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MG Midget and Sprite Technical - 948 Uprated clutch

A little while ago (in fact might have been a couple of years ago...), some of you guys had kindly been advising me about an uprated clutch that would be suitable for the engine in my Sprite Mk2 and that fits to the normal 948 two dowel flywheel. The engine is still currently being rebuilt (948 bored to 998, balanced & strapped bottom end etc) as my brother is doing up his house rather than my engine. However due to being dragged along to Stoneleigh by a friend, I now have a few more of the remaining things that I need to get it back together and with Spridget 50 approaching......!!!!!

The clutch that was recommended used early Spitfire parts but also fitted straight to the two dowel flywheel. I have been fortunate enough, through a friend of a friend, to have been offered a clutch that sounds like it is the right one (combination of early Spit & small block A series) that was specified together by AP for a project that later fell through, so is still in its boxes.

Part numbers as follows (all Delphi / AP Borg & Beck):

Release Bearing HD3299

Driven Plate Assembly 160mm HB9721

Cover Assembly 159mm HA2873

I've tried cross referencing on the AP website, but it doesn't recognise those numbers at all for some reason. The clutch diameter seems right diameter (6 1/4'' / 160mm). Can anyone here help confirm if this is likely to be the right one?

Thanks!


Paul H

Paul,

The Spitfire 6 1/4" cover plate has 9 springs vs the Minor 6-spring cover. The AP competition version at the time was based on this 9-spring version, and used an uprated driven plate as well.

I used a standard Minor driven plate with the Spitfire cover for many years in a quite warm 948 in our Minor, before fitting the 1380. The release beaing is standard Minor.

How does what you have compare visually with the Minor parts?

Richard
Richard Wale

Here's the only pic I have of the actual parts:
Paul H

Trying again....


Paul H

Paul,

Picture??
Richard Wale

Paul,

Posted while you were uploading!

If the o/d and spline are correct that should be ok. Do you have a picture of the cover plate?

Richard
Richard Wale

Only the boxes, showing the part numbers. I'll see if I can get some more from the seller.

Thanks!
Paul H

Paul - I thought you had caught a nasty case of Riley Iley Spolly Olly Tiddly Diddly Itis, and were about to sell your lovely early Sprite?
Nick

Nick, tbh at the moment with a blown engine, and last on the road in '05, it would be pretty worthless if I tried to sell, so I thought that I might as well fix it :) Once it's going again, father has generously offered to drive it at least once a week!

In the meantime, Google has produced the following info on the clutch:

Driven Plate Assembly 160mm HB9721 fits: '62 to '64 Spitfire

Cover Assembly 159mm HA2873 fits the following: Austin A30 35 40 Farina Healey Sprite midget Minor 948cc

Release Bearing HD3299 fits the following: Austin A30 A35 A40 Farina -62 Healey Sprite 58-63 MG Midget 61-3 Minor 49-61

Are the applications for the cover & drive plate the right way around? I was never very good at remembering how clutches work....

Otherwise it seems to be what I'm looking for!!
Paul H

The later 1275 sprite driven plate, at 6.5in, will fit inside a frogeye spring back cover assy.
Alan Anstead

Doesn't that require a 3 dowel fitting though, instead of the 948's two dowel one?
Paul H

Paul, all the above sounds correct. The cover should look like the original Sprite one but with 9 springs instead of 6.

Good to see you again and good luck on getting the car finished for 'Spridget 50'

Mark.
Mark Boldry

Paul,

The parts seem to be the wrong way round for an A-Series.

You need the Spitfire cover plate and A-Series driven plate or centre disc.

Unless, the cover plate has 9 springs??

The Spitfire driven plate does not fit the splines of the A-Series box, I am pretty sure?

Richard
Richard Wale

Mark, I'll try to get it there, but I suspect that it won't be roadworthy by then, so will have to bring it up on a trailer.

Thanks Richard - I'll see if I can det some more pics & dimensions of the components, & will post them up.
Paul H

Years ago (too many to count) i ran a slightly !! warm morry minor also 948 using standard centre plate and spitfire 1200 cover plate (ex frog engine). Fitted straight on.

Unfortunatly the half shafts didnt agree with the 5.5J wheels and snapped regularly - as did crankshafts if over reved !- No money for 'performance' parts in those days - still situation normal LOL.

