cv joint reattachment after engine drop

[Bill wjw]

82 911 SC I had a new axle on the passenger side put in my car by a good Porsche mechanic when I first got in 5 years ago. Two summers ago I replaced the driver side with a new axle. Broke it and the trailing arm in an accident. (another story)

The newest drivers side inner cv uses shorter bolts than the originals and had no paper seal indention. Just totally flat surface. The still original transmission flanges have the indention for a seal. No Schnoor washers or moon washers with the new replacement axle..

The passenger side replacement CV has the indentation for the paper seal as does the original transmission flange. Upon disassemble I found only one paper seal attached to the CV joint. No seal on the flange and no Schnoor washers or moon plates.

For reinstall I bought 2 paper seals. New bolts for the passenger side. Reused the bolts on the driver side. I cleaned up both sides and put the glue sticky side of the seals in the transmission flange indentation. Snugging the bolts, not torqued yet, I have 2-3 threads showing through the flange on the passenger side and the bolts not quite through the driver side flange.

It looks like I have 2 different styles of CV joints on the two replacement axles. It looks like newer replacement axles do not come with the Schnorr washers or moon plates, only bolts with no type of washer.

What do I do here to make this safe. I was thinking to pull both cv joints off the transmission flanges and take the paper washer off the drive side and put it in the indentation in the cv. That would leave no paper seal on the driver side and a seal in each indentation on the passenger side.

I think this would give me the 1 1/2 to 2 treads showing past the transmission flanges on both sides. What about the question of no washers or moon plates on replacement axles?

I am trying to get it right. Any thoughts? Hope this makes sense!
Bill

[ClickClickBoom]

Reconstructing Constant Velocity (CV) Joints

[Bill wjw]

I have read this thread and related links attached. Why do replacement axle assembles omit washers and moon plates. Is it necessary to get washers and moon plates and customize the bolt length for a safe assembly? Anyone with experience with the newer replacement axle types?

[island911]

Sheesh, CCBoom, quite the thread there for anyone to wade thru. FWIW, Page 12 is where that thread gets interesting.

Bill, the Schnorr washers and moon plates are attempts to help mitigate loosening problems. But, really, the assembly can be solidly bolted together without either. The big player here is in having clean, dry mating surfaces and solidly torqued fasteners. This means the flange surfaces need to be especially clean. (too often, the CV grease is all over both surfaces, allowing movement ... which allows fasteners to walk out)

[L8apex32]

In my experience, replacement axles come with the correct length bolts and, I believe, replacement Schnorr washers.

In your case, I'd use Schnorr washers and bolts long enough to have a thread or two showing past the flange. These bolts of varying length are available at hardware stores (they aren't that special.) I'd not use moon plates. I would torque to 28 to 32 ft-lbs and then check some time later just to be sure they are still tight.

[ClickClickBoom]

Originally Posted by island911

Sheesh, CCBoom, quite the thread there for anyone to wade thru. FWIW, Page 12 is where that thread gets interesting.

Bill, the Schnorr washers and moon plates are attempts to help mitigate loosening problems. But, really, the assembly can be solidly bolted together without either. The big player here is in having clean, dry mating surfaces and solidly torqued fasteners. This means the flange surfaces need to be especially clean. (too often, the CV grease is all over both surfaces, allowing movement ... which allows fasteners to walk out)

The collective wisdom contained in that thread is vast. If reading technical bits from the likes of Grady and others is "wading",I don't know what to say. If spending 45 minutes to prevent the woes of a CV bolting failure is too tedious, try waiting for AAA in the mountains, I did, and missed the start of my work trip. There has been many misconceptions on this forum suggesting plenty of not so good ideas, like using split lock washers. There are very few areas of this chassis where incorrect processes can cause a life threatening situation like a lost CV can. Lose it on the "right" side and you might get to buy a new transmission case or plenty of other stuff in that area. I did my replacement correctly, and am secure in the knowledge it is operating correctly using the best fastener systems available. I give daily mental kudos to Grady and the others who spent lots of time imparting their knowledge in this area. Fasteners aren't glammy or shiny or super trick, but they are important to a degree often overlooked.

