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Flywheel diameter TR4A


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Would somebody who has a flywheel lying around be so kind as to measure it for me ?

 

I went to fit the new clutch assy this morning and it's either the wrong one or the flywheel is incorrect, but don't know which. The latter is possible because the car came in boxes and could just have got accidentally switched, although it fits perfectly onto the end of the crank.

 

The clutch cover is about 1/2" too small diameter and thus the bolt holes don't line up.

 

Anyway, the flywheel diameter I have is 11 1/16" or 282 mm (ignoring the ring gear), and the distance between diametrically opposite holes is 10.5" or 268mm. The ring gear is of the bolt-on type.

 

Thanks,

 

Anthony

Edited by Superaquarama
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Hi Anthony ~

 

I've got a 4A lightened and balanced flywheel fitted to my 3A. It's off the car at the moment and I've just measured it for you.

The diameter (not including the ring gear) is 11".

Hope this helps.

 

Tom.

Edited by Fireman049
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Many thanks as ever, guys.

 

It looks as though the flywheel's correct since it's the same as Noel's and Tom's, so has to be an incorrect clutch kit.

 

It came from David Manners so I'll get onto them on Monday, they're always very helpful at sorting problems and David himself will come to the rescue if necessary.

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Mmm, still a bit confused here.

 

Firstly we have myself, Noel and Tom with a distance of 10.5" between diametrically opposed cover mounting bolt-holes, and all presumably TR4A engines.

 

Secondly the flywheel 'patina' shows that the previous clutch plate diameter was 9"

 

But then Rimmers catalogue says that a 4A clutch plate is 8.5" diameter, and this is indeed what Manners have supplied too, and the clutch cover bolt-hole diameter is a fraction under 10".

 

Whereas only the earlier TRs have 9" clutches, up to and incl. the TR4 - again according to the Rimmers catalogue.

 

So Ashley's comment above seems to be correct and it seems I actually need the 9" clutch kit. Our 4A is no. 25 off the line so is a very early car; maybe the first ones had the earlier clutch and Noel and Tom also coincidentally have early engines ? The 'Original TR' book mentions changes to the clutch at CT50125 (first 4a was CT50001), but doesn't specify what,other than to say they were minor and parts were interchangeable.

 

So further thoughts, anyone ?

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Solid axle 4a`s start at CT50001 whereas IRS 4a`s start at CTC50001 You never know what has been fitted to the cars over the years but it is possible that earlier units were being used up at the end of a model line.

Stuart.

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Thanks, Stuart.

 

I've just been looking at earlier postings on the sidescreen forum, where folks have fitted the 4A clutch, and it seems the simplest solution would be to drill & tap new holes in the flywheel for the smaller clutch & cover. But not something I'll do myself as it needs to be über precise !

 

The smaller diaphragm clutch appears to be stronger and lighter, both in actual weight and pedal pressure, so it wouldn't seem sensible to revert to the older type clutch. Oddly, though, the old thrust bearing was of the later type, so it's still a bit of puzzle.

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Thanks again, Ashley. And could be, Alec, but I'm beginning to think that the flywheel may be off a TR4 as the car came in bits from a vendor who had a couple of other TRs as well.

 

I took it to the engineers' today and the chap commented that the flywheel teeth didn't look as though they'd been meshed in a very long time as there's quite a bit of surface rust on them, whereas the car was up & running until not much more than a year ago. However, the teeth seemed to agree perfectly with the hi-torque starter teeth, which was a relief.

 

Anyway, we're putting in new bolt-holes so it will be back to standard should any future issues arise.

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