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MG MGB Technical - Clutch Release Bearing

I'm going to swap in another engine shortly on my '72 Roadster. While engine out it seems to make sense to put in new clutch assembly. Bought Borg & Beck clutch kit with roller bearing clutch release. The plastic housed bearing appears to be just a press fit into the clutch arm, rather than using the two clips as of old. I came across this arrangement 8/9 years ago when I last replaced the clutch, but wasn't convinced so filed down the bearing sufficient to be able to use the two clips.

Has anybody else come across this way of attaching the bearing, and if so what did they do?

BTW, I searched in the archive for this subject, but I can only see messages going back a couple of months.
Peter Allen

The after-market one I used with a conventional clutch kit used the clips. In normal use there is a spring continually pressing the release arm and hence the release bearing against the cover plate, so under those conditions it can't really fall out. But if you should happen to use the release arm to push the slave piston right back into the cylinder it will pull the release bearing away from the cover plate, so what happens then depends on how well the bearing is attached to the arm.

If you have a different gearbox with a guide tube for a roller bearing it would probably be OK without clips, but the V8 still used clips.

Something to check is how concentric the release arm holds the bearing to the first-motion shaft. I had a roller bearing break up, and the previous graphite bearing, which I think was down to them being non-concentric. I've corrected that, and am now back with a graphite, so time will tell.

Check the friction plate fits the gearbox shaft first, and carefully clean and lubricate the bearing pivot, shaft splines and pilot bearing with the correct grease before assembly.






paulh4

You might find it helpful to read Paul's article on clutch ball bearing release bearings here http://mgb-stuff.org.uk/clutchr3a.htm#changeb
Mike Howlett

Thanks, both. Yes, I had read that article - very useful. I'd had a couple of carbon bearing failings - the last in France on the way back from Le Mans, which is why I switched to the roller bearing that's been in the car these last few years. The concentricity issue I'll check - I'm replacing the clutch arm bush and bolt, as well. Bearing in mind I haven't got clutch issues at the moment. It just seems to make sense to replace the clutch while I'm switching engines.

It was this clipless push in bearing that I was bothered about. When you pivot the new bearing in the arm (I've a spare box, that I'm practicing on), by a few degrees, as it would move in use, it springs out the arm. It's a standard box. On basis this design must have been out a few years anybody buying the Borg & Beck three piece kit would have come across it. I may just end up using the release bearing I modified the last time around for clips. The old design seems safer.
Peter Allen

Peter,
you'd have to ring up and check rather than trust my memory but I think MGOC saying the Borg & Beck clutch kit they sell (fir the midget) at least is to the correct spec.

Or see here. - https://www.ebay.co.uk/itm/203260005636
Nigel Atkins

Mine 5 years ago was AP and fortunately came with graphite. But had it come with a roller I still have the graphite that came with the kit I used in 1994 but fitted the roller.

That link is AP, but there have been various mergers over the years. Some suppliers don't say what type is in the kit, some do, and some like Moss give you a choice.

paulh4

This is the one I bought - admittedly a couple of years ago, but in anticipation of this job. If you look at the picture of the roller bearing you may be able to see what I mean. As it stands, there's no room for clips.

https://www.ebay.co.uk/itm/124510971900?epid=248948266&hash=item1cfd6ea7fc:g:3toAAOSw2xRYiLj7
Peter Allen

Several adverts show those 'square-ish' pivots rather than round without clips, other round pivots with clips even though it is a 'roller' bearing. There is a huge variation in prices on eBay all apparently for the MGB 4-cylinder. You might expect that, but QH can be £80 or £146. More of a minefield than usual, perhaps.
paulh4

Borg & Beck are just a First Line company now.

This is the kit you have, kit reference GCK109HDR (heavy duty roller?) - https://webcat.firstline.co.uk/ApplicationsDetails/9334/HK9679/

"This Borg & Back clutch kit has a heavier duty roller release bearing and is a replacement to the original carbon thrust bearing kit - GCK109". - https://www.ebay.co.uk/itm/181910075618

- BUT -

there's another kit that shows (later) bearing retainer 'springs', kit reference GCK109AF. - https://webcat.firstline.co.uk/ApplicationsDetails/9334/HK9694/

Nigel Atkins

Mine's the HK9697 kit, as per Nigel's second link. Presumably, somebody somewhere has proved that this change of design actually works...

As an aside, on Paul's point on prices, I don't get how vendors can sell what basically looks the same product at such widely varying prices. You can sort on price and then find best price for a given brand, spec etc, which is what I did with this. I'd be guessing most people would do this. If you've got more time then you can ring the changes on descriptions on the off chance (?) somebody's made a typo, got their spelling wrong etc.
Peter Allen

"somebody somewhere has proved that this change of design actually works"

Hmmm. Probably cheaper, but given how many complaints there are about parts quality these days I wonder about the 'works'.

The retainers in the third kit look like the original type from what I can see.
paulh4

This thread was discussed between 28/08/2021 and 31/08/2021

MG MGB Technical index

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