Bah, needs just a bit of welding gov'nor!

Location: Sunny Brittany

In my best Navy Lark, Leslie Phillips voice - ooh nasty!
Steve V.

Location: Polegate, East Sussex, United Kingdom

Has anyone experienced this before?

No, never.
Seen plenty of loose rivets, though,

And if you paint your flywheels, I rekindle you got too much time on your hands

Yes but not with a seven. On a rally to the Pyrenees in 2009 a pal with a Pembleton Brooklands tore the centre out of his clutch plate and 3 years ago I did the same with mine. Cured with a new "sprung" clutch plate.
I had a job to dissuade the RAC call centre not to send an inspector to find out why I had lost motive power. Fortunately after 20 minutes of explanation they just sent a recovery truck and I only had to wait one hour...

hi R.

i get plenty of crape come in with the good stuff i buy.

but i have NEVER seem that one.

i know if you put a rule across the clutch plate all of them are now bowed, from over heating. from decades of use.

so it makes sense they will fail at some point.

tony

Location: huncote on the pig

a quike PS, it looks like the engine has recently been rebuilt. is it something from the rebuild thats caused this????

tony

Location: huncote on the pig

Almost like the trans and engine are out of line, causing the disc to flex every revolution??

Location: Vernon British Columbia

I've never seen anything like this. I can envisage that once a crack forms it would run round pretty quickly. I'd guess that the flywheel has been swashing at some stage with this clutch plate in. Crank whip would have the same effect. The bulk of the fatigue perhaps being in a previous engine not necessarily this one? Mixing flywheels and cranks and repeated lapping could end up with a swash, I admit it's not something I check on a built up flywheel - but if this is the only known failure it should be low risk?

Dave

Location: Far West of New Zealand

Dave's point is a good one. It does seem that it would be worth measuring the run out on the flywheel both radially and axially. it would be a shame to have it happen again!

Regards, Stuart

Location: Whangarei, New Zealand

I think that there may be a power/driver issue. I've often wondered how much BHP the A7 transmission can cope with. However, I would've thought the clutch would burn out or certainly slip (with tons of oily smoke!) before this type of damage happened. My other thought was sudden engaging the clutch from high revs was another possibility, Steve Hodgson and I have a neighbour who drives like a maniac and has done loads of previously unseen damage to engines and gearboxes by not quite 'respecting' them.

Location: Ferring, West Sussex

Did the previous owner drag race the car?

I'll get me coat...

Like the others, never seen that before but I have seen a flywheel with a similar issue developing. Got one here in fact. More the result of a bit too much lightening than anything else but as Malcolm was driving it when it actually, went, I've always blamed him!!

Steve

Location: North Yorkshire

Or perhaps someone got violent installing the trans, like hanging the trans on the splined shaft or forcing the trans side to side try to align the splines?? Is that possible? I haven't put mine together yet.

Location: Vernon British Columbia

This looks very much like a fatigue failure,caused by the plate being under stress.
The photo shows no marks on the boss, but is there a possibility that it has been in contact with the flywheel nut? I know its an unlikely long shot, but I can't think of any other reason that would cause such a failure.
J

Location: As far east in Kent as you can get

I go along with Dave. Some years ago I had a few good cranks and flywheels. none of which were paired so I decided to pair them up. It was quite an exercise but I eventually ended up with them all mated with negligible run out. A flywheel with 0.030" rub out on one crank was perfectly OK on another.
Is the flywheel nut tight? There doesn't appear to be a tabwasher behind it and yet it is only just on the crank, usually there is a bit of crank thread protruding beyond the nut when fitted with a tabwasher.

Location: North Yorkshire

Banter on top form today - well done all! :)

Flywheel running true.

No lock washer but tight - glued on?

No hot rod driver - most chilled-out driver I have met in an very long time actually :)

I am still inclined towards historical problem - the rivets show signs of over exuberant "retightening" at some stage, perhaps starting a crack...

Keep it coming please!

Hi Ruairidh, Could it have any thing to do with the Spline jamming.
very interesting it is one of those problems you need to know the answer to before you fit the next one.

Good luck
Colin

Location: TINOPAI NZ

Charles - totally agree :)

Colin - spline 'very' loose in the gearbox female spline.

With bent cranks, worn and lapped tapers etc it is not surprising that flywheels run out but the chance of a random countering mate seems low In many cases careful scraping may be more beneficial than lapping. .030 run out would not be much near the centre.

Various situations can be imagined but all would lead to problems operating the clutch unless it had exceptional travel, and/or show rub marks on the flywheel. With the wrong front bearings the crank can move excessively but would take little to resist. It is unlikely the hub would be bent, but a major engine fail might have set it crooked in the plate. Considering that in their day many Sevens were run with very worn mains, it is surprising that even more loose rivets, worn splines and damged gearbox nose bearings are not encountered.

Perhaps all was soaked in rust killer acid at some stage.

If the hub is not bent and the splines good do not discard!

Location: Auckland, NZ