1) The older 10mm bushings are no longer available from GM, correct? The guy at the parts counter only shows one part number for all C5s, regardless of year.

2) Can the newer 12mm bushings fit in the older-style torque tubes if you use different fasteners? My '99 bushings are 1.10" long, and I can get a bolt with a 12mm shoulder that will neck down to thread into my tube.

3) Are the 12mm bushings stronger than the older 10mm ones?

4) I'm assuming running two (or possibly even one) solid bushing is not the smartest thing to do? I was considering trying it with two solids and measuring runout to see how bad the binding might be.

Thanks for any help.

 

Grant,

I know you can't run two solid bushings unless you use a Carbon Fiber internal shaft like LG Motorsports sells but that puts the project in the $1500 range. I have read on here that some have bought bushings from BMW dealers. Try search on torque tube bushing and see if you find the posts discussing them.

Paul.

 

I have, I've also looked at some of the aftermarket BMW bushings. I'd really like to stick with OE stuff if I can - there are a few posts claiming that the BMW pieces are weaker than the GM parts.

 

I'm thinking that "one number for all C5s" is for the entire drive shaft assembly. The torque tube (drive shaft) couplings - what you're calling - "bushings", have never been offered as a separate item from GM. Your '99 has the smaller diameter drive shaft (58mm?) and if you keep it, you must use the couplers that have the 10mm holes. As I recall, during the '02 model year I believe, GM changed over all torque tube assemblies to use the 65mm diameter drive shaft and it uses the 12mm couplers instead of just installing it in the Z06s, which were the first to use it in '01.

BTW, I switched over my '99s complete torque tube assembly to the later (larger 65mm drive shaft inside) and just as a precautionary thing I replaced the drive shaft couplers that were in it. The BMW couplers are made by the same German company that supplied the couplers used in the Vettes and I've had zero issues with mine. I also agree with the comment about not using solid couplers on both ends. One end maybe, but not both.

I don't have the part numbers for the couplers handy so maybe someone can jump in here, or you could try a search. I got mine through Bavarian Auto Sport.com. BTW, their website is a pita if you don't know the specific BMW model number to plug in to access parts for, so I would suggest getting the BMW number first and then you can just plug in the part number. They refer to them as "guibos". Their pricing was considerably better than a BMW dealer.

HTH

BTW, when you pull your old bushings out, you'll see "Made in W. Germany" - yes that's correct "W" Germany - molded into them. My '99 had this.

 

I have this BMW part number for the 10mm 26 11 1 225 624. Check this Thread out also;

http://forums.corvetteforum.com/show....php?t=2043749

 

Yeah, I know this, which is why I'm wondering if the 12mm couplers will fit in an older tube if you use different fasteners. I guess I'll just order some and find out.

I can't seem to find any part numbers, searching for "torque tube coupler".

 

The 12mm will not fit in the older torque tube.

 

Thanks, but why not? Is it just the size of the bolt holes (12mm vs. 10mm)? That can be fixed with fasteners. Or will it not fit inside the tube or something?

 

I'm pretty sure the bolt-hole center-lines are going to be spaced further apart since the "propeller shaft (drive shaft) hub" and the "propeller shaft spline shaft" mounting flanges are of a different dimension too.
HTH

 

Damn... I may just go with aftermarket (tougher than stock, supposedly) BMW couplers.

The GM part # I got from the dealership was 12456212. Unfortunately that shows up as a part for a '97-'04 car, which I'm guessing means its a 12mm part. Oddly, the part doesn't show up in GM Parts House's database, but it does in GM Parts Direct's.

 

It physically will not fit. The diameter of the newer bushing and the flange is larger than the earlier tubes.

I bought a used tube off a Z06 just for this reason. I wanted to be able to use the larger/stronger bushings.

 

Just got off the phone with Fichtner Chev and apparently GM IS now offering a coupler but it seems they are only offering that one part number. What's even crazier is that in their "application" info, they are showing a quantity of "2" for the automatics but "1" for the 6 speeds. Yeah, right. Somebody in GM SPO (Service Parts Organization) has got things screwed up.

If you want to be on the safe side, just order a couple of each number from Bavarian and return the ones you can't use. As I said, they are a good bit cheaper than the BMW dealer.

HTH

 

That's why I did the same thing last year. I wanted the later, larger size driveshaft (65mm vs 58mm). In doing my research, I found that starting sometime '02 (IIRC) GM switched the torque tube driveshaft assemblies for ALL C5s (not just the Z06s) to use the newer, larger design. I found a good used TT assembly out of an '03 C5 from justcorvettes.com in Missouri and it was priced right at $600.00. You DO however have to specify 6spd vs auto as they are different.

HTH

 

I'm guessing its the 12mm part?

Some aftermarket couplers made for BMWs are coming tomorrow. Hopefully they'll work. I'll post pics and durometer readings then.

 

Did you get the durometer readings?

 

I didn't bother, the BMW (made by fabi/bilstein) ones were flimsy as hell compared to the OE unit. I did find other cars the OE units come on though, the Opel Omega A and B. I'm not sure if you can get replacements, but they are on page 51 of this catalog.

Instead, I ordered two solid aluminum couplers from LG and bolted them together. The result was terrible run out! I can't believe anyone even has luck bolting a single solid coupler on these cars, the wobble was so bad (about .025" on the front, .020" on the rear). I'd imagine one solid plus one rubber coupler would tear up the rubber one pretty well. The shaft itself was straight, but the flanges where the couplers bolt to (and possibly the couplers themselves, though I didn't have a good way to measure them) were not. Of course, other cars could easily have better tolerances than mine.

I originally took the assembly to a machine shop and told them to "make it straight". They said they couldn't (I'm not sure why). So I bought some washer shims from McMaster-Carr and set about reducing the run out. Using shims in the .001" to .005" range, I managed to get the run out down to less than .001". This was a bit of a pain in the ***, because you've got to torque the coupler bolts down to 52 ft-lbs before measuring the runout, loosen, then try again.

Bolted all together, the torque tube assembly spun more freely than it did when it came out of the car. Assuming the bearings hold up, I'll have saved a bunch of money vs. an LG setup. If they don't, at least I'll already have the couplers necissary.

I think there is a bit more driveline noise. During a rough idle, shutdown, or lugging the engine, where each individual power and compression stroke has a more pronounced effect on the shaft speed, there can be a bit of a rattle. I think this is normal without the rubber damping these strokes a bit, and it sounds similar to (but much quieter than) my Supra did with a lightweight flywheel.

 

PM 2002MatrixSC and ask him about the nightmare he went through running two solid bushings. Interesting story.......

 

"2002MatrixSC" doesn't seem to be recognized as a member here. Can you post what you know of his story?

I can say that if I just bolted up two solid bushings into my torque tube, I'd be surprised if the thing would even spin!

 

I don't want to speak for him, let him tell you in his own words.

http://forums.corvetteforum.com/member.php?u=171557

 

I think you will find that the BMW bushings and GM bushings are made by the same German company.

These are the 10mm bushings that came out of my car and were replaced with the BMW busings. As you can clearly see they are "Made in Germany".