solid driveshaft?

jim_ss409

jim_ss409

Well Known Member
Supporting Member 5
303Radar said:
If you're wondering about critical speed and drive shaft length, here are some more links:
http://markwilliams.com/driveshafttech.aspx
http://markwilliams.com/driveshafts.aspx

Because this company is about 20 miles or so from me, I may order my one piece drives haft from them.

According to my engine builder, he's never had a bad experience with Mark Williams equipment and their stuff is used on 5 second dragsters.
Click to expand...

Well I just got off the phone with these guys. I ordered a new drive shaft for the Pontiac.
We're changing over to a Powerglide and we had to get a different yoke, the new yoke was shorter so the old driveshaft was now too short.
I was going to order a new steel drive shaft similar to what we have now but since it's pretty long I thought I'd check it out on the "Critical Speed" chart...
http://markwilliams.com/driveshafttech.aspx
We had a 3 1/2" driveshaft that's 56 1/2 inches long so we had a critical speed of about 6,500 rpm. That was fine with the old engine but the new one peaks at 7,500 and we'll probably be closer to 7,800 crossing the line.
Even after deducting a bit for converter slip the drive shaft will probably be turning about 7,500 rpm,,, plus it needs to be an inch longer, 57 1/2" so the only thing that's rated for that speed is a carbon fiber drive shaft. :cry
http://markwilliams.com/detail.aspx?ID=326
I did some research and at our horsepower level it should be practically unbreakable,,, that's good. :beer
It should weigh about ten to twelve pounds less than the driveshaft we have now,,, that's good. :beer

It cost's $1,032,,, That's bad! :cry:cry:cry:cry
 
jim_ss409

jim_ss409

Well Known Member
Supporting Member 5
By the way, when I took off the old yoke, I looked at the splines and they were twisted right where the output shaft of the transmission ended.
If you look closely at this picture, you can see the twist.


This was a Spicer forged steel yoke not something made in China and we twisted this with the old 476 ci engine with iron heads.
The new yoke is made from heat treated 4340 Chromaloy so it should be plenty strong.
 
303Radar

303Radar

Well Known Member
Supporting Member 2
Holy Cr@p! Looking at that yoke, you might have been on unknown borrowed time. While the cost sucks, good to know you have something which should be bullet proof.
 
9664imp

9664imp

Member
When doing the one piece DS does the top of the X need to be moved up any? The reason I ask is I want to have my DS as level as possible with the eng/trans.
 
models916

models916

Well Known Member
Supporting Member 7
I did nothing to mine. Could check it against the axle bump stops and make adjustments as needed.
 
oldskydog

oldskydog

Well Known Member
Supporting Member 10
Get one of these and never have to worry about the driveshaft breaking...............just everything else.

 
BSL409

BSL409

Well Known Member
Supporting Member 6
jim_ss409 said:
Well I just got off the phone with these guys. I ordered a new drive shaft for the Pontiac.
We're changing over to a Powerglide and we had to get a different yoke, the new yoke was shorter so the old driveshaft was now too short.
I was going to order a new steel drive shaft similar to what we have now but since it's pretty long I thought I'd check it out on the "Critical Speed" chart...
http://markwilliams.com/driveshafttech.aspx
We had a 3 1/2" driveshaft that's 56 1/2 inches long so we had a critical speed of about 6,500 rpm. That was fine with the old engine but the new one peaks at 7,500 and we'll probably be closer to 7,800 crossing the line.
Even after deducting a bit for converter slip the drive shaft will probably be turning about 7,500 rpm,,, plus it needs to be an inch longer, 57 1/2" so the only thing that's rated for that speed is a carbon fiber drive shaft. :cry
http://markwilliams.com/detail.aspx?ID=326
I did some research and at our horsepower level it should be practically unbreakable,,, that's good. :beer
It should weigh about ten to twelve pounds less than the driveshaft we have now,,, that's good. :beer

It cost's $1,032,,, That's bad! :cry:cry:cry:cry
Click to expand...
Well I had to do the same my shafts are 3-1/2"od .083 steel 59-1/4" long at 7100 rpm:eek and with the new engine in 61 I figure close to 7500rpm and i have already bent two steel ones in the 62:grumble

IMG_0175.JPG IMG_0176.JPG
 
jim_ss409

jim_ss409

Well Known Member
Supporting Member 5
Yeah, we just installed ours a few days ago. I didn't weigh it but it's amazingly light. It's hard to believe something that light is strong enough but apparently they're plenty strong.
They do say you have to be careful not to gouge or nick them because it will create a weak spot that can cause the shaft to fail.
From a safety standpoint, if a carbon fiber shaft does fail they say it will pretty much disintegrate and not come bursting up through the floorboards.
I'm hoping to never find out about that myself. :scratch
 
303Radar

303Radar

Well Known Member
Supporting Member 2
I bet, for a high price, you could get Mark Williams to do a two piece carbon fiber drive shaft :brow:bow
On the up side, it should be just a bullet proof as it would be over kill!
 
nate64

nate64

Well Known Member
Supporting Member 1
Well, I'm staying with the two piece style because my chassis is completely done. Im doing a frame off and finishing the floors as we speak. I will be running an ls1 with a 76mm turbocharger. I bought a low miles ls motor for 400 bucks, cant beat an ls with boost. 500-600hp to the wheels easy all day. Should be fun. Ls1 tech.com has great articles on the swap for our cars. Now, 348-409 setups are just cool as hell, but its a money issue so take it easy on me ;)
 
models916

models916

Well Known Member
Supporting Member 7
The length of the 4l60 and such makes the 2 piece nearly impossible to align the angles because the center bearing very limited to adjustment.
 
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