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MG Midget and Sprite Technical - Clutch alignment tools

Can anyone please advise the the dimensions of the clutch plate alignment tool for the various models and if there is any difference for the Triumph engine.
I have measured a ribcase pilot shaft diameter at 0.496in but do not have a clutch plate to measure the clear bore diameter.
Many thanks
S G KEIL

Here is my A-Series alignment tool. The spigot end is a smidge under 1/2", the splined bit is 13/16". I don't know anything about Triumph engines, they are the arch-enemy!

Les Rose

I bought an alignment tool years ago which consists of a whole set of cylindrical 'bobbins' that slide onto a steel mandrel. You select the ones for the crankshaft end needle roller and the clutch plate according to the vehicle. I once had a table of the sizes for different applications. That has long since disappeared but you just match up the sizes that fit best.
GuyW

"Arch enemy" that made me chuckle Les 😊
Jeremy MkIII

I intended to make a number of simple tools to cover all Spridget variants using acetal material with only plain diameters as splines are not necessary.
Really need a measurement from bore of friction plate.
I could also address the use of Ford gearbox but not sure if they are all the same or further variants.
Cheers
S G KEIL

I have the same Guy, but over the years one or two bits have disappeared (probably when I've lent it out) so if I need a diameter I no longer have I just put a bit of tape on a smaller size.

Trev
T Mason

I had a kit like Guy mentioned but it disappeared years ago. No idea what happened to it.
There's a universal kit on eBay for £10.85, but it's all metric, as things are nowadays.
(Sigh...)
I've improvised many times by rummaging through my embarrassingly large collection of sockets and finding some that are a good enough fit. That works okay.
I'd respectfully suggest caution about using acetal for it though. The stuff slowly absorbs water and oil which causes it to swell and distort over time. This caused me a lot of headaches in the past as it was used extensively for underwater tooling because of its near neutral buoyancy in sea water. Things would subtly twist out alignment and machined swivel joints tighten up and jam because of dimensional changes.
Greybeard

Greybeard,

Respectfully, are you confusing nylon with acetal. Nylon is less dense than acetal, closer to water, and known for water absorption where acetal is not.
David Billington

I too have a full clutch plate alignment set made by Sykes Pickavant that will handle anything but thought it could be useful to record the details for all possible variants on engines and gearboxes fitted to members Spridgets and to publish in Mascot.
Engines - BMC 948, 1098, 1275, Triumph 1500, Rover 1100, 1400, 1600, 1800, Ford ????, Nissan, ????
Gearboxes - BMC Smoothcase, Ribcase. Triumph, Toyota, Nissan, Ford, ????
Also possible variations in backplate thickness as I have already made a special crankshaft pilot bush having an extended length for use with a pressed steel backplate to provide max support to a ribcase gearbox input shaft.
Looking at the cost variation for Moss I would also query if some of the crankshaft bearings are needle roller and not plain bushes ?
Hence request for any information regarding key dimensions.
I have a stock of acetal (Delrin) that is rigid, stable and easy to machine so material of choice for many special bits and pieces
Cheers
S G KEIL

I haven't got said tool. I do it by eye. Always works fine. 😁
anamnesis

My two clutch alignment tools.

The one on the right sounds like the one Guy described. It must be over 40 years old.

I couldn't find it when I rebuilt my engine during lockdown so bought an 'official' one - then found the bobbin one!

If I remember correctly, I got on better with the old but can't remember why.

C

C Mee

Early 1275 engines had a plain spigot bush, whereas later 1275s used a needle roller. The ID is the same.

Like Anam, for years I did alignment by eye. I now use an old first motion shaft for A-series. For MGBs, at least 4-synchro and later 3-synchro models, a short length of electrical conduit does the job.
Dave O'Neill 2

For whatever system you use, including these various alignment tools, I find one still has to align by eye - check the tool exits the clutch fingers or cover plate thrust washer centrically as it will tend to droop if left to its own devices. I also eyeball the edge of the driven plate relative to the cover pressure plate and to the machined surface of the flywheel, rotating the crank to check all around. Anyone would think it was a complex and difficult task!
GuyW

I attach a couple of photos showing :
- my 55 year old Sykes Pickavant clutch alignment set with a couple of extras that have enabled every clutch encountered so far to be addressed
- initial prototype for A series Spridgets
Hence looking to make similar simple tool for any variants from standard.




S G KEIL

I suspect that the significant part of that Sykes Pickavantis the large conical pieces to centralise the spindle on the clutch cover fingers. Without that, as with the other device illustrated, one needs to visually estimate when the spindle is truely centred.
GuyW

Cones centralise the friction plate to the crankshaft spigot bush thus enabling the gearbox to be fitted which would not be possible if misaligned.

A lot of bits and pieces in the SP kit that whilst fully effective when dealing with limited vehicles it is far easier to use a simple tool like the other shown.
S G KEIL

My clutch alignment tool ;)

Tim Carter

Centralising only the splined driven plate and the crankshaft spigot bush still allows for a degree of wander of the shaft and can result in a slight off centre. From the SP kit the two larger cones in the foreground do look to me as if they would give some further accuracy by aligning with the cover fingers, giving 3 points of contact.
GuyW

This thread was discussed between 04/03/2025 and 12/03/2025

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