After a couple of years off doing other projects, I've finally come back to my Locost. I've started by re-positioning the engine and re-doing the engine mounting system as I wasn't happy with it, but I need some other opinions before I go ahead and crack out the welder.





Here's the main problem when it comes to positioning:



I know that ideally I want the two prop faces parallel but that isn't going to work. Its only a few degrees out and i'm not overly bothered about UJ wear, its not going to be doing any huge distances or speeds.

Any other thoughts?

Adam

The UJ actually runs better at a slight angle, they don't like being in a straight line.

You my be lucky if you take off your oil filter and take it to your local parts store they may be able to find one that would fit which is smaller.

also, you may have some trouble welding that wood as it tends to be difficult to work with...

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Originally posted by Mark G
The UJ actually runs better at a slight angle, they don't like being in a straight line.

You my be lucky if you take off your oil filter and take it to your local parts store they may be able to find one that would fit which is smaller.

also, you may have some trouble welding that wood as it tends to be difficult to work with...

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UJs do like a slight angle, but the gearbox and diff flanges must be absolutely parallel to cancel out the cyclic speed changes you get from an angled UJ. i.e the angles of the joints at each end must be equal and opposite.

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Originally posted by matt_claydon
UJs do like a slight angle, but the gearbox and diff flanges must be absolutely parallel to cancel out the cyclic speed changes you get from an angled UJ. i.e the angles of the joints at each end must be equal and opposite.

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It's not really the UJs that are the problem, it's the vibration through the whole drivetrain due to the vehicle/engine speed fluctuating with each revolution of the propshaft.

I expect a very slight misalignment is allowable, although I couldn't say what a safe limit would be, but really you want to aim for the flange to face straight backwards.

There's a video here that kind of explains the issue. It's an interesting watch for an engineer anyway but spin on to 3:15 if you don't want to see the rest. http://uk.youtube.com/watch?v=xgQgm3GwaFs

I can see the problem.

Hmmm.

Do you have to use UJs in the propshaft? Would it be possible to say use CV joints in the front section and UJs in the rear section?

[Edited on 27-8-08 by phelpsa]

interesting video, made me a little paranoid now.....lol.
i.ll have to go and check mine out.

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Originally posted by matt_claydon
There's a video here that kind of explains the issue. It's an interesting watch for an engineer anyway but spin on to 3:15 if you don't want to see the rest. http://uk.youtube.com/watch?v=xgQgm3GwaFs

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http://www.dp-graphics.nl/seven/engine-4.jpg

I've seen many installations where the prop faces aren't parallel, like the photo /. Has anyone actually had any trouble?

It's also OK if the angles on the joints are equal and in the same direction. In bike engine layouts it's possible to have the front half of the prop with equal angles and the rear half equal/opposite. In this diagram:


Prop angles

The top two cases are OK and will give constant velocity, the bottom is bad. If the front half of the prop is like the middle diagram and the rear half like the top (or straight) then you should be OK.

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Originally posted by matt_claydon
It's also OK if the angles on the joints are equal and in the same direction. In bike engine layouts it's possible to have the front half of the prop with equal angles and the rear half equal/opposite. In this diagram:


Prop angles

The top two cases are OK and will give constant velocity, the bottom is bad. If the front half of the prop is like the middle diagram and the rear half like the top (or straight) then you should be OK.

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Originally posted by phelpsa
Has anyone actually had any trouble?

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Originally posted by blakep82

i think just about every lorry has a prop shaft angled down from gearbox to axle.

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^ yeah, parallel, but at different heights

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Originally posted by blakep82
^ yeah, parallel, but at different heights

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ahhh, cunning

Perhaps I'm missing the point here, but why not simply move the offending chassis rail...

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Originally posted by motorcycle_mayhem
Perhaps I'm missing the point here, but why not simply move the offending chassis rail...

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