Hi all

I was was having a debate with a guy today who said he wouldnt touch a MK with a barge pole as they don't handle very well and that the geometry is all wrong at the front,especially the steering rack area.
I told him mine handles very well and that having owned an evo seven,sti scooby and various other types of performance cars that i was pretty well qualified to make the statement

He is a well respected grass track racer and in fairness he does no how to drive!

I would like to know other peoples comments on the MK handling and inparticular how well suited to track days they are

Cheers

Im happy with my indys handling.

You dont happen to live in the Howden / Gilberdyke area do you?

Check my video clip at the bottom

Handles well to me

http://www.locostbuilders.co.uk/viewthread.php?tid=27282

[Edited on 8/6/05 by subk2002]

To be fair the steerring rack isn't perfect, and some geometry is comprimised for the classic seven look but they can't be considered bad handling cars.

Adam

Hi Carnut

your right
how did you know

im no racing driver and havnt driven any other make of kitcar but the mk is the best thing iv ever driven .my kit has the same standard parts as most other mk's iv just uprated the front brakes.
i was at oulton park today and gave an r500 run a for his money for a few laps but he got away in the end but pritty much whooped everything else and got my times down to 1.55 by the end of the day after a little tuition from bourne

I'm doing sprints with mine..and I'm not happy with mine just now.....It's (me and the car) work in progress though..I'm competetive with some people and a bit behind others..There's definitely better handling to be had from it..

It sits too high at the front just now,
It currently understeers waaay too much in slow corners....I'm probably not driving it properly either.

It'll get better

Colin

Maybe you could use a temperature guage on the tyres after each run. Data is where it's at and finding out stuff like that could only help. Would possibly point you in the correct direction regarding springs, camber etc.

I'm hill climbing mine and I am not competitive yet.
I am up against some very quick Westfields (and very quick drivers) so I am not expecting to be winning any prizes!

I think I have ample power, but lose a lot in the corners. I am not sure why, but I accept that I am probably in need of some training. (course booked)

however, looking at some pictures, I seem to get a lot of body roll and this is causing some noticable (unfavourable) geometry changes at the rear. I am working on dialling this out.

I am also thinking about anti roll bars or uprated springs.

I would like to lower the front a bit too but I am worried about my sump......

Also I am thinking that tyre pressures are quite important - what pressures do everyone use?

I have 15 inch wheels and 195/50 tyres.

Cheers

Mark

Hi mookaloyd

Did you hill climb yours at harewood last weekend?

for the road i think the indy is fine, for he track i suspect a car would benefit hugely from a proper set up session, corner weights, camber, ride height, tracking, tyre pressures, tyre choice, driver ability can all add up to make a huge difference.

I have heard rumour that the front suspension pickup points are slightly unsymetrical on the indy chassis, but this was from a rival manufacturer and I have no backup to support this, so take it as you like

As said the sierra upright has it's limiting factors, the cortina upright is 'supposed' to give better geometry, but I think the shortened sierra rack will give better bump steer (or rather lack of )

In any case it's all swings and roundabouts and I think no two cars would ever perform the same as they are all so unique unless fully setup and then they still may have different characteristics.

A perfectionist would probably opt for rose joints all round, but unnecessary for the road, only really justified for race use imho.

Ned.

[Edited on 8/6/05 by ned]

Hi sonic

yup

my best time was 71.63

Class winner was 62.28!!!!(new class record)

I wasn't quite last though

Were you there?

Cheers

mark


[Edited on 8/6/05 by mookaloid]

I'll try taking tyre temps John...

Ride height's the first thing to sort out..

Like you Mook, I'm thinking anti-roll bar(s) could be next...


tyre pressure.....I'm using yokohama 048r's now... tried from 14 - 22 psi...settled on 17 front and 16 rear... for the moment.

As I said I'm doing sprints...so the tyres are more or less cold...but I definitely notice more front grip by the second or third lap

Andy thoirs has changed his front springs...Drew, did he comment on the difference?

I'm currently competitive with similar engined cars...and that's un-setup...

He was trying to make up an anti roll bar setup aswell colin.he didnt mention the springs,his accellerator cable snapped up the straight

Hi Mookaloid

No i wasnt there,its the only meeting i have missed this year!
I saw a MK listed on the entries and wanted to come and support but i was in London for the weekend

Are you having a go at the next meeting?
if so i will come along and introduce myself

I must say that i fancy having ago at Harewood myself sometime,i have been stood watching for long enough

quote:

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In any case it's all swings and roundabouts and I think no two cars would ever perform the same as they are all so unique unless fully setup and then they still may have different characteristics.

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Hi Sonic,

I have sent my entry in for July but I have to wait and see if I get in.

But always good to meet fellow MK drivers

Re Tyre pressures I have been trying 19 all round but from the pictures, the outside rear seems to go very flat at the bottom on heavy cornering!

I think I will try another couple of pounds at the next meet.

I think It would probably be a good idea to try a track day for improving the setup. On a hill climb or sprint you only have 4 or 5 runs totaling not much more in minutes, so it's hard to judge what is going on!

Cheers

Mark

Re Anti roll bars: Snoopy & co have developed a front one for the indy but I am not convinced that it will fit the pinto engined cars as the engine goes too far forward

no such problems with the bike engined ones though.

I would like to try front and rear ones if I can get some

Have you any ideas on this col?

Mark

[Edited on 8/6/05 by mookaloid]

What is the typical shocker setting are people using

Mine has the standard Gaz shockers and wondered how many clicks people are running front and back

My tyre presures are around 22 psi front
and 24 psi rear and it seams great for road use
ive tried every thing from 14 psi up on 195x50x15 tyres

I have the protech shocks

1 click off max for the hill climbs and 3 clicks off for the road.

Sonic, what engine do you have?

Mark

[Edited on 8/6/05 by mookaloid]

Sonic - Lived in Howden all my life up until last November - anyone I might know ??? Where are you located ?

I'm thinking about fitting a rear anti roll bar to my Avon after seeing the body roll Pat (Avoneer) got on his track day last year, but would I realy need a front one too?

This is a great thread.

Once mines running i will be keeping a log of all my set up changes.

Luckily for me my mates garage has just ordered an all singing set up jig with corner weights!!

Lucky You

Yup.

But i think he was only talking about £70 + VAT for a full geometry set up for a kit car.

Thats only the cost of two dyno runs and just as worth while IMO.

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]

quote:

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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]

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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!

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??)

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

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

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..

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]

Are the front bottom wishbones parallel to the ground with the 350x7 springs?

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!

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]

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

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

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

How would just fitting a rear anti roll bar an no front affect the car?

Cheers

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.

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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.

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Originally posted by Northy
How would just fitting a rear anti roll bar an no front affect the car?

Cheers

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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

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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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

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quote:

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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

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Originally posted by nreThere, that feels better!

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