[Trackrash]

This recent thread may have the answer. Please help me feel better about my CV-Axel installation

[Bill wjw]

I have read all of those post more than once and the information is very helpful in deciding how best to proceed with two different replacement axles. I did a search and much reading before I replaced the broken axle 2 summers ago. I remember then I used only what came with the the GKN Loebro from here at pelican. I used the new shorter bolts that came with the axle and there was no seal. I learned from my research that being fastidious about the mating surfaces grease free was most important. I was, kept it clean and torqued to specs.

When I disassemble the GKN on the driver side for the engine drop the bolts were at correct tightness and surfaces were still clean. No grease leakage. The disassemble on the passenger side was really torqued down, way past 34 ft lbs. paper seal on the cv and again no leakage.

I was extremely careful to keep the mating surfaces and bolts free of grease yesterday. I tightened the bolts with an Allen wrench tight enough by hand to seal in any grease. Tonight I will torque to specs.

My plan is to order new bolts, schnorr washers and moon plates. I will figure the length of bolts for each side and cut to proper length with seal, washers and moon plate in place. I will note this info. in my Bentley for future reference. The bolts can be loosened slightly and replace with the complete set up 2 at a time.

I will feel good about this since I have had much information to consider. I wish it were true the ignorance is bliss. It takes some work to not remain ignorant.

[stormcrow]

Bill,

Just make sure the bolts come through showing at least two threads when you do the replacement. I did some work on my CV joints two years ago. Same problem - bolts shorter because the flange on the boot side was thicker.

Not paying any attention I installed the same bolts. Checked everything and ran the car. Did another inspection and checked the torque. Everything fine. Well about 3 months down the road I was sort of getting on the throttle coming onto an on ramp when all hell broke loose.

The CV joint bolts came lose and the shaft did a tad bid of damage to the underside of the car.

What I realized was that the shorter bolts were the problem - they came loose - I was lucky that more damage hadn't been done.

I replaced the bolts with longer ones - and as a safety precaution I installed nuts on the back side for reassurance. Been two years not and not a problem. Definitely make sure your bolts are long enough and do go through showing at least two threads on the other side.

[Kemo]

couple of follow up questions...what size are the schnoor washers? M8? and where would I source some moon plates?

[Ayles]

Originally Posted by Kemo

couple of follow up questions...what size are the schnoor washers? M8? and where would I source some moon plates?

eBuggies.com - Dune Buggy, Off-Road and VW Parts since 1968

[ClickClickBoom]

Guys,
I have a '84 Carerra with 8MM CVs, the Reconstructing CV thread is definitive. I had an axle come loose because I didn't follow Grady's recommendations. I was luck to have no damage since it was the outboard and I immediately pushed the clutch in. The flailing of the loose axle could have caused massive damage to the related parts. The design of the 8MM bolt used is at the ultimate design limits for the 12.9 bolt, anything less than perfect execution will lead to a less than stellar outcome. I did assemble the CVs using Grady's recipe and some basic technique using the Nordlock NLX series and have had total success, and I drive hard, daily. The settlement issue I described was explained to me during a 45 minute conversation with a NordLock engineer. I learned more about materials and engineering during that conversation, than I had in a long time. Read the thread, use your skills and enjoy the process!

[CCM911]

I have seen them come loose at the track on occasion, but luckily, mine have never come loose. My secret is to torque them all more than once. I usually do at least three rounds to make sure all is well. And I bought new bolts after using the originals for three engine drops.

Now if you really want to get fancy, forget about the "Schnoor Washers" and "Moon Plates", and have the heads of the bolts drilled so you can safety wire them against each other. That is the most elegant solution I have seen to date.

