Reconstructing Constant Velocity (CV) Joints

[Grady Clay]

Aah lawyers…..

Many (most?) racers in the ’69-’76 era threw away the roll pins and just used the four M10 bolts. It made for faster transaxle R&R. Clearly the pins were not essential if the bolts were tight.

“Let me repeat something that has been said many times. The CV bolts do not transmit the axle driving torque in shear or bending, they only provide the clamping force. It is the shear friction that transmit the driving torque and it is generated by the high pressure provided by the CV bolt clamping force. This is the reason why it is so important to maintain the highest clamped pressure for the steel-to-steel surfaces. That is why the proper torque is ESSENTIAL.”

Does this meet with your editorial approval? Hehe. Me don’t no english so goot.

Thanks Randy.

Best,
Grady

[rcwaldo]

[i]
Who on this Forum has the ability to measure the hardness of steel parts?
It would be very instructive to know the relative hardness of the surface under the CV bolt head, the Schnorr washer, the “half moon” washer plate, the tin CV cover, and the outer race of the CV.


[/B]

Grady, send some sample fasteners to me and I can "Rockwell" test them for ya at work. Fairly easy to do. Let me know.
Be glad to help!

[randywebb]

It does.

Actually - you see the scientist above - not the lawyer.

I like my pins - a lot easier to reinstall the things...

[jpahemi]

Grady:
Any info from Schnorr regarding the original vs. the McMaster versions?
j.p.

[rcecale]

Grady, Randy, gang...

I've been practically exiled from the BBS here for a while...just a few posts here and the, but I thought I should come here and post an update on my own particular situation.

Since I didn't have a lot of time to spend disassembling my CV joints, I decided to just spring for a new pair of rear axles. Plus, I figured if I just replaced/rebuilt the inner CV's, it would only be a matter of time before the outer ones wore out, ant that would require replacing the axles anyway....so, new axles were ordered. Old ones removed and new ones installed in just a few hours.

While doing the replacement, I took care to do a little "prep" work. Using some degreaser and a ton of Q-tips, I cleaned out the threads in the drive flanges of all grease and grime. Cleaned them until a clean Q-tip wiped around the inside of the threads came back out white....reminded me of when I was cleaning my rifle while in the Marine Corps.

Once cleaned, I installed the new axles and torqued to spec. New bolts, schnorrs and half-moon clips all around. That was almost 500 miles ago.

Climbed underneath tonight to have a look and check for tightness of the bolts. It was great to find that EVERY bolt was just as tight as they were when I installed them. Not one loose bolt on either axle.

Sadly, though, while the klunking noises have reduced quite a bit, they still exist. But, I think I may have found the source.

Whenever I need to raise the rear-end, I use the method suggested by John Walker. Positioning the floor jack underneath the exhaust cross-over flange, I raise the rear-end high enough to set the jackstands in place. It was while I had the weight of the car/engine on the jack that I took a look at the engine mounts (as was suggested here a few months ago). Here is a pic of what I found.

Driver's Side:


Passenger's Side:


Time for some new mounts???

Randy

[jpahemi]

WEVO SS all the way!!!
j.p.

[rcecale]

jpahemi,

To keep this thread on topic, I started another thread about engine mounts here.

Randy

[Tut]

If you suspect that the CV joints are bad, is there a test, procedure, whatever, that you can do under the car, when everything is still together, that would help you along with your diagnosis?

Grady?

Thanks for an incredible amount of information in this thread.

[Grady Clay]

CVs are occasionally mysterious about their failures (in Randy’s case it was easy). The characteristic noise is a “snap” or “click” usually under load and cornering.

Some things you can do are:

Feel the CV boot. If the cage has broken some of the pieces and balls may get pushed out into the boot.

Confirm there is no significant rotational play in the CVs. (Very subjective.)

Confirm the axle shaft can move axially about 1 cm or so. Try this in several different rotational positions. It should be relatively free to move.

With the car properly supported and the suspension “hanging”, rotate the rear wheels by hand. Listen for a “pop” or “snap” sound. See if you can feel it in the axle shaft.

In some cases it might be worthwhile to run the car while supported in the air. Be very careful, two flimsy jack stands may tip. You might try this both with the suspension hanging and with the suspension supported. Be careful that a tire can’t rub a jack stand. You can load the CVs by lightly applying the brake. If you run the car in the air, take EVERY precaution.


If in doubt, service the CVs for inspection. The cost of grease, four boot kits and new hardware is insignificant compared to the damage that can be done. A little extra maintenance is a good thing for peace of mind.

