Ex-Marlon E85 Update & Help Request

[Mr Tidy]

My current Z4 tramlines quite a lot, but I've learned to live with it for now.

If it still happens after I've worn my run-flats out and got proper tyres on it I'll investigate further.

Strangely my 1 Series used to start to do it sometimes when the tyres were down to around 4mm, especially if the outer shoulders had worn more than the rest of the tread and even more so if the pressures had dropped a bit. But new tyres always cured it.

I hope you find a solution as the 3.0Si has a great engine.

 

[MrPT]

Firstly, congrats - you bought a well known forum car and a good’un.

What’s your reference point for the tramlining? They all tramline a bit and it can be quite disconcerting if you’re used to driving some that doesn’t get tugged about quite so much.

 

[n1cecupoftea]

Can probably flog the tyres to make up some cash if you're swapping? (Since you said there is lots of tread).

Definitely worth considering, thanks.

Be interesting to know if the tyres clear this up. Have you had the wheels re-balanced? Could be exasperating the handling?

Good idea, thanks. I will get this checked when I get the 2nd alignment done.

 

[n1cecupoftea]

My current Z4 tramlines quite a lot, but I've learned to live with it for now.

If it still happens after I've worn my run-flats out and got proper tyres on it I'll investigate further.

Strangely my 1 Series used to start to do it sometimes when the tyres were down to around 4mm, especially if the outer shoulders had worn more than the rest of the tread and even more so if the pressures had dropped a bit. But new tyres always cured it.

I hope you find a solution as the 3.0Si has a great engine.

When researching the issue I found a few 1 Series, E46 & E85/86 owners; recommending changing tyres sooner than you would on other cars. Your experience backs this up. Thank you.

Agreed on the engine. Sounds great, particularly with the modified backbox, has more than enough power for UK B-roads, solid reliability (I have found a couple of US N52 powered cars that have done over 500k), lighter than most four cylinder engines, and I am currently averaging well over 30mpg despite driving enthusiastically. Such a shame that normally aspirated straight sixes aren't made anymore.

 

[n1cecupoftea]

Firstly, congrats - you bought a well known forum car and a good’un.

What’s your reference point for the tramlining? They all tramline a bit and it can be quite disconcerting if you’re used to driving some that doesn’t get tugged about quite so much.

Agreed on the car, it was a major bonus to buy a car from a Z4 forum moderator that was well known to the community. Even if it did help Marlon defect to Porsche.

Excellent question on the tramlining reference point! I have never had a car that tramlined badly. My previous weekend car, a 2006 MR2, tramlined a little when I first got it, but that was sorted by tweaking the tyre pressures. My weekday car, a 2014 Clio, doesn't tramline at all.

I have compared the three cars and any changes or tweaks made to the Z4 on the same stretch of road near me, which is particularly bumpy and rutted. I could comfortably drive the Clio and MR2 with one relaxed hand on the wheel. In the Z4 I need two clenched hands on the wheel on the same piece of road. I realise I have to accept some tramlining but I think I can improve it a bit.

 

[n1cecupoftea]

As I said in my opening post, during the first wheel alignment they couldn't get the rear camber within specification. -1.4 was the highest they could get it without putting the toe out.

The technician pointed out this issue straight away and took me to the ramp to show me. I asked him to demonstrate how the camber is adjusted, which he did, and this tallied up with the instructions I found on newTIS.

I would appreciate your thoughts on this. Is -1.4 rear camber enough for road driving only? And what would prevent them getting this within spec? I am guessing that this would be caused by worn rear suspension but my BMW specialist is adamant it is fine.

Thanks again for all the answers so far. I really appreciate it .

 

[kis]

That camber is generally more desirable than the "stock 2.5" as it's more like the Z4 M spec (which works on the non M's as well).

Most people want less understeer, which is inherently built into the factory setup. This is particularly apparent on non Z4 M models with so much more rear camber than front.

