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Help with fitting centre main bearing strap??
Posted: Mon Feb 13, 2006 6:35 pm
by picky
I am currently fitting a centre main bearing strap to my 1098cc, But I am unsure as to how much to machine off the top of the main bearing holder to fit the strap. Do I want a flat surface all the way down to the level of the mounting bolts?? As this would mean quite alot of material to remove. I have access to a milling machine to do this.
Many thanks for your help,
Tim
Posted: Mon Feb 13, 2006 6:56 pm
by bmcecosse
No - you just machine a nice big flat on the cap - then make up packing pieces to go between the cap bolt flats and the strap - but leave a 5 thou pinch gap at both sides. Of course you now need longer bolts, and they need to be the highest grade possible. I did this many years ago - managed to find some Allen Cap bolts (X rated) with the correct thread. But really - this is a bit of an extreme measure - not at all necessary on a road-going car!! I did it on a 998 Mini engine that was then revved to 9K!! The 1098 will snap it's crank if you rev it much over 6k for any length of time - unless you are lucky enough to have one of the Spridget 1098 engines - with the bigger ''Cooper S" main bearings ??? Much better mod will be to lighten the flywheel and fit a crankshaft damper, and balance the rotating assembly.
Posted: Mon Feb 13, 2006 7:16 pm
by Matt
The 1098's that BMC are talking about have an engine number beginning 10CC. (just a point of interest
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Posted: Fri Feb 17, 2006 11:43 am
by picky
thanks for advice everyone.. just wondering about the pinch gap.. do you mean that the packing washers should be 5 thou higher than the middle of the bearing cap, or should the bearing cap be 5 thou higher than the washers??
Thanks,
Tim
Posted: Fri Feb 17, 2006 1:52 pm
by Alec
Hello Tim,
the latter, otherwise the strap will not touch the cap. How thick is the strap you intend to use?
Alec
Posted: Fri Feb 17, 2006 4:16 pm
by bmcecosse
Aye - leave a gap of 5 thou between the strap and the packing pieces. You will have to find a way of mounting the oil filter casing inside the sump.
I lke your exhaust manifold picky ! Is it Minisport item ?
Posted: Fri Feb 17, 2006 6:16 pm
by picky
ok thanks for info... The strap I bought as a kit it is about 3/4 inch thick piece of steel and it came with longer bolts.
Thanks bmc! actually the LCB exhaust is a maniflow item that I sprayed with silver exhaust paint to stop it rusting.
Tim
Posted: Fri Feb 17, 2006 8:48 pm
by bmcecosse
Looks great Tim - I have two spare Mini lcb units which I hope will become one Minor lcb once the weather improves!