James
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| posted on 21/12/04 at 04:44 PM |
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I'll admit I don't really know what roll-centre actually means. (Got a decent link?). Guessing it's not as simple as the axis about
which the chassis rotates to follow a droop on one side.(?)
Having read your post several times I'm still not sure I agree!
I'm saying keep 'L' and it's two brackets the same.
Also, keep the rear lower bracket the same.
Just move FU1/2 by rotating it about the axis of it's wishbone bolt hole.
Are you saying the suspension geometry will change if FU1/2 is attached to a different part of the chassis, even if the wishbone bolt hole is in
exactly the same place?
James
.... who's glad he kept his front suspension 'book'.... 
[Edited on 21/12/04 by James]
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krlthms
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| posted on 21/12/04 at 06:40 PM |
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Quote:
"My tranny tunnel would have to be as high as the rest of the chassis. And it looks like the prop would be too high up to meet the
diff."
Hello,
Mainly thinking of your second problem.
Have you thought of tilting the engine/gearbox fore to aft so that the prop end of the geabox points down a little bit, so that it permits coupling
to the diff.
If you do, yoou would probably need to fit a dry sump, to assure adequate lubrication of all the cylinders.
The other thing I noticed in your drawing is the gearbox side of the bell housing extends significantly lower than the engine side; why is that, and
could it not be machined off, or cut and welded?
Cheers
KT
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MikeRJ
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| posted on 21/12/04 at 07:25 PM |
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James, I have a +4" wide +1" high chassis and went through this a while back.
By making the upper and lower parts of the chassis both 4" wider with no other changes, then all angles stay the same, although the roll center
will have changed anyway.
By making the chassis 1" taller, you essentialy change the angle of the tubes the the suspension mounts to. In order to get the correct camber,
the top wishbone now needs to be a little longer. Again this will also change roll center. This is exactly what Ned shows in his drawing.
The good news is the difference is pretty tiny, certainly well within the adjustment available on the Transit rod end. I haven't bothered to
work out just how far this moves the roll center, probably a worthwhile exercise for a rainy day.
quote:
Originally posted by James
I'll admit I don't really know what roll-centre actually means. (Got a decent link?). Guessing it's not as simple as the axis about
which the chassis rotates to follow a droop on one side.(?)
Pretty much, it's the axis about which the car rolls when cornering, i.e. outside suspension in bump, inside in droop. Trouble is, it
dosen't usualy stay put anyway, but tends to move around as the suspension moves, which makes analysing it a little tricky.
Have you got a copy of Alan Staniforths book (Competition Car Suspension)?
[Edited on 21/12/04 by MikeRJ]
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Simon
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| posted on 21/12/04 at 07:54 PM |
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Adam,
Can't see why. Best place for it if you ask me.
Bike weighs (with me) about 300kgs and has 101ft lb torque. Car will weigh about 600kgs and will have 200ft lb. Therefore I have a bike that is very
tractable from about 30mph to 200mph in top, and a car that (with this gearing) will likewise be tractable from about 25mph to 120 (136 with new diff
I have) in top.
Neither require changing down to overtake (which should help with fuel economy for car), though it is nice to know that the bike'll do 86mph in
first gear if I want it.
ATB
Simon
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krlthms
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| posted on 21/12/04 at 09:40 PM |
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Liam,
Is your footwell wide enough for pedals, feet etc?
Cheers
KT
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ned
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| posted on 21/12/04 at 10:22 PM |
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James,
When I lend you my copy of PPC I'll dig out the staniforth book aswell so you can have some nice bed time reading over christmas 
Ned.
beware, I've got yellow skin
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Liam
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| posted on 21/12/04 at 11:30 PM |
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quote:
Originally posted by krlthms
Liam,
Is your footwell wide enough for pedals, feet etc?
Cheers
KT
Just about! The bottom rail runs back straight like that cos I gotta accommodate the front prop. But the footwell panelling will bulge out to give
enough room for my 6'+ size 12 feet buddies to be able to drive. It's fine for me cos I'm short and only size 8 feet. When I drive
the pedals will be further back in the footwell where it's wider. The two rails above the footwell are what my adjustable pedal box is gonna
slide on.
My pedal spacing will be about the same as a Lotus elise - not very much - to allow me to hop accross the pedals easily for left foot braking and heel
and toeing and all that. Here's some elise pedals...
