mini bike engine diff ?????

mini bike engine diff ?????

Author
Discussion

retroracing

Original Poster:

477 posts

199 months

Sunday 2nd May 2010
quotequote all
Hi guys, I have just bought an old very light weight racing mini !!! but with no engine.
I'm trying to descide what to put in it that would suit track days and to put it up a few of the local hills.
I was thinking of maybe a 1275 as thats probably what it used to run, all be it a very breathed on 1275 looking at the rest of the car.

Or I was possibly thinking bike engine, such as fireblade or ninja in terms of bang for my buck. However the diffs seem a fortune and even more than a nice 1275 motor, before i've even sourced a bike engine!

I have heard about some of the hill climb boys and girls modifying the standard mini diffs to take a sprocket,and then therefore a bike engined chain and sprocket arrangement.

Does anyone on here have any more info about how to modify a mini diff to chain drive???? many thanks

Tangent Police

3,097 posts

183 months

Monday 3rd May 2010
quotequote all
Fiesta diff is what you're thinking of.

It will be a lot of mucking about. You need to mount the diff in bearings and then have enough space to mount the engine with the sprocket in the right place. Not easy. It'll put you out of the road going or mod prod classes and you'll be up against all sorts of crazy stuff.

If you're going sports libre, or whatever, you may as well put in an Audi V8 on a FWD box in the back and add a 100 point cage for when it inevitably leaves the course backwards at 130mph


Skyedriver

18,864 posts

289 months

Monday 3rd May 2010
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The single seaters with bike engines, back when I was on the hills, used mini diffs, open, held in bearings withthe sprocket bolted to the crown wheel. Was always facinated how it worked and took loads of pics, not digital unfortunately, but if you went to a hillclimb and headed for the little Jedi etc......

Tangent Police

3,097 posts

183 months

Monday 3rd May 2010
quotequote all
I wouldn't like to comment on the life of a mini diff run dry, perhaps with dirt in it also!

I think the fiesta may be a sealablish unit.

Mr2Mike

20,143 posts

262 months

Thursday 6th May 2010
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Quite a few mid-engine BEC (bike engine car) kit cars have used car diffs converted for chain drive. The favourite method seems to involve sealing the diff by welding plates over the open areas (around the spider gears etc), fitting a grease nipple and pumping the thing full of grease.