renrut
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 posted on 24/8/09 at 10:06 AM |
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Chain diff sprocket mounting
I'm in the process of building a road legal bike engined Seicento. The engine is gonna be in the back driving the rear wheels via a diff. To
keep costs to a minimum I'm using the Seicento diff out of a 1108 FIRE engine gearbox. The question is how do I go about mounting it and making
sure its all centred and secure enough?
My intention was just to drill holes in the crown gear and bolt the sprocket to it. 3 problems with that:
1: The crown gear is only 165mm diameter including the helical cut teeth. THe sprocket mounting holes are on a 160mm PCD and are 10mm diameter.
Obviously this isnt great.
2: I've been told that the crown gear is likely to be made of tool steel and therefore a b***h to drill.
3: The sprocket doesn't centre on the crown wheel at all, so the chance of me gettign it centred by hand is pretty much impossible. Is any off
centre-ness likely to break the chain with ecentric motion, or will it just be a bit less efficient?
So what should I do? An adaptor plate seems like a good idea but still leaves me with 2 of the three problems unless I get it professionally machined.
Any advice much appreciated! :-)
PS I don't have easy access to a lathe or milling machine.
Why are all the fun things in life expensive!
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imp paul
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| posted on 24/8/09 at 10:20 AM |
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flak monkey can help with lathe or milling machine some 1 off stuff his name is David give him a pm mite be worth your while 
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renrut
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| posted on 24/8/09 at 11:15 AM |
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Cheers. Will U2U him and see what he suggests. What do other people do to mount sprockets on Sierra diffs?
Why are all the fun things in life expensive!
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cloudy
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| posted on 24/8/09 at 11:16 AM |
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By far the easiest way is to remove the crown, then send the diff away to somebody like B&C express who will make a sprocket to match the bolt
pattern and diameter - it wasn't expensive..
James
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ReMan
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| posted on 24/8/09 at 01:21 PM |
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Interesting,
I am considering front engined, when I get a minute
http://www.locostbuilders.co.uk/viewthread.php?tid=114476
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renrut
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| posted on 24/8/09 at 01:26 PM |
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I looked at front engined but my engine of choice is a V-twin. And fitting it sideways didnt solve any of the problems.
There is a blade engined seicento floating around Fiatforum somewhere. Ran the output of the bike engine straight into the car gearbox input shaft.
Was lethally fast in a straight line ubt the engine was that far forward it completely ruined the handling :-(
I'll keep an eye on yours though, looks like a good concept...
Why are all the fun things in life expensive!
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ReMan
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| posted on 24/8/09 at 01:39 PM |
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I was thinking Aprillia V twin in the front, still looking for the right car.
Once I have one, between other jobs I review the possibility of this, If it wont work, then rear eng it will have to be, or not!
I sawe the blade one, it had been lengthened in the wings I think?, not my bag, I want something standard and pick up off existing mounts
Cheers
[Edited on 24/8/09 by ReMan]
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renrut
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| posted on 24/8/09 at 03:43 PM |
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Yeah bear in mind a V twin is very long so you either need it sideways, which means you need a very short rwd diff. Or you need a very long engine
bay.
The honda V twin I have is about 650mm long, and to avoid having it silly high it needs to sit in front of the diff.
Rear eng has been done a lot for grass trackers as I understand it but all are little more than spaceframes with a seicento or cinq shell dropped on
the top. I'm aiming for something a bit more civilised.
the blade one was lengthened. I reckon you could fit an inline 4 in where the original fiat engine sits and chain drive it to a diff. The blade one
was so long because it retained the car gearbox as well so had a huge gear selection to chose from.
Why are all the fun things in life expensive!
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