I have a question about CV Joint bolts

RickKlem · 06-30-2003, 03:05 PM

Is there something special about the 8x50mm bolts for the CV joint .
I want to put my Joint back in tonight, and was going to pick up a standard 8x50mm bolt (if I can find one)from Home Depot or somewhere. Or is this some kind of " special" bolt that has to be purchased from Pelican? If they are then I'll just have to order them and wait.

I know this sounds stupid , but I had to ask

Rick

Superman · 06-30-2003, 03:14 PM

Good question. Hopefully we'll hear from one of our boltological engineers, but I'm thinking that, as long as the bolt is a high enough grade (you would not want to use an inferior bolt in this application), and as long as it is the exact correct length (wrong length can give you problems), then it should work. Also, I would have a strong preference for the allen head, and it is important to use the Schorr washer on these fasteners. With a "search," you can easily find stories of heat exchangers that have been beat to a pulp by a loose axle when these bolts fail or back out. At speed, the carnage might be immeasurably worse. This is not the fastener to take chances on.

Jim Sims · 06-30-2003, 03:17 PM

Yep; they're class 12.9 screws. Not all metric socket head cap screws are this high strength grade; there is a weaker class (10.9?) which is also commonly sold. Check and make sure. The weaker screws can twist off under the proper tightening torque and a loose CV joint can do a lot of damage. Cheers, Jim

island911 · 06-30-2003, 03:26 PM

I found, at the local Lowe's hardware mega-store, that in *that* particular size, their metric socket-head cap screws had "lobro" stamped in the head. I figured they were okay.

RickKlem · 06-30-2003, 03:31 PM

Island911,

You are joking.............................. right!!!

island911 · 06-30-2003, 03:39 PM

No joke. . I was stunned.
I figured Lobro likely spits out a few sizes in such huge quatities, that they give the best price . . . I guess.

Jim Sims · 06-30-2003, 04:01 PM

I wouldn't want to bet my heater boxes that Lobro means class 12.9. The could also be 10.9. Jim

Early_S_Man · 06-30-2003, 04:41 PM

The only 'special' requirements for CV-joint bolts is that they MUST BE DIN property class 12.9!!!

And ... Don't use the torque setting for M10 bolts on the smaller M8 bolts!!! Even DIN 12.9 bolts have a yield point, and that trick is a way to verify it!

Bought some M6 DIN 12.9 Allen bolts at Home Depot a couple of weeks ago ... $0.53 per pair!

Oldporsche · 06-30-2003, 04:53 PM

Believe it or not, your Catapiller dealer probably has the high strength allen bolt you need. Since Catapiller is now a world wide manufacturer many of their parts are metric. They stock metric nuts and bolts that are of very high quality and are reasonably priced.

Good luck,
David Duffield

island911 · 06-30-2003, 05:05 PM

Good point Jim.
Though metric socket-head cap screws typically are made from high strength steel (grade 12.9 in metric).

. . .found one.

Though, my mistake, it says "LOBO 12.9"

Eugene at Pelican Parts · 06-30-2003, 05:27 PM

Quote:

Originally posted by RickKlem
was going to pick up a standard 8x50mm bolt

When you said 'a' bolt, did you mean you were just going to replace one? If you're going to mix and match, I suggest you do three, alternating them with the allen heads. My concern isn't huge, but I'm sure there is a tiny weight difference between the allen socket and hex cap that will cause a slight rotational imbalance.

And don't forget the ribbed washers.

Decolliber · 06-30-2003, 05:50 PM

I notice that these bolts are specified as simply M10 X 50. Don't bolts usually have a pitch specification in between the thread diameter (10) and the length (50)?
Is it necessary to put in new bolts when installing new axles? I reused the old ones because I stripped a couple of the new triple squares that came with my new axles. Wondering if I should replace the damaged ones and install 12 new bolts.

