4 Wheel alignment...not again!

[Davz]

Going in for an alignment this week and would like to get a good setup. Anyone got any advice on settings?
Please note my zed is on eibach springs and whiteline arb's which are the same thickness as a z4m and an 18" staggered wheel setup with 15mm front and 20mm rear spacers, brand new goodyear f1 assy5's.

I am no expert in the field of suspension so I have read into the subject but also read so much conflicting information on this subject on this forum and also other forums.

I have read that the z4 is set with too much rear camber and not enough front camber so that it understeers to make it safer for the average joe. While I am no time attack driver I don't mind progressive oversteer, I don't want oversteer with no warning and it just snaps out on you. When I was young I used to love my 205gti 1.9, the front end grip was amazing and lift off oversteer made it fun but it also was rather dangerous as it could really snap into oversteer and would leave you facing the wrong way Older and wiser means I would want to avoid this.

Before I fitted the new suspension set up the replaced falkens had worn the rear on the inner edges as though there is too much toe. The fronts worn on both the inner and outer edges but really severely on the inner edges.

What I am after is neutral handling where tramlining is non existant, I am fed up of those brown trouser moments where the car darts about all over the place on a bumpy road, I want to steer where the car goes and not have to react to bump steer all the time, its down right tiring! I want it to feel solid and planted.

I don't intend to track it and would like a setup that preserves the life of the tyres as much as is feasible in my quest for zero tramlining.

Rear.........With wider tyres on the rear can I run less camber than the front, will this be too dangerous for the road due to oversteer? Regarding toe.....zero? toe in or out? I am thinking -1, would this be too little, would -1.5 be safer? Toe in of 0.03? to keep it stable under braking and at high speed, while working to prevent oversteer due to the reduced camber.

Front............screw out the camber pins and go for max camber? More grip to counteract understeer? but will this tramline and bump steer? Toe....zero? toe in or out? I am thinking -1.5 with slight toe in of 0.01 / 0.02 to prevent tramlining?

Any advice and numbers greatly appreciated.

 

[lucasxdiniz]

My recent experience:

https://z4-forum.com/forum/viewtopic.php?f=2&t=116963

To add on to that now that I've driven the car a bit harder, handling is much improved! Handling feels completely neutral but if I want to, I can make the rear lose grip and have some fun with it as I can actually control the drift whereas before the rear would snap back and not be very playful. Turn in feels incredible and with my current tyres and suspension I have zero tram-lining and feedback is decent if don't hold the steering too tightly (EPS after all...). I have a lot more confidence and pleasure driving my car now.

edit: It's late and I haven't thought this through, but I don't think you should be getting any significant/noticeable bump steer. I think the drop of 15mm isn't enough to make it that noticeable... I certainly don't experience any (bilsteins, eibachs, 12mm spacers front, Asymmetric 5s). It's possible your alignment is all over the place and unsymmetrical left to right and you have really s**t handling. Keep us updated.

 

[Davz]

Thanks for the feedback Lucas. I have been reading your thread but didn't want to hijack it.
Your suspension set up is virtually identical to mine, bils, eibachs, F1 assy5, I just have whiteline arb's at z4m thickness that is different.

Can I ask why your rear camber is -2°15 when the csl and z4m spec is -1°50.

 

[PDJ]

I had my car set up a couple of weeks ago

I am a mechanical maintenance tech by trade

Have built a Westfield almost 500bhp/ton and spent a lot of time around Cadwell

All the different suspension set ups are a compromise with one thing or another so there is NO perfect set up

When I built my Westfield it was fully rose jointed and solid mounts on everything. The steering was set up parallel and toed out under bump so the harder you pushed the front end down the more it toed out and dragged you into the corner.

Now with a Z4 that is set up on rubber bushes there is compliance and movement in the bush so lets just say you have exaggerated toe out, as you brake hard the rubber bushes will flex and give more toe out same happens when you accelerate hard don't know what happens when the suspension is compressed into bump have not measured it. But it comes down to the length of the steering rack, steering arms and the position of the pivot points, which BMW fixed.

The front camber can be adjusted at the bottom of the strut by adding shims between the strut and the hub a 12mm washer will do the job you just need some new slightly longer bolts.

The rear is limited by the size of the hole/slot which BMW gave you (possible to file it longer if you remove it all not worth it)

If you want it to go round corners like a race car then it is not going to be too good in a straight line it will become nervous and or wear your tyres on its edges and the limit of grip could become a switch with little warning.

Below is what I had my Z4M set to and so far seams ok had the chance to push on on a nice flowing road/track 6500rpm 3rd gear and the traction light on and all very smooth no need for opposite lock all very calm.

