tips!

 

Here is Bill's response:

"Yes, over the past 5-7 years I have had many customers and/or inquiring individuals who experienced the same phenomenon and so far I would say that ten out of ten times the whirling sound was completely eliminated by installing a new bell housing.

I speculate that one of the most common mistakes that are made when installing these transmissions is for the installer to use the transmission-to-bell housing bolts to suck the transmission in the last .300” when the transmission doesn’t completely insert by hand. The bell housing is strong enough to hang the transmission unsupported when bolts are in place but will distort when using the bolts to draw the transmission completely flush when having interference/alignment issues during install."

I don't think the distortion theory is my case. I know I didn't pull the transmission in with the bolts when I changed the clutch. It slid right in place. Who's to say they didn't do this during the factory install. Anyway, Bill agrees, one way or another if the clutch housing is not perfect it causes the "whirl".

I'm going to install shims to hold me over until the next clutch change. Then I'll measure everything carefully and either machine or replace my clutch housing.

If anyone else tries this alignment test I would love to hear if your results were as good as mine!

 

Well, I think you are on the right track. I don't have that problem since I have a damn auto.
BTW, it was Two Guys Garage that had the show on the bellhousing alignment.

 

Here's a link to my Corvette sound. http://homepage.mac.com/wrighthome/iMovieTheater6.html
Check it out and let me know what you all think. Atok, is this the sound you have as well?

Jason

 

It's very similar to the sound mine makes, just a little louder. Mine sounded like that when I did "Test #1" above.

If you're not sure your transmission has the GM factory fill I would drain it ASAP and change the oil to the Castol BMW stuff. For what you paid for the oil we can be sure it's not the Castol stuff. Maybe they filled it with ATF!!!! Go to your BMW dealer and ask for the part number in the Tech FAQ sticky in this forum. Then when you change the oil, loosen the bolts off like I did and jack the transmission up/down. My guess is you'll find a position that makes the transmission silent.

 

How did you get to the top bolts between the transmission and bell housing? I've got my 90 on jack stands to do my exhaust.

 

The top passenger side bolt is easy to get to, there's enough room. The driver's side bolt is a royal PITA. I used a swivle socket and a long extension (3/8" drive tools). When I retorqued it I used a very long extension and swung my torque wrench back by the tail shaft...one click at a time. Be careful of the sensor just below the bolt. The bolts shouldn't be too tight, 40 lbs-ft is the GM spec.

 

Well this fix isn't as good as I thought it was going to be. I shimmed my ZF and it did make it substantially quieter while sitting in the garage (virtually silent), but now that I have it on the road it's not helping all that much. Once the oil warms up the sound is back, not quite as loud but still there. Oh well, I guess we'll have to live with it.

 

Tonight I changed the crankcase and transmission oil. I believe I found the culprit to my whirl. The bolt is missing from the lower passenger side where the transmission attaches to the bellhousing. This is the side that has three bolts. So, either the person who replaced the clutch lost the bolt and was too cheap to buy a new one (not likely) or the bellhousing threads are stripped (that's where I'm putting my money).

If they are stripped, that supports ZF Doc's hypothesis that people try to pull the transmission towards the bellhousing using the bolts and cause warping. My bellhousing is probably warped and stripped. I'll buy a bolt and see if it is stripped. Anyone know where I can get a bolt?

This sux! Let this be a lesson to always inspect a car before buying.

Here's the damage so far:

• Transmission Whirl - missing bolt from transmission to bellhousing; possible stripped threads and warped bellhousing
• Deadly shake at speeds above 60mph - I've identified rear tie rods need replacing. Hopefully that solves this problem.
• Battery died last weekend - add to list of why I like manual transmissions; $80 for a new battery

I've had the car for two weeks!

 

Well that just bites. I think I would check the torque on the other 4 bolts just in case they are too loose (40 lbs-ft is what you want). Actually, probably wouldn't be a bad idea to loosen them all off and retorque them using the pattern GM recommends.

You should be able to get a bolt from any parts store to hold you over for now. I'm not 100% sure but I think they are M10 x 1.25 bolts. I would eventually order the proper bolt from GM.

 

Okay Jason, I'll still sell you my 94 if you want

 

I was reading through posts on dual mass to light flywheel conversions tonight. I am now wondering if the sound I am hearing is the result of a PO performing this conversion. Would someone mind listening to my Vette and telling me if that sound is same as for car with light flywheel? Here is the link again. http://homepage.mac.com/wrighthome/iMovieTheater6.html

Thanks for the help,
Jason

 

That is definately not a lightweight flywheel noise. WHen you swap out to a fidanza or similar, it sounds like rocks in a dryer.

 

Thanks for checking it out.

Jason

 

Can someone provide me with the tightening sequence and torque lbs for the bolts that connect the ZF-6 transmission to the bellhousing?

Thanks,
Jason

 

BOLT TORQUE SEQUENCE SHOULD BE HORIZONTAL THEN VERTICAL IN INCREMENTS OF 7-16 N.M (5-10 LBS. FT.)

40 Lbs. Ft. is what the Service Manual calls for.