Richard.
richard boobier

Cherry has a competition clutch, and frankly it's a pain in the leg. Very soon now it will need replacing, and I'll be fitting a standard one, I think.

Is this just curiosity on your part, Paul - or do you think your 998 is going to need a seriously uprated clutch? I've been reading my previous owner's notebook, and the comp. clutch was fitted in 1980 at the same time as the Derrington engine, cam and head, but it's hard to believe (from present performance) that it's necessary.
Nick

It will be on the normal 3.5J rims - the 5.5J ones I have cause massive tyre scrub on the rear arches :( so hopefully won't be snapping halfshafts!

Nick, the old clutch used to slip like crazy when changing up at about 6.5 / 7k, but was fine the rest of the time, which is why I reckon it just wasn't up to the job. I'd be very interested to know more about how Cherry's clutch behaves though - will you be at the London MASC meet tomorrow eve?
Paul H

I used standard 1098 clutches for years on a 998cc race car, but not surprisingly they occasionally broke up at 7,500 RPM+!

Wanting something lighter and not a specialist race part, I found the simplest, (and cheap) answer was to have the small capacity 4 bolt flywheel re-drilled to take the standard 1275 clutch (pressure and driven plates). It needed an extended release bearing, for which I picked up a roller version from Frontline.

As this was for a race car the parts and assembly were balanced afterwards. Since then, 30 or more race starts, 7500 RPM and 85ish BHP; no problems, touch wood.

Andy
Andy Pie-Crust

The 1275 clutch is a back-up plan, but the crank, flywheel etc have already been balanced so I'd rather avoid that unless I have to. Had I thought of it before that was done, I would have chosen the 1275 though!

Regarding the clutch drive plate, just seen one on eBay that is listed as fitting both Spridget & small Triumphs

http://cgi.ebay.co.uk/CLUTCH-PLATE-SPRITE-MIDGET-HERALD-SPITFIRE-NEW_W0QQitemZ140155566380QQihZ004QQcategoryZ27383QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem

Although for a 1275 Spridget, presumably the splines wouldn't have changed between 948 & 1275?

The clutch I'm looking at was I believe apparently specced originally for a Reliant of some form & I've seen another clutch listed as being for both a 948 & a Reliant Robin:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=180200672430&ssPageName=STRK:MEWA:IT&ih=008

Does all this mean that the clutch I'm looking at is thus ok, or am I being stupid & missing something glaringly obvious?

Thanks :)
Paul H

Paul,

While all the A series boxes used the same splines AFAIK the 1275 which that plate seems to be for used a 6.5" clutch and the 948 a 6.25" clutch so you may want to verify that it is the correct size with the vendor to fit the 948 cover. The cover you linked to says it is for a 948 sprite which should be the 6 spring cover, I thought you were after the spitfire 9 spring cover.
David Billington

The 6.5 1275 clutch plate can be used with the 948 6.25 cover / pressure plate.
It can also be used on a Triumph Toledo.
Alan.
Alan Anstead

Sorry - I should have been clearer - those ebay links aren't the parts I'm looking at buying, they are linked to purely due to what the ads say that the parts also fit - the 1275 one is claimed to also fit a Spitfire, suggesting that Spits have the same spline pattern.

Alan - do you know if Toledos use the same spline pattern as Spitfires & Heralds?

David - I hope the one that I am looking at is a Spitfire 9 spring (still waiting to hear back).

TBH, it's looking more & more like the clutch I described in my first post isn't going to be worth the hassle :(
Paul H

Did a five speed Sierra conversion on a Triumph Spitfire. When it came apart we were expecting to fit an avenger clutch plate, as part of the conversion, but everything seemed to have shrunk. It turned out a previous owner had fitted a Toledo engine but fortunaely the MM Spares 6.5 1275 Sprite / Sierra Splined clutch plate fitted. I have no experience of pukka Spitfires.
Last but one conversion I pulled a 948 to find it had been running the 1275 plate under a stock 948 pressure plate. That car is now a 1098 with type 9.
Alan.
Alan Anstead

Thanks Alan :-)


I think I'm slowly getting my head around all this!
Paul H

This thread was discussed between 27/02/2008 and 14/03/2008

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