How do I know how much camber I need to set up ?
Discussion
Presumably your tyres are wearing on one edge? Settings depend on many things so it's difficult to give guidelines, but assuming that there's nothing especially unusual about your car (between 60:40 & 40:60 weight distribution, rear wheel-drive) I'd start with:
Front camber: 0 to +1mm
Toe-out: 1mm
Caster: ~4 degrees
Rear camber: +1 to +2mm
Toe-in: 1 to 1.5mm
Notes:
1) First, check that you're not scrubbing the tyres because of excessive camber change on steering;
2) If your car is front-wheel drive, increase front camber and decrease rear.
From these settings, have a look at how evenly the tread is working when the car's moving (find a dry surface, eg. car park, pour some water down to make a puddle & drive through it, then look at the imprint straight & cornering). you should be aiming to get the pattern as even as possible across a range of cornering conditions, to maximise grip.
That's a very simple start, but better than getting over-complex until you're somewhere in the ballpark.
Hope it helps!
Front camber: 0 to +1mm
Toe-out: 1mm
Caster: ~4 degrees
Rear camber: +1 to +2mm
Toe-in: 1 to 1.5mm
Notes:
1) First, check that you're not scrubbing the tyres because of excessive camber change on steering;
2) If your car is front-wheel drive, increase front camber and decrease rear.
From these settings, have a look at how evenly the tread is working when the car's moving (find a dry surface, eg. car park, pour some water down to make a puddle & drive through it, then look at the imprint straight & cornering). you should be aiming to get the pattern as even as possible across a range of cornering conditions, to maximise grip.
That's a very simple start, but better than getting over-complex until you're somewhere in the ballpark.
Hope it helps!
Edited by tlracing on Sunday 10th June 19:57
tlracing said:
Front camber: 0 to +1mm
Toe-out: 1mm
Caster: ~4 degrees
Rear camber: +1 to +2mm
Toe-in: 1 to 1.5mm
Toe-out: 1mm
Caster: ~4 degrees
Rear camber: +1 to +2mm
Toe-in: 1 to 1.5mm
Hmmm... not sure which bit of thin air you plucked these settings from!Camber is usually measured in degrees and as a starting point I'd use 0-1 degree negative, though if you are serious you need to establish correct figures by testing and ideally checking with a pyrometer.
Caster you have limited control over on most cars and it can vary substantially according to design. I'd say measure what you've got, then try to equalise it side to side, to begin with.
Toe out on the front on a RWD car? Sure, if you want it to feel directionally unstable and 'pointy', with a tendency to wander and tramline! I'd use toe out for hillclimbing and sprinting, but for road use I'd stick to toe-in if I were you!
Rear camber... just an observation, but if it's the Dutton on your profile, you can't easily adjust rear camber on account of it having a live axle. They can be adjusted by heat shrinking one side of the axle tube, but it's a skilled job and most people don't bother.
Oh... and if it is the Dutton on your profile that we're taliking about, my first port of call would be the Owner's club (or talk to other owners at the kit car shows) to see what they recommend as specific setting for that particular car.
Sam_68 said:
Hmmm... not sure which bit of thin air you plucked these settings from!
'Fraid not. Settings are roughly those I'd start with on any of the cars (race or road) that I've set up or tested over 25+ years.Yes, I'm quite aware that camber can be measured in degrees but, unless young Mr Gooner has a camber gauge, it's a lot simpler to convert to mm and simply measure. On a 15" wheel, 1deg = 0.6mm. Easy, huh?
My point about caster was simply that the tyre wear could be unconnected with static, straight-ahead alignment, so better to check any changes before fiddling.
Toe-out is perfectly acceptable on a RWD car - Exige S1 factory settings, for example.
tlracing said:
Toe-out is perfectly acceptable on a RWD car - Exige S1 factory settings, for example.
