Hi,

Between the bike gearbox output shaft and the diff, do any of you guys use a flexible propshaft coupling like you get in a BMW propshaft set up to take the shockload of selecting gear away from the bike gearbox.

In a bike the rear wheel has a cushdrive within it to do absorb the shock of selecting gear to prevent damage to the gearbox.

Has there been any issues with not using the coupling for anyone? Should I consider this in my build?

Cheers
Col.

[Edited on 30/3/16 by colimp66]

You could use a resilient (TRT) propshaft.
http://www.baileymorris.co.uk/en/kit-cars-self-builds

These have a resilient two piece tube built into the propshaft and are recommended for bike engined cars.

The common part to add to a propshaft of a BEC is a TRT section (torque resilient tube)
This does what you want.
I've just had a prop shaft made up for mine with with a TRT section by Dunning & Fairbank,not driven the car yet though with it fitted,but I did run the car last year just with a solid propshaft so should get a good idea of difference the TRT makes.
I asked D&F about using a flexi drive like the BMW'S use and they said they are not suitable.

Cheers guys,
Sounds like the TRT has to be a certain length from what I have read on here now that you have pointed me in that direction.
The trouble I have is that I don't have much room for a TRT by the looks of the information I saw as I want to put the engine in the original position of my Hillman Imp with a reversed upside down diff.
Hence why I mentioned the BMW prop coupling as a shock absorber for the transmission. They are often used in the driveline of an Imp instead of the Lotus donuts.

Cheers
Col.

The Sierra, and possibly the granada had one as standard, I did have one in my Kit but it started breaking up so replaced it with a conventional set up. They apparently do not like much mis-alignment but when you consider reusing one from a donor they will be 20+ years old! If you do use one make sure you have a prop catcher as well, there are horror stories out there when they have broken up.

I wont be using a 20 year old donut as I know how they break up and cause a lot of damage. The BMW ones and Lotus donuts are still available brand new so that is the only option in my mind.
There wont be much of a prop as such so no real need for a prop catcher. The donut will simply be a spacer between the bike gearbox and the diff to take the shock load of engaging gear or sudden power like the TRT will do so it saves the bike gearbox from breaking.

Cheers
Col.

New ford ones are available too, its just that they are sometimes slagged off as being a terrible thing without realising that they have a finite life span. They can be quite large diameter too if you are limited for space.

Mocked up the rough position of engine an diff to show how short any prop would be and the reason I thought of using the BMW prop coupling or similar.

Any thoughts welcome.
Cheers
Col

Thanks for the replies and advice guys.

Minitici I have spoken to Andy at Baileymorris who was very helpful and put me on the correct path for the connection between my engine and diff.
I now have a better idea of how it will work out.

Cheers
Col.

Surely a contender for the worlds shortest propshaft?!

Out of interest what was the suggestion?

I've seen this setup used on a fury menace


Description

Cheers
David

Minicooper that was one of the options we discussed, spot on.

The uj's allow for a bit of movement and the rubber donut takes up the shock load all in a very short compact unit in the same way I need it.


Cheers
Col.

I have a new Blackbird rubber coupling/gumbo from Nova Racing sitting on the shelf waiting for a project if you need one.

Hi Alan,

How much are you asking for it? Could you post a photo of it or pm please. ?

Cheers
Col.

Hi Colin,

I'll take a photo of it tonight and send it over to you. It was £240+VAT so £150 including postage would be half price.

Regards
Alan