Best,
Grady

[Tut]

Thnaks, Grady. I'll give your suggestions a try.

[}{arlequin]

is there a particular type of grease that's best for cv joints? if one is hard to find, are other types suitable as substitutions?

thanks

[randywebb]

use an EP type grease -- extreme pressure

always use a quality name brand (tho the brand might not have been known to you last week...)

synthetics are good, eh?

most will say that they are FOR CV joints right on the pkg

Of course, Pelican sells good grease...

[jpahemi]

Isn't the grease a speciel moly/graphite blend that usually comes in blue tubes, used specifically for CV's?
j.p.

[randywebb]

yes - think I've seen some of that -- forget the brand

I've seen some with lead in it too...

[Tut]

Grady,

Hope all is well with you.

Finally had a chance to get the car up in the air to check out my CV joints per your instructions. All was quiet, with no popping, clicking, or bumps. Proper axial movement. Two boots shot, so I'll replace them all and service the CV joints. Some questions:

What is the proper pitch for the M10 50mm bolts?

Does it make any difference what the finish is on the bolt, provided that they're 12.9?

Is the only place to get Schnoor washers from Schnoor? If so, will they sell in small quantities (like a bag of 100, or whatever)?

OK to use the moon plates a second time?

Is it ok to use the self-locking axle nut again, or should they replaced?

Any other thoughts?

Thanks.

[}{arlequin]

small hijack....

first, i reused the moonplates w/ no problems... just cleaned them up before reassembly

second, i had no idea what length of cv bolts i had on the car, so when ordering from mcmaster i did the shotgun scatter approach and bought 45mm, 50mm, and 55mm. I believe I only used 50mm so if you are interested in a box (way more than you need) of the others, let me know.

don't know about the axle nut, mine is the castle type so I only put in new cotter pins

mcmaster sells washers very similar to shnoor called belleville that work in the same way as shnoor. many here have used them successfully

[Tut]

bump

Grady, are you there?

[k9handler]

very good info in this thread. =o) I just purchased 4 of the CV boot kits since mine are looking aged...but reading this thread has been quite an eye opener. I am going to drop the engine/tranny soon to replace the clutch and associated clutch parts so I thought I would replace the CV boots as well. The kicker is I need to do this job in one day...I have done the clutch job in one day before, but adding the CV boot replacement may push me over the time limit.

OK...my question is can someone post a drawing of the press method to remove the shafts from the CV joint? I see the points to support on the CV joints but I dont see where the press/pressure is applied.

EDIT: Another question.

I just went out and looked at my CV joints (Outer) and they have bolts securing them like the inner ones...so does this mean I can pull them without removing the wheels as described in the 101 Projects? And...would it be possible to remove both boots while only removing one CV (i.e. sliding the boot over the entire axle lenght and off)?

[Grady Clay]

Tut,

Sorry, your questions escaped me.

”What is the proper pitch for the M10 50mm bolts?”
M10 is 1.50 (M8 is 1.25)

”Does it make any difference what the finish is on the
bolt, provided that they're 12.9?”
Yes, there is some discussion about this. Porsche plated
the replacement bolts for a while in the ‘80s and went back
to plain black finish. Some mechanics won’t use plated bolts.

”Is the only place to get Schnorr washers from Schnorr? If
so, will they sell in small quantities (like a bag of 100, or
whatever)?”
I e-mailed them a month ago, I’ll try again.

”OK to use the moon plates a second time?”
Yes, inspect for any raised places.
You can also turn them over.

”Is it ok to use the self-locking axle nut again, or
should they replaced?”
Yes, the self locking nut is a “use once” part. The earlier
castile nut can be reused if OK and with a new cotter pin.


Smitty,

Plan the work, lay out all your tools, get a knowledgeable
helper, start early, have all the parts ready, have the
torque specs written out, etc.

Here is the diagram Randy (Pelican rcecale)needed.




The easiest way is to pull the entire half shaft out, including
the stub axle. That way you can get it in a proper press with
the inner race supported, clean and re-grease everything and
torque the CV back onto the stub axle. There will be a better
result and it will go faster.

Yes, you can do it leaving the stub axle in place. However it is
next to impossible to get the outboard CV reattached to the
stub axle. Most who try it end up taking the stub axle out
after a frustrating hour.

Best,
Grady

[k9handler]

thank you Grady, so since my CV's have the 4 bolts on both the wheel/shock trailing arm can all stay in place? The bolts on the outer CV's will likely give me a hell of a time as I don't think they have been off in quite some time.