Yes, it's perfectly acceptable, but tends to result in very 'pointy' handling, as I said. For every RWD car you can quote as having 'factory' settings of toe out, I'm willing to bet I can quote fifty that have toe-in, for that very reason. My own Sylva is set to toe out (for Hillclimbs and Sprints - contrary to manufacturer's standard recommendations!), but as a basic setting on an unknown car, I'd still recommend toe-in.tlracing said:
Yes, I'm quite aware that camber can be measured in degrees but, unless young Mr Gooner has a camber gauge, it's a lot simpler to convert to mm and simply measure. On a 15" wheel, 1deg = 0.6mm. Easy, huh?
Obviously, they didnt have digital spirit levels 25+ years ago.
Personally, I started out with one of those PACE camber gauges with the plumb-bob that read against a scale on an ally plate, but these days you'll find that £25 spent at B&Q will save you an awful lot of fannying round with plumb lines, tape measures and trigenometry.
...and, regardless, are you saying that you'd recommend positive camber as a basic setting?
tlracing said:
My point about caster was simply that the tyre wear could be unconnected with static, straight-ahead alignment, so better to check any changes before fiddling.
If that's what you meant why did you say simply that caster should be set to 4 degrees? 'Design' caster settings can be very variable indeed... anything between 1 and 10 degrees wouldn't raise my eyebrow, particularly. Assuming non-adjustable wishbones, it's not easy to get much variation, anyway, so you're really stuck with shimming the wishbones fore and aft to equalise what you've got, side to side.Out of interest, how does Mr Gooner accurately measure his 4 degrees of caster, though, if you're assuming he's only got a tape measure?
What tyres are you using and what are you using the car for? Check the tracking before changing camber/caster etc. I wouldn't go for toe out on a road car maybe just make the wheels parallel as a start.
tlracing, the settings you mention are not really specific to anything as wheel size will affect the camber/toe angles when you use inches/MM rather than degrees to measure it, yes I know you say a 15 inch wheel will have 1deg of camber at .6mm (or whatver) but what if the OP is running a different size wheel.
tlracing, the settings you mention are not really specific to anything as wheel size will affect the camber/toe angles when you use inches/MM rather than degrees to measure it, yes I know you say a 15 inch wheel will have 1deg of camber at .6mm (or whatver) but what if the OP is running a different size wheel.
To be fair camber isn't usually a killer for inner edge of tyres in isolation .. but any toe-out and negative camber usually is - dragging the tyre inner edge sideways down the road isnt a good plan. So Sam68's suggestion of sticking a bit of toe-in on your car is a good start.
As your original question was how to eliminate inner edge wear you could simply keep changing the toe in until you eliminate it .. it maybe wouldn't make for a very balanced car and you might destroy a few sets of tyres working what what was a really good setting but you'd sort your wear issue eventually. Some of the numbers from tlracing are strange as an initial suggestion for an unknown car. I don't know what his 25 years experience is in so maybe those setings work well in some unusual road car somewhere, they're not what you would instantly think of as good starting point settings though for a car with rapid inner edge tyre wear.
I've missed somewhere what car you're referring to .. your profile doesn't seem to help either. If you let us know what you're driving that might help .. but essentially follow sam68's posting and see how you get on. Lets us know in 2000 miles time
As your original question was how to eliminate inner edge wear you could simply keep changing the toe in until you eliminate it .. it maybe wouldn't make for a very balanced car and you might destroy a few sets of tyres working what what was a really good setting but you'd sort your wear issue eventually. Some of the numbers from tlracing are strange as an initial suggestion for an unknown car. I don't know what his 25 years experience is in so maybe those setings work well in some unusual road car somewhere, they're not what you would instantly think of as good starting point settings though for a car with rapid inner edge tyre wear.
I've missed somewhere what car you're referring to .. your profile doesn't seem to help either. If you let us know what you're driving that might help .. but essentially follow sam68's posting and see how you get on. Lets us know in 2000 miles time
trackcar said:
I don't know what his 25 years experience is in so maybe those setings work well in some unusual road car somewhere
Quite, you don't, do you? But having worked on everything from Formula Vee to GT's & prototypes, I'm quite happy with life...If the inner edges are wearing so significantly with his existing geometry, then it's likely there is either (a) visibly far too much camber or (b) a big camber change during motion. Taking it out to zero to minimal positive will highlight which it is. As I said, this are a starting point to try and isolate the cause.
