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One piece driveshaft

16738 Views 91 Replies 39 Participants Last post by  AAIIIC
I know the driveshaft is a two piece or three piece...whatever! My friend changed his in his GTO and what a difference to power to the wheels it made! Can we do this mod and what are the negatives to doing it? I am surprised to have not heard this question yet on here but maybe I missed it. Looking forward to the replies and answers! Thanks in advance!
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What, exactly does this mod do for you? I can't see the benefit. The "improved driving" of letting out the clutch/no clunks" etc...didn't that come from the diff bushings?


The mod made for this car lost the flex coupling, and lost the hanger bearing and rzeppa head assembly...

Overall between the factory shaft and the shaft i used in the car it is probably around the same weight as the original.
I could lighten the stl shaft up some more and make it come in a few pounds lighter.
The AL shaft or Cf shaft would be lighter, but there both going to be very tight in the tunnel and need to shave the tunnel at the hanger bearing structure points. (Cf is 3.750 diam / AL 4" diam)

I did another caddy the other day and im looking into yet another way to get around the front tripod set up a totally different way....

Now the other issue is cost....

What i did for the caddy the other day was a huge diff in cost to the caddy replacement, and if he should later on upgrade to the single pc shaft he just needs the front fix i go with which will save him money since the rear section can be used on the new shaft...


Pretty much the benefits are cost, and there is some performance benefit since you lose the flex disc.

Just be a little questioning of what someone does..... For the length the shaft has to span in 1 pc and what the car is capable of a single piece less then 3.5" diameter is pushing safety...
A 3" single pc shaft in stl i wouldn't do....
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Super shafts are you the one that made the driveshaft for the O.P. ?
Super shafts are you the one that made the driveshaft for the O.P. ?
Yes Supershafts fabbed my DS. Taking the car to the dyno this Friday (TTP ) . Will post the numbers and video.
K I thought so but wanted to confirm . Super shafts what's the going rate for a aluminum shaft ?
Pretty much the benefits are cost, and there is some performance benefit since you lose the flex disc.
Excellent points. Especially the flex disc. That thing sucks. Thanks for responding, and nice job with the idea/execution/testing and feed back! :)
K I thought so but wanted to confirm . Super shafts what's the going rate for a aluminum shaft ?
I honestly don't know, the 4" is a very tight fit and the rear needs to be held much tighter then it is with the factory set up.. (which is another thread/issue)
I can tell you the mustang which also has the slip sleeve dilema is around 690, but the caddy has the rzeppa end to deal with and the fixed end tripod at the trans...that's going to add to the cost, and then the hanger structure is another issue to lose

If you guy's ever blow up your trans, lose that particular style t56 and get the slip yoke version.

The shaft can be so much lighter with the slip yoke version over the fixed style shaft
Every pound is equal to 20 lbs carrying in the driveline.. so losing 10 lbs in the driveline is like losing 200 lbs of carrying weight.
I honestly don't know, the 4" is a very tight fit and the rear needs to be held much tighter then it is with the factory set up.. (which is another thread/issue)
I can tell you the mustang which also has the slip sleeve dilema is around 690, but the caddy has the rzeppa end to deal with and the fixed end tripod at the trans...that's going to add to the cost, and then the hanger structure is another issue to lose

If you guy's ever blow up your trans, lose that particular style t56 and get the slip yoke version.

The shaft can be so much lighter with the slip yoke version over the fixed style shaft
Every pound is equal to 20 lbs carrying in the driveline.. so losing 10 lbs in the driveline is like losing 200 lbs of carrying weight.
Ya I dont think a 4" will fit either, Id like to see a one piece made. But It would only be worth spending the $$ if it was alittle lighter then stock.

And keep us updating on how to keep the rear planted better too.
The 4" would fit, but it won't be a take the factory shaft toss it to the side and bolt the 4" in, it would require a solid mount/brace at the pinion housing, and the hanger structure needs some attention...

They don't make a slip sleeve for the 3.5" AL shaft, they make a reducer for the 4" slip sleeve to 3.5", but once you add that it up the cost and it's no longer lighter then a stl lightened 3.5" shaft.

CF is the other option, but at twice the cost of AL, and 3.5 times that of stl.

As for the keeping the diff from becoming it's own self help grenade, it needs a fairly simple brace at the front pinion to the frame support to keep it solid.
Im working with another Cad on that issue.
i was thinking of making a cross brace but i just got my v and havnt had time to look under the car to see what i can do but it would be nice to have a cross brace and front pinion brace to eliminate alot of movent i think reason why it brakes is to much shockload from the movment, if you think of a solution let me know im interested as it would be weeks before i can get underneath my v
If...ok when....I do a one piece driveshaft, I'll be machining a piece for a safety band. Bonus.....screw it into the holes that hold the carrier bearing! BAM!
Well one reason is that it's not cheap, and theres really not much power gain from it. It would help with driveline clunk, but that would also make the rearend see that much more abuse. Plus BMR stated that their shaft was to big to be used with the factory resonator, and while that doesn't bother everyone, it will hurt some of the sales. Add that to the already low number of Vs, and you don't have a very good business case.
Plain and simple it is better to have a one piece, I'm way above 500 HP, and my next upgrade is going to be a one piece shaft, way too much movement from launch, plus I'm going 9 inch with 3:55's, gotta stiffen it up back there, that clunk is not good. Too much flex, I'm already resonator less, so what ever I have to do, it will be worth it!
Plain and simple it is better to have a one piece, I'm way above 500 HP, and my next upgrade is going to be a one piece shaft, way too much movement from launch, plus I'm going 9 inch with 3:55's, gotta stiffen it up back there, that clunk is not good. Too much flex, I'm already resonator less, so what ever I have to do, it will be worth it!
You're quoting a post from 16+ years ago to respond to someone who hasn't been on the site in about 6-1/2 years. I'm sure he'll be happy to see the response!

In the meantime, I merged together a few threads about 1-piece driveshafts.
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