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May 16, 2012 13:14:13 GMT
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Hi
I'm currently turning a garage full of bits into a project. Slowly. Anyway, I need to learn more about types of rear differential and prop shaft. I've got my head around the difference between a torque-tube and a Hotchkiss drive. But I *think* there is a difference between two types of diff? And one would be good for independent rear suspension?
Ideally, I want to keep Hillman Imp rear suspension, which has swinging arms and drive shafts. So, what kind of rear diff could I take apart, keep the centre bit and get something made up to accept the drive shafts?
Even if someone could give me suitable links or search phrases on google then I could get a bit further forward. I'm not even sure what to search on atm.
TIA
Graham
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stealthstylz
Club Retro Rides Member
Posts: 14,961
Club RR Member Number: 174
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Rear diffs and gearboxesstealthstylz
@stealthstylz
Club Retro Rides Member 174
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May 16, 2012 16:05:54 GMT
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How much power does it need to handle? MX5, BMW, Mercedes, RWD Vauxhall (omega, Carlton etc), Jaguar, Corvette all are useable.
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May 16, 2012 16:08:56 GMT
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Not a lot - he's planning to use an Imp engine. 39bhp as standard. ;D
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May 16, 2012 16:48:54 GMT
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Yep, or I could go mad and nudge up towards the heady heights of a sport engine - 55bhp book value.
Seriously won't be handling much power... you must be on the Imp Club forum too, or very psychic!
Graham
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May 16, 2012 17:17:29 GMT
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You could use the Sierra diff - so you could use the 930 prop with adapter/new flange to go onto diff.
Re : drive shafts - you could use the Imp outer and have the sierra shafts modded to take the uv so keeping the setup nice and simple at the hub end.
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Last Edit: May 16, 2012 17:28:58 GMT by donSpeed
1965 Imp
1982 Golf GTi
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May 16, 2012 17:18:44 GMT
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If you look on that other forum for Imps and search out Niall's rx imp you'll find pics of his VW shafts. Do the same sort of thing as him with the Sierra ones = Win
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1965 Imp
1982 Golf GTi
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May 16, 2012 17:24:53 GMT
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you must be on the Imp Club forum too I am James over there. And in real life. ;D Sierra has an indepandant rear setup, with a diff mounted to the bodywork and driveshafts to the wheels. Like this:  A live axle is rigid and has the diff mounted internall, with hidden driveshafts:  Whatever gearbox you go for, a diff from a car with IRS is the way to go - it'll be fairly easy to mount in place of the Imp transaxle, and then you'll just need to have the outer half of the Imp shafts grafted onto the inner half of the diff shafts. |
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Last Edit: May 16, 2012 17:25:06 GMT by jrevillug
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May 16, 2012 17:26:10 GMT
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you must be on the Imp Club forum too, or very psychic! Graham Just beat me to it James lol Sorry I meant Independant not live xle d'oh ! |
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Last Edit: May 16, 2012 17:29:50 GMT by donSpeed
1965 Imp
1982 Golf GTi
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stealthstylz
Club Retro Rides Member
Posts: 14,961
Club RR Member Number: 174
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Rear diffs and gearboxesstealthstylz
@stealthstylz
Club Retro Rides Member 174
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May 16, 2012 17:40:59 GMT
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Sierra will take too much power to turn. I reckon at a push MX5 would be OK, though I'd be looking for something like a Suzuki Cappucino diff or similar.
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May 16, 2012 17:43:45 GMT
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I would imagine if its going to be imp powered it needs to be light and a Sierra diff will have a lot of unused strength which usually equals excess weight, why fit a diff that can handle 300bhp if you only have 50?
Find something smaller and lighter is my advise.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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bxer
Part of things
Posts: 457
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May 16, 2012 17:54:01 GMT
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Sierra will take too much power to turn. I reckon at a push MX5 would be OK, though I'd be looking for something like a Suzuki Cappucino diff or similar. Can you explain "too much power to turn"? I can understand that the gears and the whole thing would be a lot heavier than required so you'd have more inertia, but surely all diffs should have minimal friction losses? or are the losses proportional to size/mass of the gears, so you design to the minimum size to lose a reasonable proportion of the available powah, meaning if you started with 39hp, there wouldn't be much left? Just googled Suzuki Cappucino, hadn't realised they were rwd!  |
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May 16, 2012 18:07:16 GMT
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You could always use a Robin axle !
Sierra diff has been used in many applications and is a popular choice on motorbike - trike conversions. I too would be interested in the science behind the "too much power to turn" scenario
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1965 Imp
1982 Golf GTi
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May 16, 2012 18:28:27 GMT
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The Sierra IRS is a popular choice because its cheap, easy to get bits for , has quite a choice of ratios (and LSD) and quite easy to fit, personally I try to build stuff that's only as strong as needed, adding lightness is the same as adding power and it also improves handling and braking at the same time.
What about the front diff from a 4x4 Sierra?
They are substantially smaller and lighter, less choice of ratios and no slipper though.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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May 16, 2012 20:08:52 GMT
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I can see that loss of power thing being an issue. I mean, if a diff takes 0.4 bhp to turn, then it's taking 1% out an Imp engine but only 0.075% out of a Sierra Cosworth... on the other hand, who'd notice 1%?
More of an issue is Ebay being full of people thinking that a Sierra diff is useful for all sorts of kit cars therefore they can up the price. Especially if they have a Cosworth diff...
Off to look up independent rear systems. I wonder if Robin's were indy or live?
Cheers guys, I feel a bit further forward now, in my head if nowhere else...
Graham
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May 16, 2012 21:10:13 GMT
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Live axle on the Robin
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1965 Imp
1982 Golf GTi
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,543
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May 16, 2012 21:24:35 GMT
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Herald? Its a self contained unit with prop flange at the front and output flanges each side. Mount to chassis and brew suspension to suit.  |
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Last Edit: May 16, 2012 21:28:04 GMT by Seth
Follow your dreams or you might as well be a vegetable. |
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sonus
Europe
Posts: 1,392
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May 16, 2012 21:39:56 GMT
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What about a Honda CRV rear diff? Supposed to be lightweight and strong.
Smaller 4x4s like suzuki swifts also has smaller and probably lighter rear diffs as well.
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Current
1968 TVR VIXEN S1 V8 Prototype
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MG ZT 1.8T - sold
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Anglia68
Posted a lot
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Posts: 2,050
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May 16, 2012 22:18:20 GMT
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Freelander diffs are used a lot by bike-engined 7 owners as they're reasonably small and lightweight but still strong.
No personnel experience of them though,just what I've read on the interwebs.
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That Herald diff looks like just the ticket. Does anyone know what the E30/E36 range of BMWs use? I had a quick scoot through ebay and there are plenty of those on there and they appear cheap...
I think I'm going to have to find a gearbox first, and then when I have ratios on the back of an envelope find an independent diff with the right ratios inside and go from there.
I'll bookmark this thread though as there's some good ideas here!
thanks guys!
Graham
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stealthstylz
Club Retro Rides Member
Posts: 14,961
Club RR Member Number: 174
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Rear diffs and gearboxesstealthstylz
@stealthstylz
Club Retro Rides Member 174
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May 17, 2012 12:13:12 GMT
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To make diffs stronger they have to be built bigger, and therefore there's more weight to turn. It's not small amounts either. A guy from the cruise uprated his car from an 8" Ford axle to a 9" Ford axle, and with no other changes lost 20 w/hp.
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