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Discussion Starter #1
I have a 2005 M6 GTO making a little bit above stock HP, when I purchased it there was already a one piece 700 hp driveshaft installed. I broke that one at high speeds due to it not being balanced(I think) and replaced it with a DSS 1000hp single piece with their billet 4 bolt pinion. I still get bad vibrations above 120 and I don't dare push the car past 135, i've been chasing the vibration for the past year with various bushing etc but nothing helps so I bought a DSS 1000hp 2 piece that will mate to the 4 bolt pinion I already have. Problem is I never had the original center support bearing bolts and i cant find out what size they are.

In a nutshell-
Need to know center support bearing bolt sizes
Why is my car shaking at high speeds
Does anyone want to buy a lightly used 1000hp DSS singe piece? Part number is GTOSH3-A
 

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Worthless reject member
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44,178 Posts
you might want to check the driveline angles to make sure both u-joints are going to be at the same angle, so that their motion cancels each other. trans and differential centerlines should be parallel, even though they are offset.

i would get a thread detective from a hardware store, climb up under the car and start trying it out on the bolt holes for the center support bearing.
 

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2006GTO M6 dd-drag-roadcourse
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The Bolt size for the center carrier bearing is 10mm - 1.50. I had to tap one of the holes years ago when I installed my DSS 1000hp 2 piece. One hole was stripped from the 5 different driveshafts i've had in and out over the years lol. Found a pic of the tap I used and it was 10mm-1.50.

That brings me to your vibration problem. I tried a 1000hp 1 piece. No matter what I did I couldn't get the vibration to stop. It was down right scary past 120mph. Doing high way pulls with my buddies in "mexico" was a no-go with the 1 piece. Felt good at lower speeds though, with how connected it felt vs the stock 2 piece and the two other after market 2 piece stock replacements I tried and blew up.

I finally went to the best driveline shop in my area and had them take a look. They said everything was great with the pinion angles and the driveshaft was perfectly balanced.... So I gave up, sold the 1 piece, and bough the DSS 1000hp 2 piece with the aluminum/chromoly combo. One of the best upgrades I've ever done. Has the solid connected feeling like the 1 piece but has the smoothness of the factory 2 piece. Has held up great with 4,500rpm launches on drag radials at the track and super sooth all the way up to 155mph where the factory governor kicks in.

Here's a couple pics comparing the stock ds, vs the 1 piece, vs the DSS 2 piece... and a couple close ups of the bad ass heavy duty center carrier bearing on the DSS 2 piece
 

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Discussion Starter #8
Awesome reply. I feel a lot better considering that’s the exact 2 piece I purchased. I would be downright angry if I spent 2k on driveshafts and never solved the problem.
Thanks man.
 

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I installed the two-piece driveshaft and immediately the problem was solved. Doesn't feel any different than the 1 piece and I can go 155MPH with little to no vibration.

For the record the stock threads for mounting the center support bearing are 1/4-20.

GTO44 i read your post wrong and didn't realize you tapped the holes to 10mm-1.50 so when i tried to use the bolts obviously it didn't work. I still have the exhaust off so i might go ahead and drill and tap them for that size anyway.

Thanks for the help
 

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hmmm. ill have to find my bolts and check them. cant remember where i placed them. they shouldnt have been standard thread though.

Edit: Cant find them and not a clue where i would have put them at this point
 
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