I've heard so many things so here goes... I have seen many $500 aluminum aftermarket driveshafts, I was comparing mine to one a freind just bought for a Mustang. His is a 3" diameter deal from Mark Williams (I think!), I have one that came from a 2003 Chevy Trailblazer XLT that is 3.5" diameter. The question was asked a while ago on another forum, on how strong the factory shaft is, one reply was how much HP did the vehicle have from the factory, that's how much HP it is rated for so the 3.5" steel shaft with 1350 yokes that I pulled from a 98 Astro van was only rated for 190 HP? well it seemed to handle the 750+ HP 1.23 60 ft. time transbrake launches in my 455 Pontiac powered racecar just fine for years... I looked at the driveshafts in a couple 2500 HD's, some with 6.0L motors and 1 with a diesel and they have the same series shaft in 3.5" aluminum, I figure if it can handle being in a truck with a 13000 lb. towing capacity it should be able to handle quite a few HP... What do you think? Thanks D. Miles

 

I agree with you that the large diameter shafts are strong as you would expect. Ultimately it comes down to material and dimensions. I'm not sure what they are using for aftermarket shafts, but I've been using Crown Vic and Aerostar shafts for years with no issues. I have a hard tiem buying that Mark Williams is doing anything much more special for their $500 shaft than what the OEMs are doing.

 

Hell i just went to the driveshaft shop i have used for 20 years and he made mine out of 3.5 chrome molly with 1350 yokes and joints . I had the rear yoke so he built the tube with a yoke for the TH400 was $79.00 and balance to 10,000 rpm and charged me $189.50 when i picked it up i already paid the $79.00 for the slip yoke so thats $268.50 for a nice custom built shaft and it runs smooth as silk.

 

Driveshafts are rated for torque. They have a speed rating also but this is more dependant on balance than materials and dimensions. There are two factors to consider:
1. The torque at the shaft is the engine's torque + whatever the converter adds at stall if it is an auto or whatever the inertia of the engine exerts when you pop the clutch on a manual all multiplied by gearing. Gearing being the first gear ratio of the trans plus the low gear of a transfer case if four wheel drive. A 4X4 doesn't need much engine torque to produce large torques at the shaft.
2. The other factor is traction. If the wheels slip it reduces the torque so the torque the shaft actually sees is only as much as the traction available translated back through the overall gear ratio (final drive and tire diameter). This means a car with 2.73 ratio rear end can put a lot more stress on the shaft than with a 4.10 ratio all else equal.

 

Not sure if this is relevant to the post but, diameter, and length determine at what speed the shaft is safe. Search driveshaft critical speed.... long shafts need to be larger to be able to turn rpm.

 

Wall thickness and material are in the critical speed calculation also. Basically the stiffer the shaft the longer and/or faster its critical speed.

 

That's what she said.

 

LOL! Thanks for the answers guys... I installed some Brute Force U-Joints today and got it in the car, should have this thing out for a spin in a day or two... Can't wait! Here's a pic of the aluminum shaft next to the stock 2 1/4" G-body unit.

#ad

 

Got one in my s10. Was out looking at it today and the guy that owned it before me installed the front joint backwards.
Grease fitting after the yoke.

 

Yup! Saw that more times than not... A lot of people don't know that trick. I guess it really wouldn't matter behind a stock 4.3L or 267. It was actually my Snap On tool man that tought me that when I was a young buck just starting out at Meineke right out of high school. Sounds like it's time for some Brutes for ya!

 

How long have you known about the Afro Van shaft it a G body? I have an older steel shaft in my car, and got criticized by one of the "knowledgeable" members for using it on another site.

http://www.maliburacing.com/forum/viewtopic.php?f=4&t=110513

 

He ran that joint that way behind a transmission breaked 383 and had sprayed it also.
I know I don't have that kind of luck..........

 

I didn't use the Astro shaft in a G-body, I used it in my full tube chassis 65 LeMans I built. Back to my first post where I mentioned how a guy said that a factory part is only good for the HP/TQ of the vehicle it came from, so that heavy wall 3.5" dia. 50 3/4" long shaft with a 1350 rear joint was needed behind the 190 HP 4.3L, espescially in front of that bullet proof 7.5 rear!

It seems that the deeper the pockets of some guys the worst "stock" parts are. I can tell you probably 100 stories of examples where stock parts are perfectly fine and then was replaced by the "good" stuff that failed but here's one:

Back in 1990 a freind of ours got back into racing, he built a 77 Firebird with a 400 small block Chevy, it had the stock 8.5 rear that was posi but only had 2.56 gears. The car was in really bad condition with rust and all. He picked upa 79 Buick Regal that someone had been racing, it already had an 8.5 rear and had been gutted. He pulled the engine/trans from the Bird and dropped into the Regal but he moved it back as far as possible for weight transfer which was about 2.5". He used the Firebird shaft which is 4" shorter than the G-body shaft so it was about 1 1/2" too short. It ended up being a forgotten detail over the years and the basically stock 400 sbc that started off running 12.20's went to a deasently built 350 with Bowtie heads that ran 11.00's and ended up a Motown block with a 4.125 bore and a 3.625 stroke 393 with Dart aluminum heads that ran a best of a 9.99 with about 2-2 1/2" of yoke hanging out on a T-350. He bought a back halved 69 Nova and sold the Regal to his friend who immediatley had a 3" S&W shaft built. I'll never forget the day when he got to the top of 2nd gear and BOOM!!! the shaft broke right in the middle and the back part of the shaft came through the floor and damn near made it through the roof, he was only running 10.50's! My friend rolled the Nova and his friend sold him the Regal back and the too short Firebird shaft went back in running 10.00's and 9.90's. I can tell you this, I've been racing for 25 years myself but have always been racing with my parents all my life and we have never had an aftermarket driveshaft, the only ones I have ever had trouble with were the stock 2 1/4" pencil-neck geek G-body shafts... Thanks D. Miles