Liam
 
Rescued attachment elisepedals1.jpg
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Liam
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| posted on 21/12/04 at 11:33 PM |
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My feet are only size eights and i can bridge the brake and throttle easily. Beautiful to drive. Just far enough apart is all you need, any further
hinders the sporty driving experience IMHO.
 
Rescued attachment 2002_0506_142406AA.JPG
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krlthms
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| posted on 21/12/04 at 11:42 PM |
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Liam,
Thanks, it makes sense now. I actually was wondering about the parallel rails, now I know.
Incidently, when they say Elise is "pure", they are not joking; exposed glue, bare steering column, pretty industrial environment. I have
seen locosts that are much better finished.
Cheers
KT
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phelpsa
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| posted on 22/12/04 at 12:06 AM |
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[remembering the old times]
We sold the Elise to build a Locost
The Elise was a great car, but with the motorbuild 160bhp kit and a pretty much straight through exhaust it was amazing.
A 110db metalic orange elise was pretty eye catching, and everywhere you went people stared.
[/remembering the old times]
Anyway, back on subject.
My pedal box has about an inch between the (2) pedals, I am 14 and have size 10 feet, which leads me to wonder 'have I put them too close
tegether?'
Adam
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krlthms
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| posted on 22/12/04 at 04:12 AM |
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quote:
Originally posted by phelpsa
[remembering the old times]
We sold the Elise to build a Locost
The Elise was a great car, but with the motorbuild 160bhp kit and a pretty much straight through exhaust it was amazing.
A 110db metalic orange elise was pretty eye catching, and everywhere you went people stared.
[/remembering the old times]
Anyway, back on subject.
My pedal box has about an inch between the (2) pedals, I am 14 and have size 10 feet, which leads me to wonder 'have I put them too close
tegether?'
Adam
Depends if you like to drive barefoot (I am only half joking)
Otherwise, as George Bush the father would say: not prudent at this juncture!
KT
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ned
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| posted on 22/12/04 at 10:12 AM |
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Adam,
Happy birthday for whenever it was, last time you posted your age you were still 13! 
Ned.
beware, I've got yellow skin
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phelpsa
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| posted on 22/12/04 at 10:52 AM |
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Well, i'm more 14 than 13 (a month or there abouts) I think I meant to put 13, but I can't be sure
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James
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| posted on 22/12/04 at 01:02 PM |
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quote:
Originally posted by MikeRJ
By making the chassis 1" taller, you essentialy change the angle of the tubes the the suspension mounts to
Sorry but I don't agree there. If you look at an MK Indy- the chassis is 1" taller but the brackets are in the same place as a book
chassis.
Clearly, you have to keep the LA/LB tubes at the same angle- because there are two brackets. MK have done this by extending LA/LB veritcally*
by 1".
This then leaves you two choices for FU1/2. You can either keep the tube at the same angle and extend it 1"** (but weld it to a slighly
different place on the 'J'&'F' rails.
Or, you can twist FU1/2 about the axis of the wishbone bolt (ie. keeping the wishbone bolt in the same place in space relative to the other bolts) so
that one end will be welded to it's original place and one will be somewhere else.
The wishbone bolts are all staying in exactly the same relative places.
Best Regards,
James
* The tube is bent at the top.
** When I say 1" I means slightly more than that to compensate for it not running vertically.
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James
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| posted on 22/12/04 at 01:05 PM |
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Think of it this way:
If I cut the top layer of rails off my chassis I can add 1"* of tube to all the tubes that support the top layer and then weld the top layer of
chassis back on.
You can't tell me that the relative positions of the chassis brackets have moved!!!
Cheers,
James
*Slightly more for the angled tubes
[Edited on 22/12/04 by James]
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andyace
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| posted on 22/12/04 at 01:43 PM |
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I sort of agree with James however I would guess that if you extend the supports at the same angle the distance between the top rails (left and right)
on the car will increase slightly giving you a slightlly wider top but should not effect the position of the brackets.
Neds picture is sort of correct in that it shows the horizontal bars remaining at the same width which does mean the angle changes.
So in order to keep the angle, the width of the bottom can increase by 1 inch and the top width will increase by 1 inch + a little bit.
I will draw a picture if it isnt clear!
