GaryM
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| posted on 8/5/05 at 03:17 PM |
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Front Suspension Travel (In bump)
Can anyone give me an idea of how much front suspension vertical travel (of the stub axle) they get in bump, measured from a level lower wishbone.
I've got a standard book setup (Cortina uprights) and I only get 60mm before the upper wishbone transit drag link ball joint fouls on itself.
Cheers
Gary
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JoelP
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| posted on 8/5/05 at 05:21 PM |
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a common problem this, most upper wishbones have the transit ball joint pointing up slightly to give more play.
IIRC, mine goes up about 3 inches (from loaded) and down just over one. I also have a small amount of preload on the shocker to help prevent it
bottoming out.
not been tested to extremes yet though 
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Peteff
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| posted on 8/5/05 at 06:49 PM |
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pointing up slightly to give more play.
If it's already angled up surely it will give you less travel combined with the angle of the top wishbone?
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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JoelP
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| posted on 8/5/05 at 06:52 PM |
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on sierra hubs the top bit points in quite a lot i used MK top bones anyway, so dont blame me!!! 
this pic looks like the bones on mine dont diverge enough, it an illusion
and again, im still missing that bolt!!!!
[Edited on 8/5/05 by JoelP]small.jpg)
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britishtrident
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| posted on 9/5/05 at 11:56 AM |
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This is an issue on some Cobras but not on Locosts.
The dampers only have 2 inch/52mm travel from fully open to full bump anyway 70mm if the bumpstop is compresed to a really extreme degreee how much
this translates to at the wheel/ball joint depends on the wishbone leverage ratio and angle of the damper, but is going to be about 60mm on a typical
setup --- full droop to full rebound.
[Edited on 9/5/05 by britishtrident]
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GaryM
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| posted on 9/5/05 at 01:47 PM |
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With the lower wishbone level to the ground i've got 60mm of bump travel and 95mm of droop travel (I measure that as potentially over 6 inches
of total travel). In both cases the travel in limited by the ball joints fouling themselves.
I've selected Gaz 13" shocks for the front suspension as they give me 3" of travel to the bump stop which can compress a further
1/2".
The crux of my problem is that if I position my top damper mount so the damper body hits the damper bump stop at the full range of the suspension
travel (i.e when the ball joint fouls) then as the damper bump stop compresses I will be over straining the ball joint
OR ALTERNATIVELY
If I position my top damper mount so the damper body fully compresses the damper bump stop just before the ball joint movement limit is reached.
Trouble is, this way, approx the last 1/3 of my suspension travel (in bump) involves compressing the rubber bump stop (not good surely?) and really
I've only got approx 40mm of unincumbered bump travel.
Does that make sense?
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britishtrident
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| posted on 9/5/05 at 03:41 PM |
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Normal "book" front dampers are 12" between eye centres fully open, The Transit rod end is a drag link end from a beam axle
vehicle hence dosen't require much articulation, The dampers normally suplied for use on locosts selected with this in mind.
see this pdf from Darren's (GTS) site http://www.gtscougar.freeserve.co.uk/locost.pdf
If you still want more travel it should be possible to use a different design of wishbone to accomodate a different ball joint such as a Metro or
Fiat/Lada but this will demand a bit of inginuity to make it adjustable for castor.
[Edited on 9/5/05 by britishtrident]
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GaryM
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| posted on 9/5/05 at 04:04 PM |
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British Trident, thanks for your input.
Bearing in mind the damper's rubber bump stop is 1" thick and can compress to half this thickness. Would you agree the only safe way to
ensure the mechanical limit of bump is never reached (i.e the ball joint fouls itself) is to position the damper so the damper's bump stop is
approaching 50% compression at this point?
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britishtrident
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| posted on 10/5/05 at 07:48 AM |
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Yes ---
Thinking it over it might interesting to compare different makes of Transit drag links --- I suspect some manufacturers joints will allow more
articulation than others.
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GaryM
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| posted on 10/5/05 at 03:13 PM |
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I've just tried a transit drag link from a different supplier. Even before I tried it on the car the balljoint's range was obviously
larger.
With it fitted it gave me 35mm more bump travel.
35mm extra, i'm so happy!!!!!!!!
Thanks Trident
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