Locking fastners for CV joints

Gary Gibbs · 03-20-04, 07:55 PM

Thought I might take a minute and update everyone on the availability of good quality locking fasteners for CV joints. For those who have been worrying about this here you go. They are made by stage 8 fasteners. The are essentially a 12.9 grade 12 point head bolt with a grove cut in to permit the use of an indexable tab and e-clip.

BuzzClarke · 03-20-04, 10:28 PM

Gary:

What potential problem with 500 to 600 HP motors are being addressed with these bolts/fastners.

Regards, Buzz

Gary Gibbs · 03-20-04, 10:50 PM

There is basically no great method of locking the fastners. You can use locktite (grease all over the place makes it difficult to implement), or use safety wire (must drill all of the bolt heads). This is the easy and effective way to lock the bolts. I am a big fan of being able to lock all fastners when possible. This is common race car and aircraft practice.

**J What?** · 03-20-04, 11:46 PM

These are great locks for headers. I use them. But headers have peculiar problems that require these things. The heat from the exhaust will take any hardness out of a bolt or LOCK WASHER and burn out any type of loctite compound. That is why these were designed. The heat from the exhaust will turn any hardened lock washer into a flat washer first time out.They are a pain in the ass to lock with the snap ring particularly on the bottom bolts. For all
other situations I prefer to buy drilled bolts and safety wire.

JOSEPH · 03-20-04, 11:54 PM

Hi Gary, A while back I asked the same question because I wanted a second opinion about the lock washers that the local Porsche racing team use on the GT3 cars. They gave me a set of 12 to put on my CAV. I will post the picture again. they have the same grooves on both sides of the washers. They torque them to 60lbs. on the race cars ond 50 lbs. on regular street cars. Does anyone know how many lbs. of torque on the 016 Getrag? Joe [img]/ubbthreads/images/graemlins/confused.gif[/img]

JOSEPH · 03-20-04, 11:57 PM

I forgot to mention that can be gotten at any Porsche dealers parts dept. [img]/ubbthreads/images/graemlins/smile.gif[/img]

Gary Gibbs · 03-21-04, 08:55 AM

J-what: Where can you buy drilled head metric fasteners?? I would normally go this route also; however, I have not seen such a beast.

I have drilled heads many times before, and this is an option. The only problem I have with that is it is not a lot of fun. If I only drill a single pass through the head the holes frequently end up in poor safety wire orientation after torque. Predrilled aircraft style bolts usually have 3 passages so you have a hole 60 degrees. I see no real problem with this Stage 8 setup as the bolts are top notch and the locking system seems very adequate. I had no problems with e-clips and everything went on rather quickly and easily. With the slight assymetry of the lock tab grooves (thus can be flipped) and the fact it is 12 point fasteners the tabs can be oriented to have little to no play. I found it easier then drilling a bunch of bolt heads [img]/ubbthreads/images/graemlins/smile.gif[/img]

91740Gt · 03-21-04, 09:19 AM

These anti-vibration washers are known as Schnorr washers and are available in imperial and metric sizes and should be available from most good engineering or workshop suppliers and not just Porsche retailers.
Regards,
Graham @ GTA Racing.

JOSEPH · 03-21-04, 10:36 AM

Graham, Thanks for the info. How good are they? Have you had good luck with them? Have you ever had them come loose? Joe

**J What?** · 03-21-04, 03:22 PM

Gary,
you can get an, ms bolts from Coast Fabrication, Wicks Aircraft and many of the homebuilt aircraft suppliers. I am sure there are others. Wicks seemed to be better priced but they do not carry the big bolts needed for some of the old design cars, like mine. One word of caution. For simplicity these bolt diameters are measured in 1/16th of an inch so a 7 is a 7/16. Length is meaasured in 1/8 and if they stuck to their system a 32 would be 3 inches long, they aren't. the bolts are actually a a little longer, I suppose for washers. So when you order make sure the actual length is what you need. Back to the clips, I don't know if I would trust the e clip on a rotating assembly, like your 1/2 shaft. As I said, they were invented for stationary header bolts. If physics apply, when the 1/2 shaft turns the heavy side of the clip will work it's way to the outside and leave the opening of the e clip ready to exit the bolt. I really think you should safety wire that assembly.
Bill

Sorry Gary I missed the Metric part. I would still try Coast. They should know a fastener supplier that will have them.

**J What?** · 03-21-04, 04:35 PM

OK where is my head. MS and AN bolts are measured in 1/16 inches so a 8-16 should be 1/2X 1 inches. As I said before , they are always longer than the number would have you believe so, always look at the grip chart before purchasing.

Gary Gibbs · 03-21-04, 05:05 PM

I am very familar with the AN/MS/NAS system as I have purchased thousands of bolts at surplus and have them in little drawers on my workbench waiting for service. The grip length is a bit confusing. With MS/NAS bolts (e.g. NAS 1103-1120 series) the grip is equal to the dash number times 1/16". Thus a -8 will have a grip length of 8/16's or 1/2". With AN bolts (equivalent to Grade 5 but better) the dash number does not correspond to the grip length and is different for each diameter. You then need to look at a grip chart.

I love this system, but unfortunately for CV joints you are stuck with metric. The ZF uses 10 mm bolts. I had a concern about the e-clips flying off, but after talking to the Stage 8 tech rep and doing a little math I think things will be just fine. For example, at 200 MPH the clips will only be subjected to 9.5 g's. When installing and removing the eclips the force appears to be a couple hundred times their weight (next to nothing). Thus it would take a couple hundred g's to throw them off. Something like 1000 MPH. I did not measure the release force, but it seems much much more then ten times their weight. I plan on keeping an eye on them after I run on the track. If I throw a clip I will be forced to drill heads and safety wire. As an added benefit the tabs will tend to tighten the bolt with centrifugal force albeit a very small force [img]/ubbthreads/images/graemlins/smile.gif[/img]