DIY: Half-shaft R&R - Outer CV Joint Rebuild

[tjm3]

No, not even close. There's a couple of good youtube videos about this(found one below). Unfortunately friction welding requires some heavy duty equipment. That small bead in the middle of the outer cv joint/spline is where the melted material is forced out during the process. Watching this video, the spline piece would be on one side and the outer ring of the cv joint on the other.

http://youtu.be/-aEuAK8bsQg

[pbonsalb]

There did not seem to be welding when we removed the caps but maybe it is so fine that it looks almost like crimping. One guy here got the caps off without damage and reinstalled them after the rebuild or regrease (do rebuilders really use new balls and cages?)

[tjm3]

The friction welding is a very precise operation. There are two pieces - the spline and cup and then the outer cv joint piece.
The BMW rebuilt units have new cv joints and the outer is cut off and a new joint welded with this process. That's why the BMW rebuilts cost $550 or so. I've heard that the cv joint races can be re-machined and larger balls installed but I could never verify this. I've purchased brand new Chinese units for $75 each just to see what they look like. They use the recycled spline/cup with the new cv joints and the outer is friction welded. They have a solid axle shaft instead of hollow like the BMW originals. One of the two I bought and installed made some clicking noises so I think the CV joint quality is questionable. For $75 I wasn't expecting too much but they're not too bad. I forgot the company name. I'll add it later. You can buy German CV joints from GKN (GKN.com) but they cost about $125 each for the inners. The outers you need to call because they have no bolt holes AND there's the welding problem. I suspect that BMW buys from GKN.

I take the caps off on a lathe by cutting the crimp. There's a second groove on the cv joint closer to the end. I made a tool to recrimp the cap into the second groove.

[gotboost79]

TJM3, Youre right to a point, its not a complete rebuild since new parts are not available to replace everything but certainly is the best option unless you go with new units from bmw if theyre even around anymore. Friction weld actually isn't welding in a sense since nothings being melted together rather its a machining process to join metals together. Had to google that

- - - Updated - - -

The friction welding is a very precise operation. There are two pieces - the spline and cup and then the outer cv joint piece.
The BMW rebuilt units have new cv joints and the outer is cut off and a new joint welded with this process. That's why the BMW rebuilts cost $550 or so. I've heard that the cv joint races can be re-machined and larger balls installed but I could never verify this. I've purchased brand new Chinese units for $75 each just to see what they look like. They use the recycled spline/cup with the new cv joints and the outer is friction welded. They have a solid axle shaft instead of hollow like the BMW originals. One of the two I bought and installed made some clicking noises so I think the CV joint quality is questionable. For $75 I wasn't expecting too much but they're not too bad. I forgot the company name. I'll add it later. You can buy German CV joints from GKN (GKN.com) but they cost about $125 each for the inners. The outers you need to call because they have no bolt holes AND there's the welding problem. I suspect that BMW buys from GKN.

I take the caps off on a lathe by cutting the crimp. There's a second groove on the cv joint closer to the end. I made a tool to recrimp the cap into the second groove.

Good info, thanks.

[tjm3]

Friction weld actually isn't welding in a sense since nothings being melted together rather its a machining process to join metals together. Had to google that

Look again. The two pieces of a friction weld are definitely 'welded' together under friction heat and pressure. I don't think there's any other way that these two pieces could handle the torque at each wheel otherwise.

[pbonsalb]

I thought we were talking about the thin metal cap that goes under the boot. That cap does not handle any torque.

[tjm3]

Yes, the cap is crimped and definitely not a torque issue. In fact, the main reason I see for the cap is just to keep the range of motion limited enough so the balls don't fall out of the joint while it's being handled for installation or for shipping. I received one of those new chinese made axle shafts without the cap that had moved to an angle of about 45 degrees from straight and got stuck. The balls moved to a position that locked the cv joint tight and couldn't be recovered even with a good amount of force. I had asked my supplier if I could try it and got the OK to try anything as it would be going back as defective anyway. Couldn't unlock it.

I'm hoping that the friction weld issue above was for the spline/cv joint attachment.

[z54]

im just about to give up!Grrrr
i cant get the last ball in.

i have tried every possible way, i think im done. so frustrated

any advice, maybe im doing something wrong. it goes in perfect with 5.

thanks in advance

[Butters Stoch]

im just about to give up!Grrrr
i cant get the last ball in.

i have tried every possible way, i think im done. so frustrated

any advice, maybe im doing something wrong. it goes in perfect with 5.

thanks in advance

For the outer joint, put all the balls in, then wiggle the joint nice and easy. It will all fall in place. ALSO remember on the outer joint, you need to line up "big to big". Those that have done this will know what I mean. If you line up "big to little " it will bind.

[z54]

So is this photo "big to big" or "big to small"

Thx

[Butters Stoch]

So is this photo "big to big" or "big to small"

Thx

The photo os "big to small" . But when installing the joint, the other end of the retainer tapers. Therefore when you line then up big to big, it falls in place big to small.

[tjm3]

I'm stayin' out of this one. I will say that the joint can go together the wrong way, in which case it just won't move at all in any direction. It's also much more difficult it you try to assemble the joint dry.

[Butters Stoch]

I'm stayin' out of this one. I will say that the joint can go together the wrong way, in which case it just won't move at all in any direction. It's also much more difficult it you try to assemble the joint dry.

Correct, this is why its important to line them up. You have a 50% chance of this happening. I built 4 cryo treated M3 axles in the last couple months. First one took almost 2 hours to get the outer joint together. Once I figured it out. 5 min. I have found loading them up with grease is better to keep the balls in place.

