CV Joints - Rebuild or Replace?
 

Hey all -

I am in the process of having my Transmission rebuilt. When I removed the CV Joints, the ball bearings fell right out.

Is this a problem or can I rebuild the CV joints? I have heard that the rebuild can be a bit challenging - like a Rubik's cube.

Looks like new CV Joints would be about $320.

Parts to rebuild including boots are about $60.

I have an '84 911 - apparently things changed a bit in 85.

Any advice appreciated.

Nearly all of the CV joints I have inspected were worn. Many were pitted. In my experience, it is fairly rare to come across CV joints that are fine and can be cleaned and reused. I think that if someone disassembled, cleaned and repacked them annually, they would stay fine for a long time. But nobody does that. Used, worn ones can of course be cleaned and repacked. And generally they will provide service. So....I guess it is up to you. My advice, if you can afford them, is to simply replace. Or clean and inspect. Look at the wear surfaces on the races. Pitting is bad. A little wear/discoloration is acceptable. They are not difficult to disassemble and reassemble. There are pictorial, step by step instructions. Probably posted on this site somewhere. Not difficult at all to disassemble and reassemble. Messy, but not difficult.

If they are in fair shape rebuild

If they are heavily warn replace.


Some excellent threads on this are easy to find with the search function.
Type CV Joints

Rebuild is not bad, it is very greasy. :eek:

You will need
2 Roll paper towels
5 pair of rubber gloves
Half gallon of lacquer thiner (Cuts the grease)
Brake Cleaner
Metal cans or bowls for soaking

This the best one I have found.

http://forums.pelicanparts.com/porsche-911-technical-forum/222537-reconstructing-constant-velocity-cv-joints.html

It not that bad, spend some time reading the CV threads they contain all the fine points.

take some good closeup pics of the ball bearings & of the cages - post

or just buy rebuilt ones if $$ is not that big an issue

Everyone is correct in this set of threads. It is like a Rubick's cube. It is greasy. It is not difficult.

But it will suck time. Lots of time for the DIY "noob" (like me) doing this job. You can't really put them back together wrong as they will not pivot freely. They will freeze.

I would suggest to scope it out before you buy the gaskets, seals and grease. Clean them up and see if there are heavy wear marks on the thrust surfaces. Slight wear marks are ok.

If I had to do it again, I would spend the money and get new.

the bolts, people...the bolts...

since yours is 84, I suspect you did not see any washers with the six hex bolts holding the CV to the gearbox and hub flunges. getting the bolts in grease free is near impossible but i encourage you spend time and try.
also, get moon plates and schnorr washers if you can.

http://forums.pelicanparts.com/porsche-911-technical-forum/293582-m8-schnorr-safety-washers-p-n-cv-thing.html#post5388505


besides that, rebuild and repack. CVs can go many many miles.

CV Joints - Repair or Replace
 

Thanks - will update you all this weekend with pics.

An entire new rear axle is only $420 if you go genuine Porsche. You can get one on this website for $320 from GKN and not worry with the grease! 911-332-024-15-M60

As to grease free bolt installation, this works pretty well:


Clean bolts 1st
Install all bolts & tighten to 5 ft/lbs less than spec
Remove 1 bolt at a time, clean hole with brake cleaner & compressed air
Clean, dry & reinstall bolt
Final torque & you're done fairly quickly & without too much mess.

BTW, I don't know if the link provided above states this. . .I haven't checked it out, but there is a way to redo these (as long as no pitting on the balls or 'races' (if you can call them that) to where you can get the balls to ride on unworn areas of the outer and inner rings. Once you get one clean and figured out, you'll see what I mean.

I dissagree with MT 930 above: You will probaly need at least 3 rolls of paper towels.

Pics - as requested. I am leaning towards cleaning and repacking - due to other projects I have to complete right now. Open to suggestions on this....

Seems to be some wear - balls look perfect.

http://forums.pelicanparts.com/uploa...1276469629.jpg


http://forums.pelicanparts.com/uploa...1276469668.jpg

looks like minor wear but not too crazy re the color changes...

what does it feel like to your fingertips? to your finger nail?

