Caster & Camber Setting.

[mikey]

I would be grateful of your advice/experience in geometry set up. I have had the caster camber set up twice on mine but I am experiencing a lack of bite from the front end on cornering which leads to a lack of confidence. Also noticed greater wear on the inside of the front tyres. Ignoring the inevitable comments about Dax’s not going around corners I feel that it is nowhere near what it should be on cornering ability. The people who I have taken it to in the past ( 2 separate garages ) certainly knew how to charge and one used an optiflex system, the other laser gauges. However they did not inspire confidence in me that they knew what they were doing although they talked a good story. I am not talking high cornering speeds, at moderate speeds there is a feeling of drifting on the front end. Everything is tight and no wear etc. Can anybody help advise me as its an area I can not get my head fully around as to whether caster or camber or both is likely to be causing the effect. A web site thjat goes through troubleshooting would be useful if anybody knows one. I am not adverse to paying for setting up, but as I say, twice so far.
I would appreciate your thoughts as I am running out of pairs of trousers.
Regards.
Mike.

[wilf]

Mikey - would not call myself an expert by any means, but I think a little more castor angle might liven up your steering. I did that to my car, after I felt the steering was a little "dead" around the straight-ahead, it improved things. I would hope that some more knowledgable folk than I might chip in here.

If your front tyres are wearing out on the inner edges it could be insufficient toe or a camber problem. Again, more toe in could sharpen up the turn in.

Out of interest, and to understand what weight you have over the front wheels, what engine do you have fitted?

Lastly, try pushing your front tyre pressues up a little - easiest and cheapest thing to try first.

Could also recommend Cheng Lim at Thunder Cars to help set your car up.

HTH

Wilf

[mikey]

Thanks for replying wilf. I am running a Chevy 350 smallblock with Alloy heads, so slightly lighter than the norm,but still heavy. Tyre pressure change dosent seem to make much difference unfortunately.
Mike.

[Bob]

First what is set to now
Wear on the inside of the tyre is indicative of too much negative camber. It could also be caused by incorrect toe look at the wear pattern if the sharp edges of the tread piont towards the center of the car it could be too much toe in If they point outward its to much toe out. I dont know what Dax recomend the front toe to be: but as a general rule on a car with the rack positioned in front of the center of the wheel it should zero or slightly toed out , this is because its difficult to achieve true Ackerman angles with a forward positioned rack. So with the front wheels toed out slightly the tyres do not scrub so much on turn in to corners. I had my Sumo set to zero but have changed 1/2 a degree toe out per wheel 1 degree total toe and I think it feels better but that just my opinion. Dont go greater than 3 degrees though or your straight line braking will suffer and the car will wander all over the shop under hard braking. I hope that helps it a matter of trial and error until you find what suit you and its often a trade in between handling and tyre wear. I am putting together an article for the magazine on suspension geometry and set up . I put a request in for web usesr to post any improvement or changes they had made to they're car set up what the results were but I only got one reply thanks Nigel. Which is apity because ther must e awealth of knowledge out there for us all tap into. Which was my main reason for joining the club.

[alex]

Mike,

What you describe sounds very similar to the problem I had with my Dax initially. Even at relatively slow speeds going round corners it felt very unstable. I hadn't even checked the castor/camber but when I did I discovered the castor was around 7 degrees when it should have been more like 2 degrees.

The reason ? I had the front wishbones round the wrong way. It's easy done. After correcting this the car was transformed. I didn't think it was possible to fit them wrong.

Check out the recent post on AK front lower wishbone fitting.


Alex

[Mole]

Worn inside edges on tyres can indicate too much negaitive camber (as has been said) but might also indicate too much toe out. Like you, I have little faith in garages when it comes to wheel alignments. They never seem to take much care hanging the gauges on the wheels which, although I'm not an expert, doesn't seem right when you're looking for differences of a millimetre or so over the width of the car. I've taken cars to garages before now and asked them just to tell me what the settings were- not to change anything. Not surprisingly, I got different answers from different places (on the same day?!)

