3 replies to this topic

[Sprocket]

For those who do not want to read the where, why and what fors, the correct torque figure for the taper boss to pressure plate bolts on a Verto clutch is 40-45lbft . Also, if the bolts do not have thread lock applied, use some loctite. Do not install them without thread lock.

A short explanation of the current problem

It is becoming more and more apparent that problems with Verto Clutches failing is as a result of the wrong torque setting being applied to the taper boss to pressure plate retaining bolts. Failures can be partial or total with the bolts shearing off, or just plain falling out.

Here are some of the most recent

http://www.theminifo...showtopic=60548


NOTE:This refers to the taper boss, or flywheel hub, of 2 part flywheels NOT the pressure plate, diaphragm or clutch cover to flywheel bolts

http://www.theminifo...x...c=57094&hl=



These failures are as a result of the taper boss being 'no longer available, NLA'. Clutch kits are now supplied without this taper boss. New bolts are usualy supplied, if they are not, take the kit back and buy a kit that does supply the bolts. These bolts may or may not have thread lock applied.

This is where the confusion arises. There is no well documented torque setting for these bolts, both the Haynes and the Rover workshop manual do not list a torque setting for these bolts as at the time of writing, clutches were supplied as a complete assembly from the factory, thus no need to assemble dissassemble. Only in recent years is it the case that the clutch kits are supplied 'incomplete'. However, what people do assume, is that the torque figure listed, 18lbft, for the pressure plate to flywheel bolts ( the bolts around the perimeter of the flywheel) is the correct figure. Its not, it is no where near enough to generate the clamping force to prevent the the whole flywheel assembly from moving on the taper boss. High shear loads are directly applied to the bolts acting like a big pair of bolt cutters. Alternatively, the bolts shake loose as they have been supplied without thread lock applied and none has been used at the time of assembly, the 18lbft torque value again is not enough to prevent the bolts from working loose.


I in the past have used 45lbft, but recently a member on this forum said he spoke to Minispares and they quoted 40lbft. in which case, the correct torque figure for the taper boss to pressure plate bolts is 40-45lbft . Also, if the bolts do not have thread lock applied, use some loctite. Do not install them without thread lock.

[Dog]

Does this apply to pre-verto too?

[Sprocket]

I would say so if its one of those ancient pre verto flywheels with the seperate taper boss. There are some pre verto flywheels that have been converted in this way by using the Verto taper boss, machining out the center of the flywheel and bolting the boss in place. You can reclain expensive lightweight flywheels in this way when the taper is beyond repair. I believe Fast Carl has done a few of these.

[rozzer!]

a friend of mine called me on monday as he had a problem with his clutch and he popped over. well, he didnt quite make it as his clutch did on the roundabout between the a12 and the m25! i instructed him on which clutch to get and i went round today to fit it. upon removing the clutch assembly, which "fell" off with the aid of a puller and no hammer i disassembled the clutch. i would post pictures but i dropped something on my phone rendering it useless till further notice! pressure plate undid ok from the flywheel without any problems. the centre plate was a bit glazed from the wheel spinning that ray has done! the thing that worried me was, how can i describe this, not slashes but not scratches either, somewhere in between. i instected teh pressure plate and boss at this point and discovered 1 bolt had been making contact with the centre plate making all the noise, and the other bolts were hand tight. this was not good! the centre plate didnt look that old and the entire assembly seemed "clean" which leads me to believe that the clutch had been changed recently, and leads onto the lack of "torque wrench use" that has been noted before. the surface of the flywheel and the pressure plate were both ripply in feeling and we used an old flywheel of mine which i took along as i assumed after the original conversation with ray that the rivets had chewed into the flywheel surface. mine needed a clean up of the gunk that had collected on it previous but was immaculate compared to rays one. the new clutch kit came with a torque setting of 44lbft of torque for the boss. it was in the literature with the clutch. this may get over looked by some people. i double checked this with this forum to make sure. also looked up the flywheel to pressure plate torque figure. then with a 2nd pair of hands from ray torqued everything up. we fitted everything up and hey presto it all checked out perfectly!