CV Joint Bolt Help!!

[Hugh R]

Pulling my engine what kind of socket head bolt attaches the CV Joint to the trannie. I thought it was 6 mm, but I may have rounded the first one. Any quick help greatly appreciated. Is it a Torex or what? Oh, its an 84

Thanks in Advance.

[Jeff Alton]

Some are 12 point and others are allen head. Make sure they are really, really, clean before you put a bit in the head. Worst case of you can get all the others off is to cut the head off the stripped one and pull the CV off, then the remained of the bolt can be removed with pliers or vice grips...

Cheers

[Hugh R]

Any idea on size of 12 point or hex looks like hex to me.

[Jim Sims]

Should be an M8 socket head cap screw which usually has a 6 mm inside hex as the wrenching feature although very rarely a triple square may be used (not likely on your car). Clean out the inside hex throughly so the hex bit will register completely. If the inside hex has been rounded, in this situation where there is usually enough room, I would use a pair of small "vise grips" on the outside of the cap screw. Ensure the vise grips are applied very tightly. Another option is to get a "torx" bit that is a little too big and hammer it into the hex recess for a force fit. In either case you will need to replace the M8 socket head cap screw. Merry Christmas, Jim Sims

[bbh03]

Get the triple square bits. THe hex tends to round them out too. Once rounded, you will need bolt extractors to remove them and worst case, an angle grinder.

[rcecale]

Hugh,

Merry Christmas, Marine!

However you end up getting the CV Joint bolts out, you'll want to take a lot of care and clean the flanges out really well before you install the new ones. Any type of degreaser and lots of q-tips will do the trick.

Think back to when you were cleaning your rifle for inspection...that's how clean I got mine, and they haven't backed out a bit. I checked them at 100 and 500 miles and they're still as snug as when I installed them.

Oh yeah, new Schnorr Washers too.

Again, Merry Christmas to you and yours!

Randy

[Grady Clay]

Hugh,

Get in there with some brake clean and a bristle brush
to clean the internal hex of each bolt. Unless you have
a Turbo or Turbo Look, you should have M8 bolts that
use a 6 mm Allen wrench. It is conceivable someone
installed 12-point bolts. Looking at clean bolts will tell.

Make sure your 6 mm tool is like new. Stubborn bolts
can be removed using this Snap-on tool PIT 160. You
load it in the un-screw direction with the big wrench
and strike it with the big (48 oz) steel hammer. (Wear
safety goggles.) This both releases the tension in the
fastener and at the same time shocks it in the un-screw
direction in addition to the wrench torque.





If you attack the bolt on the passenger side that is at
2-3 O’clock and the one on the driver’s side at 9-10
O’clock, you will have the most clearance. (The axle
angles to the rear.)

Penetrating oil on the exposed threads at the back side
of the axle flange will help. Rotating the wheel CW on
the passenger side and CCW on the driver’s side will
help get the solvent up the threads. Tapping the
fastener will also help.

Here are two good threads on CV joints.

“CV Joints”
CV joint disassembly

rcecale Randy
Reconstructing Constant Velocity (CV) Joints
Reconstructing Constant Velocity (CV) Joints

You are going to need new bolts, new Schnorr washers,
your calibrated torque wrench, and a like new 6 mm tool.
I think your CVs use a gasket so you will need two new
gaskets. The torque spec for M8 bolts is 33 ft-lbs.

Do your CVs have the plate washer under the bolt head?
If not you should install them. This will take a slightly
longer CV bolt. Read the above thread.

After you reinstall the CVs, double check the torque.
Check again after a week of driving and again after a
month or so. The CVs come loose way too often.
Probably from improper procedure and not re-checking.
This was true even when your 911 was new from the
Factory. This should be part of regular service on your 911.

Best,
Grady

[Hugh R]

Hey thanks guys! Great advise as usual. I try all this stuff and report back.

Merry Christmas all!

[Grady Clay]

Here is a M8 with 12-point wrenching and a 6-point.




The 12-point is a Inbus. The 6-point is a Kamax. Both are 12.9.

Best,
Grady

Go Broncos

[randywebb]

12.9 is the strength rating of the bolt (aka socket screw) -- you have to use the high strength fasteners, ordinary bolts cannot be used safely

[Hugh R]

Got them all out!!! The visegrip trick worked on four of them. It seems that at least three had been "pre-rounded" for me by a PO's mechanic I'll order new ones from PP, perhaps the torex type with the lock washers.

[Jim Sims]

12-point is not torx but triple square (aka XZN). Strength class 12.9 socket head cap screws with an inside hex will be fine to use and likely a lot easier to locate than ones with the triple square wrenching feature. Jim

[Hugh R]

Thanks Jim. Where do you get these 12 point machine screws, Pelican, didn't see them. I guess an industrial fastener place should have them. Also, Randy, whats a "Schnorr" washer, my machine screws had no washers.

[Fishcop]

Hi Hugh

The Schnoor washers are a locking washer with fine serrations or teeth on both sides and are slightly "domed". They are compressed when the bolt is torqued to spec and greatly assist with the prevention of these bolts backing out.

[rcecale]

Here's a couple of pics that may help. You can get these from our host.





#21: Schnorr Washers #22: Moon Plates


Used Moon Plate, showing indentations from torquing down on the Schnorr Washers.


Hope these pics help, Hugh.

Randy

[rcecale]

Hugh,

The Porsche OE part number for the bolt is: 900.067.073.01 and 999.332.102.02 for the lock washer.

The guys at Pelican can confirm these and give you the part numbers for the moon plates.

Randy

[Hugh R]

Hey guys, no washers and no moon plates, with a couple of "pre-rounded" cap heads its a wonder they didn't come loose. I recognize those types of washers, just didn't know they had a name. Thanks for all the help.