Driveshaft/u-joint question

[cableface]

So, my drive shaft starts vibrating the other day. Well, more like knocking. I had previously changed the flex disc and knew that wasnt the problem so I figured it was probably the center bearing. I went ahead and bought the part and got everything apart. The bearing definately needed replacing but I'm not 100% sure that's what caused the problem.

While inspecting, I noticed that the caps of the u-joint between the two driveshaft parts are cracking badly. I called the stealer and they said that that u-joint is not sold separately and that I would have to buy the entire driveshaft. OUCH. I really need to replace that u-joint. Does anyone know if you can buy them anywhere at all??? Is there an aftermarket part, or am I screwed?

Also, what do I need to look for when inspecting the rear CV joint?

[mattyb]

having to buy the whole drive shaft is a legacy of german engineering and what a great scam it is. I have heard of on this forum some of the guys take the whole section to a maching shop and have the uni drilled out and a new one pucnhed in. However it seems to be a very exact process, maybe do a search here and see what comes up. if it works its better than having to buy a whole new friggin drive shaft. best of luck and let us all know how u got on.

[shogun]

contact one of these companies
http://www.bimmerboard.com/forums/posts/275627

[Bellicose Right Winger]

This site has some BMW ujoints including one for 535's, but doesn't list yours. They do list the dimensions of they ones they offer. If you measure yours, maybe one's right. Many years ago I had a staked-in ujoint fail in my Mercury Capri. I pressed the old one out in a vice by simply forcing the end cap over the stakes. This deformed but did not completely remove the stakes. On reassembly the replacement joint snapped right into the place where remnants of the old stakes were. A prick punch provided additional security. The driveshaft worked perfect. Now this was a relatively simple one-piece DS, but I'm tempted to try it again if and when the I need new ujoints in the Bimmer.

http://www.rockforddriveline.com/Staked%20Ujoints.PDF

Paul Shovestul

[shogun]

In general all the shops which repair trucks, farm and construction equipment, need a lot of these parts and probably have a number on stock. Just visit such shop and ask. Maybe even the small village farm equipment repair shop can help, at least they know where to buy and they have the equipment to change the parts on your driveline and balanace it if necessary.

[M.Rad.]

and I don't want to replace it with the same moronic assembly for $500.00.
I can see no reason for such a design. Since the diff. is solidly mounted there is little to no movement to compensate for (see: every Corvette since 1963).

I'm contemplating taking it to a local driveshaft shop, having them fabricate a one-piece shaft with the CV joint at the back, and a set of U-Joints just aft of the Guibo. This will give pleanty of flex without having a "hinge" in the middle.
And I don't buy "the engineers know what they're doing" routine. Otherwise we wouldn't be constantly hopping up our cars, we'd leave them as builtI'll let you know how it goes.


Any comments/thoughts?


Regards,
M.R.

[mattyb]

good points made. would be interested to see the straight thru driveshaft idea happen and the results.

[Bellicose Right Winger]

If the center bearing is the only problem, then I'd just change it. It's not that difficult a DIY procedure. But if you're paying someone to do it then a remanufactured DS is the way to go.

Now that these cars are aging you should be able to get a reman DS for under $400. I doubt you can have a custom one built for less.

Not sure about new Corvettes, but all of the car's I've seen with one piece driveshafts had a splined, sliding joint in the tailshaft of the trans to compensate for movement, thermal growth, and allow for assembly.

A one piece DS can only have two flex joints not the three (CV, ujoint & guibo) you've proposed. A three flex joint design, like BMW's, only works with a center bearing. If BMW didn't have a center bearing to allow the driveshaft to hinge, you wouldn't be able to remove it without pulling the engine/trans or dif. BMW's CV joint does allow for some, although limited, axial movement. This limited axial movement will likely make installation difficult and require very precise measurements. I suppose it would be possible to design an adapter for the BMW trans output flange to allow a u-joint to bolt up like GM and Ford use to connect to their differentials using u-bolts. $500 is starting to seem like a bargain.

Paul Shovestul

and I don't want to replace it with the same moronic assembly for $500.00.
I can see no reason for such a design. Since the diff. is solidly mounted there is little to no movement to compensate for (see: every Corvette since 1963).

I'm contemplating taking it to a local driveshaft shop, having them fabricate a one-piece shaft with the CV joint at the back, and a set of U-Joints just aft of the Guibo. This will give pleanty of flex without having a "hinge" in the middle.
And I don't buy "the engineers know what they're doing" routine. Otherwise we wouldn't be constantly hopping up our cars, we'd leave them as builtI'll let you know how it goes.


Any comments/thoughts?


Regards,
M.R.

[stargazer_61]

I ended up replacing the entire D/S. I kept blowing through support bearings. The U-Joint was stiff on one axis, causing a severe vibration/knocking between 25 & 40 MPH. A good local shop here, which does a lot of 4x4 work, prefers to NOT work on BMW shafts. These are sealed joints that are staked in. I got a quote from a shop in Raleigh, NC, recommended by Shadetree Mechanic, that was higher than the cost of replacement. The new D/S came with a new CV & support bearing.

There should be no radial play in the CV. It should be very quiet. When I was trying to diagnose it, the mechanic in Chapel Hill said that there would be a "tinging" sound if the CV were bad.