DarrenW
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| posted on 9/6/05 at 10:43 AM |
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Why not get him to organise a saturday locost meet for you local boys whereby he can agree basic check and set-up for £50 cash. If anymore work needed
he could book them in for later.
Im very surprised that you guys are considering anti roll bars etc. There are planty of cars out there without them that handle very well. I would try
and set the car up correctly first before throwing cash at the problem. If setting it up doesnt solve it then perhaps there is a more serious problem
to fix first. To me arb's should be used to improve what is already at its optimum and not to compensate for something that is inherenntly
wrong.
[Edited on 9/6/05 by DarrenW]
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mookaloid
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| posted on 9/6/05 at 02:55 PM |
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quote:
Originally posted by DarrenW
Im very surprised that you guys are considering anti roll bars etc. There are planty of cars out there without them that handle very well. I would try
and set the car up correctly first before throwing cash at the problem. If setting it up doesnt solve it then perhaps there is a more serious problem
to fix first. To me arb's should be used to improve what is already at its optimum and not to compensate for something that is inherenntly
wrong.
[Edited on 9/6/05 by DarrenW]
Please don't get me wrong I am not saying there are faults, I am just saying that I need to find quite a few seconds to get competitive on the
hill climbs, if I can get a couple of seconds on changing geometry and settings and if anti roll bars get me a couple more seconds then I'll
want some
Cheers
Mark
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colibriman
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| posted on 9/6/05 at 04:41 PM |
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yes..lets put things in perspective...I'm not happy because I'm trying to get fantastic handling and maximum grip on cold
tyres.....driving balls out for a minute or so and expecting wonderful things to happen........hmmmm am I looking for too much? NO! I just want to
make whats good, better!
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SVA ready Mk Indyblade possibly for sale.....if the offers good...!
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athoirs
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| posted on 9/6/05 at 05:07 PM |
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Hi colin,
I have lowered the front so that it is lower than the rear by about 15mm. On the last sprint at knockhill it was wet so I had the dampers full soft
and still spun it twice in the wet getting on the power too early.
On Mondays track evening I left them soft in the dry and it seemed to be going even better round the corners!
I have some 200lb springs which I am going to try in the front ( someone did this and found it much better not sure who??)
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colibriman
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| posted on 9/6/05 at 05:21 PM |
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Andy...
Knockhill weather was terrible...in a way I'm glad I didn't get an entry..
I've been told by a few people now that ,as you have done, it needs to be 15mm lower at the front....mine is the exact opposite of that...
I've just taken my shocks n springs off the front of the car and they are 9'' 250lb that are on it...
Mook,
Not too sure about the rear anti roll bar... is it not stiff front end and a soft rear..()...I think that how the women should be anyway...not
saggy..just soft
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SVA ready Mk Indyblade possibly for sale.....if the offers good...!
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mookaloid
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| posted on 9/6/05 at 05:29 PM |
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I was just looking at this frame from a video may mate took, and I wondered if a rear anti roll bar might help....
what do you think?
Cheers
Mark
 
Rescued attachment roll.JPG
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colibriman
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| posted on 9/6/05 at 05:35 PM |
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I know...pictures of my car in a bend shows it to be rolling at the rear too...as you said..your tyre looks very flat!
my mate Garry has anti roll bars on the front and rear of his westie..he is running wide slicks though..so I don't know how that affects
things..
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SVA ready Mk Indyblade possibly for sale.....if the offers good...!
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athoirs
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| posted on 9/6/05 at 07:50 PM |
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Colin,
The origional springs from MK on the Protech shocks were 350x8.75
the next set I tried were 350x7 to lower the front of the car and I think was much better.
I put on the 250x7 tonight and it was hard to tell if it was any better.. maybe a little..
managing to get 45mph round a roundabout.. holding it with one finger.. and easy to control the rear end ..
ps if you want try out the 350x7's first give me a ring I am away at the weekend but I can leave them out for you
[Edited on 9/6/05 by athoirs]
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carnut
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| posted on 9/6/05 at 08:42 PM |
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Are the front bottom wishbones parallel to the ground with the 350x7 springs?
