Vibration is still there!!! Please help me before I give up and sell the car!

[FastGT94]

This vibration is driving me nuts!!!

For those that don't know the issues here it is. The car vibrates quite a bit around 35-45 mph (coasting in neutral or in gear). The vibration can be felt in the shifter as well as the steering wheel.

Cliffnotes version. Basically there are two different vibrations (at least I'm calling them different):

1.) Coasting around 35-50 mph
2.) Every gear at 1900 - 2100 RPM

But the vibration isn't really there when sitting still and reving in neutral. At least its not as strong if its there at all...

I realize that this could indeed be two separate issues but I'm trying to tackle the rolling vibration first. Here's what I've done so far to try and eliminate it.

-New crush sleeve and pinion nut
-Balanced drive shaft
-Checked input shaft end play (got .000", could it be too tight, and would this cause a vibration?)

I'm going to have the wheels balanced first to see if that could be the problem and then I'm going to look into the input shaft bearing race possibly being shimmed too far since I had NO endplay. Can to tight of a clearance on the input shaft cause a vibration?

Also, when I installed the tranny, it went in up to about 1/8" of a gap between the trans and the bellhousing and I had to lightly (very minimal effort if at all) snug the tranny bolts to get it to pull into the bellhousing all the way. I'm now being told that this shouldn't happen but what would be causing this?

During the initial clutch install I replaced:

-Clutch (new pressure plate and disk)
-Throwout bearing
-Clutch Fork
-Bearing retainer (Steel)
-Pilot Bearing
-Rear Main Seal
-Tailshaft seal on Tranny
-Pinion seal on rear end
-Pinion Nut and Crush Sleeve
-U-Joints

So needless to say there's a lot of variables going on there. I'm most concerned with the fact that the trans had to be "pulled" into the bellhousing a small amount before it was fully seated.

I appreciate the continued help in this issue I'm having!

 

[FastDriver]

You're worried about it too much if you haven't recently balanced your tires.

It obviously has to be a rotating part, and the fact that it doesn't do it when you rev in neutral factors out any engine imbalance. Next, if you haven't already, try reving with the clutch pedal out and the car in neutral and that will ensure you're not having any clutch or input shaft imbalances. FWIW, I've never heard of a transmission being the problem of a vibration without it being obvious, though I'm not discounting the possibility.

If you have no vibrations to this point, then the vibration problem has to lie in the following possibilities: the rear end of the transmission (a .01% likelihood), the driveshaft (a ~20% probability), the rear end internals (.01%), tire balance (75%), rear-end offset (5%). What I mean by rear end offset includes everything from pinion angle if the car's ride height has been changed to any damage that may have caused the axle housings to come out of alignment.

my 2 cents,

Chris

 

[Jameasun]

are you sure that the driveshaft is indexed corrected to the rear diff?
second, did you use all the same bolts to install the drive shaft?

 

[FastGT94]

Same bolts to install the driveshaft. The driveshaft was balanced off the car so I'm not sure that there's any way to index it with the new balance of it.

I'm definitely going to check the wheel balance first, but there was no problem immediately before the install. I find it hard to believe that the wheels suddenly got out of balance (No weights lying around the garage floor). But anything is possible I suppose.

 

[JB66]

Borrow a set of wheels and try it. Make sure your pinion angle is correct. Too small an angle will produce vibration even though the driveshaft is balanced. Try duplicating it on a frame type lift if nothing else works.

 

[bear108]

A buddy of mine had a similar problem a while back. He brought it to me and one of his tranny mounts was shot. Not really sure if this is your problem, but it is worth a shot to put your car up and check all of your mounts, tranny motor. Can't hurt.

 

[FastGT94]

I think I'm going to do it like this.

1.) Get the wheels balanced
2.) Jack it up and look for anything rubbing like the exhaust and look at the mounts (even though they're brand new)
3.) Try mounting the driveshaft in all 4 possible positions. (Before winter)

If nothing works from there, I'll have to start looking at the clutch and flywheel.

I'm going to check everything over the winter. I have a friend who will balance my wheels for free so no problem there.

I was just told that you shouldn't get your driveshaft "zero balanced". I don't understand how you could put an imbalance in a driveshaft and know where to assemble it to the rear end... For instance, if you get an aluminum driveshaft, are those imbalanced? Oh well, one step at a time...

 

[Rockin302]

Just a thought, have you checked the harmonic balancer? I had a similar vibration issue, coasting or in gear, so I went and purchased a FMS Aluminum driveshaft and it solved my prob. I also found out that my u-joints were worn.

 

[FastGT94]

U joints are new. I'm going to take a look at the balancer too, but I replaced it about a year ago and really don't think its going south.

I took a quick look at it yesterday when it was running and there's no wobble to it at all. I had one go bad on me before so I know all about that. No rubber coming out of it that I could see. I'm going to look at it closer next time its up in the air.