[berny2435]

nice work. Axles look like a $375-$425/pc investment before shipping costs and core chargers. so for me, since I like to keep my used parts, it'd cost about $1,000 for remanufactured axles. No wonder why you are doing this.

Honda S2000 axles cost like $100pc for remans. $410 shipped for upgraded stuff that are properly built with new shafts. I understand that the outer has parts that basically can't be remanufactured. have to get new which adds to the cost of replacement axles.
http://www.laskeyracing.com/shop/axles.htm


Anyone know what they cost from raxles.com?

[Butters Stoch]

DSS shafts are $1000.
You can buy reman axles for under $100 from pep boys, advance etc. Not sure you can get the M3 axles tho.

So far the cryogenic treated axles I have built are holding up. Both sets are in 500+ whp cars (mine and Pbonsalb) . Right around 30 passes @ the drag strip using drag radials. Not sure how long they will last, but its worth a shot.

[z54]

I'm stayin' out of this one. I will say that the joint can go together the wrong way, in which case it just won't move at all in any direction. It's also much more difficult it you try to assemble the joint dry.

tjm3
Dont stay out of it. Say what you want to say.

Im still struggling with it. Pretty disappointed with myself, i must be doing something wrong. Im not giving up yet!

[gotboost79]

tjm3
Dont stay out of it. Say what you want to say.

Im still struggling with it. Pretty disappointed with myself, i must be doing something wrong. Im not giving up yet!

I'm guessing you're having issues putting the balls back in. Make sure to lay it on a table and have the outer cup resting on the edge. Do not push the shaft w the balls deep in the cup, that was a major mistake I was making. Laying it on its side gives you the leverage to have the cup on the very edge to put the final 2 balls in imo. That was the hardest to do. Here's a pic of how the cup and shaft are positioned, you should almost see all the balls slightly hanging a bit, close to edge of it. I hope I made some sense to help someone doing this. First time was hell for me, 2nd one took 5 min literally. Pic of how it's laid on its side w balls showing on the outer edge of the cup.




I know it sounds a bit confusing. If anyone is having trouble doing this and has facetime available, lmk via pm, would be glad to walk someone thru this process.

[M3only]

Second the above comment and that picture is a fantastic representation of how everything should look when you're installing the balls. The more leverage you have, the easier it is to use gravity and center the shaft while rolling the joint over to install each ball. Also, what helped me, was to install each ball in a row, instead of the suggestion to install them in every other slot.

[328 Power 04]

Just so you know, for Inner Joints

Porsche part number 91133203001 (used on 964 Turbo, 993 Carrera, 996, Boxster S) is the EXACT size and exact part you would need for inner CV joints. GKN Loebro brand is ~$80 online at AutohausAZ.

Outer diameter 108mm
Width 32mm
Splines #28 (~30mm inner diameter)
Bolt Circle 94mm
Bolt Hole 10mm

I used two of these to rebuild Z3 M Coupe inner CV Joints.

I'm still looking for Outer CV Joint options through the Porsche range.

[tjm3]

I'm still looking for Outer CV Joint options through the Porsche range.

The inner CV joints never were a problem. You can source them from several places including GKN.

The outers will always be the problem. The outer CV joint and the spline piece are two separate parts. The CV joint is available, you just can't do anything with it without cutting the spline from the CV joint and re-welding. This is why the BMW rebuilts cost $500 a copy. The Chinese rebuilts use new CV joints, a solid axle (not hollow like the OE) and the spline from old cores for under a hundred bucks. Sure, the material is probably not up to GKN par but I still can't see how they do it so cheap.

[OKsweetrides]

FWIW, after using some trusty calipers, the cage and balls from the inner CVJ (which another has found complete replacements for) appear to be the same with the outer CVJ. So if your friction welded piece is in good shape, the cage, race, and balls should interchangeable with fresh 9113xyz cvj parts. As long as you keep the balls/race/cage from the same group together, iin theory this might be a new alternative. I will 2x check when i get new units in and have a spare axle in my inventory again. It can make a 550$ axle now down to 200$ for rebuild on both ends sans outer friction weld portion.

[tjm3]

Not a bad option as it gets about 2/3 of the parts replaced at the outer joint.

All of this is good and I would do any of this to MY car. For someone without resources or someone having to warranty these parts I would need to think twice. If the money is there then the best option is the BMW rebuilts. Considering the cost of 2 CV joints, shipping and tax, new boot kits and clamps (the kits never seems to have the right size clamps) and the time involved to do the work the BMW pricing looks a little better. But I'm a cheapskate so I go the labor intensive route.

By the way, how's OKC these days. Haven't been there for a while. I was there years back with the FAA when those million dollar northside properties were having a hard time selling for under a $100K. Things improve?

[Braymond141]

I left the limiting shields out of my outer CV rebuild (they were trashed). Aside from needing extra grease to keep the CV lubricated, you just have to be very careful installing the half shaft. Too much angle and you'll pop your bearings outs. I expect it to be fine, but given how easy these are to do I'll just order another axle set if I'm wrong.

[Butters Stoch]

I left the limiting shields out of my outer CV rebuild (they were trashed). Aside from needing extra grease to keep the CV lubricated, you just have to be very careful installing the half shaft. Too much angle and you'll pop your bearings outs. I expect it to be fine, but given how easy these are to do I'll just order another axle set if I'm wrong.

It will be fine. I've built and cryo treated a couple sets. As you stated, keep the axle straight.

[Braymond141]

It will be fine. I've built and cryo treated a couple sets. As you stated, keep the axle straight.

Thanks butters. I thought so. X5 is the same on the outer front CV so I didn't see the harm