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clutch backing plate
https://ausmini.com/forums/viewtopic.php?f=5&t=18017		 Page 1 of 1
Author:  simon k [ Sun Apr 09, 2006 9:00 pm ]
Post subject:  clutch backing plate
the motor is coming together nicely... next bit I have to tackle is the clutch backing plate - it's groovier than Kev was in 1972....

I want to get it machined, but is there anything I need to do with it at the same time, like machine the posts (the knobby bits that go through the flywheel) down?

I ought to get the flywheel machined at the same time, right?
Author:  drmini in aust [ Sun Apr 09, 2006 10:39 pm ]
Post subject: 
Well generally whatever you take off the backplate needs to come off the 3 posts too whilst you are at it.
Otherwise, you are reducing the clamping load of the diaphragm.
Ideally the diaphragm spring should be FLAT when the backplate/clutch plate/straps/flywheel are torqued up, do a dummy build and take a peek under the diaphragm cover to check.
See http://www.minimania.com/web/DisplayID/ ... ticleV.cfm
for Chichm's theory on it. Yes I believe he's right. :wink:

<edit> yes face the flywheel if it needs it before doing check above.
Author:  simon k [ Mon Apr 10, 2006 1:08 am ]
Post subject: 
thanks Kev - I read that article a little while ago, but forgot all about it, I'll have a fiddle

here's a query - what do you do about centering the backing plate? I've always just held them up and shoved the bolts in , but is there a right way - old SP #64 says to use some special tool, but I've no idea what that'd do :roll:
Author:  drmini in aust [ Mon Apr 10, 2006 7:16 am ]
Post subject: 
I hold the backing plate up from behind while I get the top bolt in, leave loose. Then put the other 2 in, leave loose.
Then, I remove one at a time to put Loctite 262 on the threads, screw them all in evenly and torque up using calibrated left arm and ratchet.
Reason why I Loctite them- I had a screw work loose, once...... :wink:
Author:  Stuartminidlx [ Mon Apr 10, 2006 7:37 pm ]
Post subject: 
i went through this. in the end i sent it to GR and he machined, lighten and balance the flywheel and backing plate for a very good price. i would give him a call.
Author:  simon k [ Mon Apr 10, 2006 8:39 pm ]
Post subject: 
drmini in aust wrote:
I hold the backing plate up from behind while I get the top bolt in, leave loose. Then put the other 2 in, leave loose.
Then, I remove one at a time to put Loctite 262 on the threads, screw them all in evenly and torque up using calibrated left arm and ratchet.
Reason why I Loctite them- I had a screw work loose, once...... :wink:


yeah, that's all I do too... just thought there might have been a proper way
Author:  Mick [ Wed Apr 12, 2006 4:21 pm ]
Post subject: 
Does just putting the bolts in ensure that it is centered? I thought there would be some room for the backplate to wander even with all three bolts in, or is it simply compelled to line up?

I worried about this recently on my own engine, I just measured and used my eye till I was fairly happy.
Author:  drmini in aust [ Wed Apr 12, 2006 7:22 pm ]
Post subject: 
Mick,
It IS centred, because the 3 sets of straps are all the exact same length. Unless the strap holes or the bolts are worn... :lol:
Author:  simon k [ Thu Apr 13, 2006 9:18 am ]
Post subject: 
drmini in aust wrote:
Mick,
It IS centred, because the 3 sets of straps are all the exact same length. Unless the strap holes or the bolts are worn... :lol:


but what if the backing plate is off centre, even though the straps are the same length, can't it be a little bit up or down through the holes in the flywheel ?

I'm about to do dad's clutch, so I'll see ;)
Author:  drmini in aust [ Thu Apr 13, 2006 5:33 pm ]
Post subject: 
Simon it is simple geometry- if the 3 holes in the backplate & flywheel are accurately positioned (they are, if not homemade) and the straps are all the same (better be, or you need new ones!), it will run true. :wink:
Author:  simon k [ Fri Apr 14, 2006 1:01 am ]
Post subject: 
I dunno Kev - simple geometry to someone who can't remember how a right angle triangle works is stretching what I can work out with a flywheel... but anyway, I put it together and it's too close to centre to tell if it's not properly centred.... I couldn't move it with a screwdriver... meh, I'm not going to question it ;)

the spring is nice and horizontal too - without me even doing any adjusting :)
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