I was just wondering does anyone have a cush drive mounted in their drivetrain?.

The reason I ask is I know motorbike gear boxes are conected to the back wheel of the bike via a cush drive in the hub to absorb transmission jerk (I know granny and eggs).

When I was hacking up my sierra 4x4 donar last week I noticed that the two piece prop has a cush drive between the gearbox and the prop. Now the question is has anyone tried to convert this for use as a sliding joint/cush drive for their locost.

Is this a mad idea if so why?

HI

This was covered a few weeks ago so have a look for the full version but IIRC the concenses was that most if not all were running without cush drive without any problems.

Gordon

Yep read that now.

The reason I was considering a cush drive was to keep the gear changes as smooth as possible. I thought it would probably help to preserve the gearbox also.

So then has no-one on this forum used a cush drive then?

A few people I know have got one on their Westfield BECs, either as a proper cush drive as part of the prop flange, or as a TRT (torque tube) built into the prop itself.

To be honest tho I can't feel any noticable improvement in gearchange smoothness / driveline shunt on their cars, and one of the chaps with a cush drive has broken one gearbox during the course of 2 trackday seasons so its definitely not a guaranteed fix.

I think personally its more to do with how and when you change gear rather than whether you have a cush drive. If you bang it down the box at high revs and try to use engine braking lots then the dogs take a beating but if you adjust your gearchanging so you brake in the higher gear, then go down your gears later in the process when the revs are lower, its a lot kinder on the box.

Chris

[Edited on 9/1/04 by ChrisGamlin]

mmm interesting.

So it would seem that it would not be worth the extra effort to build a cush drive into the drive train.

Good good that is one less thing to worry about/design.

Cheers

I'd looked at this and wondered if rubber mounting the engine instead of solid would have the same effect in an inline situation as used in the locost. I find you get most drag if you cram it in gear with the brake engaged. I have a shaft drive bike and that has no cush drive so I think it may be more to preserve the chain than the gearbox on a bike.

yours, Pete.

cheers pete that sounds like a much simpler solution. I will give it some thought.

So does anyone have excessive vibration due a solidly mounted bike engine? I know when I am riding my bike close to the limit for a while I tend to get vibration white finger.

i use to get that just from hanging on for me dear life, the solution was usually to slow down a bit!
i thin kgeneraly bike engines have very little vibration (obviously cos they are so finely ballanced) hence it is acceptable to mount them without dampers, but i reckon it would help if you are going for comfort, but you would have to be carefull not to allow too much movment so that the prop stays alligned.



Russ.

Russ.

If you use soft engine mounts with a bike engine, you could end up with gear selection/jumping out of gear woes. I wouldn't advise soft mounting.