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colibriman
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| posted on 9/6/05 at 08:47 PM |
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Andy, thanks for the offer....
what a madman you are....I only spoke to you about an hour before your last post and you've changed your springs since the call and been out
playing already....awesome...or buck mad!
need a bike engine? - www.colibriman.com
SVA ready Mk Indyblade possibly for sale.....if the offers good...!
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athoirs
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| posted on 9/6/05 at 09:09 PM |
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mad as a hatter!!
with the 7in springs you can move front of the car from almost touching the ground up to hard on the damper stop. which is the adjustment range you
should have
i'll try and get a few photos of the front of the car after the weekend
[Edited on 9/6/05 by athoirs]
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pbura
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| posted on 9/6/05 at 09:15 PM |
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Haven't got an Indy or even a Locost yet, but I hope you guys don't mind me jumping in, because I love the subject. 
All the following is IMO, of course:
I suspect that the Indy has a much lower rear roll center than a solid-axle Locost, because otherwise it would have a tendency to jack up an inside
wheel when cornering, due to cornering forces transmitted through the angled wishbones. So it would need more roll resistance, which is not always
practical with road springs because of negative effects on ride and tire compliance. Enter the ARB.
There are a couple of schools of thought on ARBs, probably both valid. One is to spring the car very softly and trim the roll exclusively with ARBs.
I personally don't think very light springing will work on a Seven because of limited suspension travel, and because adding payload to a very
light car with soft springs will have such a great effect on ride height.
The other strategy is to minimize the use of ARBs. First, have the roll centers as high as possible without jacking; the rule of thumb for this is
about 3". Next, have springs as firm as possible without sacrificing tire grip and an excessively harsh ride. Then, add enough bar to control
the roll.
I think a couple of benefits of minimizing ARBs are (1) ARBs cause more load to be transferred to the outside tire, causing a negative effect on grip,
and (2) an ARB is nothing but an additional spring that is undamped, and if it is too stiff it will overpower dampers that are tuned for the
coilovers.
Generally, you'll want less ARB at the rear than at the front, so that in roll the rear roll stiffness does not increase disproportionately,
causing loss of grip at the rear.
From looking at Mark's picture, I would shoot for a higher degree of roll at the front than at the rear before adding bars. Maybe less spring
at the front and/or more spring at the rear. I suspect both because of the ride height, understeer, and very large degree of roll at the rear. The
springing should be put into order before, or as part of the analysis for, adding ARBs.
I don't know the particulars of the Indy suspension, but if the front was originally designed for a solid-axle car and was not modified for the
Indy, it's likely that the front roll center is too high. This would cause the front to roll less than it should relative to the rear. A way
to see if this is a problem would be to compare the chassis bracket locations to the book Locost.
This website has some outstanding technical pages (and links) about setting spring and ARB rates:
http://www.smithees-racetech.com.au/
All the calculations on the "Weight Transfer Worksheet" can be done by anyone with a bit of research and study. The object is to arrive
at initial settings that are further tuned through track testing. Personally, I think the setup service is a good value (no affiliation, of
course).
Speaking of track testing, there is a terrific post on this page about skidpad testing, by Richard Hudgins, about 2/3 down the page:
http://www.clubcobra.com/t20032-15-2.html
Very sensible approach to setting tire pressures, not to mention tuning shocks and springs.
My thanks to anyone who read this screed through to the end
Pete
Pete
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colibriman
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| posted on 9/6/05 at 09:35 PM |
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and thanks to you Pete...it must have taken a while to write....
I'm interested in this subject as well, not only because it affects me......I just don't know much about it all....and there's a lot
to consider
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SVA ready Mk Indyblade possibly for sale.....if the offers good...!
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mookaloid
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| posted on 9/6/05 at 09:52 PM |
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Hi Pete thanks for that, this is exactly the kind of input we need...
I was just getting round to thinking I need more rear spring. As body roll is a function of spring rate that would seem to be the first thing to
address.
The arb seems to be a way of getting less roll without increasing the spring rate it I understand it correctly, but as you say it seems it can have an
adverse effect on grip!
I am actually less worried about the front than the rear but I am going to get a mate to do lots of videos at the next hill climb so I can study not
only my cars behaviour but the faster ones too!
