CV Bolts!

[HarryD]

Today I was at the Maryhill Loops Road in Washington (lots of fun) and had a pulsation in my gas pedal. When I removed the wheel on the side where the accelerator rod went by the wheel area I found one of my CV Bolts had come out and the moon plate was bent. The other bolt was so loose I could remove it with my fingers.

I flattened the plate and reinstalled the bolts and snugged them up as best I could. If you look at the picture at about 11 to 2 o’clock position (circled) you can see part of the gasket sticking out.



How badly is stuff buggered up?

I am guessing I need to remove the bolts from the CV Joint and replace the gasket. Can I do this without removing the entire 1/2 Axle?

Should I replace the moon plate? Anything else I need to do?

TIA

[hienz]

Pack it up with lots of grease

[pmax]

I would clean the crud off first.

Read this tome Reconstructing Constant Velocity (CV) Joints

(recent discussion Better 8mm CV bolt?)

[HarryD]

Originally Posted by pmax

I would clean the crud off first.

Read this tome Reconstructing Constant Velocity (CV) Joints

(recent discussion Better 8mm CV bolt?)

I did read those. not clear to me if I can just separate the inner CV from the transmission, clean the bolt holes and surfaces, replace with new gasket, bolts, washers and moon plates and move on.

FWIW, my boots and CV joints appear to be fine.

[pmax]

I would clean the crud off and inspect all the bolts.

Also, I don't think flattening the moon plate is advisable since ,if I understand the thread correctly, its function is to spread out the load evenly which means it needs to be flat and flush with the CV housing.

[HarryD]

Originally Posted by pmax

I would clean the crud off and inspect all the bolts.

Also, I don't think flattening the moon plate is advisable since ,if I understand the thread correctly, its function is to spread out the load evenly which means it needs to be flat and flush with the CV housing.

The other 2 bolts are tight.

The moon washer is very soft. It took little effort to flatten so I doubt is spreads the load between the two bolts but instead provides a non rotating surface for the schnoor washers to bite into and counteracts any rotational motion of the bolt (when it is torqued properly).

It is my intent to replace the gasket, washers and bolts with new. When I was 120 miles from home and laying in a driveway on a Sunday morning, this was not an option. I did what was needed to get me through the event and back home. Following the field repair, I drove the car in anger for several miles and rechecked everything to verify it would not fall apart. After another 120 miles, I checked again a found everything intact.

My question is whether I need to remove the entire axle to replace the questionable parts or can I merely pull the 4 bolts, separate the joint from the transmission and install the new parts.

[pmax]

Originally Posted by HarryD

The other 2 bolts are tight.

The moon washer is very soft. It took little effort to flatten so I doubt is spreads the load between the two bolts but instead provides a non rotating surface for the schnoor washers to bite into and counteracts any rotational motion of the bolt (when it is torqued properly).

I'll defer to Grady for the details (http://forums.pelicanparts.com/porsche-911-technical-forum/222537-reconstructing-constant-velocity-cv-joints-
2.html#post1923348) I think we are both right.

Originally Posted by Grady Clay

The moon plates provide three functions: First they spread the
load so as to not deform the tin cover. Second they provide an
intermediate hardness material for the Schnorr washer to
properly bite into. Finally they connect two adjoining bolts to
prevent turning of a surface between the tin cover and the moon
plate.

The moon plates I ordered, but did not use, seem to be made of harder material than the softer "brass" ones.

[RDM]

The short answer is that you do not have to open up the other end of the driveshaft.

However, an upgrade to the Nordlock washers would prevent this from happening again. To do that, of course, you'd remove and replace all the CV bolts as they're generally considered single use.

[T77911S]

make sure the bolts are long enough so that 2-3 threads stick out past the flange on the tranny side.
you can get new bolts in 5mm lengths at Fastenal. you have to buy a bag or 50 but its still cheaper than buying a full set from here. they also sell the washers.

[Uwon]

Originally Posted by RDM

The short answer is that you do not have to open up the other end of the driveshaft.

However, an upgrade to the Nordlock washers would prevent this from happening again. To do that, of course, you'd remove and replace all the CV bolts as they're generally considered single use.

Single use? What makes you say that? I have not come across any Porsche shop manual that suggests single use on a G-body. Have I been missing this for the last 25 years?
Johan

[piscator]

For bolts, nordlock and schoor washers, no better supplier than Belmetric. Matt and his staff are very knowledgeable!.

Those bolts are hardened, I don't think they're 'single use.'

[pmax]

Originally Posted by Uwon

Single use? What makes you say that? I have not come across any Porsche shop manual that suggests single use on a G-body. Have I been missing this for the last 25 years?
Johan

Agreed given they are not stretch bolts as far as I know. But the heads do get buggered up so I reused them as exhaust system bolts, the length being just about right !

[tdw28210]

I believe the bolts are M8x50mm, 1.25mm thread, (partially threaded) "socket head" bolts. McMaster Carr has them in multiple flavors.

[HarryD]

Met with my mechanic this morning. Not a hard job and I decided to let him do it for me as the labor cost is minimal.

[47silver]

the bolts are 48 mm if they stick out too far they will hit the banana arm.

[gtc]

Replacement boot flanges can vary in thickness, so it is not really helpful to suggest what bolt lengths to purchase. If you also factor in the moon plates and different types of washers, your bolt length could be off by close to 10mm.

[Lyle O]

Just a word to the wise: After reading this thread, I went out and checked my flange bolts, and HALF were either somewhat loose or not up to spec (60 lb/ft for the 10mm version)! FWIW, I dropped my engine this past winter, and therefore torqued them all to spec upon re-install (April). My car is an '87, so has the moon plates. I will be adding Schnorr washers when I can source them. Lesson learned: check your flange bolts often!

[Solamar]

Originally Posted by gtc

Replacement boot flanges can vary in thickness, so it is not really helpful to suggest what bolt lengths to purchase. If you also factor in the moon plates and different types of washers, your bolt length could be off by close to 10mm.

A very good point.

I just finished rebuilding two original CV joints and replaced two with new Lobros from Pelican.

I knew I was going to use Nordlocks, (with no moon plate) which are about 2mm thick. I measured the entire stack of parts and wound up using 55mm M8 bolts. If I had blindly used the 50mm suggested length I would have been significantly too short. I used the outer stub axle to measure overall length as the transmission side looks to have more room for longer bolts.

[T77911S]

not sure why 2 washers.
make sure the bolts are 12.9
those look a little on the short side.
make sure there are 2-3 threads sticking out past the flange.

[ClickClickBoom]

Originally Posted by HarryD

I did read those. not clear to me if I can just separate the inner CV from the transmission, clean the bolt holes and surfaces, replace with new gasket, bolts, washers and moon plates and move on.

FWIW, my boots and CV joints appear to be fine.

Reread the reconstructing thread. If you try to bolt up the CV without it being surgical clean you will experience another event. Also the bolt torque is critical, 33LBFT is close to the theoretical limit for a 8MM 12.9 bolt.
You got lucky, very lucky, that axle shaft whipping about unattached can cause thousands in damage to anything within its reach, or an accident. Reread/study/memorize the Reconstructing thread like your cars well being depends on it, it does. Everything discussed above is covered in depth, that thread could be a manual.
I learned the hard way as well.