Im currently putting a zx9R engine into a small formula 750 track day car...

The engine is sat in the area that would normaly be the passenger footwell... meaning that the engine is pretty close to the rear axle...

Its a live solid rear axle..


Would I get away with having only a one piece telescopic propshaft rather than having to go for one with three UJs on it and a bearing block?


What are the pros and cons of having 3 UJs over 2?

The only slight benefit I can see of having a 3 Uj shaft is to reduce radial loads on the engine output shaft....But considering it is designed to take a chain with lots of radial load....is this really an issue?

You can see where the engine will go...here:

I can't see any justification for a 3 piece propshaft or even how you'd fit one in...

1 peice should be fine i'd think...

I looked at one of these cars a long time ago, it was a bit tatty, well very and the guy wanted too much for it so I declined, it did have a 1300 escort engine in it that he claimed gave 150bhp. Looked totally mad with the engine right next to you but made a lot of sense as far as weight distribution. I just wondered what would happen if the flywheel exploded etc..

I could fit a three piece in if I really had to, but it would require adding quite a bit of strucutre to the chassis to handle the bearing loads...

quote:

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I just wondered what would happen if the flywheel exploded etc.

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Dragsters put a super-tough bag around the bellhousing (Kevlar? Aramid? Something like that anyway).

Especially the ones where the driver sits with a leg on each side of the bellhousing!

[Edited on 25/2/08 by David Jenkins]

that might be a good idea, kevlar has come down a lot in price recently

Transverse rear engined grassers have to have a "flywheel guard" fitted. It's generally a series of 6mm thick plates (2 or 3) angled around the bellhousing with a couple of welded brackets to support it off the bellhousing bolts.
Not a huge issue if you are building a BEC though.

Kevlar isnt a bad idea....I could actually laminate the tunnel walls with a layer of kevlar and epoxy resin if I wanted to....

A shattering flywheel isnt an issue with a BEC, but a few people have had bits of the crank come out of the casing...


If I have a telescopic propshaft with Ujs to suit my rear axle, and a sepperate propshaft with a ford type UJ to suit my engine, how much is it likley to cost to have the two props joined together in the middle? (If its even possible)

[Edited on 25/2/08 by tegwin]

ballistic shields are normally fitted to drag cars, they are made of kevlar but it wont stop really high velocity parts , so they generally make them from high grade steel or titanium .

i think you can find some saftey specs on american sites about ballistic shields , the really high hp guys use a mixture of both i think .