[Edited on 22/12/04 by andyace]
[Edited on 22/12/04 by andyace]
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andyace
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| posted on 22/12/04 at 01:46 PM |
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James, Did you need to make any adjustments to get your Pinto in, I am currently stripping my donor Sierra 2.0 SOHC (+Carbs). I guess the main areas
of concern are the height. Did you have to modify the std transmission tunnel (I have type 9 gbox).
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andkilde
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| posted on 22/12/04 at 03:05 PM |
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quote:
I'll admit I don't really know what roll-centre actually means. (Got a decent link?). Guessing it's not as simple as the axis
about which the chassis rotates to follow a droop on one side.(?)
Actually James, you're spot on with your description.
The Roll Axis is a line passing through the front and rear roll centres -- the car, theoretically, will rotate about this axis as it rolls in a
turn.
Someone posted a link to an RC car site last year (which I can't find at the moment) which had excellent decriptions of Roll Centres, Scrub, KPI
and a load of other relevant info. If I turn it up I'll send it along.
Cheers, Ted
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AdamR
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| posted on 22/12/04 at 11:07 PM |
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quote:
Originally posted by krlthms
Hello,
Mainly thinking of your second problem.
Have you thought of tilting the engine/gearbox fore to aft so that the prop end of the geabox points down a little bit, so that it permits coupling
to the diff.
If you do, yoou would probably need to fit a dry sump, to assure adequate lubrication of all the cylinders.
Your idea sounds a bit drastic! I wonder if anyone has has done this before though? It's got me wondering how many degrees tilt on the engine it
would take to have to worry about oil circulation problems. Anyway, hopefully this will not be necessary with the other mods.
quote:
The other thing I noticed in your drawing is the gearbox side of the bell housing extends significantly lower than the engine side; why is that, and
could it not be machined off, or cut and welded?
Cheers
KT
Yeah, the RV8 (or my RV8 at least) only mates onto the bellhousing for the top half of it's circumference. The bottom half is blanked off with
a plate. If I took any material off the bottom of the bellhousing it would expose the flywheel and gain me at least in inch or ground clearence (if I
chopped the sump to match), but presumably wouldnt go down too well with Mr SVA!
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AdamR
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| posted on 22/12/04 at 11:24 PM |
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quote:
Originally posted by James
Think of it this way:
If I cut the top layer of rails off my chassis I can add 1"* of tube to all the tubes that support the top layer and then weld the top layer of
chassis back on.
You can't tell me that the relative positions of the chassis brackets have moved!!!
Cheers,
James
*Slightly more for the angled tubes
I agree with James on this one. The FU tubes do not join to the F and J rails right at their outer edges. At the bottom they can overlap onto the E
tube, and at the top they can overlap onto the join with S or T. Therefore you can move/change the angle of the FUs without widening the chassis and
without moving the bracket.
If the brackets are in exactly the same place, how does adding an inch in height to the chassis change the roll centre?
Ned: if I'm completely off here, then I may also want to borrow that book when James has finished with it!
Cheers,
Adam
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Mark Allanson
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| posted on 22/12/04 at 11:41 PM |
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quote:
Originally posted by andyace
James, Did you need to make any adjustments to get your Pinto in, I am currently stripping my donor Sierra 2.0 SOHC (+Carbs). I guess the main areas
of concern are the height. Did you have to modify the std transmission tunnel (I have type 9 gbox).
I built my chassis before I found my donor BIG mistake. My biggest problems were the starter fouling the LH engine bearer and the end of the type 9
coinciding with the tranny tunnel uprights. I would move these 2"further back and save yourself a LOAD of grief
 
Rescued attachment TunnelClearances.JPG
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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Rorty
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| posted on 23/12/04 at 04:43 AM |
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quote:
Originally posted by krlthms
Have you thought of tilting the engine/gearbox fore to aft so that the prop end of the geabox points down a little bit, so that it permits coupling
to the diff.
If you do, yoou would probably need to fit a dry sump, to assure adequate lubrication of all the cylinders.
In the original car, the RV8 does angle downwards by 7 degrees. You can buy a "7 degree plate" for them to level four-barrel carbs on the
manifold.
Chopping the sump and increasing the capacity is quite a simple job.
This one's been chopped by 45mm, yet the oil capacity has been increased by one litre.
 
Rescued attachment chopped_sump.jpg
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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