Reconstructing Constant Velocity (CV) Joints

[Grady Clay]

Randy,

That axial end play is normal. The transmission axle flange #12 is
bolted to the threaded piece #3 by the bolt #14. The differential
gear #2 floats (purple arrow) on the splines of the axle flange
#12. It also can float on the splines of the threaded piece #3
but not when in place. The assembly #12, #3, and #2 floats
axially in the differential housing #1. That is the axial end play
you felt. There is also some radial clearance but you probably
can’t feel it by hand with gear lube in place.
IMAGE 915DifferentialNormal02
"
"
(C) 9/1972 Dr. Ing. h.c. F. Porsche A.G.


Now, what was causing your noise? Did it just go away?

Best,
Grady

BTW, I wonder how many wrong spec versions of Bentley
are out there?

[rcecale]

Originally posted by Grady Clay
Randy,

That axial end play is normal.

Grady, you don't know how great those words from you were to read...really! I'll sleep much better, and drive better too, just having read them.

As far as the clunking noise, I haven't been able to tell if it's still there or not. I just got home from work and was going to head out and drive her around a bit to see. Perhaps it's just coincidence, but the axial movement of the flanges didn't seem as drastic after I got it all back together. Maybe the new seals were just a little tighter and didn't allow for the same ease of movement as the old ones.

I'll give her a ride and report back what I find.

Randy

[rcecale]

"CLUNK!"

Well, it's still there. ARGH!!!!

I'm trying to pinpoint where exactly's it's coming from, but with my back to it, it's rather difficult to tell. It's definitely coming from the back end though.

At first it sounded like the outboard CV joint on the drivers side...right behind my left hip. Then, a few minutes later, it seemed to move toward the center of the car...one of the drive flanges or most like, one of the inboard CVs.

There was nothing I could do intentionally to make the noise, it just happened at random. The streets around my house are quite twisty, and there are several cul de sacs that I could corner in. Some hard, some more gentle curves. Again, it just happened when it wanted to. Even backing out of the driveway didn't produce the clunk 100% of the time.

I'm afraid to say this, but I really think it may be my CV joints...maybe one, maybe a couple of them. But this seems to make the most sense.

They looked okay when I had them apart though, that's what digs at me. I mean, I'm no expert with a trained eye, but I did look at them and noticed NO wear indications. Unless you've got a better idea, I'm afraid I'll be ordering a new pair of axles in the very near future.

Randy

[rcecale]

Originally posted by DW SD
Do you just cradle the axle side of the joint and use a hydraulic press to press out the center?

Doug,

That was pretty much the gist of it.

1.) Pop this cap off.


2.) Remove the circlip from the end.

3.) Cradle the sides of the CV joint and press it right apart.

Putting it back together was a bit more tricky, but basically, just the opposite.

Randy

[Shaun @ Tru6]

This is a great thread!

I WISH my CV bolts would back out!

[Grady Clay]

Randy,

Sorry.

How about a “better” description of the “clunk.”


Is it a single noise once and a while?

Is it a “snap” or a “thud” on the range of how sharp or dull the noise is?

Is it rhythmic with the wheels or engine speed?

Will it do it when costing, in neutral, or the clutch disengaged?



OK, on to your CV disassembly – assembly procedure. Did you support the CV by the inner race or outer race when pressing off and on? I can’t tell from ”3.) Cradle the sides of the CV joint and press it right apart.”

Best,
Grady

[DW SD]

Randy,
I appreciate your attention to my question. I understand how to disassemble. I just was curious about the press itself and how you set that up. I don't have a shop-style hydraulic press. Did you use some other tool to make it work?

Thanks,

Doug

[lusso]

My car is in the shop with what sounds to be the same symptoms. I have not heard from my mechanic yet, but hopefully will have an answer soon. I'm learning a lot from thos thread, thanks Randy and Randy.
David
Ps my car only makes tha clunk in gear and clutch engaged

[rcecale]

Originally posted by Grady Clay
Randy,

Sorry.

How about a “better” description of the “clunk.”


Is it a single noise once and a while?

Yes, a single noise, occuring randomly. It does seem to happen practically every time I transition from my driveway to the street. There is a little dip where the lowered curb meets the asphalt.

Is it a “snap” or a “thud” on the range of how sharp or dull the noise is?

Much closer to a snap than a thud. It has a "crisp and solid" sound to it. Similar to a slide hammer, or rapping the handle of a breaker-bar against a brake caliper (installed)

Is it rhythmic with the wheels or engine speed?

Nope, it's more of a single clunk, occuring when there is a change in attitude of the car. While travelling in a straight line, I don't think I notice it. Around curves seems to be the times when it happens.

Will it do it when costing, in neutral, or the clutch disengaged?

Haven't really tried neutral, but if I am coasting with the clutch pedal depressed, it can and will make the sound. My driveway has a slope to it, and my car sits fairly low, so I tend to take the transition from into and out of the driveway at an angle. I usually am coasting with clutch disengaged at these times. Again, I do hear it most of the time during this transition.

OK, on to your CV disassembly – assembly procedure. Did you support the CV by the inner race or outer race when pressing off and on? I can’t tell from ”3.) Cradle the sides of the CV joint and press it right apart.”

Best,
Grady

The best way to describe where I supported the CV joint is with this pic. The red blocks serve to indicate the support block positions. Hope this helps!





Randy

edit: I suppose it would be nice to see the pics I spoke of.

[Grady Clay]

Randy,

The noise is consistent with a damaged CV. I would take a look. I know that isn’t what you want to hear but better safe ….

What may have happened is the outer race got supported and not the inner. Many times I’ll bet the CV will press on the splines without any damage. If it is slightly cocked and takes force, some of that force is transmitted to the cage and it can crack.

