RWD input shaft support bearing - 1108cc Fiat Fire engine

Clutches, gearboxes, exhaust and intake systems, lubrication and cooling systems, engine bay layouts etc
Guy Croft
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Location: Bedford, UK

RWD input shaft support bearing - 1108cc Fiat Fire engine

Post by Guy Croft » July 2nd, 2006, 5:44 pm

I did two input shaft support bearings for Huw Davies' Fiat 1108cc 'Fire' engine for his single seat race car, see

The photo with that series shows the early one which proved insufficiently robust, the bearing worked loose in the rather thin housing, so I beefed it up with a heavier housing and bigger bearing. (see below) I consulted a helpful technical engineer with NSK Bearings at Newark not far from me regarding the fit of the bearing, this is very critical because it will seize or break loose if the fit in the housing is wrong.

You generally have to have a support bearing in the end of the crank on a rear-wheel-drive gearbox otherwise the gearbox input shaft will flop around, those single seat 750 MC gearboxes (Huw uses an old Reliant box) don't have the right bearing array in the box to hold the input shaft steady.

I was told by a 750MC racer that you could not run a race clutch (7 1/4") with that box, that there would be wear problems, but with my layout it seems ok so far. I was told we'd have to use a conventional organic clutch.. I like a challenge. I don't think there is much room for anything heavier on the flywheel, and anyway the size of the bearing is similar to that used on the 131 2 liter, so hope it lasts.
HD FW adaptor type 2 fitted.JPG
HD FW adaptor type 2 fitted.JPG (25.71 KiB) Viewed 9208 times


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