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Author: Subject: mid engine bike rear end: repost
rv1890

posted on 5/4/06 at 03:56 PM Reply With Quote
mid engine bike rear end: repost

I recently posted this on chassis in the general section, and noticed this forum was more appropriate.


I was wondering if anybody had advice for me. I have a yamaha FJ1200cc from a old bike of mine. I was thinking about making a shaft drive dsr/csr/locost. I want the engine to mount in the rear, and I plan on having it connected with a shaft (more like u-joints with a small shaft on each end ) to a rear differential. The rear differential would be out of a subaru or anything with a IRS differential. As you can tell the engine would be mounted horizontally, and the driver would be pushed more towards the front of teh vehicle. I may make it an indy style car.

1) First of all, is there any major issues concerning this???? Is this idea completely out of reach or is feasible??...has it been tried??

2) If possible, will there any issues with gearing?? In other words how would i go about choosing a rear end that has the correct final drive ratio. Is there even an optimum ratio?? Is there a specific rear end differential that would compliment the bike engine well?

Thank you., and I appreciate any and all help.

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rv1890

posted on 5/4/06 at 04:07 PM Reply With Quote
To make things more clear. Im from the states and I noticed these things called Legends race cars. They utilize the same engine with a toyota celica rear end. These are front engine and mine would be mid, and my driveshaft will consist of u-joints wil a small shaft. Im sure this has been done.
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trikerneil

posted on 5/4/06 at 04:24 PM Reply With Quote
See my reply to your previous post.

In the Legends I think you'll find they turn the engine through 90 degrees, remove the yamaha middle gearbox and drive directly from the gearbox using a propshaft adapter





ACE Cafe - Just say No.

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rv1890

posted on 5/4/06 at 04:35 PM Reply With Quote
Thanks trikerneil. So this would be possible with a short driveshaft and everything mounted in the rear, but is it a good idea??
Most the people with mid engine bike motors are running expensive chain drive differentials. I can find pretty much any rear end from a local car salvage yard for cheap, and machine down axles to proper length if needed. Is there any options I havent researched yet??, or any less expensive diffs.

thanks again

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tadltd

posted on 5/4/06 at 04:49 PM Reply With Quote
We used this approach on the LMP (follow the link to our web-site to see pics).

www.turner-auto-design.com/thelmp.htm





Best Regards,

Steve.
www.turnerautosport.com

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rv1890

posted on 5/4/06 at 05:05 PM Reply With Quote
The turner design is what Im looking for. Looks sturdy and seems very durable. The web site says it uses a six speed sequential gearbox. what kind is this?? can it be obtained at a salvage yard, and rebuilt?..



anybody else utilize this design???

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tadltd

posted on 5/4/06 at 05:07 PM Reply With Quote
We used a Kawasaki ZX12 engine, which has a 6-speed sequential 'built-in'. The differential is from a BMW 318i, but the car can take any E34 BMW diff'





Best Regards,

Steve.
www.turnerautosport.com

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rv1890

posted on 5/4/06 at 11:59 PM Reply With Quote
Thats sounds great. There are a plentiful amount of bmw's in my area. Thanks.....You said that any E34 will work. I thought E34 was 88-95 5 series. So will any e34 or a 318 work?? How do I go about figuring out what final drive ratio ear end I would need to compliment my bike engine well.? The 318 seems to be 3.38 in manual and 4.44 in auto. I was thinking about using a rear end off a 1990 thunderbird SC (3.27). how would that work


P.S. Is there a link that explains all this. I dont mean to bother with all the questions.

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rv1890

posted on 7/4/06 at 01:15 PM Reply With Quote
Maybe I asked the wrong question on that last one. when searching for a rear end to be driven by a bike engine what characteristics should I be looking for? Certain drive ratio I should be searching for?? Im pretty it needs to be posi. The bmw diff as mentioned by Turner design shoulds good, but what im sure the ratio matters.
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russbost

posted on 23/4/06 at 03:38 PM Reply With Quote
Depends what size rear tyres you're intending to use, a popular ratio seems to be around 3.2:1
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