smart51
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| posted on 1/2/13 at 02:20 PM |
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Weaving at speed
I'm now road legal. Eventually. My first trip out on the trike was fun but at 70MPH it weaves a bit. Back off and it's fine. What
causes weave and what should I do to stop it? Two front wheels, one rear and RWD BTW.
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maccmike
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| posted on 1/2/13 at 04:11 PM |
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mine was doing the same at around 90.
figured it might be castor.?
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ReMan
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| posted on 1/2/13 at 04:12 PM |
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Just a thought,
What is your rear wheel/tyre? Is it a bike type/profile, or Car type
And could it be slightly out of line?
www.plusnine.co.uk
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smart51
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| posted on 1/2/13 at 04:35 PM |
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It has a whole lot of castor angle and a fair amount of trail to try to give it self centring. Castor is good right? It has the original bike tyre
on the back. I'd thought about putting a car tyre on it when the bike one wore out.
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Slimy38
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| posted on 1/2/13 at 04:56 PM |
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quote:
Originally posted by smart51
It has a whole lot of castor angle and a fair amount of trail to try to give it self centring. Castor is good right? It has the original bike tyre
on the back. I'd thought about putting a car tyre on it when the bike one wore out.
I thought that sort of excessive castor was just to get it through the IVA, and you dial it back a bit for normal driving?
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ashg
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| posted on 1/2/13 at 05:02 PM |
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Try raising or lowering the ride height at the rear
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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omega 24 v6
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| posted on 1/2/13 at 05:14 PM |
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Toe in will maybe be too small. Toe out makes for a VERY nervous car esp underbraking.
If it looks wrong it probably is wrong.
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Phil.J
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| posted on 2/2/13 at 02:23 PM |
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Try not to use more than 7 degrees of castor, and check carefully for bump steer, the root of many higher speed handling problems.
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smart51
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| posted on 2/2/13 at 04:51 PM |
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Good suggestions, thanks. The toe angle was set for MSVA self centring. I've changed it a touch but maybe a bit more is needed.
When I changed the castor angle, it introduced a lot of bump steer, which I removed by moving the steering rack. The beauty of an open wheeled car is
that you can see the front wheels move when bouncing on the chassis. There's no bump steer now.
I'll look out the C spanner and adjust the rear ride height. A quick test will show if it helps.
Will tyre pressures have much effect? It's hard to know what to set them to in a car that weighs less than a quarter of a tonne.
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Mark Allanson
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| posted on 2/2/13 at 06:34 PM |
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The theoretical tyre pressure is the max psi (embossed on the tyre) x the actual weight on the tyre in kgs (or lbs) / the max load of the tyre in kgs
or lbs (use the same unit as the actual weight) = a good starting point.
The max load may be embossed on the tyre or you will need to convert the load index (185 70 R13 82H - the index is the 82) to kgs.
Try here for a conversion table.
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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smart51
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| posted on 3/2/13 at 04:19 PM |
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thanks Mark. For my front tyres that works out at 9 or 10 PSI. I had them at 20. I've set them at 14 PSI ready for the next time it is dry
and I'll see if it makes and difference.
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