Good afternoon all. Does anyone understand all the basics of Suspension set ups? My new car has 20 Rosejoints on it, The front wheels go up ,down, top of strutt has a concentric mounts, the ARB is replaces by a compression strutts and the standard TCA has been replaced by a billet alloy arm which is also adjustable, combined with coilovers and it all gets a bit technical. (I wont even start on the rear, it's gonna be the traditional Gp4 Mk2 escort 6 link set up ,Watts. and I've not even started on prop angles yet either!!!)
I sort of get how different settings can make different things happen, ie, by having a wider front track you can push it more before oversteer occurs, and Gary from Retro motorsport was explaining to me the other day the benifits of having higher traveling rear radius arms on the axle. But what are the basics to a good set up? Should all strutts ideally be 90 degrees upright, all wheels as far out wide in the arches as possible?What's the benifits of a negative camber on font wheels? Will a solid rear axle grip better than independant rear suspension?
If you look at the photo you'll see that with my comp strutts it pushes the bottom of the strutt toward the front of the car, away from staraight up, is this allright?
Any advice or knowledge anyone?

Andy

 

Brom, Tony Nuts, Martin H, any other of you handling supremos know anything?

 

The best thing I can suggest is you break it down into the various aspects of Geometry. I'll admit some of what I say is a bit sketchy, but hopefully you'll get the idea. Remember that every car is slightly different in use and character, so you'll have to find something that suits your style.

Castor angle.
The more castor angle you run, the more straightline stability your car will have. The downside is it makes the steering heavier as you turn the wheels. Normally (though not always) the castor will be the approxaimate line of the damper. So the slight angle it is on your car is fine. Also consider that as the car drives foward any bumps will want to puch the front wheels backwards towards the rear of the car so the inclination will help resist this.

Track
Obviously the wider the track the more stability you'll get when cornering, the car will reisist to a degree body roll, as it won't be able to get a twisting effect. (moment)

Camber
Negative Camber is better as it projects the weight outwards slightly from the car, which again increases stability.

Toe
Generally a little Toe Out gives a more over steery car than Toe In which tends towards Understeer. If you can imagine that Toe out will give slightly more steering angle on lock than toe in. The downside is that as you drive foward the wheels are pushed more toe out which decreases stability. Toe in tends towards more straight line stability as when the wheels are pushed outwards the go neutral toe.

Compression struts
I have no real idea about, other than I think they pre-load the suspension a bit and I believe gives less resistance to small bumps?

Suspension settings - Again a bit sketchy from here
Is divided into 3 parts
a) SPring rate
b) Compression (damping) (IIRC also Primary ride)
c) Extension (Rebound) (IIRC also Secondary ride)

IIRC a) controls the amount of movement of the suspension b) controls the speed of that movement and c) controls the speed at which the car returns to the normal position.

So a Basic "adjustable" Konis kit on a RST with springs and dampers only controls a) and b) which results in the soemtimes bumpy ride you get as you need c) to be different. Faster so the wheels are on the ground more I think.


Corner weighting
You want all corners to have the same weight distribution, which is achieved by getting all the above right to put the correct amount of load through the suspension to each wheel. Its not as I once thought the adding of ballast to a particular corner of the car.

Rear suspension
A solid rear beam axle cannot adapt to bumps on one side of the car without upsetting the other side, hence why independent is better.

Im sure some of the things here are wrong. So hopefully, someone will enlighten us

 

Call me at work and I can talk you through it, bring the car in and I'll set it up.

will take for ever to go into great detail.

Also there is no right or wrong(in some case there is) but basically you have adjustment to suit most objectives, castor/camber settings would be different dependant on the uses and surface the car is used on, same as spring rates etc.

 

I dont know fuck all but presume with some technical help the lissis s1 with coilovers and adj tca's and tie bars will handle better that just having Konis lol

 

plenty from the bloke you mentioned above imo

 

andy,

I pop over later if your about

Alex

 

I'm probably taking the engine out tomoz afternoon Alex if you're about, best to text first though as little man's got whooping cough (not what an 8 week old needs!) and Bex got Gasrtoentorightous (sp!lol) so this is subject to change!
Cheers dude
Andy

 

While there are a shed load of scientifics you could get into, with a Mk2 there are a set of basic datums you should be applying.
There is some 30 years history of Mk2 Escort setup data basics you should be considering, THEN, with all of the adjustability you have built in, ONCE you have driven the car, and have a list of handling complaints, THEN you can start playing around with setups.
Presuming that you are building the car for you, you will need to tailor the car to your preferences, but start with a set of known, proven settings, that you can adjust from.

 

Andy,
See if you can find any of the books written by our mate Allan Staniforth Excellent reads

Your old car was at Croft today - it managed a finish I think

 

I'm not an expert but I wouldn't be so happy not to have anti-roll bar :-(

 

But he has compression struts, what would an anti roll bar do that they wouldnt apart from allow very fine tuning of the roll?

 

I have no idea how they would act against roll. Maybe somebody could explain that too me, but for what I understand that comp-struts stuff is just a way of transforming standard TCA into triangular shaped armas on Grp.A car.

ARB acts like a aditional spring in corners and at the same time it transfers some of dumping to other side shock-absorber.

 

mmmmmmmmmmmmmmmm!

 

No mate the WRC

 

oooooh, have you still got the pics of it, post em up or email em to me please buddy!

 

Andy, you need to set the cars ride height, then adjust everything so its square at the rear, I don't think you have top arm adjust ment on your 4 link brackets, so you'll have to live with the top arm at probably a slight downwards tilt to the front, the lower arm set level with the ground (this is as close to neutral as you'll get with your set up.
At the front set 5 degrees of castor, toe straight, and camber at 1.5 deg neg. Spings... softest you can get away with. Start at 250 f and 180 rear
Then book a track day. as you've just set the car to a known base.

If the cars all oversteery try raising the lower arms at the rear. Start at the rear as you havnt got a lot of adjustment with your set-up. Buy a tyre temp gun to set the pressures, inside+middle+outside divided by three will give you what the center temp should be, if yours is higher then drop the pressure a tadge, and visa-versa. The temp gun will also tell you the camber settings on the front, Higher out side edge = more camber needed. Drive the car some more... 20 min sessions,don't go flat out, you need to set a rhythm and only adjust one thing at a time. A little toe in and see what happens, toe out, again see what happens, Unless you have someone with you who can adjust a known handling trait out of the car this is what you'll have to do. Just use the time wisely and dont showboat to passengers, you wont have any anyway will you!. See what happens to the car with each adjust ment and record what you do. With castor you want to adjust that by feel, some drivers like loads and some less, it does have an effect on camber in corners but really only with armfulls of lock.. so dont panic to much about it. ... as said getting Staniforths Book will guide you through what you need to do and also give clues what to adjust to dial out or dial something in.

After you done all that You can start buying springs and see the effect the have... fast track go harder, tight and twisty go soft, those rates above are soft for a track escort. Once you have a large book of data then worry about corner weights.... cos that will confuse the hell out of you.

 

knew you'd be along in a minute Gary!

PS - you about this weekend? (saturday most likely!)

 

yep .. but not to late, got something to do that night, can't remember what it is though

 

cool i'll give you a bell before i do anything!