I'd caution those using the BMW couplers, pics inside.
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
I'd caution those using the BMW couplers, pics inside.
A little synopsis. I destroyed my stock couplers after about 50k miles and probably 1000 drag strip passes. That is to be expected I suppose. I went ahead and replaced the bearings as well as new bolts and BMW couplers and reassembled. I have maybe 3k miles and about 5 passes on these. For about a month I've been having a very minor shifter vibration which I figured was my clutch. Yesterday I did a quick 1st through 3rd WOT blast and was greeted with a very sound screeching sound. I limped the car back home to discover one broken coupler bolt and 2 couplers that are beat up. I took a few pics but I just cannot understand how the bolt could break. Even when my OEM couplers were nothing but strings the bolts just bent (most of them). This time I have all straight bolts but one broken. I checked the run out on the prop shaft thinking maybe that was putting undue stress on the bushing but the max run out is .010" in the center. Anyone have any opinions as to why the bolt may have broken? Both the bears I replaced still spin freely, quietly and true.
Thanks
Dave
Thanks
Dave
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,126
Likes: 19
From: Streamwood illinois
yes, everything is fine. Run out on the shaft is ok and everything is perfect. Trying to find OEM bushing and it seems pretty difficult to do. BTW, this is with less than 10 drag strip passes and pretty tame driving.
Dave
Dave
Team Owner
Joined: May 2005
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From: Flagstaff Az.
Melting Slicks
Joined: Jul 2007
Posts: 2,939
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From: Simpsonville SC
St. Jude Donor '09-'10
For drag racing, I would recommend switching to the aluminum couplings. Mike Yeager @ EastCoast Performance is a vendor on this site, and sells them. I put an aluminum in my rear coupling, and a rubber in the front.
Front:
Oh, since I have a 99 A4, I upgraded my bolts:
Front:
Oh, since I have a 99 A4, I upgraded my bolts:
Last edited by clif; Jul 19, 2010 at 07:24 AM.
Melting Slicks
Joined: Jul 2007
Posts: 2,939
Likes: 7
From: Simpsonville SC
St. Jude Donor '09-'10
Yes... later torque tubes had the larger bolts, so, since I upgraded my car, I wanted a stronger torque tube. I replaced the propeller shaft as well with a custom made one from the Drive Shaft Shop, through Mike Yeager.
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Melting Slicks
Joined: Dec 2003
Posts: 3,315
Likes: 17
From: Near Jacksonville Fl.
I doubt the coupler failed the bolt, the bolt failed placing an undue strain on the coupler causing what you found.
If you are drag racing I'd highly recommend upgrading to the 12mm bolts.
If you are drag racing I'd highly recommend upgrading to the 12mm bolts.
Melting Slicks
Joined: Dec 2003
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From: pawleys island sc
Last edited by 99 vett babycar; Oct 12, 2010 at 09:49 AM.
Former Vendor
Joined: Jan 2008
Posts: 4,202
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From: Greenville SC
there seems to be 2 different "BMW" couplers out there. One is made of a material that's significantly sofer than the OEM and another one that's compareable to the OEM. I've purchased mine from a BMW parts house called Autohaus (google it) and they are indisstinguishable from OEM.
Le Mans Master
Joined: Oct 2000
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From: Oak Harbor WA
Race Director
Joined: Dec 2004
Posts: 13,760
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From: Haymarket VA
I got mine from a BMW dealer and they clearly said "Made in Germany" on them. Just like the stock GM ones did. I've pushed 577RWHP and 530RWT through them without problems. I run 315 PS2's which don't have a lot of traction.
Former Vendor
Joined: Jan 2008
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From: Greenville SC
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Last edited by Mike Yeager@Eastcoast Performance; Jul 22, 2010 at 09:08 AM.
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