Feels very smooth. There is a very slight rounded indent in every other "track" (don't know what to call them.) The indent is not deep 1/10th mm or so?

What's the risk in repacking these and using them?

IMO, this is not only a financial decision. What is your threshold of pain for doing this kind of project?

Do you plan on having them off again, say, next year for an engine drop or bearing replacement? If so, rebuild the CVs and drive them 'till they break.

If this is something you want to do once and drive the car for the next 5 or more years, trouble-free then buy new. CVs are a PITA, especially the kind we have. I have never had one come loose, BTW, after careful re-torquing after driving a bit. I get grease everywhere when re-assembling (like most mortals) so don't sweat it.

very low risk - some just run them until they get noisy - yours weren't, right?

the real question is the $$ vs. the fun of R&Ring them again sooner than if they were new ones

Thanks for the advice. Mine were not noisy and I would rather spend the $250 saved (or so) for just CVs OR $400 saved (or so) for axles on other more critical stuff right now.

I only drive 3 to 5k per year - so I think these will last awhile!

Again, I'm sure you see what I was talking about now as far as arranging things to run on unworn surface areas. I've done this on several CV's, even a pair of really noisy ones on a 44, got an additional 100k out of them after doing so.

Good luck and have a blast!

Does the order of the ball bearings matter?

Do I need to install the same CV to the same side of the car?

I am not quite sure if can backtrack and figure out what went where exactly - but don't want to create further problems due to wear patterns.....

Immediate Advice appreciated - as I want to start tearing these things apart tonight!

It is always best to put it back the same way it came apart. But I would not go so far as trying to match the bearings back to where they were. If you notice there is a small groove around the circumference of the outer assembly. Note if the groove is inboard or outboard, that is how you want it to go back together on the car. I would recommend you dry assemble, check for proper movement and rotation, then pack with grease. Also make sure you torque the bolts to 32 foot lbs. in an alternating sequence.

I would re-pack em. Until you get some grease in them they might be a little bit sticky and clicky. If they are smooth after grease goes in, you can feel good about putting them back on the car.

Rusnak,

Do you know how it feels when you put them back together the wrong way and they don't swivel right? Then you have to turn the outer ring around. That is what I was referring to. It is hard to explain, but if you don't remember how they go back together visually then you can save a mess of grease by assembling them dry fist and checking the swivel. Of course if you are 100% sure you are putting them back together right the first time then lube away.

I know this because I have put them together the wrong way with grease. SmileWavy

Shane

Some folks take careful measures to know which pieces went exactly where. That way they can reverse the whole assembly so the main wear will be (usually) in a different, less worn, place. Or then can reverse the orientation of the inner and outer races, again to move the wear.

However, these are all made with a fairly high degree of Eli Whitneyan precision, so if you don't know which goes where, don't sweat it. It really doesn't matter (other than the two ways, only one right, of lining inner up with outer). I have noted the ring around the outside, but never seen anything from Lobro or Porsche to tell me that it matters.

Some folks are fanatic about moon plates and new schnorr washers. I use neither - just more weight (though if you have them, why not use them - the weight is something only a racer would give 10 seconds thought to). As long as they are well torqued (and it is a good idea to retorque after a hundred miles or so of driving, just in case), they won't come loose. At least mine haven't.

A criss/cross torquing pattern may be the best practice. But I torque in a circle because it is the easiest as I rotate the wheel, and I am least likely to miss one. Again, seems to work.

And rebuild kit? What kit? If your boots aren't torn, reuse them. Get some high pressure grease and reassemble.

My rule of thumb has been no pitting on the balls, and no grooves you can palpate. Shiny is fine - just means the race has been burnished. Of course, if the defects are small, I'm inclined to reassemble.

At one point one heard about wear on the cage part. The balls were supposed to snap into place in it. If they do, this makes reassembly somewhat easier. But the last new set I got had a loose cage - nothing snapped into anything. And the races, where not worn, looked like yours - striated and a little rough in appearance. In addition, you could see where the outer race had been heat hardened - it was blue toward the inside, and steel silver toward the outside. Unlike those of yore, which were a nice black everywhere. So I guess loose balls are OK?

