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Homespun BEC Middy Transaxle?
andkilde - 21/2/04 at 07:23 PM

Hi All

I'm knocking some ideas around on drivetrain configuration and was wondering if mounting an IRS style diff directly up to the output flange on a bike engine might be possible (ie. inline configuration with driveshaft deleted).

Either turning up a direct mounting flange on the lathe or perhaps using a rubber flex "guibo".

Most bike engine middies use either chain drive or spectacularly expensive bespoke transaxles. The chain drive route requires some machine work for bearing carriers, fitting up some sort of oil-tight housing around the diff and, with all the mechanical bits (chain, bearings etc.) hanging out in the open, looks to be an un-ending maintenance item. A proper transaxle look a wonderful solution but I'm cheap...

Just eyeballing it - it seems possible, adds a bit of length over a transverse install but a bike engine & transmission is very compact.

Any thoughts?


malcolmstoddart - 21/2/04 at 07:40 PM

dunno how much torque they will take but could look at putting a fenner-flex coupling between the gearbox output shaft and the input shaft of the diff unit, the come in all manner of sizes and come with taper lock bushes for the shafts and a tyre in between..look for them on websites failing that u2u me and I will get a data sheet for you..( no connection to me but use them at work and are good there..)


andkilde - 21/2/04 at 08:26 PM

quote:
Originally posted by malcolmstoddart
dunno how much torque they will take but could look at putting a fenner-flex coupling...


Yeah, my wife is a hydraulics tech and had me looking at magnaloy couplings which are similar to Fenner's -- the folks that make them are only a few miles from here and she gets them at trade rates -- their website even has recommendations for internal combustion applications. I'd rather just whip up a solid adaptor (for weight, cheapness & simplicity's sake) but I'm not sure if that's advisable.

Cheers, Ted


Hugh Paterson - 21/2/04 at 08:53 PM

Ted, we use a very small driveshaft with C.V.s couplings on the Coram LMP, still allows movement fore and aft on the splines, seems to work for us not sure if there would be any benefit by bolting it straight on to the diff, worth a try I suppose see if it goes bang
Shug.


andkilde - 21/2/04 at 11:47 PM

quote:
Originally posted by Hugh Paterson
Ted, we use a very small driveshaft with C.V.s couplings on the Coram LMP, still allows movement fore and aft on the splines, seems to work for us not sure if there would be any benefit by bolting it straight on to the diff, worth a try I suppose see if it goes bang
Shug.


Cool! I like ideas that others have tried successfully before me <g>.

I'm having troubles finding detailed images of the Coram LMP. Has the kit-maker gone tits up? or is his site just down for a re-vamp?

Cheers, Ted


ProjectLMP - 22/2/04 at 02:05 AM

Another option with the coupling would be to use a cush drive. My quaife unit uses one. If you need I can post a picture. This would be shorter than a propshaft.


andkilde - 22/2/04 at 04:02 AM

quote:
Originally posted by ProjectLMP
Another option with the coupling would be to use a cush drive. My quaife unit uses one. If you need I can post a picture. This would be shorter than a propshaft.


That would be great, I've seen a few different styles -- the rubber disk used in BMW driveshafts, a rubber cruciform (looks like a moulded u-joint) used in early Mini's and the picture I've attached is an industrial coupler used for joining driven shafts together (available splined in addition to the keyed version shown).

http://www.andkilde.com/coupling.jpg

Thanks, Ted


Hugh Paterson - 22/2/04 at 09:27 AM

Ted, Coram went tits up last year, but the car/design has not, have a look in the photo archive on here under tadltd. We lurk and hide in here now and then the website will resurface when the car is about to be relaunched. Steve working on a car engine package/development to supplement the BEC build thats completed.
Shug.


Noodle - 22/2/04 at 10:18 AM

quote:
Originally posted by andkilde
quote:
Originally posted by ProjectLMP
Another option with the coupling would be to use a cush drive. My quaife unit uses one. If you need I can post a picture. This would be shorter than a propshaft.



That would be great, I've seen a few different styles -- the rubber disk used in BMW driveshafts, a rubber cruciform (looks like a moulded u-joint) used in early Mini's and the picture I've attached is an industrial coupler used for joining driven shafts together (available splined in addition to the keyed version shown).

http://www.andkilde.com/coupling.jpg

Thanks, Ted


Looks like a bike cush-drive.

Cheers,

Neil.


[Edited on 22/2/04 by Noodle]


andkilde - 27/2/04 at 01:15 AM

Hey, just had a run through MK Engineering's site:

http://www.m-keenan.freeserve.co.uk/Banshee.htm

Looks like Martin had the idea long before I did, maybe he'll have a nice coupler to sell when he's finished putting the Banshee together.

Cheers, Ted