R400D: Reducing front camber to save uneven tyre wear

[John Vine]

My R400D has pretty aggressive camber, resulting in very uneven tyre wear.  As my use is road only, I'd like to do something about this - say, by reducing camber.

What would the effect be on general road manners, handling, turn-in etc?

JV

[ScottR400D]

John, on my R400D I have the Jack Webb rose joint rod ends so the adjustment of camber and toe is quite a short job. 

On track I run about 3 degrees camber and some toe out. On the road I run 1.75 degrees camber and parallel toe. (Slightly vague on exact numbers because set up by Luke Stevens for me and he tells me the turns of the TREs and the steering arms to move between track and road. 

On the road, the track setting leads to a slightly twitchy car that will tramline on rough roads. It's MUCH nicer with the road settings and, on the road, the gain in grip and turn in of the track settings isn't missed at all. 

Using these settings the tyres wear very evenly. 

[John Vine]

Thanks for that, Peter.  Very useful. 

If your tyres wear evenly with a road setting of -1.75 deg, I'm guessing that my camber is significantly more negative than that as my fronts have distinctly more wear on the inner half of the tread.  Maybe the toe isn't quite right either?

I'm shortly taking the car into Millwood's, so I'll discuss geometry etc with Eric.

JV

[Geoff Brown]

JV: I am in the same boat as you. My set up is 1.3 degrees camber, plus 10 minutes toe.

The scrub to the front tyres was something I knew would occur but considering the wear limits allowable in law the three quarters of the tyre is down to my unusable limits of 2mm by the time the inner 30mm of width has scrubbed off to nothing.

I found that my set up aids turn in but does not make the car at all twitchy. I tried the car with a more conventional set up but it did not feel arrow like on turn in & directionally stable.

I am still running on CR500s but changing to ZZS in a few months. I want to retain my current settings but that depends on how the car feels on the new rubber.

[ScottR400D]

Unless you're using a very wide front tyre Geoff, they're well illegal when the inner 30mm is scrubbed off to nothing!

Seriously though, I'm surprised you see that wear with that set up. I notice very little with 1.75 camber, though I don't run toe out on the road. 

[OldAndrewE]

Yes, you would need 240 mm of tread width for 30 mm bald to be OK.  The requirement is for central 3/4 to be legal (above 1.6 mm)

[SLR No.77]

My experience is that toe in or out can have more effect on tyre wear than camber.

[7 wonders of the world]

I dropped my camber to 1.3 NEG but increased castor as this effect dynamic camber and applies more as steering is applied, toe is set to 10 mins TOE OUT

Who set our car up JV..?       did they give you a set up print..?

What tyre size are you running..?

 

 

[Paul Richards]

"My experience is that toe in or out can have more effect on tyre wear than camber."

I agree with Stu. I'd first check toe settings before altering camber.

[Beagler]

Wear on inner tyre means excessive toe out.

[John Vine]

Well, thanks for all the feedback, chaps.  Most helpful.  

As I'm fitting new tyres (ZZS 195/50 R15) on the front today (moving the old fronts to the rear), I think I need to get the tracking checked asap just in case.  I'm getting a full geometry check at Millwood in early April.

Neil: Vg question.  Back in 2014, CC fitted a long front chassis after my little contretemps with an erratic delivery van.  I'm assuming they would have set up the geometry at the same time, but I don't have any print-outs.  AFAIK, the tracking hasn't been checked since, although I did have the car flat-floored in Sept 2019 at Millwood.

Geoff (#4): is your 10 mins of toe in or out?

JV

 

[John Vine]

I've just put new ZZS on the front and moved the old fronts to the rear.  These are the old front tyres:

LH:

 

RH:

 

Mileage for both is about 5400. 

I measured tread depth at the indicated points.  Outer/inner depths for both are the same at 4.5mm / 2.5mm.  Given that a new ZZS is 5.5mm, that means I've lost 3.0mm on the inside but only 1.0mm on the outside.

The thing that puzzles me is that the inner edges show no signs of feathering at the block edges -- normally an indication of a tracking error, I thought?

JV

 

[ScottR400D]

John, did you swap your 'old' fronts, that are now on the back, on their rims so the least worn part is now on the inside? That would even out the wear, though putting tyres with that wear pattern on a different axle isn't a particularly good idea, IMO. 

Watch the handling until the tyres get scrubbed in in their new positions.

Excessive toe will often create feathering but, IMO, your wear is down to camber not toe. I think you must have quite a lot, possibly track setting, of camber. 

A flat floor set up should definitely include camber and toe checks. 

[Geoff Brown]

JV - Yes 10 minutes tow out. 

With careful measurement my MoT inspector says that the tyres pass with the inside wear down to & just beyond the bars. 

Yes 10 minutes tow out does exacerbate wear more so than 1.3 camber but I am quite happy to pay the price of feathering for good turn in without tramlining.

[aerobod - near CYYC]

John, I would do a tyre demount and an inside to outside swap, and as Peter said, treat them like you are breaking in new tyres. If you just reduce camber, it will change the feel and grip levels, likely increasing understeer. Based on the current wear, you are about halfway through the tyre life, so will have a tyre that is fairly evenly worn out after another 5,000 miles if swapped inside to outside..

[John Vine]

Re #13:

I simply moved the wheels from front to rear.  

I'd agree that the uneven wear does appear to be camber-related.  And yes, I too suspect I have too much neg camber.  I'll find out shortly and post up Millwood's results.

Out of interest, what change in handling characteristics can I expect should the negative camber be adjusted down from (guessing) 4 deg to CC's recommended 1 deg 20' +/- 15'?

Also, I note that CC also recommend rear negative camber of 1deg 30' =/- 15'.  That would seem to be good news as far as my wheel swaps are concerned in that the uneven wear is the right way round.  Is that a fair assumption?

JV

 

[John Vine]

Re #14: Thanks, Geoff.

Re #15:  I'm not sure I understand that, James, as I've put new tyres on the front.

JV

[aerobod - near CYYC]

I think you would still want to swap the tyres inside to outside John, as the somewhat lower rear camber will still continue the wear pattern although more slowly. I would be surprised if you have 4 degrees on the front, even 2.5 degrees with zero toe-in and normal road use will create that sort of wear (as has been the case with my car), but is can be easily rectified with some hard track use

[ScottR400D]

James is right, you'd see that sort of wear from much less than -4 deg of camber, in prolonged road use. It will be interesting to see what you have actually got. 
 

As for the question of what effect will reducing from what seems like a track setting to the more normal 1.5 deg or so, I think you'll   find it more directionally stable and you won't notice the lack of grip unless you're driving harder than you probably should be on the road! 

[John Vine]

Thanks, chaps.  I'll sort it all out when I visit Millwood.

but is can be easily rectified with some hard track use

As I no longer do trackdays, that could well be the problem!

JV