Hi,

I have a 1275 (1100s based) that is basically freshly rebuilt (new pistons, rings, bearings, rebored 40 thou, reground crank, new oil pump, water pump, reground cam) all done by a professional endgine rebuilder.

What I added was a new ultralight steel flywheel, new (second hand) backing plate and my existing pessure plate and clutch plate (only 5000kms old) All on my old but good cond. gearbox.

It has a really bad vibration all through it, (diagnosed as engine, flywheel etc out of balance, not metal on metal, spent hours going over what it could be with a couple of respected mini people) so;

It is coming out to be stripped down, balanced and reassembled.

My question is;

What should I do with it all stripped down?
Cam change (road use, needs to be traffic jam friendly)?
Diff rebuild (I have the bits, just ran out of time last time)?
Other?

Cheers
Matt

Before you go to all the trouble of pulling the engine and gearbox out and stripping it. Check the alignment of the flywheel and clutch. 1275 engines (both 1100s and cooper ) were pretty good balance wise and even when you send them away for balancing they come back with little or no machining.

The clutch- flywheel is a fairly different scenario - its only a couple of hours to replace the flywheel with a standard one and see if you still have the problem. Making sure that the "A"s all line up properly.

I think the general consenses is that the Russell RE13 cam is the way to go. If you do a camshaft change, make sure you use new cam followers regardless of the limited milage on the old ones. Apart from that let the engine breath properly witha 1.75 (or better) and extractors.

Most 1100S gearboxes were already 3.44.

Good advice,

I will do a flywheel change first, and see if that eliminates the vibration.

I have all the As lined up with TDC now (no A on the flywheel of course)

The only thing different is the ultra light steel flywheel, all other parts are standard A series, and were fine on the old motor!

Yep, i agree on the breathing side of things, I have twin 1.25 SUs, with a maniflow steel manifold, and Maniflow LCB (1.75" pipes).

The motor goes sweet apart from the vibration.

Cheers
Matt