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MG Midget and Sprite Technical - Carbon thrusts. One for Alan A?

Rather than drift too far off topic in bernie's t9 clutch release design problems thread, I've started a new one just for carbon thrusts.

Hi Alan, I read your comments about release bearings with interest.

Having converted to a T9 with a concentric slave with roller release, over 13 years ago, I've not experienced "bad" carbon thrusts. The last one I bought was an original part. When I took the ribcase out, after some 30/40k miles of use the carbon thrust was still in good condition. It's sitting in my loft along with the ribcase g/box.

Many people here report poor carbon thrusts these days. But I've wondered if that's really a completely accurate picture. Now I have a midget with a ribcase again, and a carbon thrust, I need to know the "true" picture. It's fine at the moment, but I have no idea of how much wear there is in it. I don't really want the expense of converting to a roller release, if good quality carbons are still readily available.

So my question is simple. Who sells good quality carbon relase bearings, and are they as good as the originals?
Lawrence Slater

hi I think the issue is that 'new' carbon thrusts are a poorer quality. I replaced the clutch recently and the thrust that came with the kit was inferior to the original one both in the quality of the casting and the density on the actual carbon as it was clearly much softer. I managed to source a NOS borg and beck ( not the 'new' borg and beck!) and all was well.
Bob Beaumont

I only use the usual suppliers.
I do have a carbon recently discarded by a Spridget newcomer because he was scared by the myth. Plenty of mileage on it. But then he has replaced most of his car due to myths & paranoia.
Even rollers fail!
Alan Anstead

Like Bob, I would try to source a NOS item.

I even keep good used bearings, just in case!
Dave O'Neill2

surely it just needs a phone call to a trusted supplier to find out what the current situation is
Nigel Atkins

Lawrence, take a read of Colin Dodds' site in Oz - he explains about the soft carbon modern pattern parts. Then again he uses this to back up the sale of his Teflon coated replacement thrust so one wonders if it's true or just more FUD. Like Dave O, I have a few NOS ones and also keep good s/hand ones 'just in case'. Really we are just hoarders ;-)
David Smith

Hi David, could you email me off line re your NOS carbon bearings please?
Steve Clark

You have e-mail
Alan Anstead

My understanding is that carbon thrusts are no problem, either the originals or new replacements. EXCEPT, there was a period of time when there were replacements on the market that were sub-standard and those Spridgeteers unfortunate enough to get hold of them experienced failure after a fairly short period of use - measured in thousands of miles at best. The parts were identifiable by having two holes in the outer margin of the carbon ring.
As identification of the faulty items was easy, and the information well circulated at the time, there shouldn't be too many still in use or being supplied any more. So it was really just a temporary problem, now largely resolved.
Guy W


I'm not sure that was the only problem.

I ordered a new thrust bearing from M*ss a few years back and the dimensions of both the carrier and the carbon ring were wrong.
Dave O'Neill2

Oh, OK Dave. I hadn't come across that one.
Guy W

Ah. A bit uncertain then. Sounds like there are both good and perhaps some bad out there. Maybe I'll just convert the Midget to a t9, as an extreme way of solving the "problem" lol.

There's a thought. I know there are roller conversions, but has anyone installed a concentric slave in a Spridget box?
Lawrence Slater

yes, there are racers with concentrics on ribcase boxes. But the simplest remedy might be the teflon=coated bearing from Colin Dodds in Oz that I referred to in my previous post.
David Smith

Peter May sells a conversion mounting that bolts inside the ribcase (smooth too I suppose) bellhousing so that a concentric can be fitted.

He had one at race Retro a couple of years ago.

Red it was :)

How much is the concentric conversion? Sounds interesting, -- for anyone who doesn't mind wasting a few quid. Like I do from time to time lol.
Lawrence Slater

This is off his online catalogue, doesn't say a price though Lawrence

Aha belay that, the price is in the catalogue text.

215, could be a bargain if you think how much buggering about you might have had to do.

Mind you, were it mine I might just do the buggering around for the interesting times it guarantees.



Since I've already got a couple of spare T9 boxes, I think I'd be better off buying a Burton concentric setup, or even cheaper, the bellows setup that Guy mentioned on the other thread, and putting the rest towards the remainder needed to convert the thing to a T9 box. Or maybe just spend 100 quid on 1/2 dozen or so carbon thrusts.

Not much point spending too much on a Spridget box, that although quite now, will probably be buggered in 30/40K miles.

Lawrence Slater


pays yer money, you gets the choice

I would go type 9 again every time

(unless I go back to setting up a Getrag some day)

Lawrence, the saving compared to Burton's prices wasn't in the cost of the concentric slave (the bellows bit as you call it) but in the mounting block and spacers. That bit I made for 5. Burton's price seem disproportionately high on those. The only bit that needed working out was the thickness I needed as it depends on the combination of the other parts used - clutch, bellhousing and slave. That is why Burton sell a variety of different spacer rings. Oh, and the plumbing was a tad problematic!
Guy W

Ah thanks for the clarification Guy.

Well I won't be keeping the Midget long enough to make it worth my while converting any of it. I'd never get the money back. So if I need a carbon, I'll just source a decent one, or if I have to,I could even use the one from my old box in the loft.
Lawrence Slater

This thread was discussed between 25/01/2014 and 27/01/2014

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