understeer!!!

[mikeyp]

took the car out for an outing last night. it was it's last drive for a little while cos i've got some engine probs i need to fix but that's another topic.
it was raining a bit and the roads were wet but not really any standing water anywhere. on roundabouts the car just understeered loads, like really loads and loads.
due to my engine probs i was only going slowly (30ish) and as soon as i wound the lock on to go round the roundabout the car started to slide wide from the front. had to brake and crawl off the roundabout at around 15-20mph.

happened at the next 2 roundabouts i came to, i also tested it coming off the roundabout and it's the same in the other direction aswell. i treid to 'flick' the car into the roundabout to get the back to come round to counter the understeer but the front didn't have enough grip to get it to flick even with a proper lift off and turn in.

i only had the tracking done yesterday which greatly improved the handling. the driver's wheel was very toe out and the car wanted to pull left all the time and had loads of bumpsteer.
after doing the tracking (just factory settings) the car goes much more in a straight line with no steering input and has a lot less bumpsteer but still some.
this was my first wet outing in the car.

tyres: toyo proxes 4 205x40x17
suspension: bc coilovers with camber adj front about 1* (only going on the adjuster markings, not measured properly) front 5 clicks from soft, rear 3 clicks from soft. height 330mm front, 335mm rear (cetre hub nut to arch)
the wheels are all balanced and true, no other handling mods on the car.

checked all the suspension yesterday and only the inner ARB bushes looked worn, everything else was fine with no play where it shouldn't be.

any ideas?

 

[Spikey]

Rear Uprated antiroll bar helps understeer. Different coilover set ups.
Which toyo Proxes have you got?

 

[mikeyp]

they are marked as "toyo proxes 4". not the better ones i don't think.

 

[johnsy]

Dont see much point in running negative camber round the doors, try a more neutral camber setting,

with -1deg camber the outside of your tyre aint doing anything and the inside will wear out a hell of a lot quicker, save the negative camber for fast road and track use,

 

[Sunny-D]

Dampers should be softer on the front than the back

 

[fubar andy]

Quite a few people say that about fronts softer, however I've tried this and reverted back to harder on the front that the rear...

...I guess its what you feel happy with...and I have very little understeer :thumb:

 

[campbellju]

Your ride height balance with damper settings will cause this. If you want wet handling you need to raise your rear another 5mm and as you don't have a rear arb 10mm might work better. Having them nearly level in the dry can make for stable car in the dry but the balance is all wrong for the wet.

Damper settings can be subjective but stiffer front dampers will reduce the ability of your tyres to turn in. Having your dampers tweaked correctly can turn an poorly handling car into a dream.

You never really said what your toe was or is. You naturally compensate if one wheel is out by turning the wheel. Toe out on the front is not a bad thing but too much will give you problems.

The camber setting is just a nominal marker and you need to measure it. Even if it were 1 degs on the front this is the minimum you'd want on our cars.

Having said all that, start with basics, check for wear on the outside of your front tyres and check tyre pressures all round.

 

[campbellju]

Quite a few people say that about fronts softer, however I've tried this and reverted back to harder on the front that the rear...

...I guess its what you feel happy with...and I have very little understeer :thumb:

Agree. After putting a lot of effort into eliminating understeer I had to run slightly stiffer front dampers and toe in at the rear to put some stability back in again.

 

[PobodY]

Ah! So the extra weight means that the convetnional wisdom (from places like Whiteline) is misleading? Softer bushes maybe, but not actually softer dampers etc?

I don't have any of this fancy stuff on mine; just lowering springs. It doesn't oversteer (even when I tried drifting in the snow... that cost me a pair of wishbones plus a rim), but it doesn't understeer terribly off roundabouts. - It did take me a while to get used to the way an AWD car handles though; I was used to RWD where you can effectively powerslide the roundabouts etc. With the R I find it best to enter the corner a little slower, but really power out of it as soon as you've hit the apex... whether that's a good practice, I don't know.

 

[mikeyp]

my front toe was set to factory so 0* +/-1, i went for +0.5

2 people are saying softer fronts and then one of them changed their mind in the very next post.
some are saying stiffer front.

some are saying run no camber and some are saying at least -1*.

tyre pressure?? well they are 32psi, what should they be?

raise the rear ride height to 340mm at the rear.

add toe in at the rear. how can i do this, it doesn't look adjustable???

i'm feeling a bit lost with all this now????

 

[PobodY]

You need to experiment a bit; what works on the track isn't for the road and vice versa.

