stingry

I am about to start my car up after a engine, driveline, chassis and suspension rebuild.

I cannot help notice how small my driveshaft is in relation to everything else. My current drivehaft is about 2" in diameter. I have heard that it may be a "torque tube", ie designed to twist?

Why so small?

70BBvert

Don't know why only 2", but it is the same for 4spd cars from 63 - 70 or 71. Then the dia changed to 2 1/2". The 2" dia driveshaft is a thicker wall tube though.

norvalwilhelm

I twisted 2 of them before I upgraded to 3 inch. Yes 3 inch will fit our tunnels with a little cleanup right at the transmission yoke.

stingry

Thanks.

Does your BB have the same size shaft?

If not is it possible to use a BB/muncie driveshaft on a SB/Muncie?


[Modified by stingry, 12:56 PM 3/18/2004]

stingry

Norval,

Where did you get the 3" shaft and how much?

What sort of cleanup?

Do you mean removing glass or steel to fit it in?

Thanks,

Pete

70BBvert

Small block & big block were the same. 4 Spd vs. auto were different lengths,
29 7/8 " for manual & 29 1/2" for auto. But things started changing when the borg warner trans was used & the Turbo 350. Especially with the slip yokes. IIRC all went to 2 1/2" diam in 71 or 72.

I have a later slip yoke so Ii will need to use a 1310/1330 combo u-joint at the front. The smaller dia slip yokes are hard to come by.

Jim

stingry

Thanks.

Hopefully I can find a larger one through the aftermarket.

My 2" driveshaft looks like a piece of rubber hose next to my half-shafts!

Cheers,

Pete

aharte

There's a good reason your halfshafts are thicker. They have to deal with 3.x (whatever your rear end ratio is) times as much torque as the driveshaft.

stingry

That makes sense.

My rear end ratio is 3.36:1

I still don't like my driveshaft but it does make sense.

70BBvert

You could easily get a larger diameter driveshaft made up. Just need to keep in mind that the slip yoke & pinion yoke would need to be changed also. Not sure whats available there other than the 2 1/2" diam versions. May need offset u-joints (1330/1350) to go larger than 2 1/2"

Jim

norvalwilhelm

Any drive shaft shop can build you a new 3 inch driveshaft. I paid $240CDN complete for a 3 inch tube and 2 new ends plus balancing.
The only place it gave any problems is right where the yoke came out of the transmission. The fiberglass floor had a seam that I ground down in one spot and repainted. The yoke just kissed it lightly so a little work with the grinder quickly increased this one spot.

442olds

I had wenco industries build (http://www.wencodriveshafts.com/custom.html ) my driveshaft. Its a 3" and they garanteed it to handle well over 1000Hp. I figured that would be enough of a factor of saftey. I can't remember but I think it was $240 with spicer ujoints and I sent them the transmission yoke i wanted to use. Had it back three days after they recieved my yoke.

I looked at Denny's driveshafts and they wanted over $300 and they were on a two to three week lead time.

RestoVette

stingry wrote: "I have heard that it may be a "torque tube", ie designed to twist?"

A torque tube is a setup where the drive shaft runs through a tube which is rigidly attached to the differential and swivels at the front end. Concept was used on older (40's) Chevy products.
http://www.oneleft.net/Automtive_Def..._Parts_S_Z.htm

Torque Tube
A solid steel drive shaft enclosed in a hollow tube, with a single swivel joint at the front.


[Modified by RestoVette, 4:55 AM 3/19/2004]