Westfield SE Suspension Geometry ?
Chris Cowap
suspension on a Westfield SE (Actually an 88 chassis I think)
The build manual only suggests ride heights, which is limited use due to
different tyre sizes. There is also a potential clearance problem on my car
as I am using the new style wing brackets which share the top wishbone rear
mounting bolt. The top wishbone runs very close and occasionally fouls with
it.
Ive not tried the factory yet as I keep forgetting to call them during the
day !
Thanks
Chris Cowap
AWM
"Chris Cowap" <nos...@here.co.uk> wrote in message
news:El4da.422$ae7.1...@newsfep1-win.server.ntli.net...
Try
0.5 to 1.5 negative camber
1 to 3 mm toe in
7 degrees castor (must be equal both sides)
shocks set fairly soft.
AWM
"Chris Cowap" <nos...@here.co.uk> wrote in message
news:El4da.422$ae7.1...@newsfep1-win.server.ntli.net...
Try
0.5 to 1.5 degrees negative camber
1 to 3 mm toe in
Castor 7 degrees (must be equal both sides)
Dampers set fairly soft
>
Chris Cowap
I also need some idea of the wishbone angles if pos'
At the mo' the cars running some nasty old 185/70x13' Pirellis but I'll be
changing these to 185/60's soon - sump clearance isnt a problem as ive fited
a shallow alloy one.
Any idea of the best coil spring compressors to suite the dampers ? The
usual halfords types are too big to fit between the coils.
Cheers
Chris
AWM
> Thanks,
>
> I also need some idea of the wishbone angles if pos'
>
> At the mo' the cars running some nasty old 185/70x13' Pirellis but I'll be
> changing these to 185/60's soon - sump clearance isnt a problem as ive
fited
> a shallow alloy one.
>
You mean 185/60x13 Xr2 style --- ? not sure if that is a good idea
especially if you are swaping Pirellis for a cheaper make. While 185/70x13
aren't the most suitable size (for a start they dammed heavy), the height
is right to give reasonable geometry without having to muck about with the
rollcentre and steering rack height. 185/60x13 tyres will lower the car by
3/4" of an inch which is a lot on a car already running very low.
For road use 100mm ( 4inch ) ground clearance is the minimum you can safely
get away with (usually on a Seven the bellhousing not the sump is the first
to scrape) so if you fit 60 section tyres on 13" rims you will end up having
to move the inner wishbone pivots and steering rack quite a long way to keep
a reasonable geometry.
I would suggest you swap to 14 inch or 15 inch rims as much better tyre
choices available for these rims, they also give better ride comfort and
grip/traction and deal with pot holes better. A 185/60x14 (or 195/50x15
or 185/55x15) will give the same height as the original 185/70x13" or
165/82x13"
David Helliwell
from "Chris Cowap" <nos...@here.co.uk> contains these words:
> The build manual only suggests ride heights, which is limited use due to
I built an '88 SEi and used to go to Thames Valley OC meetings. The late
Arthur Mallock gave us a talk on suspension design as a result of which
one of the members had Mallock sort out the front geometry on his car.
Computer analysis showed that the rack brackets were too high and that
bump steer was a problem. The rack height was corrected by Mallock on
this car (welded in a lower posirion). I don't know if it helped or not.
On my car the castor was not adjustable but as a result of an accident
which damaged the front suspension (and the chassis, not noticed !!!!!
by Terry Nightingale) I discovered that there were two different top
wishbones which gave different castor angles. I sold my car in '92 so I
know nothing of subsequent developments.
Incidentally, the on-the-limit handling of my car was not to my liking
as it went straight into oversteer with little understeer and no drift
in between.
Best of luck.
AWM
"David Helliwell" <puc...@zetnet.co.uk> wrote in message
news:200303171...@zetnet.co.uk...
> message <El4da.422$ae7.1...@newsfep1-win.server.ntli.net>
> from "Chris Cowap" <nos...@here.co.uk> contains these words:
>
> > The build manual only suggests ride heights, which is limited use due to
>
>
> I built an '88 SEi and used to go to Thames Valley OC meetings. The late
> Arthur Mallock gave us a talk on suspension design as a result of which
> one of the members had Mallock sort out the front geometry on his car.
> Computer analysis showed that the rack brackets were too high and that
> bump steer was a problem. The rack height was corrected by Mallock on
> this car (welded in a lower posirion). I don't know if it helped or not.
>
stiff.
Part of the bumpsteer problem is the rack width between the iner ball
joints -- Ford racks are just a bit to wide for 7 style cars, whats needed
is a track rod end to mate a Triumph rack to Cortina suspension.
Chris Cowap
The tyre choice is more or less due to the fact the Caterham Superlight R500
used 185/60x13's on the front, and 205/60x13's on the back. I get your point
re Ground clearance though. - I changed to the alloy sumpdue to the fact
that the original steel one had been bashed to bits as it was lower then the
bellhousing. - Alloy one is slightly higher than the bellhousing.
Still need to know best angle for wishbones and steering rods - Should I be
looking for top wishbone, steering rod or bottom wishbones level ?
Chris
"AWM" <not...@nowhere.freeserve.co.uk> wrote in message
news:b555br$kvc$1...@sparta.btinternet.com...
Jonathan Barnes
Suspension is a bit of a black art...
I have a rough rule of thumb starting point, for a wishbone set up with the
top links about 2/3 as long as the bottom.
The lines through the pivots extended should intersect 1/2 to 1 1/2 track
lengths outside the opposite wheel, at between hub high and 3/4 hub high.
to set up the steering for zero bump steer, as the wheel moves the pivot
point of the steering arm moves in an approximation of an ark, the rack
joint should sit at the centre of this ark.
Working out the ark centre to determine arm and rack lengths and rack
position is a nasty exercise in solid geometry.
--
Jonathan
Davrian 8, BMW M3
Remove AT to reply
AWM
> Thanks
>
> The tyre choice is more or less due to the fact the Caterham Superlight
R500
> used 185/60x13's on the front, and 205/60x13's on the back. I get your
point
> re Ground clearance though. - I changed to the alloy sumpdue to the fact
> that the original steel one had been bashed to bits as it was lower then
the
> bellhousing. - Alloy one is slightly higher than the bellhousing.
> Still need to know best angle for wishbones and steering rods - Should I
be
> looking for top wishbone, steering rod or bottom wishbones level ?
>
> Chris
>
The geometry and suspension on the Caterham is quite a bit different from
the Westie & Locost for a start on the Caterham the rear roll centre is much
lower also the Superlight is much lighter at the front, as a K series
engine is only slightly more than half the weight of of a Pinto.
I don't know what the exact weight distrubution is on the Westie but a Pinto
Locost which uses essentially the same chassis has a weight distribution of
about 47% front 53% rear, on the Caterham Superlight this is going to be
nearer 42% front 58% rear more the sort of weight distribution you expect
to see on a rear engined car and ample justification for the differing tyre
section sizes. With a Pinto/CVH or even an Xflo engine sitting just behind
the front wheels it is hard to justify having the rear tyres more than one
size bigger than the fronts. Ideally say 185/60x14 on front 195/60x14 on
the rear, but as the difference isn't very big it would be easier to use
185/60x14 all round and balance out any surplus oversteer by fitting a front
antiroll bar on the front.
If you want still to fit 185/60x13 on the front ------
The adjustments in the geometry are really just a matter of setting the car
to the desired ride height then plotting out the changes in roll centre
height on paper is suspect the front roll centre height will have to be
lowered by moving the inner pivots of the upper wishbone upwards