Whew, that was a long title.

Anyway, further to the recent thread regarding the RR transfer box as a final drive, this occured to me as a great idea.

I then moved from there to another potentially great solution, unfortunately with one fairly fundamental flaw.

Suzuki Jimny transfer box.
Solid, so no diff, so little use on the road, according to all logic, which I won't argue with.

Not such a hindrance off road.

Low range, around 2:1 so very high geared as a final drive.
High range, 1:1, so impossibly high as a final drive.

However, some bikes have fairly short reduction gearing anyway, so a high final drive isn't always a huge problem.

Err, that's about it.
Two pretty big flaws, but just look at it, how neat would that be.

If it actually worked, which it pretty much won't.

The transfer box is much smaller, proportionally, in real life.

[img][/img]

The SJ transfer boxes self destruct for a pass time though.

The Borg Warner box is a big solid piece of kit, quite whether it would mate up to a bog standard R1 I would not be so optomistic, there is a lot of gearbox to turn over. So yes we did talk re lighter options, but the BOrg Warner comes with viscous lsd already, and fairly easy to source. If your not bothered about lsd , then the SJ might be an option. Our early thoughts were acheiving good traction with potential to do hillclimbs & sprints, so I/We decided the vc lsd was the best way forward.


Mated to a pokey supercharged BB engine might be sufficient to still offer decent performance, while still suffering with spinning over a big box.

In my initial research I spoke with RPM (http://rpmgearboxes.com/) who were up for building a gear driven transfer case and machining it to run my Quaife atb. Cannot recall what money they were after, but it wasnt anywhere like Elite/Powertec/Quaife.


DRD racing make mention on their website of a gear driven transaxle lsd, but they told me they were selling that many solid drives they couldnt keep up with orders. I dont think they have realised how many they could sell if they priced them right.

I have had a good input from another locoster, who has good knowledge of RR boxes and has offered an option to "loosen" up the Borg Warner to make it more usable for the purpose.

Its still an unknown quantity till the car becomes a runner, we are all keen to see what happens.



My Quaife atb & sprocket is still in my garage pending this working lol....

What are the ratios of the borg warner transfer boxes, high and low? With a supercharged honda blackbird if you keep the wheels smallish I would of thought it would be just doable

Cheers
David

quote:

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Originally posted by Minicooper
What are the ratios of the borg warner transfer boxes, high and low? With a supercharged honda blackbird if you keep the wheels smallish I would of thought it would be just doable

Cheers
David

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13 inch wheels....


High 1.206 :1
Low 3.244 :1

what are you trying to achieve with this idea though? Surely its heavier, bigger and more expensive than just using a normal sierra diff?

Which way are you suggesting the sierra diff goes in ?

Engine lengthways in the back. Bike engines are pretty square so it makes no odds whick way round it goes, small cush drive linking them. Also gets the exhaust out easier. Or, chain drive if you want it the other way round. Chain drive is probably more expensive, but its then a hell of a lot lighter than a 4x4 transfer box, and you have much more control of final drive.

As zil hinted, the zook transfer box is small but has no diff so no use here.

Dont mean to wee on the chips, by all means convince me if it has advantages!

The supercharger on Ivans engine would foul a sierra diff if it configured as you suggested.

If I list what I asked/desired from my Fiat 126 car, then the current plan might make sense.


A car able to provide two seats, spaceframe, Quality brakes & suspension, able to compete in msa run sprints/hillclimbs and also pass an iva. The car must be reliable, strong, safe and very fast - oh and different !


The early plan was to use a Quaife atb chain driven diff, I bought one and it lives in my garage. It would of been easy to assemble a car and use this setup, however dont compare the wheelbase of the Fiat with a Mini, it is 9 inches shorter (top of my heed)

So to put the engine transversely and use the Quaife, would only give me 10" between centres for the chain, that is a very short chain to put a lot of bhp through. I dont want to spend 20 minutes driving hard on a trackday, to have to come back in to let the chain cool down & adjust.

We discussed extending the wheelbase to improve this, but I wanted to stay within the confines of the Fiat shell.


I have a budget to work to , so while it would be good/simple to drop in a Powertec axle/Elite , I am not spending £3500.



Sierra lsd diffs were also discussed, two options here.

1) Put the engine fore/aft infront of the axle, cush drive as you suggest out to the axle, bobs your uncle !, however I didnt want the engine for a left armrest, so we are back to the Fiats tiny wheelbase and me wanting a 2 seater car. I have pics of one like this somewhere, a burst crankcase and pistons parts flying doesnt look like fun with the engine as an armrest.

2) Mount the engine fore/aft with the sprocket pointing forwards and put the Sierra lsd infront of the engine, ie mount the engine behind the axle. I have seen grasstrack cars like this, and while it is feasible the weight distribution looks pretty severe. Grasstrack car on loose stuff with a locked diff will manage the tailhappy handling, however it wasnt for me.


Sticking with the theme of reliability, a gear driven box utilising a lsd was agreed as they way forward, full of oil, strong and reliable. There are grasstrack cars using gear driven boxes but they have solid axles, so no use for the road. I had a few discussions with various people , and while a lsd gear driven box could be done, it would add cost to the project, it is not written out of the plan at the moment, we are just pushing on with the RR box.

So while I am not piling up advantages here, you will see the development has come from sticking with the 126 bodyshell dimensions, tight budgets and me wanting reliable motoring.


If the Borg Warner doesnt work out, I will deal with it, it wont be the end of the world. Long term maybe I might speculate on a Powertec or even a custom made gear driven box with lsd.


My current options are not massive, seeing as Ive picked probably one of the smallest cars on the road, oh to have the wheelbase of a MK Midi / Riot etc then I could use my Quaife.


My build with Nat & Cal is fluid ! we are all open to change/swap/alter/amend/bin - re-visit any of the current options that have been taken so far. So no your not p!ssing on our chips and I hope this explains.


PS Hats off to Nat&Cal for outside the box thinking, gets 10/10 from me......