Cheers
Mark
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Northy
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| posted on 9/6/05 at 10:01 PM |
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How would just fitting a rear anti roll bar an no front affect the car?
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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greggors84
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| posted on 9/6/05 at 10:34 PM |
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It would cause more weight transfer at the front as it is rolling more. Means the car would have more understeer. Useful if the car oversteers easily.
Chris
The Magnificent 7!
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Spottty
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| posted on 10/6/05 at 02:29 AM |
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quote:
Originally posted by greggors84
It would cause more weight transfer at the front as it is rolling more. Means the car would have more understeer. Useful if the car oversteers easily.
Thats odd because I added ARB's to my Volvo wagon. It came with a 19mm up front and nothing in the rear.
I added a 25mm up front and a 25mm in the back. It made the car much more tail happy. I can oversteer it any time I want now, something I couldnt do
with out the rear bar.
Best thing to do for a build....
Ditch the wife! 
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nre
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| posted on 10/6/05 at 10:26 AM |
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quote:
Originally posted by Northy
How would just fitting a rear anti roll bar an no front affect the car?
Cheers
Contrary to other replies, a rear ARB will give more weight transfer at the rear, and hence you will get less understeer/more oversteer.
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Northy
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| posted on 10/6/05 at 10:29 AM |
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I just want to limit the roll a little.
I'll try and get a picture of Pats car at Elvington to show you.
Cheers
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing!
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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pbura
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| posted on 10/6/05 at 12:25 PM |
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Cheers, Colin and Mark, it's a fascinating topic for me and there's always something to learn. I can't wait to try out some things
on my own.
Graham, usually the need is for more added roll resistance at the front, because the rear should have a higher roll center, and be sprung more stiffly
to deal with bumps (so that front and rear rebound from a road irregularity at about the same time). Though Sevens have higher-rated springs at the
front, the wheel rates are usually lower than the rear because of the angles of the springs and their placement in relation to the wheels. If you’re
getting a lot of body roll at the rear and little at the front, I’d recommend increasing the rear rates and possibly decreasing the front springs.
Also, there might be something awry with your roll center heights.
Off to outside work for the day!
Pete
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mookaloid
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| posted on 10/6/05 at 12:30 PM |
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quote:
Originally posted by pbura
Cheers, Colin and Mark, it's a fascinating topic for me and there's always something to learn. I can't wait to try out some things
on my own.
Graham, usually the need is for more added roll resistance at the front, because the rear should have a higher roll center, and be sprung more stiffly
to deal with bumps (so that front and rear rebound from a road irregularity at about the same time). Though Sevens have higher-rated springs at the
front, the wheel rates are usually lower than the rear because of the angles of the springs and their placement in relation to the wheels. If you’re
getting a lot of body roll at the rear and little at the front, I’d recommend increasing the rear rates and possibly decreasing the front springs.
Also, there might be something awry with your roll center heights.
Pete
Great info Pete - I just wish I understood it
Cheers
Mark
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nre
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| posted on 14/6/05 at 03:14 PM |
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quote:
Originally posted by pbura
If you’re getting a lot of body roll at the rear and little at the front, I’d recommend increasing the rear rates and possibly decreasing the front
springs.
Pete
I hear this kind of phrase mentioned a lot, and never quite understand this concept of more roll at one end of the car than the other. The front and
back of the chassis are after all part of the same structure, which (ignoring the fact that this will have a small amount of torsional flex)
therefore will always roll by the same amount. This is what enables you to tune the cars handling by tweaking the front and rear roll stiffness. You
can reduce the amount of roll by adding stiffness at either (or both) ends of the car. Adding it at the front will also tend to give more understeer,
adding it at the rear will tend to give more oversteer.
There, that feels better!
Cheers,
Neil
[Edited on 14/6/05 by nre]
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pbura
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| posted on 17/6/05 at 11:28 AM |
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quote:
Originally posted by nreThere, that feels better!
You are soooooo right, Neil! I had forgotten this (blush), trying to figure out what was going on with mookaloid's car on page 4. I guess roll
is just more evident at the rear because of full-width bodywork.
Bollocks aside, I still endorse trying to work out roll resistance and ride quality on paper before pulling out the checkbook.
Pete
Pete
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