[uwanna]

Here's a link to a solution I use to prevent CV bolts from coming loose. Stage8 fasteners.
The thread talks about a group buy, that is ancient history, but you can see pics of the product. One nice thing is the use of 12pt aircraft grade bolts instead of the Allen head type. Makes installing/removing a breeze.
Stage8 Locking CV Bolts for ALL 911/912

You can buy them direct from Stage8 :
#8332 CV JOINT 8MM*| Stage 8

[Alan Lindquist]

I didn't have a torque wrench the first time I did this and just snugged them with a grunt and went back around and gave them a good check for "tightness." More than likely, they were over torqued. I dabbed white out across the bolt and flange and each week jumped under the car real quick with a light and inspected both sides. The lines have never budged, so they are secure and so far... not breaking.

[ClickClickBoom]

Originally Posted by CCM911

I have seen them come loose at the track on occasion, but luckily, mine have never come loose. My secret is to torque them all more than once. I usually do at least three rounds to make sure all is well. And I bought new bolts after using the originals for three engine drops.

Now if you really want to get fancy, forget about the "Schnoor Washers" and "Moon Plates", and have the heads of the bolts drilled so you can safety wire them against each other. That is the most elegant solution I have seen to date.

The thread on fasteners covers this possibility. All About Nuts and Bolts
Safety wire isn't to maintain torque, it is to retain the fastener in position. I tried the safety wire thing and after 30 years as an Aircraft and Powerplant mechanic, couldn't get the safety wire tight enough to prevent rotation. It isn't really that complex, follow Yoda Grady's teachings and you will have success.

[Ned, NYNA11]

And the easy way to tighten them up and torque them when you are all done is to use 1/2 inch extensions to reach the fasteners from outside the wheel, car in neutral hand brake off using a prybar across a couple of wheel studs with the end against the ground.

[BlueWing]

Just curious, why is there a loosening issue? Torque or HP? I have over a million miles in 2 VW Jetta Diesel Coupes. I wore out the output shaft bearings every couple of years. Every time I replaced the tranny I put in a rebuilt set of axels. They used moon plates and I reused the 12pt bolts. I did it so often I just tightened them up and of course a week later I would give my quick overall on the tranny swap and all was well. I never had a CV bolt loosen on me ever.

Just came to mind as I just moved 5 020 VW trannys to a back shed, I keep them in stock for my VW Veggie Oil Powered Grumman Kubvan

Terry

[Walt Fricke]

I like the 12 point bolts because it seems it is harder to round the points than it is the usual hex. Porsche used the 12 points on 914s, and maybe VW does also? I've used my bolts until the inhex strips, but with the 12 points that never happens. No washers, no plates, but no problems. I gave up on the grease retaining gaskets (some suspicion they lead to a false torque, so to speak, then settle/squish so bolts loosen if not caught and retorqued in time).

Gray Permatex silicone, just a bit, works fine for a seal. And I wrap the CV with silver body tape in case some grease still wants to get around the axle side cap. The tape stays on, amazingly enough, at least so far.

Loosening happens when you don't stretch the bolts far enough so that the friction between the mating faces is adequate to keep the faces from working against each other. Keeping lube out of there has to help with friction. Once they start working the bolts can back out. Nordlock and similar devices would prevent this, but you still want the torque, as it is not the shear strength of the bolts which transmits the power, but the clamped two faces.

This is why everyone recommends a recheck some miles/time after you replace anything here.

[frankc]

I also went with the Nordlocks when I installed my axles a few weeks ago. I'll be checking torques again this weekend and I'm curious to see if any of the bolts lost more than a minor amount of torque due to settlement.

I also purchased moon plates, but since my CV boots are the solid flange type (not the stamped steel cover), I wasn't sure if there would be any advantage to using them. Do the moon plates still offer an advantage for the solid flange boots? In post #29 of the "Reconstructing CV Joints" thread mentioned above, Grady states:

"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."

So does Grady's second function still apply to my case (no tin covers)?