One Piece Driveshaft

[asubimmer]

There seems to be talk about a single piece driveshaft for years on here but there isn't a ton of info about it. I thought about it in the past but never went through with it. The only reason I'm thinking about it again is because it seems like it would be lighter (even though the gain would be VERY small, ie not noticeable) but mainly it seems like it would last longer. I'm taking the getrag 240 off my 24v swap for a new tranny and trying to decide if I should do it this time.

There seems to be a lot of people saying that doing this would be a train wreck and a lot of people saying its fine...

First with the "problems"
"Also, replace the centering bushing. It sits in the front of the driveshaft and keeps the driveshaft centered on the transmission output shaft. If it's loose or missing the flex disk has extra stress trying to keep the driveshaft in-axis even if it's otherwise aligned." This brings up where some say you need to install a U joint at the front of the driveshaft. Also, adding a U joint to the front and removing the guibo would add vibration.

But there are people on BFC running these on FI setups w/out "problems".
ex..http://forums.bimmerforums.com/forum...d.php?t=954811

I know doing this would make it harder to remove the driveshaft BUT if it was a single piece it wouldn't have to be removed near as often. Plus I have holes in the trunk to get to the diff bolts easier.

Also I am using the stock material, not aluminum or carbon like some prev threads mention, due to class rules. This car is not my DD, its being prepped for bmw club racing.

http://www.ultrarev.com/product.php?productid=46998

[jlevie]

I really can't see the point in this. A drive shaft and CSB is usually good for well over 150k. So it isn't as if it has to come out a lot. And since the manufacturing costs of a single piece drive shaft are lower than what the BMW engineers used, it seems very likely that they had a good reason to use a two piece drive shaft and CSB.

[Teaguer]

I can see the benefits and the downfalls .

Thats being said , I'm a bit skeptical of their ricey description :

"This is our 1 piece conversion for the BMW E36 platform. The shaft is 606-T6 aluminum with 7075-T6 plats to convert the ends. This shaft weighs 17lbs and being we are removing the hanger bearing it will make the car seem more athletic and give it a smoother power transfer. Unlike other aftermarket shafts for BMW's this has a slider system that will let the shaft move in and out during racing and the chassis flexing. This is the first of many BMW products you will be seeing from DSS.
"

Also be aware of any seller that misspells the word "warranty" . :D

PLus going by their own description it actually sounds like it still is a 2-piece construction .

[bender]

one of the problems with a one piece drive shaft is that it needs to be a rather large diameter in order for it not to whip due to its length... do a google search for critical speed.

that being said, it most likely would not be able to be a bold in replacement on an e30.

you would most likely need at least a 3.5" diameter chromoly or aluminum drive shaft.

my car is a little different, but i had to remove / relocate my e brake and reshape the tunnel to allow for more room with mine.

not saying its a bad idea - just might not be necessary in the grand scheme of things.

how much power are you trying to make?

[bender]

i'll also put it out there that I'm not a fan of DSS, and provided me horrible customer service.

check out mark williams racing products

[Rocla]

I know doing this would make it harder to remove the driveshaft

How come? Undo bolts from both ends and slip it out.

[asubimmer]

I just posted up that out of the box 1 piece as an example but yeah it seems almost like a 2 piece still. I would have it done locally if I went through w/ it.

But yeah they do have to be larger than a stock one because of the "whip". The center of a one piece would bow under high rpm's if it was the stock diameter.

Thanks for that info about DSS bender, and for the other company.

[asubimmer]

I really can't see the point in this. A drive shaft and CSB is usually good for well over 150k. So it isn't as if it has to come out a lot. And since the manufacturing costs of a single piece drive shaft are lower than what the BMW engineers used, it seems very likely that they had a good reason to use a two piece drive shaft and CSB.

I haven't spoke to BMW personally and neither have you. You know what they say about assuming. A one piece driveshaft under MOST circumstances are better than 2 piece units. But there are advantages and dissadvantages to both. A two piece one is usually easier to reduce vibrations.

So in short yes BMW had reason to use them, they build performance cars but don't sarifice luxary...

[bender]

the picture above of the DSS one is as once piece as it can get. You still need some sort of slip yoke in there to account for body flex, etc that could effect the length.

you can see it a little better in this pic of mine (of course they don't send you that pretty accordion cover)

[nando]

you could have an ix shaft lengthened about 12". it has a slip yoke on the end with a big nut so you can collapse it for easy removal. and it already has the right flanges for the diff and transmission.

[asubimmer]

nice work nando. You don't happen to know how large they are in diameter and how thick the metal is do you?

[nando]

i'm not sure, it's pretty big though, I'd guess 3.5". I might still have the core from my rusted ass parts car, but I have no idea when I'd get out there to look at it (especially in this weather).