 

[89roadster]

Have you switched the front tires to the back and vice versa?

 

[tjm73]

If you had to "draw" your tranny in by tightening the hardware (even alittlebit or gently), it's installed incorrectly. Take it out and re-install it correctly. I'd bet the problem is directly related to the tranny install.

Did the trouble start after ther tranny install? Or did it exist prior also?

 

[FastGT94]

Before the tranny install. What could be wrong that caused me to have to draw the trans in towards the bellhousing?

I'll try switching the tires too.

 

[SKYWALKR]

Bro, I feel your pain. I had the same issues after my tranny/clutch install. I to was at the point of driving it off a cliff... then the heavens opened and the light glimmered on me. I actually had three issues... 1. as mentioned a bad transmission mount, although I think this had minimal effect. 2. The new U-Joints I recieved from the Auto parts store were incorrect. They fit in correctly but the powertrain shop I went to found them to be wrong, probably the biggest factor. 3. One of the eyelets on my driveshaft had some play in it also found at the powertrain shop. Those guys saved my sanity I was beginning to question if it had done that before the swap, when I knew it didn't...

Just my experience... I hope this helps you!!!

S/F
Luke

 

[FastGT94]

Thanks, I actually just ordered an Aluminum Driveshaft from Buyfordracing.com ($199) so I'll install that when it gets here (I'm guessing a week) and I'll give that a shot. Lots of people are pointing at the driveshaft so It's worth a shot. After that, I'm going to look into the pilot bearing possibly not properly supporting the input shaft due to my installing the tranny by pulling it into the bellhousing with the trans bolts. I don't think anything was damaged but that's the next step after the driveshaft...

 

[FastGT94]

I clearly have two different vibrations and I've made some headway with the standing still one at 2000. I'm begining to think that the standing still one isn't something to worry about but I'm still going to look into it.

Here is what I've done to try and pinpoint the standing still one thus far:
-Last night, I tried taking the drive belt off to see if the vibration was still there and it was, which proves that all accessories are fine.
-Checked the balancer and its fine
-Put the trans in gear with the clutch in and gave it 2000 rpm. The vibration was still there which now limits the vibration to:
-------Flywheel balance
-------Clutch / Pressure Plate Balance (defective from factory)
-------Pilot bearing was defective (may not be properly spinning on the input shaft)

So to solve the standing still vibration, I'm going to drop the trans, put in a new pilot bearing being careful not to damage it and find a shop that balances clutches and flywheels. I'm not sure where to start looking for a place like that. Maybe the shop that balanced my driveshaft balances flywheels too... oh well


As for the Rolling Vibration, I ordered an aluminum driveshaft and I'm waiting on it, I think this will solve that issue. Otherwise I'm going to get the wheels balanced in the meantime and see if anything is up there.

Please feel free to keep shooting suggestions in the meantime, I'll report back once I make some more progress.

Thanks for all your help and suggestions!

 

[Notched]

chekc the driveshaft. thats what my cars problem was when it vibrated... turns out 3 of the 4 bolts were had maybe, 2 threads in the hole, and the 4th was halfway in.. lucky i didn't die or something

 

[JB66]

When you have the tranny out, reinstall the bellhousing and measure the depth from the tranny mounting surface to the center of the crankshaft (inside the pilot bearing hole). Then measure the tranny from the mounting surface to the end of the input shaft. My thought is the input shaft may be bottoming out in the hole and that's why you had to 'pull' the tranny in. You may be able to see it on the tip of the shaft also. This might have caused damage to the needle bearings inside your tranny and cause your vibration.

 

[FastGT94]

Here's my question though, if the bellhousing and trans are the same and weren't altered, how can the depth change? There's no play in the inputshaft so it can't be sticking out any further than it was before I put the new bearing retainer on, right? Feel free to correct me here, as transmissions are something I'm just gaining experience on.


Also, I've eliminated the trans from the standing still vibration with the "clutch in, trans in gear" test. Nothing in the trans would have been moving when reving the engine this way and the vibration was still there.

However, it may still pose a problem for the rolling vibration. We'll see once the new DS is here.

 

[JB66]

Did you put in a pilot bearing or bushing? I'm just shootin' off some thoughts on why you had to pull the tranny in. Did you fit the bearing on the shaft before installing? I've seen some 'pushed' deep into the crank when they didn't fit right. If it's too loose, a vibration is possible also. Don't know, just ideas.

 

[FastGT94]

Now that one makes sense to me. I didn't test fit it so a loose input shaft does make sense. Either way, the tranny comes back out this winter, so I'm going to look at that very close.

I know you're shooting out ideas and they are GREATLY appreciated believe me. I only ask questions since I'm new to transmissions and sometimes need clarification. Thanks for the idea!