Trans or Driveshaft yoke problem??

[Chris 96 WS6]

Since the M6 went into the car, there has been this vibration is 6th gear...sort of like something from the trans was rubbing/touching on the car somewhere.

It has progressively gotten worse, and after the last debacle of a track outting, the car shook violently all the way home at anything more than 65mph.

It now does it in 5th gear too and even in 4th, though not as bad, as you approach 65mph and over.

Its been visually confirmed by at least 3 people including myself that there's nothing touching/rubbing except the Y-pipe rubbing on the tq arm cross member, but that has been insulated with header wrap, no way it could cause this bad of a vibration.

I'm thinking it could be the front yoke on the driveshaft. Its a stock steel piece with a rear conversion U-joint, but with the punishment a McLeod twin disk puts out I think the front yoke/u-joint could be toast.

I just hope its not the transmission. Since it is speed related and not RPM related, I'm thinking it has to be the driveshaft. doesn't go away when you push the clutch in either. And it feels like it is right under your butt or in the trans tunnel. Oh yeah and it shook the trans mount bolts loose last time to the track, LOL.

[gettinthere]

Did you use the same DS when you did the swap?

[Chris 96 WS6]

Yep, its the same DS. Never felt the vibration with the A4. But the M6 came out of a friend's car and worked perfectly before he pulled it.

The only caveat to that is I had an LS1 driveshaft for a long time and the stock steel DS sat for about 3 years, I put it back in not long before the swap.

[gettinthere]

You can use the same shaft, so it should be fine. The M6 one is a bit shorter, but it doesn't create a problem.

The stock shaft may have bent slightly over the years of sitting.

[Chris 96 WS6]

Well it fits, even with the 9". It sat up on its end when it was off the car for 3 yrs. The stock steel ones are notorious for being out of balance but this is massively out of balance, so if its the DS I think the front U joint is bad.

[gettinthere]

Do you get any wiggle on the yoke?

[Chris 96 WS6]

Do you get any wiggle on the yoke?

I need to get under the car. I know I twisted the splines inside the DS yoke when I went to the track in April...and that was on Nittos (bow to the power of the Twin Disk).

I'm going to pull the DS this weekend and inpect.

[gettinthere]

That's most likely it. Go back to an upgraded steel shaft.

[NXSLT1]

I twisted the splines on my yoke a few months back and it had a helluva vibration at anything over 60 mph or so. Pushing the clutch in and coasting only made it worse. More than likely that's yer prob. Don't get a strange yoke unless you are gonna get it balanced, mine was way out of balance and it vibrated just as bad if not worse before I had it balanced.

[baddogz28]

It's also my opinion that your DS is at fault. Keep us posted.

[Chris 96 WS6]

I'm going to check it Saturday, will post the results.

[ziptie]

Did you ever figure out what the problem is, I am having a similar problem and I am curious as to what remedies yours.

[Chris 96 WS6]

Not yet...Several hundred dollars later I know it is NOT the driveshaft.

Its either due to excessive pinion/DS angle, or something's up with the transmission. I'm not going to have time to mess with it until later in the month though.

[Flip94ta]

Did you check the rear ujoint yet? Its really common to overtighten the strap nuts and distort the caps. Take the straps off and spin the caps to see if it spins freely or not. If its notchy theres your problem. A $14 fix.

It will shake the crap out of your car if its the problem. It starts as a hum 30-40 mph, then bad harmonics 40-50mph and above that it will shake the crap out of the car.

[Chris 96 WS6]

Honestly I have zero time to do even little things during the week. It will be next weekend before I can check it, but that will be the first thing I'll do, then I'll set the pinion angle.

[Grims]

So, did you figure it out?

[Chris 96 WS6]

Yes, I think so.

Took three tries at adjusting the pinion angle but finally got it right and the vibes went away. My gear backlash is way out of whack now though due to extended highway speeds with the vibes.

[97wsfix]

Hey Chris, this forum is such a great resource! I have the very same vibration issue and have gone as far as replacing the driveshaft. I'm curious to know how you adjusted the pinion angle? Thanks!

[Grims]

With an adjustable torque arm I would think.

[97wsfix]

I thought that might be the answer but I was hoping for something less expensive.:mad:

[97wsfix]

Can anyone recommend one?