Jim Sims · 06-30-2003, 05:54 PM

The CV joint bolts may be reused. I am also of the opinion it doesn't matter if a couple of the heads are different in terms of balance; there is likely more out of balance due to the grease in the boots not being equally distributed.

Jim Sims · 06-30-2003, 06:15 PM

Unlike the situation with the US socket head cap screws which were always high strength SAE grade 8; the metric socket head cap screws are available in class 8.8, 10.9 (somewhat rare) and 12.9. The 8.8 class is approximately equal to SAE grade 5. It is also unfortunate that the class 8.8 socket head cap screws can be obtained with the "black oxide" finish that makes them appear to be the same as SAE grade 8 or DIN 912-12 class 12.9. This class problem caused some grief (twisted off fasteners) when metric socket head cap screws were first extensively introduced into the US. Cheers, Jim

ChrisBennet · ChrisBennet's Garage

One needs to exercise caution when selecting fasteners, especially 12.9 grade ones as the applications they are used in is usually more critical. This is one of those pennywise, pound foolish things.

While the bolts at Home Depot or Lowes may have the correct grade stamped on them, you really have no idea where they came from. Are they from Germany, Italy (usually good) or Brazil, Taiwan or someplace (maybe not so good)? It isn't enough to just recognize the bolt markings either, as counterfeit bolts are something you need to worry about too. When I buy a critical fastener I want to know the provenance of that bolt.

12.9 grade bolts from a box labelled made in Taiwan These were used to hold the pressure plate on a friend's 911.

These bolts weren't from the hardware store, they were from a "reputable" metric fastener house.
-Chris

P.S. Are you sure SC's used ribbed washers? The PET doesn't list one for the 8mm bolts and all the SC's I've worked (several) were "missing" them.

RickKlem · 07-01-2003, 03:32 AM

Chris

That was going to be my question as well. I looked at all of the drawings that I have, and called Peilcan . I can not find anywhere that shows a ribbed washer. Or any kind of washer for that matter ,that is used on that bolt.

As for the country (place) where the bolt was made, how can I tell , if I purchase them from home depot or our fine host ? I'm sure (hope) that if I bought it from pelican that it would be of the best quality (German made)!!

????????

Rick

ChrisBennet · ChrisBennet's Garage

Quote:

Originally posted by RickKlem
Chris

That was going to be my question as well. I looked at all of the drawings that I have, and called Peilcan . I can not find anywhere that shows a ribbed washer. Or any kind of washer for that matter ,that is used on that bolt.

As for the country (place) where the bolt was made, how can I tell , if I purchase them from home depot or our fine host ? I'm sure (hope) that if I bought it from pelican that it would be of the best quality (German made)!!

????????

Rick

I would stay clear of Home Depot for critical bolts and I would ask our host the provenance (where they come from) of the bolts you are buying. I believe Wurth tends to use quality Italian bolts (despite the "Made in Germany" labelling on the bags).
-Chris

Jamie79SC · 07-01-2003, 09:30 AM

I'll second the 'no washers on the SC' comment. I've done my inners and outers ant there were no washers in mine.

RickKlem · 07-01-2003, 10:08 AM

I called Pelican back and spoke to Steve. He said that the waher was needed. The one for my year model is $1.00 x 24 = $24.00 for lock washers. I cant see paying $24 bucks for lock washer's (06 cents at hardware store.).

Tell me I can use regular lock washers as long as the fit. Please!!!
Rick

Early_S_Man · 07-01-2003, 10:39 AM

Not all Lobro CV-joints came attached with Lobro Allen bolts ... mine came from the factory with RWS bolts! As were the M6 x 25 mm bolts I recently purchased at Home Depot for use on a Nissan valve cover ... to replace some Phillips-head screws!

The clutch cover application illustrated above is NOT a highly-stressed application at all! The OEM bolts are DIN 8.8 and the normal M8 18 lb-ft torque is specified!!! The faulty bolts were clearly not a DIN 12.9 bolt, unless they were severely over-torqued!!!

Counterfeit bolts are a very serious problem these days!!!