I've ended up checking tracking with a tape measure. It sounds crude and doesn't always work if your car has lots of bits hanging down in the way underneath but if you take a tape measure from the central ridge at the front of one tyre to the central ridge at the front of the other - as high up as you can without bodywork getting in the way, and then do the same at the back of the tyre, you'll soon see if its toed in or out. If you try this three times and drive round the block each time and get repeatable results, you can have some degree of confidence in what you see. Obviously, you mustn't jack the car up to do it! It's not really accurate enough to adjust the tracking but will certainly tell you if it's a mile out! Most manufacturers quote it in terms of millimetres at the rim. If you're working at the tyre, but only part way up, you'll be in a similar street. I'm surprised that someone else suggested 3 degrees earlier. I've not known it be much more than half a degree either way on most cars I've worked on.

Why not take it to a show and see if you can persuade someone from DJ to throw it round the block and tell you if it feels the way it should? Also, a front anti-roll bar might give it slightly better initial turn-in. Are you running a limited slip diff? I've known this make some cars understeer quite strongly initially.

Good Luck.

[wilf]

Just as an aside, one of the neatest gadgets I have is a "Gunsons Trackrite" - it's a little swivelling platform thing you drive over, tells you the exact toe in /out you have on a rolling wheel. Dead easy to use.

Wilf

[normanh]

Wilf,

Have always had my tracking done by one of those things....always found it to be accurate. I use an old fashioned tyre fitting establishment, and no matter what the prob they have always sorted it out. Age &/or experience are obviously the key to getting the best set up. As has been said, having the equipment is different to knowing how to use it! (i think a vicar once said that):7

[kev]

If the car feels vague in a straight line with no bite on turn in sounds like too little castor or too little toe in. The fact that it is scrubbing the inside edge of the tyre sounds more like too much toe out. If you can you should make up a castor gauge (inclinometer), with the car level the two lugs that hold the brake caliper should be approx 0.5degree off vertical tilted at the top to the front. This is the kingpin angle which is adjusted with the shims on the top wishbone. If in doubt a good place to start is to put all the adjustment shims at the back of the wishbone, this may give too much castor but at least you should notice the difference. This could weight up the steering and make it heavier. Don't know what the Dax should be for toe in but with fat tyres you don't need much to scrub the edges, I guess a good starting point would be to ask your local tyre and battery emporium to set the toe in at 0 to a sixteenth. Check the camber by looking long and hard from the front,at the front wheels pointed straight ahead. There should be no discernable camber(unless you've got micrometer vision which my mate has :+ ) i.e. the top of the tyre shouldn't noticeably be in, in comparison to the bottom of the tyre. e'g / . But you can't beat having the suspension setup correctly by someone who knows, so my advice is find an expert you can trust.

Just a thought, have you got a lsd diff? these can make a light car have a tendency to go straight on if they are too tight

regards
Kev

[mikey]

Sounds like I should get one of these if they're not ultra expensive. Problem is most garages have problems with setting up the mirrors on the equipment to see under the front of the body and the radiator helps block the view.

In addition I have discovered that the top wishbone arms on mine are unequal in length (older design), with long arm to front that I presume automatically pushes the ball joint back. I am now wondering if the three shims plus this are giving me too much positive castor and whether this can have the sort of effects I am experiencing. I have always noticed an ammount of bump steer on bumpy roads and I believe too much caster can cause this. I am starting to think that my problem may be a combination of a number of things. The frustrating thing is that its not from lack of investment. It just shows you thyat you can not simply rely on the fact that you have had it set up or cheked by supposedly professionals.

If you dont mind me asking where did you get your Gunsons from as it sounds like it gets over the problem of limited vision and low bodywork etc.

Cheers all you Guys for the sound advice I will keep all posted when I have found out the main cause as it may help others.
Mike.