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Discussion Starter #1
I received my first and extremely informative driveshaft schoolin' I had purchased the BMR aluminum DS and had somehow lost a weight on my way to Indiana from Orlando. I figured I would break in the GTO since I never drive it and it gets better fuel economy than my 05 Altima SER.

I noticed a slight vibration on my way up to Indiana, stopped in Nashville and a shop told me that a weight had popped off and that was probably where the vibration was coming from. When I arrived in Terre Haute IN, I called around everywhere, nobody would balance an Aluminum DS. I finally found a place that would do it. After putting it on their balancing machine, they found out that it had a warped somehow and they could not balance it. I thought "great, I am 1000 miles from home, what do I do"? They told me they could build me a steel one piece which they swore would hold up more than the Aluminum as they build them for dragsters all the time. I was excited and told them to do it. a couple hours later, it's done and I am ready to drive it back to my parents.

Talk about a vibration worse than you could imagine... I am not joking, sick, at 80 it starts and you could not run it above 105 without the windshield popping out from all the vibration. The DS they installed was balanced perfectly. I was stumped, they told me it might be the halfshaft... i didn't think so since I was only 410 at the wheels and didn't drag race or hard launch it.

After many talks with several techs, I found out the neat little expression. "multi-angular vibration" Manual Trans GTO's should NOT have a one piece STEEL shaft at all.

Luckily I am back in Orlando now after driving 75 which was so hard on me. Installing the factory DS back and am waiting on the BMR to be shipped from IN so I can forward it to BMR for inspection.

Apparently due to the GTO's engineering the two piece shaft is a must because of the angle of the rear pinion and trans. The BMR shaft was great since it absorbed the vibration caused from the angle problem however the Steel shaft sends the vibrations right through to your TEETH.

DO NOT GET A SINGLE STEEL SHAFT, YOU VERY WELL, MIGHT REGRET IT.
 

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burnout silver star award :)
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hmm interesting. i will be watching for somebody with experience with these parts to chime in.
 

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good info..thanks for posting.
 

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I heard about the angular misalignment. This just confirms it.
In the not to distant future, I plan on seeing if it is possible to align the diff to the tranny.
Still, great info.
 

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Member #804
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Hang tight, theirs a solution on the way ;) Should be ready for annoucement before end of the year. It may cost a few bucks but driveshaft vibration will no longer be an issue. Keep your existing BMR pinion adapter. You will have to remove the spacers (which is part of the problem anyway.)

proxses said:
I heard about the angular misalignment. This just confirms it.
In the not to distant future, I plan on seeing if it is possible to align the diff to the tranny.
Still, great info.
Correct me if i'm wrong, anything more then 3* of driveshaft angle will cause vibration, in order to make the 3.5" driveshaft work with the GTO subframe, you would have to tilt the pinion angle up to match the driveshaft angle or use a two pieace driveshaft.

Spacing the rear axle case down only creates more driveshaft angle. So like anything in engineering its a series of compromises, smaller diamter driveshaft vs. shimming the diff to use a larger driveshaft.
 

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Blowed Up...
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Man this sucks and I am sorry to hear about it.

For those that don't know his BMR DS is the one out of my car. I never had any issues with that DS at all. I hope you get everything sorted out and again I am sorry to hear about this.
 

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How are you liking that rear end? Did you get a chance to beat the hell out of it in some tight high speed turns yet!?
 

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I can see where that would be a problem, but am surprised it's M6-specific. That problem would likely vanish with the use of double-cardan CV U-Joints at both ends of the driveshaft (example here). If I was having a shaft built, I'd insist on them, even with the extra cost involved.

I learned what you discovered with my Jeep Wrangler - lots of vibes after lifting it with standard single U-joints at both ends of the shaft. I had a shaft built with a double-cardan joint at the tranny end, and the vibes magically vanished - even with a standing 10-degree angle between the transfer case output shaft centerline going into a 16" driveshaft (didn't need a double-cardan at the axle end too because my housing is already degreed).
 

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wannago faster
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I have a 3.5 al/ds on my 2005 a4 and have no vibration at all. Just lucky I guess.

Greenville Eddie
 

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Member #804
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6 speed cars for the most part only have problems with 1 pieace driveshaft.
 

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Have Bar, Will Travel
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The automatic must absorb some of the vibration. It might cause early failure of the Automatic tranny as well.

Although its possible that the automatic sits at a different angle.
 

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hmm I've been running the D-S (last I knew, they weren't an approved vendor here) version of the aluminum shaft for a coupla months now with no issues whatsoever, although I haven't run the car up over ~120MPH since installing it.... coincidentally (or not?) i also have one of the Harrop covers installed, with the 'revised' mount they brought out.

.
 

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I have a 3.5 AL on a M6, 3.91's and have been over 115 mph with no vibration, although I did spend the extra 60 to get it capable for 200mph
 

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Discussion Starter #14
TrakDay said:
How are you liking that rear end? Did you get a chance to beat the hell out of it in some tight high speed turns yet!?
I love the KAAZ and the 3.73s way too much.... it's pretty much bad ass. I used the Auburn's in all my Rustangs and loved them as well. I believe the the KAAZ is the only way to go with the stock rear in these GTOs. I believe that the KAAZ is as good if not BETTER than my old Auburn setups. But, obviously I am partial now.

I am hoping that BMR will find what happened to the DS. It's in the shop now, getting the factory DS reinstalled, springs and Hotchkiss.

Other than this mis-angular vibration issue with the DS I am happy. When I was up north in Indiana, the temp dropped into the low 40's and my car came alive, was playing around on the curves and hit sideaways in 3rd, felt like I was on ice, it was sweet especially with 420 at the wheels. It would have been nice to get a dyno at that temp. NOW I NEED DRIFTING LESSONS.
 

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05GoatBoy said:
I have the CF and been over 140 with no vibrations. :D
Remarkable isn't it?;)
 

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ohios 1st N only 9 second GTO
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drive shafts humm i have a custom made all aluminum one made by a well know big company and its good for 1000hp and well made does not have that adapter ..this is the realk deal it had a 1350 u joint and comes complete with new billet yoke,my car has went 11.71 at 120mph with 1.9 60 workin on the 60ft times now no wheel hop cars a A4 drag bags ar all have done to rear end,and nittos 274/40/17 they are not as good at the track as the M/T but work well on the street..aka last longer..anyone interested in the shafts can pm me i can send you in the right direction... RC
 

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rcsfastmonte said:
drive shafts humm i have a custom made all aluminum one made by a well know big company and its good for 1000hp and well made does not have that adapter ..this is the realk deal it had a 1350 u joint and comes complete with new billet yoke,my car has went 11.71 at 120mph with 1.9 60 workin on the 60ft times now no wheel hop cars a A4 drag bags ar all have done to rear end,and nittos 274/40/17 they are not as good at the track as the M/T but work well on the street..aka last longer..anyone interested in the shafts can pm me i can send you in the right direction... RC
Punctuation is your friend.
 

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Been here for a long time...
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May or may not be GTO specific. Steel driveshafts and T56 don't work well together. Started having problems in the F-Body in 93. There was a TSB out that if the customer complained about vibration, change to a 3rd gen aluminum driveshaft. They finally fixed the problem in 98 when all 6spd F-Bodies got an aluminum driveshaft. A4 cars didn't have this problem.

I think its more T56 specific than car specific. The goat might be worse than the F-Body though.
 
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