Axle bolt, washer and plate confusion

[D911SC]

I searched but can't be sure exactly what I need to do here.

I replaced the axles on my 83 SC with PP ones (part 923-332-033-02). These are the 6 hole joints. The bolts came with it and are shorter (47mm) as compared with the originals at 50mm. The new ones are also torx heads (take an 8mm bit) not allen heads as the originals are.

When I pulled the old axles off there were no schnorr washers or plates. Checking the parts list I am not 100% clear if the plates are needed for my axles.

I tried to torque up the bolts and they are just a fraction too long leading me to think that I need the washers at least. It's only the last couple of clicks on my torque wrench that causes the hub to bind.

Can someone please confirm that it's just the schnorrs I need or do I need the plates as well?

Thanks in advance
Darren

[Bob Kontak]

Based on the parts pdf you have the correct axle. However, the washers and plates appear to only be for the SC/SPM (special model) which I just found out is the Weissach edition. The Turbo and SPM take 10mm bolts and the standard SC takes 8mm.

I went through the confusion a few years back and ended up putting washers on my new standard SC bolts. I had no clearance issues that I recall and the axles are still on (street driving).

Sounds like your new axle shafts hubs are a little shorter. I am not speaking from wisdom, but I would just put some washers on.

Here is the parts pdf. See the rear axle section.

http://www.porsche.com/all/media/pdf/originalparts/usa/911_USA_78_83_KATALOG.PDF

[D911SC]

Thanks Bob.

I'm assuming by adding the washers that there is no compromise to the setup. After all the schnorrs are designed to stop bolts backing out.

Darren

[Grady Clay]

Darren,

Are the combination of the new CV joint and the metal boot cover (‘tin’) different from your original?
There are two different ‘thickness’ of the boot covers, one is thin ‘tin’ (~0.5 mm) and the other is a machined piece (~6.0 mm).
Which do you have or one of each?
What material is the ‘thick’ version?

Yes, use new M8 Schnorr washers.
I’m inclined to always use the ‘moon plate’ 2-hole washers.
The purpose is to have a surface of intermediate hardness between the mild steel of the ‘tin’ and the extremely hard Schnorr washer.
Regardless of anything else, the CV joint bolt must go through the flange about 1½ threads AND not contact the transmission casting when you push the flange to minimum clearance.

Your new 47 mm M8 Torx CV joint bolts, what strength class is stamped on them?
These must be strength class 12K (12.9) bolts.
Keep in mind that a Torx wrench size is not metric. These are T-size, like T3, etc.
Do not use a hex wrench on a Torx wrenching bolt – even if it seems to fit.

Best,
Grady

[D911SC]

Grady,

I took my old axles to my local Porsche guy so he could assess them. He said they were not worth rebuilding and showed me various areas of wear. I left them ther and just ordered the new ones. I do have a pic which shows what they looked like. The bolts are longer than the the ones that came with the new axles. I haven't checked the rating on the new bolts but will do so when I get to the car next - to make sure they are 12.9's. I have a torx set so am using the right bits but thanks for pointing out not to use the hex wrench as it does actually seem to fit.

When I tightened the new bolts without washers or plates the axles turned no problem. The bolts only made contact on the last minor turn of the torque wrench. This makes me think that the clearance issue will be OK once I use the schnorrs.

I don't have any moon plate washers but could order them if necessary. I follow the reasons for having them but as the originals didn't have them do you think it's OK not to use them. Would a standard 8mm flat washer be a bad idea?

I appreciate your comments on this.

Darren

[D911SC]

here's the pic of the original axle

[Grady Clay]

Darren,

The transmission axle flange is supposed to have a bit (~2-3 mm?) of axial ‘play’.
When checking for the clearance between the ends of the CV joint bolts to the transmission casting, be sure and push the flange (and CV joint) toward the transmission to minimum clearance.

I think this situation (no Schnorr washers or 2-hole plates) was a case of the ‘bean counters’ overruling the engineers.

NEVER use a single flat washer.
The reason for the 2-hole plate washer is so the smooth plate washer can’t turn against the smooth ‘tin’ cover.
The two holes act as a ‘locking device’ for each other.

Your old axles have the thin ‘tin’ boot cover.

Best,
Grady

[D911SC]

Thanks again Grady.

I noticed the 'play' on the flanges so I'll remember to push them in when checking the final clearance. I think the main issue is with the flange on the trailing arm.

I've ordered Schnorrs so when they arrive I'll report back. Hopefully my bean counter (aka wife) doesn't check the credit card statement.

Point noted on the single flat washer!

Much appreciated,
Darren

[Bob Kontak]

Good info. Thanks Grady.