Hope that makes sense not too good at getting across in writing I know

 

[Davz]

Thanks PDJ, very informative, yes the suspension of a road car is always going to be a compromise sat on all those squidgy rubber bushes!
Looking at your spec sheet, you have gone for a degree more front camber and in spec toe in but minimal at 0°01. With more camber do you find it tramlines/bump steers?
Rear camber is just slightly out of z4m spec but the rear toe in is considerably less, how does this affect straight line stability at higher speeds, particularly on uk bumpy roads? Is turn in from the rear quick due to a lack of toe in?

 

[PDJ]

To be hones I thing you would need to have it set up to what ever you think and then try it and change it if it is not to your liking

Bumpy rods are never going to be a nice place in a sports car BMW spend hours/days /weeks at the ring to get the car how they think it should be and it is not that bumpy

Bumpy roads probably would need a slightly softer spring set up which is another can of worms along with damper rates, ride hight, tyre pressures etc.

Mine cost me £60 so not the end of the world, if I did or do not like the set up or want to try a more aggressive set up.

 

[lucasxdiniz]

Thanks for the feedback Lucas. I have been reading your thread but didn't want to hijack it.
Your suspension set up is virtually identical to mine, bils, eibachs, F1 assy5, I just have whiteline arb's at z4m thickness that is different.

Can I ask why your rear camber is -2°15 when the csl and z4m spec is -1°50.

Do you live near London? I wouldn't mind letting you drive my car if we ever meet up.

That was a judgment call by the alignment guy. We found that N/S/R wouldn't go higher than -1.8°, he didn't explain why but he decided add more negative camber instead of getting as close to -1.5 as possible. I didn't question it, at the time I assumed it is so I can lose traction more easily when tossing the car around from a straight line (more camber = less grip in a straight line) but then as the weight of the car is transferred to the outside wheels and the car leans on them I have more grip and can control a slide more easily. Not sure if my reasoning is right in this circumstance, but it certainly feels like it. Rear is more stable at high speed corners as well when you really don't want to lose grip at the rear and understeer is a bit safer.

Edit: -ve signs are important.

 

[Davz]

I've been driving the zed for a couple of days now after an alignment. I had it done on a John Bean 4 wheel system, competitor to hunter.
I have gone for a z4m setup but asked to go with -1.20 front camber and rear toe in of 0.07 as different to z4m.
Analysis of the pre alignment showed front camber of -1.18 with toe in of -0.13 and -0.08 and the rear camber of -2.22 and a toe in of 0.04 and 0.10! My rear tyres, before installing the new f1's, were worn at an angle and the nearside was badly worn on the inner edge, almost at the canvas. So it was decided to reduce rear toe in to 0.04 and camber to -1.5, spec for z4m is -1.5 camber but with a massive total toe in of 2.22, I think this is going to really wear the tyre inner edges but give you very high speed stability.

So final figures ended up at Front -1.19 camber, 0.02 toe in. Rear -1.51 camber and 0.03 toe in.

I have tested at high speed, red lined 4th gear and a few second spurt in 5th (needed to brake for a bend) stability was excellent, zero wander, no tramlining or bump steer.
I then sought the bumpiest roads (lots of those to choose from!) and drove at 60 mph, finally I can accelerate hard and cruise on these type of roads without needing a change of underwear! I could hold the wheel with just thumb and forefinger and steer the car, it finally changes direction with my input and not the surface of the road directing it towards a hedge. You may be able to run with zero toe in as was being advised on the forum by an alignment guru a few years back, I thought about it but i'm too cautious! lol.
Cornering in both wet and dry is excellent, feels neutral and changes direction to my inputs, grip is high but I do have new f1's allround. I am now a very satisfied zed pilot and thoughts of selling it have now gone completely.

For shropshire drivers I can recommend priorslee motors, they only charge for labour, it took 1hr to set up and they charge £60 an hour inc vat. I would advise giving all the bolts a few squirts of penetrating oil days before, I did this for two days beforehand, this will make it much easier to undo everything and reduce the chances of having to pay more.

 

[scarlet-jester]

So I am having exactly the same problem with bump steer. This is my thread on this where it was set it up as a E89, then on taking it back set it up correctly, but it is still all over the road. https://z4-forum.com/forum/viewtopic.php?f=2&t=116462
2006 3.0 Si, M-sport suspension, running 225 45 17 8J

This is the latest printout of my current setup. I have subsequently gone back and had the fronts replaced with Falkens too so have FK510s all round now. Although not unexpected, this has made no discernible difference.



I fully appreciate that the feel of the car can be an individual thing, but I simply want it to be manageable and don’t need it to be a cornering demon. As noted by you Davez you have made some adjustments to a typical Z4M set up to good effect although you have a staggered set up and spacers which I do not. Does this make any difference or can these settings be applied to mine also?

I would really appreciate any inputs as to how to get the car have better overall driveability without the aggressive bump steer.

 

[Davz]

sorry to hear you are having problems with your Zed, I know how you feel especially when it makes a zed downright dangerous, I was close to selling up.
Now that you have a complete set of new tyres, that can be ruled out, Falkens are excellent tyres.

