Digger Barnes
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 posted on 9/1/04 at 08:27 AM |
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Propshaft Cush drive
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?
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Mk-Ninja
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| posted on 9/1/04 at 08:31 AM |
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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
I'm sure I've got one, just don't know where I've put it
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Digger Barnes
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| posted on 9/1/04 at 08:42 AM |
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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?
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ChrisGamlin
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| posted on 9/1/04 at 11:19 AM |
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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]
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Digger Barnes
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| posted on 9/1/04 at 12:50 PM |
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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
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Peteff
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| posted on 9/1/04 at 03:00 PM |
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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.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Digger Barnes
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| posted on 9/1/04 at 03:52 PM |
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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.
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suparuss
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| posted on 9/1/04 at 05:12 PM |
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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.
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Rorty
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| posted on 11/1/04 at 04:32 AM |
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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.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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