CV Joint bolts locking wheel

[Porsche_911s]

I had to replace a CV boot on a '78 SC. I got the boot replaced and when going back with the bolts as soon as I start snugging the bolts down the entire wheel (including the tire) stop turning. I am using the bolts that came on the car so I would not think the bolts are too long. The boot was purchased from Pelican and says it's for 1975 to 1986. What am I missing here?

I am only working with the wheel side of the joint the engine and tranny are out so it's nothing something from that end.

Thanks,

[jacko241]

Did you put washers under the bolts? The bolts are too long without the washers.

[Porsche_911s]

The old boot has about a 1/4 inch thick metal rim on the boot. This new one is a very thin metal.

Nope, it did not come with washers OR the half moons. If it's too long without these I'll just leave it and call Pelican Monday.

Thanks for the reply.

[Porsche_911s]

Pelican has two images shown for the same part:

923-332-037-00-M84





I was sent the one that does not have the thick flange and the one that came off the car was the one with the thick flange.

Does one go to the trans and the other to the wheel??

[Grady Clay]

Stephen,

A couple of things come to mind.

In your boot replacement did you change the tin cover that the boot attaches to? Some 911s had a thicker cast/machined piece that the boot attached to on the OD. If that got changed to the thin cover then the original bolts would protrude out the back side of the stub axle and interfere with the trailing arm. I will speculate an additional 5 mm.

Another possibility is there were originally installed plate washers (moon plates) and Schnorr lock washers and they didn’t get reinstalled. That would allow the bolts to protrude an additional 3+ mm or so.

The normal process is to take the 30 mm wrench size nut off the stub axle and assemble the axle where you can see the penetration of the bolts. It also lets you work in a better lit and cleaner environment than under the 911.

Have you read this thread all the way? ”Reconstructing Constant Velocity (CV) Joints”

I recommend you use new CV bolts and Schnorr washers and follow the assembly procedure I outline in the above thread.

Absolutely re-torque the bolts after a few miles and periodically thereafter. CVs coming loose is all too common and is a safety issue.

Best,
Grady

[Porsche_911s]

Thanks for the reply. I read the posts but to be honest I just wanted to change the boot. (I thought it would be easy) The axle was out of the car and I was not working under it. I did clean the CV joint and regrease.

The bolts are just too long. I had the thicker flange and the one that was sent was the thinner flange. So, I'll either need a boot with the thick flange or order the washers and plate washers. The car is not going any where without an engine so I have time to figure it out. I just hate doing things twice...

Now, I see the part in that thread that says I will need washers and a plate washer. Not to get picky, but it would have been nice to have been asked if I needed that when ordering the part.

Thanks for the reply.

[Britwrench]

Yes, the new thin flange boot ( 923 332 037 00) uses M8 x 45mm bolts. It's a redesigned boot and the old thick-flange one is no longer available.
The plate and lockwashers were for the M10 bolts.
M8 lockwashers are available from Porsche.

A good bolt supply company would have the M8x45 10.9 grade bolts. Do not over torque them and make sure the mating surfaces of the CV joint and axle flange is grease free.

[Porsche_911s]

Okay, I'll get the correct bolts.

Thanks for the replies guys!

[Grady Clay]

The CV bolts are readily available commercial bolts and available
from our host. Make sure you get the proper grade – 12.9.



NO, SS hardware bolts won’t hack it. Your life is worth more
than some poor hardware.

The plate washers are a standard Porsche part and are
readily available new and used both 10 & 8 mm.

A constant velocity joint coming loose is a big deal. It can
do a lot of physical damage and even cause serious loss
of control. This is an issue to pay close attention to. I
can’t stress enough; re-torque the CV bolts.

Best,
Grady

[Porsche_911s]

Understood. I'll get the right stuff.

[Britwrench]

One day I'll be able to type properly,

Grady is absolutely right..12.9 not 10.9 as I wrote....

[Porsche_911s]

I'll call Pelican, I don't see the parts in the catalog but if you say they have them I'm sure they'll hook me up.

[CliffBrown]

[i]

A constant velocity joint coming loose is a big deal. It can
do a lot of physical damage and even cause serious loss
of control. This is an issue to pay close attention to. I
can’t stress enough; re-torque the CV bolts.

Best,
Grady [/B]

Grady

Seems like a good place for safety wire.

[Grady Clay]

Cliff,

There has been a lot written a lot about this. Please do a Pelican search.

My considered opinion is that it is the clamping force provided by the torque on the CV bolts that transmits the driving torque and not the shear strength of the bolts themselves. If the junction slips and applies shear to the bolts, failure is imminent. This is why having metal-to-metal contact and appropriate clamping force (proper bolt torque) is so important.

Safety wire won't help. That just prevents the head of the bolt from moving much while the junction is loose and causes the thread part to fail. I suppose it might give a few minutes relief before everything fails.

Best,
Grady

[CliffBrown]

Originally posted by Grady Clay
Cliff,

Safety wire won't help. That just prevents the head of the bolt from moving much while the junction is loose and causes the thread part to fail. I suppose it might give a few minutes relief before everything fails.

Best,
Grady

Grady

I bet you're right and I won't pretend to understand the physics of the application. I just know that on an aircraft we're required to safety wire just about any bolt head where there's the remote possibility of it becoming loose.

I'm not sure I understand your point "while the junction is loose". When I wire a bolt it does a pretty good job of keeping the bolt in one place, there's very little movement possible. As a possible comparison the bolts that hold a prop on the end of a crankshaft are secured with safety wire. I think that's a fairly equal comparsion and it sure would ruin your day if those bolts came loose.

[newbe911]

The problem with the new thin flanges on the CV boot is that is soft metal and there is not enough bearing area under the allen head to support the torque required. There is not enough clearance between the hub of the boot and the allen head for any kind of washer, I know I just went thru this. I am at this time drilling all of the heads for wire tying. Granted this may allow the joint to get some loose but it will not be catasropic.

[Porsche_911s]

Did you use this part??



Or did you just use washers?

[Grady Clay]

Stephen,

YES, that is the correct part. Never just use flat washers, they can rotate under the head of the bolt. The point of these plate washers (moon plates) is they connect two bolts together, preventing rotation. They are always used in conjunction with Schnorr washers.

If your CVs don’t have them, pay attention to the fit to the tin CV cover. There are some transitional plates and tin covers that are mutually exclusive. This thread shows one. I think the plate that Stephen shows above fits all.

Best,
Grady

[Porsche_911s]

Yes, I plan on getting that part. I was just asking newbe911 if he used this part. I'll give Pelican a call, just wondering if newbe911 knew about it.

[ChrisBennet]

Originally posted by Porsche_911s
Did you use this part??



Or did you just use washers?

I'm too lazy to look it up tonight in the PET but I thought that part was only for 10mm bolted CV's - not 1978 SC's with their 8mm bolts. They would be a nice upgrade if they exist, I've just not come across them before.
I wonder if they have them for some other model or even another brand of car?. There are a lot of cars with CV joints after all...
-Chris