Broken outer CV bolts
 

As I started getting ready to pull my motor for a clutch replacement, I noticed what seemed to be a loose CV bolt. Turns out what I thought was a blown rubber-center clutch is actually sheared outer CV bolts on one side. I have the CV joint out but haven't started on the remaining pieces left in the stub axle.
I don't have a 30mm socket to remove the axle nut and I've heard it takes quite a bit of torque to get that nut off. Should I replace the stub axle or might it be OK if I can just extract the broken bolt ends? The CV Kit with the axle is about $275. I'm considering just having it towed to a local P Shop and let them fix it. I'm open to suggestions.

Sounds like a case of loose CV joint screws succumibng to fatigue failure. If the hub wasn't making noise before, the bearings are probably okay. Take a small screwdriver and see if you can pick the screw remanents out. How is the CV joint? Jim

"I'm considering just having it towed to a local P Shop and let them fix it." Why in the world would you do that? The car's sitting at your house 80% ready for an engine drop. For $100 worth of parts from Pelican plus shipping you could fix it yourself. That job isn't hard, just messy. Fix the CV joint, connect back up your engine and change the oil. Cheers, Jim

That axle nut isn't as evil as it might seem. I got away with a half inch breaker bar and a pipe extender, along with a 30 mm Lisle axle socket. Soak it with some kind of loosener overnight. Once the nut's off the stub axle should slide right out and will be much easier to work on. If you can pick the bolt stubs out on the car great, but if not yank that stub axle out.

At what point is the bolt sheared? This happened to me last week (self inflicted) and I was able to get the bolt remnant out fairly easily without removing the hub.

Once the cv is out of the way the remnants should be easy to remove as the holes in the flange go all the way through and therefore won't be bottomed out and tight.

Before you bolt a new one on I would use the old CV collar by itself and make sure the flange holes weren't stripped during the failure and hold the appropriate torque.

On a related note what is recommended proceedure with regard to lockwashers. I ordered new bolts and lock washers from PP and got "cut lock washers"; I thought wavey washers were the appropriate ones. The cut ones seem to spread open under the torque and the small heads of the allens.

The axle nut isn't that difficult to get off -- generally, and with the correct tools, namely, a 3/4" drive socket, breaker-bar or sliding 'T-handle,' and a 4-foot section of iron pipe for a bit more oomph! I stopped trying to use 1/2" drive tools on axles when I twisted a Craftsman breaker bar clean off on a rusty VW Beetle axle nut about 35 years ago!

You may not have to remove the stub axle ... try center-punching the remnant of bolt and use a reverse-twist drill 1/4" bit after using regular 1/8" and 3/16" bits to start the hole! Clean the threads in the stub axle very thoroughly with Brakleen and test the fit of new Allen bolts in the axle female threads ... any constant drag is a hint that the axle threads are distorted.

Schnorr washers are the only kind of lock washer that should be used on Allen bolts for CV-joints!

I removed some broken bolts out of the stub axle with the stub still in place (the CV joint and axle were removed). The bolts weren't locked in and they came out very easily. Try taking them out before you remove the stub, it might be a lot easier than it looks.

BTW, my friend with the car I was taking them out of thought it was his clutch also. Unfortunately he let it sit in his garage for 7 years until he decided to do something. So instead of $100 for a CV joint and bolts, it cost him a few thousand in FI parts to get it running again.:o

Don't even think of taking this job to a shop. I did it on my Carrera and it was a cinch. Depending on the mileage, you might consider switching sides with the axles to get a little more life out of the one you're not replacing. I'm repacking a CV on my 993 tonight and have no fear. Boot kit cost me $12. A new 993 CV axle is $500. Easy decision - pay a little now or a lot later. If you don't want to deal with the repack, just buy a rebuilt CV axle for $185 or so and throw it on the car. This is not a tough job.

OK, I just replaced my CV joints but not the axles. I have a rythmic light scrapping noise coming from the rear, I was thinking wheel bearing or parking brake. What would a bad axle sound like? Seems cornering changes the tone.

I was able to remove the bolt ends with out a problem without disassembling the wheel. I got 6 12.9 grade 8x50mm cap head bolts, a new gasket, and CV grease locally and put everything back together last night. The motor started right up once I purged the air out of the fuel lines. Everythying looks good so far. I'll check the CV bolts regularly from now on. The 20 mile expressway drive each way to my new job ( I used to drive 2 miles ) is the suspected culprit of the accelerated failure. I'm sure they still would have gotten loose but probably would have taken longer and I might have caught if before the bolts breaking. Thanks for all the advice and support. Everyone on this BB are the greatest P friends a guy could hope for.
OK, no more mush, it's time to put the top down and drive FAST.

Did you install the Schnorr lockwashers under the new CV joint screw heads? Your car came with these from the factory and they are very effective in keeping the screws from loosening. If they were not there someone has discarded them in the past. Jim

All the info I can find on the SC is that it did not have the lockwashers. The Schnorr's seem to be only for the 10mm bolts on the pre-76, Turbos, and post-84's. 1976 to early '85 has 8mm bolts with no lockwashers.

My '76 has 8mm screws, Schnorr lock washers (original equipment) and c-shaped washer plates. Do you have the c-shaped washer plates? Jim

I believe the change over to no Schnorr lock washers was 1984. Jim

No washer plates or lock washers. The guys at Zim's didn't have them listed in PET and Wayne doesn't list them as available for the 76 to 84 years.

Jim:

Pelican only provides lock washers - they do not stock Schnorrs. Use the Search button to find vendors for these.

Paul:

Maybe the light stamped metal shield around the brake? Try manipulating that first. You might also back off the emergency brake shoes. Finally, have you retightened the axle nuts? Need to do that...

The bearing is going to be a deeper rumble, not a lighter, tinny sort of sound such that you'd hear with the light metal shield.

John

We'll at least regarding the 1976 cars, Pelican's site is wrong in this matter. I have the original paper factory illustrated parts catalogs for 1974-1977 911's and for 1976 they show the Schnorr lock washers complete with a Porsche part number. I bet if you give Pelican this part number they'll be able to get them from Porsche for a tidy sum each. Cheers, Jim

Schrup, did you do anything with the brakes? I failed to center the tinware that quiets/centers the pads on my brakes and one side of the clip was dragging on the top of the rotor.

Zims may not have them listed in the PET, but I have picked up schnorrs from them before. I would use them whether they were original to the car or not.