I've got a road car:
I run 36psi at the front and 32psi at the rear; that's mainly because the front is so much heavier, and I made the change after reading campbellju's thread on the subject.
I have no camber bolts nor fancy struts; so it's what ever the standard setting is (0 degrees?) for me.
I run the factory toe-in, but I also get excessive wear on the front tyres, so I'm thinking of going to none.
I don't come off roundabouts, but I don't think my car would cope very well if I try to throw it around on a track.

 

[johnsy]

running negative camber on a road car is one good way of ruining a set off boots,Been there done it .....had to buy new tyres!(not cheap)

 

[campbellju]

@johnsy I ran -2degs and -2.25degs on the road for a few years with even tyre wear. Poor tracking can kill your tyres in a few hundred miles. If you've killed the inside edge then you've either got too much toe out on the car or your bushes/ball joints are worn causing excessive dynamic toe out.

@mikeyp: This is a complicated area that has taken me many years to get my head around. My posts aren't contradictory as Andy's car and my own are setup differently to many others. In the NW there are a few of us who've been trying to stretch the knowledge base for our cars. I also agree with Sunny D too as I know where he's coming from in his short comment.

Your toe of +0.5 I assume is in minutes and is total toe in. Nothing majorly wrong here. Just focus on my first post as my second one probably isn't relevant to your car. 0 toe all round. -1.5deg camber front with -0.8 to -1.0 deg at rear.

I'll say again

Your ride height balance with damper settings will cause this. If you want wet handling you need to raise your rear another 5mm and as you don't have a rear arb 10mm might work better. Having them nearly level in the dry can make for stable car in the dry but the balance is all wrong for the wet.

For a car that can turn in when it's wet then my starting point would be 340mm front and 350mm rear.

Jim

 

[mikeyp]

thanks for the input, didn't mean to have a go it all just seemed like conflicting information, sorry if it came across as a dig at you.

i'm going to change my ride heights and camber settings and see how i get on, i'm off the road for about another week while i fix the bottom end so i won't be able to report back untill after that.

thanks again.

 

[johnsy]

@johnsy I ran -2degs and -2.25degs on the road for a few years with even tyre wear. Poor tracking can kill your tyres in a few hundred miles. If you've killed the inside edge then you've either got too much toe out on the car or your bushes/ball joints are worn causing excessive dynamic toe out.

rolling around on the inside edge of your tyres can't be a good thing , i had the whole shebang setup on one of those fancy laser jobbie's, and found that excessive camber tootling round town worn the inside edge out quicker than the outside which stands to reason really, your not gonna get even tyre wear if your not using the whole tyre

 

[pulsarboby]

you either need to set the car up as a road car or a track car there is no real compromise

if its any consolation i also agree that stiffer front reduces understeer but then again every car seems to handle differently. it will also differ with everyones driving style so theres no real golden rule as its an individual thing and a case of trial and error

 

[campbellju]

excessive camber tootling round town worn the inside edge out quicker than the outside which stands to reason really, your not gonna get even tyre wear if your not using the whole tyre

You're not driving hard enough then ;-)

Bobby's correct though as racetracks are all about lateral grip where as on the roads braking and accelerating are important.

 

[johnsy]

You're not driving hard enough then ;-)


but thats my point, there is no need to run negative camber while tootling around town your just waisting tyres, track driving is totally different, if i was going out for a thrash id adjust the camber accordinly

when iv driven to cadwell or silverstone in the past iv always set the camber to more or less 0 then adjusted it after the sighting laps, and returned to 0 for the journey home

 

[whytie]

It's all about driving style, everbodys set up will be different

 

[stumo]

Adding to what has Campbellju has already said but you might not have understood what he said...

adding ride height to the rear makes the rear oversteer more, you will have to balance how much oversteer you want when it's wet.

As you've found out having the rear only a few mm higher doesn't really do much, esp as you've no other mods.

a "free" mod that you can do is the caster mod (do a search), unfortunately unless you can do the tracking and camber yourself it's going to cost you to have that done.

the rear toe can be adjusted, have a look where the two rear suspension arms attach to the subframe and you'll see two adjustable bolts.

Adjusting the rear toe can make the car understeer (toe in) or oversteer(toe out) to a point, it's really final fine tuning thing. Whatever you do don't run more than say 0.5 deg either way or your tyres won't last long.

Front toe can do the same with opposite effects.

You're best starting with front and rear at 0deg, sorting the handling using other methosds and then fine tuning with toe.

As has been said, excess toe WILL kill your tyres very quickly.