Walt

So I finally found some time to open up and clean the other set of CV joints on one of my axles. The first side looked okay to rebuild (Pics above.)

I have already purchased the grease, boots, and circlips to do a rebuild.

This is what I found (and I think it means replace....) What do you all think?

http://forums.pelicanparts.com/uploa...1278202976.jpg
http://forums.pelicanparts.com/uploa...1278203010.jpg
http://forums.pelicanparts.com/uploa...1278203038.jpg
http://forums.pelicanparts.com/uploa...1278203067.jpg

Wow, that pitting means replace.:eek:

Per John Walker, no.
When I did mine, I made sure that the movement was smooth on all. Re-assembled with new boots and had no issues whatsoever.

Replace.


Same.

If it were mine and I had the spare $$ in that budget area, I'd replace, at least that one joint if it's the worst there.

However what's going to happen if you do run it? You'll replace it anyway in 15 - 20k miles, maybe even more? That's over 3 years to some people. It's not like these things have a habit of exploding and leaving you stranded without any serious warning signs. And the shafts themselves are a cakewalk to remove/installed and a complete replacement shaft can be installed in >30 minutes start to finish if you do it as a unit.

If I needed my $$ to go to more important items on the car at the moment, I'd run it. As Walt and I have pointed out, if you get to understand their assembly you can generally get all components to ride on unworn/undamaged areas of the races. That bright, smooth shiny area in your second pic is typically the wear we are speaking of, not the major pitting shown in the first (although I do see a bit of pitting in the second pic too). Take note of the major lines of force here that act on these to move your car in a forward direction. ie, what part of the inner race is applying force on the balls and what part of the outter race is taking it when moving the car forward. It just could be that you can avoid the pitted area of that race alltogether if you get your assembly just right. With that in mind be sure to label the shafts during assembly as to the forward direction you want them rotating in so you'll remember that when you go to install them.

So the CVs are about $80 each and my budget is already blown (had to get a flywheel.)

The plan is to tear down and degrease the other two CVs and see how they look.

If the 2nd axle is like the first, I may be able to salvage another CV.

I'll decide after I take a look at the rest.

Seems to me that the issues with CVs are related to bolts coming lose, not the internals.

More to come....

This is exactly what I was thinking of when I mentioned being stranded by a CV (that has given no prior warnings). Ask me why I know. :rolleyes:

Anyway. I think you get what I mean about the force Luke. And remember, the transmission side outer race will apply force to the inner, and the at the wheel joint it's the opposite.

I used to do these when working at a VW shop in the early 70s. The first set of pics from last month looked good and I'd recommend keeping and repacking. The very pitted one from yesterday, I'd replace.

The key to working on these is a running solvent tank. Makes the job so much easier. A lift and a air ratchet help too. Used to knock the whole job out in less than an hour with new boots.

You can assemble dry and move 'em around to ensure reassembly has been done properly and then pack grease in. There's plenty of space for the grease to flow.

Damn things last forever if you keep grease in 'em and dirt out.

Wow, you have at least one bad CV joint (second set of pics).

It's as if the metal is inferior on the second pic because of the weird pitting, which is not smooth. I wonder if those are not Lobro?

I'm not sure Lobro, at least as a separate brand, is still available. It is not what you get these days. The last I got were in a box which said GKN on it, then GKN Automotive. It also said Glaenzer Spicer, and finally had the old familiar LOBRO loge with the words LOBRO vertically on it across a CV jointed axle. Made in Germany, though. It had a Porsche-like number on one label923 333 032 00, but said "For ref only." It also did say, on a label under that, "Porsche." So it must have some tie.

I fetched one of the boxes (holding a worn but serviceable spare) from my garage in the interest of accuracy of reporting.

But it was a silver finish (not the old black), and you could see where the heat treat stopped (because it went from blue to silver on the ends. Plus the races were sort of striated rather than any kind of polish. And the balls fell through the cages, rather than snapping into place as of yore.

I have pitting on my races similar to the photos here. Can these be replaced? I mean the CV's not the entire axle assembly. Or am I just better off replacing the whole unit? I have looked for a source for just the CV's but I'm not finding anything. BTW, it is for my '66 912.