Do you get any tramlining?

looking at your spec sheet, its a good alignment, all within bmw spec for the low slung suspension, you could have gone for less camber on the rear and a bit less toe in front and rear, the rear toe is on the upper limit. To compare to mine I only have 2mm total rear toe in, yours is 5mm, I would keep a check on inner edge tyre wear. Lots of toe in will make the car stable in a straight line at high speed.
I am assuming the Toe from your spec sheet is Toe in and not out as it doesn't state +or -. If it is Toe out that will be your problem. You could get a free alignment check at Kwikfit just to verify your settings are correct. They charge £60 for front and £25 for rear if you change anything, no change no charge.........edit, just noticed you are down under....do they have a kwikfit type tyre place down under?

What are your shocks like, what is the mileage and age of them? Spring snapped?
Have the bushes been checked?
ARB links good?

 

[scarlet-jester]

sorry to hear you are having problems with your Zed, I know how you feel especially when it makes a zed downright dangerous, I was close to selling up.
Now that you have a complete set of new tyres, that can be ruled out, Falkens are excellent tyres.

Do you get any tramlining?

looking at your spec sheet, its a good alignment, all within bmw spec for the low slung suspension, you could have gone for less camber on the rear and a bit less toe in front and rear, the rear toe is on the upper limit. To compare to mine I only have 2mm total rear toe in, yours is 5mm, I would keep a check on inner edge tyre wear. Lots of toe in will make the car stable in a straight line at high speed.
I am assuming the Toe from your spec sheet is Toe in and not out as it doesn't state +or -. If it is Toe out that will be your problem. You could get a free alignment check at Kwikfit just to verify your settings are correct. They charge £60 for front and £25 for rear if you change anything, no change no charge.........edit, just noticed you are down under....do they have a kwikfit type tyre place down under?

What are your shocks like, what is the mileage and age of them? Spring snapped?
Have the bushes been checked?
ARB links good?

Yes, I get some tramlining too and under heavy braking from speed it is a struggle too.

Car is in fantastic condition and no issues with suspension that I am aware of - has 43,000 kilometres on the clock and its annual service about 4 weeks ago. I rang the tyre shop and those measurements are toe in apparently - it was done 3 weeks ago.

My frustration is that I drove it back from Auckland about a year ago now (1000k road-trip) on the old set of tyres and it never had these issues on that trip - sat on the road like glue. It always had a bit of bump steer but nothing too bad, but since the new tyres and wheel alignment, it is pretty bad. My problem is who to go to to ask what I should do TBH as I am no expert as far as this goes. Bloody frustrating - perhaps a change in camber and toe will have to be next ......

 

[MrPT]

When you say “bump steer”, which axle does it affect?

If the rear is deflecting under load or over rough surfaces, it won’t be bump steer, as such, but could be worn trailing arm bushes (RTABs).

 

[scarlet-jester]

When you say “bump steer”, which axle does it affect?

If the rear is deflecting under load or over rough surfaces, it won’t be bump steer, as such, but could be worn trailing arm bushes (RTABs).

From behind the wheel, it seems to be the front that is causing the issues. That being said, I am no expert given that I have never experienced this before with any other car. I spoke to another mechanic I was referred to and they suggested letting some air out of the tyres to see if that makes any difference - will give that a go ....

 

[scarlet-jester]

So it turns out the rear tyres had 40 psi and the fronts 38 psi - I have dropped them all to 32, so lets see how that goes .....

 

[MrPT]

So it turns out the rear tyres had 40 psi and the fronts 38 psi - I have dropped them all to 32, so lets see how that goes .....

Aha! Great place to start - seems a likely contributor, given the timing, the fact that the alignment looks fine etc. To be fair to the tyre place, it’s common practice to overinflate tyres when they are first fitted to ensure that the bead locates properly inside the rim.

 

[scarlet-jester]

Aha! Great place to start - seems a likely contributor, given the timing, the fact that the alignment looks fine etc. To be fair to the tyre place, it’s common practice to overinflate tyres when they are first fitted to ensure that the bead locates properly inside the rim.

And that was the problem - basically driving on four over-inflated footballs! Did my hill and bay run after work last night and all is not good with the world again! I may look at reducing camber a little on the back and reduce the toe a bit all round to preserve the tires - we'll see.

What a relief!

 

[Davz]

Let us know how you get on.
I agree with MrPT, I dont think a bit less camber and toe in will alter the problem, more toe in will make it more stable in a straight line.
Have you checked the shocks? I realise your car is a very low miler but age will affect shocks, rubber seals will perish. An easy way to check your rear shocks is to put it on axle stands and undo the lower shock bolt and just push the shock by hand. I found my shocks, which had just passed an mot had no resistance at all and were completely useless, that was at 50k Miles.