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Geo Settings, real experience?

Posted: Mon Mar 16, 2009 9:09 pm
by knightofni
I think the time has come to modify the geo setup. Time on the track is showing up the understeer and playing with lift-off oversteer is causing the gravel to get kinda close at times!

New tyres have improved the situation, no doubt, but I want to get the geo checked anyway and wonder if anyone has real experience of a camber setting to give a balance between road and track.

Assuming (all I can do for now) that the correct camber is currently on the car, tyre wear of those removed would indicate more negative camber would result in a more even wear. The fronts were defintely more worn on the outside. The rears only very very slightly more worn on the outside.

I was thinking of increasing front from -0.1 to -0.5 and the rears from -1.8 to -2.0. I really don't want to have braking reduced with a serious camber. I'd rather be able to brake than corner :D Any thoughts? Anyone tried values and have experiences to share?

It'll be getting done on Monday, so time to consider what to do.

Re: Geo Settings, real experience?

Posted: Mon Mar 16, 2009 10:21 pm
by roadboy
Its difficult to recommend an exact setup without knowing what tyres you run and what dampers you have but, assuming roads tyres and standard dampers.........

I would try and get as close to -1.0 on the front as you can. Probably take all the shims out and see where it sits.

-2.0 for the rear is about right.

Don't forget that toe is just as important, if not more so. I would set the front parallel and 0.1 degree toe-in either side on the rear.

HTH

Dan

Re: Geo Settings, real experience?

Posted: Mon Mar 16, 2009 10:25 pm
by mwmackenzie
SELOC Tech Wiki has this on set ups... http://wiki.seloc.org/a/Geo_Setups Missed a good run on sunday Mark, did you get your new tyres on mate? What did you go for?

Re: Geo Settings, real experience?

Posted: Mon Mar 16, 2009 11:03 pm
by knightofni
mwmackenzie wrote:SELOC Tech Wiki has this on set ups... http://wiki.seloc.org/a/Geo_Setups Missed a good run on sunday Mark, did you get your new tyres on mate? What did you go for?
Yep, especially after reading about the Ferraris. Got the tyres, just standard replacements, speak to you at the next meet 8) 2 punctures, still can't believe it! Looked at that link, but wondered if anyone had tried some values and could report on real on road/track experience.
roadboy wrote:Its difficult to recommend an exact setup without knowing what tyres you run and what dampers you have but, assuming roads tyres and standard dampers.........

I would try and get as close to -1.0 on the front as you can. Probably take all the shims out and see where it sits.

-2.0 for the rear is about right.

Don't forget that toe is just as important, if not more so. I would set the front parallel and 0.1 degree toe-in either side on the rear.

HTH

Dan
Thanks. Yes, standard 111R. I wasn't sure if -1.0 was really pushing it, so I'll see what I can get. My intention was to keep the front toe parallel as per the book, but thanks on the -0.1in pointer. :thumbsup

Re: Geo Settings, real experience?

Posted: Tue Mar 17, 2009 8:12 am
by tenkfeet
I took all the shims out bar one to balance the camber and it is better . :thumbsup Thanks Robin. :D

Re: Geo Settings, real experience?

Posted: Tue Mar 17, 2009 12:45 pm
by mckeann
roadboy wrote:Its difficult to recommend an exact setup without knowing what tyres you run and what dampers you have but, assuming roads tyres and standard dampers.........

I would try and get as close to -1.0 on the front as you can. Probably take all the shims out and see where it sits.

-2.0 for the rear is about right.

Don't forget that toe is just as important, if not more so. I would set the front parallel and 0.1 degree toe-in either side on the rear.

HTH

Dan

Agree with Dan on this one. I run no shims on the front of my car which is about -1.0 degrees. I have about -2.0 on the rear. Front toe parallel, and then adjust the rear toe to suit. More toe in means more stability, when you get all the way out to parallel on the rear, it should be very oversteery :thumbsup

Re: Geo Settings, real experience?

Posted: Tue Mar 17, 2009 3:49 pm
by GrantB
I have a problem with a `light` feeling to the front end after steering rack replacement - had geo done at cclm but was wondering if a bit more toe in is required to give the feeling back to the front end?

It could even have toe out at the moment as i thought this was the factory set up for an S1?

Re: Geo Settings, real experience?

Posted: Tue Mar 17, 2009 5:03 pm
by roadboy
You don't want toe-in at the front. :thumbsdown

Dan

Re: Geo Settings, real experience?

Posted: Tue Mar 17, 2009 5:05 pm
by Shug
aye - either parallel, or very slightly out. 0.01deg IIRC in the book...

Steering weight could also be caused by castor - although that shouldn't have changed with a rack replacement. Also possible that the rack simply was shagged and made it feel heavier?

Re: Geo Settings, real experience?

Posted: Tue Mar 17, 2009 6:41 pm
by roadboy
There is quite often a difference in steering feel between racks when they are changed. You can adjust the preload on the rack but you have to take it out to do that so that's a bit of a pain.

Dan

Re: Geo Settings, real experience?

Posted: Wed Mar 18, 2009 12:47 pm
by GrantB
Just dug out the geo report.....Current settings are parallel toe and Castor is 3 degrees.


Its definitely lighter than previously but of course could just be that the previous rack was on its last legs.

Also trust CClm as have been going there for years and always had perfect results.

My gut feeling is that its a bit of both - the preload does need adjusting slightly but there is also a difference between old and new racks.

So the big question is, bearing in mind preload adjusting will be damn timeconsuming (not able to feel a difference until rack is back in the car) - will the car loose its grippy feel with lighter steering?

I guess ultimately i may need someone with a bit more multi-elise experience to drive the thing - excuse to attend one of your road runs!

Re: Geo Settings, real experience?

Posted: Wed Mar 18, 2009 12:53 pm
by Shug
GrantB wrote: I guess ultimately i may need someone with a bit more multi-elise experience to drive the thing - excuse to attend one of your road runs!
Nail on the head there - well worth getting someone experienced to give it a quick punt.

Even sticking new tyres on makes a big difference. Jumping between my S1 with -1.5 deg camber on the front and Elaine's 111R with factory setup is definitely eye-opening.

Re: Geo Settings, real experience?

Posted: Wed Mar 18, 2009 12:59 pm
by GrantB
Yep - need an S1 owner with reasonable Loti experience near Falkirk!

Bearing in mind its been set up with parallel toe - maybe an easy fix would be to put the recommended toe out in to the geo?

Also shaping up to be a great evening so a good excuse for a road test up to Callender just to check one more time :D

Re: Geo Settings, real experience?

Posted: Mon Mar 23, 2009 7:30 pm
by knightofni
Just to close off on this. I got -0.833 (was -0 degress 50 minutes, not -0.5 before I edited this) on the front, rest standard. Front toe was quite well off. Even on the short drive home I could feel a fair difference. Hopefully this will help without causing inside wear. Will update the thread later in the year with tyre wear comments.

Cheers for all the replies. :cheers