I only replaced the CVs - bought from pelican. I considered replacing the whole assembly - axles and all - but was watching every penny.

The job required a bit of patience - and a couple of retorquing visits after I put mileage on the car - but was not rocket science.

I just replaced one of my boots. There is a little bit of pitting on one race in my cv assembly. I thought about replacing the joint, but I figured hey, I'm only spending $ on the boot, grease and gaskets....like $30. That's cheaper than the joint and it will likely go for a lot more miles.

I see axles listed for my car, but I don't see CVs by themselves. Am I just looking in the wrong place?
And why do I only see empi axles for my car? I have read I should steer clear of them.

Just caught this thread - from the first pic I would have said replace all.

Warren's great rant on missing CV repair here (plus excellent dis/reassemble instructions).

Don't scrimp on this - it sucks to not be able to trust your axles. And if they go the implications can be very expensive. Do not scrimp on new bolts, Schnorrs, and the entire routine (great tip on low torque/Q-tip clean above). At ~3/400 retorque all bolts. Peace of mind for 60K miles.

Dean T

Your '66 did not come with CVs. It had Nadella joints, which look vaguely like a U joint, though different. Not like the fat steel disk with a boot and all the innards hidden which is what CVs look like.

So someone converted your car if it has CVs.

You can certainly purchase replacements, but you can't do it by entering 1966 912 into any parts catalog.

Most likely all you have to do is measure the OD of your CV, and count the number and measure the diameter of the bolts holding the CVs to the tranny and axle flanges. The bolts will either be 10mm or 8mm. You should be able to tell by looking at the Allen heads whether they are the one or the other. Some have 4 bolts and two dowel pins. Others have six bolts. All have 6 holes in the CV.

Maybe measure the thickness of the CV, just in case. A search of posts will find various places where someone has spelled out the various combinations of width, thickness, and bolt diameter used over the years. Some (not me) even have this memorized.

Then you get on the phone with PelicanParts, give them this info, and they will be able to figure out what you have so they can sell you the proper replacement.

On these early cars I don't think it is even possible to purchase the whole assembly. That came in with the late 3.2s (I think) where the outboard CV was friction welded to the stub axle.

I wonder if it is even possible to purchase just an outer CV with stub axle already attached? I think only the whole assembly was (and is) available. However, for your pains these came pre-lubricated, and the inner CV has a stamped steel plate on its tranny side. So replacement ought to be pretty antiseptic. Entirely unlike the greasy fingers and hands experience we all love so much. But it is highly unlikely that one of these unit replacements will fit your car. And you don't need a new axle. Just four (if all are pitted) new CVs, new boots just in case, and some grease (which comes with the CVs).

If "good enough" is your general approach to things, don't fret too much about this. I don't use washers and reuse bolts as long as the Allen hex is OK. Others can do what they want, but I'm here to tell you I haven't had a bolt failure on my cars in 25 years. And with the fact that CV boots are not a lifetime item, engine rebuilds, tranny gear changes and rebuilds, major repairs, race cars, hollow axles which broke, and all I have about as much experience with CV removal and replacement as any guy not doing repair for a living could expect to have. Way more than I'd like, but that's just a fact of CV life.

Nothing wrong mechanically, of course, with buying and using a bunch of new stuff each time, if you want to.

The key here is to use a torque wrench initially, and retorque after a reasonable interval. If you do that, they won't come loose on you. On the race car I try to do that after the first track session or so - sometime on first day back on track when time permits, or at the end of the day. A couple of hundred street miles seems reasonable there. If you are using the CVs with gaskets (and are using the gaskets), there is a suspicion that the gasket may not be fully compressed on initial torquing, which is why retorquing once it has been squished some by running would be critical. But no matter what, retorquing is a small price to pay for the peace of mind it gives even if only once in a hundred CV jobs you find a single bolt will turn a quarter turn more.

Uhh, more like clean and repack is a more accurate description than "rebuild". Not sure if any CV joint rebuild can be performed by DIY or by your local repair shop. Here's a generic intro to the process of inspecting and repacking a CV joint:

Remachining Constant Velocity Joints

Sherwood