Clutch pressre plate retention

adamnreeves · Post by **adamnreeves** » Thu Apr 05, 2007 11:53 am

Hello chaps. Tried to get some bolts to fix the pressure plate to the flywheel from rimmers and was told that have none and to get from local bolt supplier.

I usually do just get fixings from local supplier but I do not know the tensile stength/grade requred.

I have worked out that I need 5/16UNF. So I have bought some 5/16UNF 1" long set screws (probably have to cut about 6mm off end).

These are grade 5, is that okay?

I also presume that I install washers and use loctite 243?

kiwicar · Post by **kiwicar** » Thu Apr 05, 2007 1:09 pm

I would use Grade 8.8 for this job (alan cap for preferance), with a split washer behind (a proper split washer not a bit of square section wire bent around a mandrel) and the correct torque setting. Others will doubtless use plain bolt and loctite but It is not my choice.
Best regards
Mike

adamnreeves · Post by **adamnreeves** » Thu Apr 05, 2007 2:16 pm

I thought grade 8.8, 10.8, 12.9 was for metric bolts. This is imperial. The guy I asked at the bearing shop said it is high tensile steel and that is it eqiv to 8.8 metric. I think grade 5 might refer to the thead fit.

kiwicar wrote:I would use Grade 8.8 for this job (alan cap for preferance), with a split washer behind (a proper split washer not a bit of square section wire bent around a mandrel) and the correct torque setting. Others will doubtless use plain bolt and loctite but It is not my choice.
Best regards
Mike

adamnreeves · Post by **adamnreeves** » Thu Apr 05, 2007 2:37 pm

Just did some searching on the net and grade 5 has tensile strength of 120,000 psi whereas grade 8 has 150,000 psi.

So I am not going to risk it just called up the place where I got them from and they have cap heads 5/16UNC 7/8". These are 12.9!

stevieturbo · Post by **stevieturbo** » Thu Apr 05, 2007 7:18 pm

Isnt the cover dowelled too ?

While I would say to use the best bolts you can....

Given the diameter of the bolts on a clutch cover, the loadings placed on them in terms of shear would be pretty small compared to other areas of the car ( eg propshaft bolts )

adamnreeves · Post by **adamnreeves** » Thu Apr 05, 2007 7:25 pm

Yes I thought the stresses wouldn't be too bad and was thinking that 10.8 should be fine but then I found out that class 5 is equiv to 8.8 I wasn;t sure. Yes it is dowelled as well. I have the cap heads now which are 12.9 anyway and they are exaclt the right length so I do not have to chop down which I hate doing anyway.

I was reading my Rover 3500 haynes manual and it says to mark the pressure plate with paint and the flywheel so that it is put back the same. Is this just good practise when re-assembling. My bits are brand new and I am guessing this does not matter?

stevieturbo wrote:Isnt the cover dowelled too ?

While I would say to use the best bolts you can....

Given the diameter of the bolts on a clutch cover, the loadings placed on them in terms of shear would be pretty small compared to other areas of the car ( eg propshaft bolts )