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Author: Subject: 4x4 front diff in bec rwd
Simon

posted on 28/9/20 at 05:39 PM Reply With Quote
4x4 front diff in bec rwd

Ok, so I like the idea of replacing the engine in a VW Beetle (aside of the one I'm building at the moment) with a "large" motorcycle engine (1000cc plus) and well, it already had a gearbox.

How about replacing the Beetle transaxle with the front diff from a 4x4 (Sierra/BMW X series etc) and then bolting the bike output "sprocket replacement" to the input of front diff (though you could stick something like the Elite reverse box in between engine and diff if you want reverse).

Cheers

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SteveWalker

posted on 28/9/20 at 05:51 PM Reply With Quote
I'm sure I remember seeing something about Freelander front diffs being used for RWD kit cars. As for bolting the engine/gearbox and diff directly together, you'd need very accurate alignment or some sort of joint to take up differences, as you've no prop-shaft and UJs to do the job.
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Simon

posted on 28/9/20 at 06:33 PM Reply With Quote
Looking at BMW diffs there seems to be a rubber connector so that might help but agree alignment would need to be good
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jacko

posted on 28/9/20 at 06:54 PM Reply With Quote
If I remember right zcars used a rear Sierra dif upside down
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jelly head

posted on 29/9/20 at 06:58 AM Reply With Quote
quote:
Originally posted by SteveWalker
I'm sure I remember seeing something about Freelander front diffs being used for RWD kit cars.


^This^

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JAG

posted on 29/9/20 at 10:48 AM Reply With Quote
I think you mean a Freelander REAR diff'





Justin


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SteveWalker

posted on 29/9/20 at 08:18 PM Reply With Quote
Quite possible. I was going from memory of something I read years ago and could easily have got it wrong.
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nick205

posted on 1/10/20 at 10:32 AM Reply With Quote
May not apply to what you want to achieve, but IIRC Ultima GTRs use a Porsche gearbox/trans-axle upside down. Upside down so they can achieve a mid-engine layout using a gearbox/trans-axle from a rear engine layout vehicle.
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adithorp

posted on 1/10/20 at 10:46 AM Reply With Quote
I've got a Freelander rear diff in my Fury. 3.21 ratio and a lot lighter than a Sierra one.

Not heard of anyone using front diffs.





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adampage

posted on 1/8/23 at 08:33 AM Reply With Quote
There is one way....

Hey, if i'm not mistaken there is a time when you would use a front diff from either a Cosworth or 911 C4 etc...

For most bike engines (Blade, R1, Hayabusa, most chain driven) the output turns anti-clockwise (if you're sitting in the tunnel looking at the output shaft) just like most car engines, that's why they fit in neatly with a 'normal' diff like Sierra / Freelander rear diff.

Similarly with shaft-drive bike engines, if the shaft is on the right of the bike, the output turns anti-clockwise, so it would fit in the same (e.g. I had a car with a Honda Pan-European 1100 which had the shaft on the right), so again you use a normal diff.

The one time you would use a Front diff is if you had a shaft drive bike with the shaft on the left (some BMWs, Honda VFR, etc) they drive clockwise when viewed from the tunnel looking at the back of the engine, so you need a diff that turns the other way, et voila - front diff from a Sierra/911c4.

Not heard of anyone doing it, and might be a bit more expensive and rare to get hold of, but it would work....

(Can't use a Freelander front diff because it's in the transverse gearbox, and you can't just use a 'normal' diff turned upside down because you're still using the diff the wrong way so wearing the diff etc).

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Mr Whippy

posted on 1/8/23 at 10:16 AM Reply With Quote
quote:
Originally posted by nick205
May not apply to what you want to achieve, but IIRC Ultima GTRs use a Porsche gearbox/trans-axle upside down. Upside down so they can achieve a mid-engine layout using a gearbox/trans-axle from a rear engine layout vehicle.


Are you sure the diff inside was not just flipped round as that is the usual method. VW bug gearboxes can also be altered using that method and is really quite straightforward.

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