Now that you have the illustration, I’ll bet that is what happened. Notice the two arrows in the Bentley instructions.

The CV has to be pressed off and on with the tin piece pushed back and support the inner race (hub). The outer race should be free to move (axially and wobble) during this process.

Sorry ....

Best,
Grady

[rcecale]

Thanks Grady. I was afraid this was the case. Looks like I messed them up myself. That has to be the hardest part to swallow.

Rather than rushing out and buying a pair of new axles, I suppose it would be worth my time to just pull the axles apart and have a look/ Who knows, maybe it's only the inner CV joints. (Wishful thinking, I know... )

The alternative to this would be to just spring for the new axles, install them and be finished with them. Sounds easiest, that for sure.

Argh!

Well, thanks again for the info, Grady! As always, you were right! Definitely not what I wanted to hear. If nothing else, I hope this thread helps others when it comes time for them to mess with CV joints.

Randy

[randywebb]

just spring for the new axles....

- nuh uh. you are too far in now. no wimpin' out and buying something...

BTW, if you install and remove the CV's 3 times, it gets easier to do - ask me how I know...

[rcecale]

Randy,

If there's a way to repair my CVs, I'm all eyes!

I've got the newer axles, with the outboard CV incorporated into the stub axle. I don't believe these are repairable.

My axle:


I know I can replace the inboards, but the outboards, from what I read, if they are worn, require the replacement of the whole axle.

If you know of a way, do tell. It's gotta be cheaper than new axles.

Randy

[Grady Clay]

Randy,

When you had the axles out, did you do anything to the outboard CVs? Did any of the press loads go through them when you were disassembling or assembling the inboard CVs on the axle shaft?

I would suspect that only an inboard CV is damaged (probably left axle from your description.) You could get one CV and replace just the damaged one. You should be able to easily tell the damage. Run your finger around both ends of the cage. You should find a crack or broken cage pieces.

HELP
When you were doing this a month ago, I picked out about 10 pages in a Factory workshop manual and a friend scanned them and sent the file as e-mail (he uses the manuals all the time for his shop employees.) They have a .jsd extension and I can’t open them. Does anyone have any ideas? It would be worthwhile to compile an exact set of instructions for this operation. I can e-mail someone this file (2.7M).

Best,
Grady

[RickM]

Grady,

Tried sending a PM but your box is full. I tried an EMAIL.

[Grady Clay]

I only have two in-boxes; snail-mail and e-mail (gradyclay@hotmail.com)

Best,
Grady

[randywebb]

Like Grady said -- but, you know, the longer this saga gets, the less I like the "improved CV assemblies" - not sure what P AG was thiking...

[Grady Clay]

Randy,

A few weeks ago I was talking to some PCNA techs about this subject. Their opinion (not PCNA’s) was that the bean counters and engineers are always at war. Nothing new there. The money side got rid of the Schnorr lock washers for a while and forced the use of the 923 (912E M8 bolts) axles and the weld-on 108 mm CVs. The result was a spate of CVs coming loose on brand new cars. Warranty claims soared. The engineers got the parts that should have been there from the start. The “Turbo” axles (actually a 928 P/N) are clearly what should be on the cars IMHO. I’ll do some searching to see if there is any campaign. Yes, they are more expensive to manufacture. You have separate stub axles, 24 M10 bolts, 24 Schnorr washers, 12 plates, and replaceable/serviceable CVs on the axles. Just like ’69; some overkill but last a long time (Those great big CVs were on ’69 912s also.)

It still doesn’t preclude torque the CV bolts just after assembly and some use and periodically at a service. I don’t think anyone has a handle on why we hear of so many CVs coming loose. The Bentley spec error and some people using M8 torque on M10 bolts are the only definitive things I have seen.

I would like to hear some feedback on how much the CV bolt turns (if any) when re-torque after the first installation. After a second torque, has anyone experience with painting the bolt-Schnorr-plate-cover with paint of nail polish to tell if there is movement?

Best,
Grady

[rcecale]

Originally posted by Grady Clay
When you had the axles out, did you do anything to the outboard CVs? Did any of the press loads go through them when you were disassembling or assembling the inboard CVs on the axle shaft?

Well, I didn't do anything "intentionally" to them. Intentionally, all I did was remove the boots, cleaned them out as best I could, greased them back up and installed new boots.

Unfortunately, when it came time to press the inboards back on, the load from the press DID pass through the outboards. Basically, I supported the outboards and pressed down on the inboards...supporting the outboards in the same location I indicated previously with the red blocks. So, there is a good chance that the outboards are toast too, I suppose.

The first clunk I heard last night would support that because like I said, it seemed to comes from right behind my left hip...outboard driver's side. After that, though, they did seem to come mainly from the center of the car.

I'll have to drive the neighborhood tonight with my wife and have her listen. Maybe, if she's lucky, I might even let HER drive so I can hear. LOL

Grady,

As far as the .JSD files, there are a few different programs that use .JSDs. The most likely one would be Paint Shop Pro . You can download a shareware version and check it out. I DID find this though...


If you want, you can e-mail them to me at rcecale@hotmail.com.

THANKS!!!!!

Randy

[RickM]

Actually, PSP wont open this type file. I've tried several programs but with no luck.

It appears the source is Jet Suite Pro which is a program that is bundled with drivers for Oki / HP multi function machines. Only available on CD with the machine.

I managed to find a copy that works with Win 95/98 but not with 2000/XP/NT so I can't run.

Grady, Do you have access to 95 or 98 at home? I don't presently. I'll be happy to send if your email can handle a 40 M zip file. (Or I'll provide a link that will require registration so you can download).