Thread: clutch bits

Originally Posted by D3Jon

Let us know how you get on Ben, I'd be really interested to know. Maybe that's the similarity between the Isuzu engined cars clutch plate and the V8 101 clutch plate mentioned earlier in this thread?

It measures 276 mm. The PN is printed on, but "V8 & Isuzu" is written on in pen. JC told me both were the same... Maybe the isuzu version can be squeezed into the V8. I note that 167 mm = 10.5"

Originally Posted by isuzurover

It measures 276 mm. The PN is printed on, but "V8 & Isuzu" is written on in pen. JC told me both were the same... Maybe the isuzu version can be squeezed into the V8. I note that 167 mm = 10.5"

I think you mean 267!

John

If the only difference is the outside diameter, 275 to 267 mm isn't going to make much difference.

Given the same clamping force from the pressure plate, the important number is the mean radius of the friction surface. i.e. (OD + ID)/4 where the OD and ID are diameters of the effective friction surface.

The difference between 275 and 267 mm is 8 mm. If the ID is the same, it only makes 1 mm difference to the mean radius.

Torque to cause clutch slip ~ Clamping force x coeff of friction x mean radius.

Originally Posted by JDNSW

I think you mean 267!

John

NO. 276mm. Maybe my tape measure is 1mm out, but that is what my (new, genuine) clutch plate measured.

Originally Posted by isuzurover

It measures 276 mm. The PN is printed on, but "V8 & Isuzu" is written on in pen. JC told me both were the same... Maybe the isuzu version can be squeezed into the V8. I note that 167 mm = 10.5"

Thanks Ben, I don't personally know JC, but I DO know he knows his stuff, so wouldn't argue. As stated the ID and OD come into play and I would have thought the most important thing was exactly matching the machined face of the pressure plates surface. Especially if fitting a replacement friction plate and re-using a pressure plate. As the info is written in pen though, there's always the chance that it's wrong and written on it long before JC bought it?

Originally Posted by JDNSW

I think you mean 267!

John

Obviously a slight typo by Ben, but John is correct, 267mm is as near as dammit equal to 10.5"

Originally Posted by isuzurover

NO. 276mm. Maybe my tape measure is 1mm out, but that is what my (new, genuine) clutch plate measured.

1mm won't make a stuff of difference, but as an aside - Pocket tape measures generally have a movable 'hanger' (the silver coloured bit) on the end that compensates for measuring up to something or hanging the tape off something (it's fixed by rivets through slotted holes that allow it to move the material thickness of the hanger itself). The movable hanger can cause all sorts of measuring inaccuracies when you want to measure something accurately, plus the hanger itself can be bent slightly. So if you want an accurate measurement use either a steel rule or start your measurement with the tape on the 100mm mark and deduct 100mm from the final reading.

Not of relevance when measuring a clutch plate of course, but it starts to get more complicated when you have to start compensating for thermal expansion or shrinkage of the tape / rule itself. Nearly all steel tapes and rules are calibrated at 20 Celsius and in the case of steel tapes at a quoted tension. Good tapes will have this info written on them. The difference on a hot or cold day over say 50m is significant - I used to do this stuff for a living and measurements had to be corrected for thermal expansion/contraction, catenary correction (sag) and of course corrected for slope. Hardly anyone does that now as they all use EDM's that correct everything automatically including the effect air pressure and temperature have on the speed of light (laser based technology).

Jon