Thoughts on the one piece driveshaft

[Bill in MN]

I've been fiddling with one piece driveshafts over the past 6 mos. or so and currently have one in the S2.

I guess "one piece" is a bit of a misnomer since there is a saddle/spline section to allow for installation but it does away with the center support completely.

I won't bore everyone with the details but after much trial and error we came up with one that works well. While overkill was achieved(rated to over 750hp) the final product with adaptor plates weighs about 2lb more than stock. It uses Neapco U joints and is greasable/rebuildable. I've no doubts up to 5lb. can be shaved off by using a more appropriate sized shaft and perhaps a bit smaller U joint.

While this is well and good I can say that one of these is not neccessary and is, in reality, not worth the money. I've invested enough into the project to literally buy another 5er!!!.

I had looked into having a bunch of them built but the lowest I could get the cost down to was somewhere in the $400 area. Aluminum would shave even more weight off but bumped the price up considerably. OEM shafts are perfectly capable of taking a lot of abuse and I don't see the value in a one piece.

If anyone wants more info, PM me. I've got pics but for some reason Yahoo won't let them post right now.

[Duke]

I'm interested Bill.

Deletion of a week link is how I look at it.

[gol10dr1]

well for right now lets hope that oem driveshaft can handle a 550 hp launch!!

[bahnstormer]

well my u joints are shot and as far as i know the bmw shaft's
joints cannot be replaced. so i need another rebuilt driveshaft....and that costs 500 i hear...

so if u got a rebuildable 1 piece for 500 in aluminium i'm game

will it fit an e34?

andrew ur guibo and u joints are gonna get broken fast me thinks =]

[Bill in MN]

I've had several PMs about coming up with an aluminum shaft and unfortunatly there really isn't a practical way to do one.

I've gone to several sources and have been told that nobody up here builds them and as far as they knew nobody even in the Twin Cities buils them either. I'm not saying one can't be had but at least up here in the sticks it's not feasable.

All in all I think it's a wash. Yes, the "one piece" is rebuildable but how many miles has everyones' original shaft lasted? Replace it with one from one of the reputable parts guys on the board and chances are you'll never do it again.

I've not done an adaptor for a guibo equipped car since I've got an auto ...you know, one of those things they put in low performance slugmobiles

[graphite]

What diameter is your shaft? 2 3/4"? I think you told me in a PM but I dont have it anymore. I would be interested in pictures of the rear part. just to see the joint.

I was looking into doing one as well but designing a adapter plate that would work well for the manual transmission (with or without guibo) is complicated because of the 3 bolt pattern that isnt a standard piece. It also makes it complicated to mate to a standard 4 bolt piece because of the spacing. I put my research on hold for now because I'm trying to buy a house and I bought big brakes and need new wheels to finish that, but I am definately going to look into it more in the near future. My only concern right now is that the guy I found to make it said 3" diameter aluminum would be needed for the length our shaft is and I'm not sure if it would fit through the rear subframe properly since the hole in the subframe is offset from the center of the diff.

If you're under your car sometime in the next few months and wouldnt mind taking measurements for me of yours I would be interested in the following.

-cross diameter of your rear joint
-diameter of shaft
-distance from front of subframe to where the rear joint is welded to the shaft
-clearances of the rear joint corners to the four sides of the inside of the subframe hole (whatever the worst case clearances are on each side when you rotate)

[Bill in MN]

I've a 2", .095 shaft. A 2", .065 shaft is avaible but isn't much lighter and would probably have issues after a few 500hp launches. There simply isn't a ton of difference between shaft sizes and their weights. The majority is in the saddle, U joint and adaptors.

The U joint is a 3.5" and everything goes in just fine through the sub frame, although there isn't a ton of room.

I've tried a few more times but Yahoo photos still won't work for a download so here's the addy. of the photo. Perhaps someone can get it to come up. I've mailed pics to Wickahead who is going to put them up for me if this doesn't go again. The pics show the steel adaptors that are not currently on the car.