed other things to get the driveshaft too long even for that trans.

Based on the order you described.

Also, I have had street cars that did this due to rust buildup on (in your case) the axle flange face. Rotor (and therefore wheel) won’t seat properly. I think you have changed enough parts to eliminate this but wanted to mention it.

^^^ That there sounds more logical to me. Bind...

Scott, we have another set of non beadlock wheels with Hoosiers we may try again for the heck of it..

Howie, I agree - has to be something rotational. We did check that at the beginning of the year, and it was bottoming out. Had it machined for clearance. Was one of the first things we found that we thought would fix it but no luck. We also ensured we are using the proper yoke for the rear bearing in the trans.

Rusty, we will continue to look at the small pieces and see what else we can think of.

WHOMP, we have had Strange and Moser brakes on it.

Chasracer, yes replacing brakes included new discs. There is a chassis dyno near us, we were already looking at that as a potential next step.

Jack, we have tried that with the car on stands and on the ground. Suspension obviously moves up and down which moves driveshaft in and out but no issues with that now but will triple check it again.

Swingarm, we and others have checked the pinion angle and no issues found there.

TD3550 and BJ, at the beginning of the year we found it was bottoming out and resolved that and thought we found the problem, but no luck. We will check out that part of the car again as well as the driveshaft and see what we find.

Thank you everyone for the replies so far, we've spent the entire season fighting this so we are all ears at this point.

The only thing different from the car on stands and going down the track is where the rearend and driveshaft is riding.
Before you jack it up on to the stands again use tie down straps or make up steel strips of some kind so the rearend/driveshaft are riding at realtime height and angle. RPM it in high gear up to at least where the vibration starts with a couple people watctching rearend, driveshaft and from the rear. Then click it into nuetral and let it coast down and see if it goes through a resonance point. USUALLY a vibration happens at lower speeds/resonance points also. Just at half the frequency so not as violent. But it may be easier to notice/pick out without all he11 breaking loose with the engine screaming, your "watchers" holding their ears (and breath) ect
Good luck.....

Well you tried your buddies tires and wheels on your car so just for the heck of it try your wheels and tires on his.
Also like stated above check driveshaft for bottoming out during suspension travel. Pull the shocks and run the housing all the way up and down to check for bind.

Had a similar issue after changing wheels. Found that I had the wrong thickness spacer under the lug nut and the nut would actually bottom on the shoulder of the stud before making contact with the spacer. Upon measuring I found that I had .065 gap and believe it or not that caused a similar lateral graph.

quote:

Originally posted by msavoia23:
Howie, u joints came with the new driveshaft - no luck. Also replaced heim joints, forgot to mention that in original post.

What heim joints did you replace?

I know you said you changed the Drive shaft. Did you check/Change the yoke? I had one crack on me caused a vibration not as violent as yours though.

imakehp, good thought, had not gone that far but may be worth a try if we can get a proper setup.

green1, we have not tried our tires/wheels on another car yet but may end up doing that this weekend. We had the shock off for a bit but don't recall moving/trying much while it was off, will look at that as well.

Robl384, we've been running the same wheels and spacers the last couple years but will absolutely look at those to make sure nothing changed, good thought.

NC3x58, we replaced the heim joints at the end of the 4 link bars that go to the housing and 4 link holes/brackets on the chassis.

Bob, yes we did buy a new yoke earlier in the year. Forgot to list that but was one of the first things we tried.

I know you are checking everything in the back but have you checked your front end (i.e. wheel balance, pins, bushings, rack, wheel bearings, etc).

Especially since you stated that it doesn't do it on the stands.
Just a thought.

quote:

Originally posted by pentastarrail:
I know you are checking everything in the back but have you checked your front end (i.e. wheel balance, pins, bushings, rack, wheel bearings, etc).

Especially since you stated that it doesn't do it on the stands.
Just a thought.

That was my thought too especially since you said you can feel it in your hands.

Hi Frank, yes we did check out the front and had it apart and it was inspected at American as well. A part of me was thinking it was something up front because you do feel it in your hands at speed, but the fact that it shakes so hard in the burnout (the same vibration feeling you feel down track) leads me to believe whatever I am feeling in the burnout is the same thing happening down track (how fast are you spinning the tires and other rotational pieces up during a burnout??). We ran Little Bubbas all last year and did not shake 1 time during a burnout, felt smooth as glass, now this year doing burnouts it vibrates so hard I almost have to get out of it early.

Have you checked the front upright bars. Older undercovers was bad about breaking them.

quote:

Originally posted by robl384:
Had a similar issue after changing wheels. Found that I had the wrong thickness spacer under the lug nut and the nut would actually bottom on the shoulder of the stud before making contact with the spacer. Upon measuring I found that I had .065 gap and believe it or not that caused a similar lateral graph.

I had that happen with camshaft bolts. Not a pretty result.

Is there any video of this at all? Like in the water vs ahead of it getting up on the tire? Just curious are there any laterals on this car?. This by far is the most severe shake/vibration i have ever heard. Looking at the graph. Pretty darn violent.When was the last time the grid was updated. Look closely at the grid charts and do a comparison.

TS393c, there is a bar in front of the battery box I believe that was obviously worked on in the past before we got the car. Appears to have been broken, welded on, and painted over. We have looked over that location very close and do not see any paint or powdercoat chipping/cracking, but without blasting the paint off not sure how else to get a closer look.

TD3550, I believe I do have a couple passes on a go pro from earlier this season. I will post the video and graph from the video'd pass later this evening.

quote:

Originally posted by robl384:
Had a similar issue after changing wheels. Found that I had the wrong thickness spacer under the lug nut and the nut would actually bottom on the shoulder of the stud before making contact with the spacer. Upon measuring I found that I had .065 gap and believe it or not that caused a similar lateral graph.

This is logical and would be easy to overlook. Nice job Robl on finding it...

I would take the body panels off and jack the car up from different areas. Let the chassis flex some and see if you can find anything broke.