Likewise, a small amount of toe-out was given as a starting point to see if it made a difference, as most people seem to just crank of a load of toe-in and wonder why it doesn't work!
Sam - If I'd meant caster should be set to 4 degrees that's what I'd have said. Likewise, I am quite happy to use string and trigonometry - at least it doesn't die if the battery goes flat!
From my experience I've always found the best way to find a decent set up is to experiment with major changes (one at a time, naturally) to see what each does, especially with a car that has no baseline from the manufacturer. Building up a picture with a good, wide data set is surely far better than fiddling a bit at a time.
So Mr Gooner:
1) Make sure there's nothing fundamentally wrong/out;
2) Use a fairly neutral set-up to begin with;
3) Experiment with quite large changes initially - that way you can be sure of their effect and, if they make things worse, that's just as good a way of learning how your car responds. Once you are in a position to understand its' behaviour you can refine the settings to make it work for you
tlracing said:
Sam - If I'd meant caster should be set to 4 degrees that's what I'd have said.
My sincere apologies!!Which bit of 'I'd start with... caster: ~4 degrees' did I misunderstand?
With regard to strings and trig, the toe-out settings for the Exige, since you mentioned it earlier, are specified at 1/5th of a millimetre +/- 1/5th ...if you can measure to a fifth of a millimetre with a bit of string and a tape measure you are are, indeed, a hero!
Ramthorne said:
Perhaps with the exception of using a pyrometer to check camber?
A bit serious for amateur set-up, I admit, but if you do a few laps of a circuit, equal readings across the tyre tread with a pyrometer are a good indication that the tyre is working well across it's full width... one shoulder running hot indicates geometry problems. Pyrometers are not that expensive, either, if you are serious about track driving, and can give good indication of correct pressures and compounds, too.Not all of us are sensitive/consistent enough to be able to judge small geometry changes purely on lap time or driving feel and waiting until the tyre is worn out on one shoulder is a slow, expensive way of testing!
Thanks guys ,I didn`t mean to start a bare keyboard finger fight ! You obviously need some more information so here goes - Front mounted engine (350 H.O Chevy) ,rear wheel drive ,60/40 weight distribution , double wishbones on front -not really adjustable for castor , Jag IRS at the back , wheels are 15" ,tyres are 215 60 15 (sp 9000) ,and it is used for hooning and the rare hillclimb but I really want just a decent road setting .
Let battle commence (again)
Let battle commence (again)
Edited by devout gooner on Tuesday 12th June 07:03
For road use start with parallel toe and see how it goes and maybe go to 10-20 minutes (1-2mm on 15 inch wheels) toe in if the straight line handling isn't good.
Camber I would go for 1 to 2 deg neg depending on the softness of your tyre walls, caster if not adjustable is irrelevant.
With the Jag rear end go for about 1mm toe in which will give you good straight line stability at speed.
That's what I use on my replica D-type which will be a similar set up to yours and I can drive virtualy hands off the steering wheel at 140mph.
What make car is it?
Camber I would go for 1 to 2 deg neg depending on the softness of your tyre walls, caster if not adjustable is irrelevant.
With the Jag rear end go for about 1mm toe in which will give you good straight line stability at speed.
That's what I use on my replica D-type which will be a similar set up to yours and I can drive virtualy hands off the steering wheel at 140mph.
What make car is it?
Edited by falcemob on Tuesday 12th June 09:35
Now he tells us... it's a Healey replica.Forget everything we've said.
For authenticity, you need to fit a set of the stiffest cart springs you can find, crank the castor up to about 15 degrees and increase the front wheel offset so that the steering is impossible to turn unless you are built like Stirling Moss' sister, then adjust all the wheels to point in different directions.
Job's a good 'un.
Sam_68 said:
Now he tells us... it's a Healey replica.Forget everything we've said.
For authenticity, you need to fit a set of the stiffest cart springs you can find, crank the castor up to about 15 degrees and increase the front wheel offset so that the steering is impossible to turn unless you are built like Stirling Moss' sister, then adjust all the wheels to point in different directions.
Job's a good 'un.
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