Front Camber
It’s reasonable to aim for maximum front camber (by pushing the pins all the way in). It will vary from car to car but this usually ends up with similar front camber in the region of 1.5 degrees plus or minus a quarter. You should then try balance the camber left and right back to whatever the lowest common denominator. For example if one goes to 1.5 and the other only goes to 1.3 get both at 1.3.

Front Toe
It's not generally advisable to run toe out on either end on the road as it's a bit too lively and not nice on the motorway with more potential for less straight line stability.

The front can be run at parallel or close to zero without any major adverse effects. It's why I often commented to aim for 0.02-0.05 on both sides.

Rear Camber
Rear camber should be in the region of 1.5 degrees plus or minus a quarter. You should then try balance the camber left and right back to whatever the lowest common denominator. For example if one goes to 1.5 and the other only goes to 1.3 get both at 1.3. You may find the stock adjustment doesn't go that low if the bushes are worn so just take the same approach as the front but aim for minimum rather than maximum camber.
If you’ve made adjustments to the front and rear camber and they end up with similar values at the front and back, keep in mind that it’s better having more camber at the front. So a setup like 1.4 front and 1.3 rear.

Rear Toe
Rear toe is the final factor then and the closer you run it to zero the more lively the rear end will be. Usual suggestion is to run a bit more than front but less than factory if you want a sharper car. With all other parameters set this is the one you could play with to add or remove oversteer to taste. I found it was not overtly lively running low numbers like 0.04-0.06. Again balance the left and right back to the lowest common denominator.

If you aren't aware the measurements are shown in minutes and seconds versus degrees. For example 2o 24 is 2.4 degrees. There's 60 seconds in each minute so 24/60 is 0.4 degrees. The numbers I mention above are in degrees so you're aiming for rear camber that reads something like 1o 15.

Full source here - it's a long post so have a flick through for what's relevant to you!

 

[MrPT]

Excellent question on the tramlining reference point! I have never had a car that tramlined badly. My previous weekend car, a 2006 MR2, tramlined a little when I first got it, but that was sorted by tweaking the tyre pressures. My weekday car, a 2014 Clio, doesn't tramline at all.

I have compared the three cars and any changes or tweaks made to the Z4 on the same stretch of road near me, which is particularly bumpy and rutted. I could comfortably drive the Clio and MR2 with one relaxed hand on the wheel. In the Z4 I need two clenched hands on the wheel on the same piece of road. I realise I have to accept some tramlining but I think I can improve it a bit.

Yeah, sound rationale, it does sound like it could be improved.

When you mention a range of tyre pressures, how low have you gone? Many people find a sweet spot with non-runflats that is a fair bit lower than the recommendations in the door jam. I think I ended up at around 31-32psi on 18s on my si; some people go as low as 28-29psi.

If your geo and suspension are both fine (as above, -1.4deg rear is ok and might even be an improvement over stock) then I’d also suspect tyres. As the tread blocks wear down they’ll transmit more small turning forces from the road. The cold weather may be contributing too, as sidewall stiffness is a huge factor (hence runflats being so much worse!).

 

[Crazy Harry]

In my experience camber can make a huge impact on tram-lining - it might be worth going back to 'stock' but first check the stupidly obvious - are both tyre pressures the same? The tyre sensors are not fool proof and it is possible (especially on runflats) to have a tyre going flat which accentuates the tram-lining with no indication in the car and from a quick look around (ask me how I know!).

 

[kis]

The first post explains they couldn't get it to "stock", this was as close as they could get... which isn't a bad thing IMO (M spec for alignment).
Post reads to me, that before adjustment it wasn't anywhere near stock. And now at least it is closer...

 

[Crazy Harry]

The first post explains they couldn't get it to "stock", this was as close as they could get... which isn't a bad thing IMO (M spec for alignment).
Post reads to me, that before adjustment it wasn't anywhere near stock. And now at least it is closer...

Yep but that's half my point in a way - they couldn't get to stock or it can not be returned to stock? Change the people working on it or look for bent/worn components but I'd look at tyre pressures as well - I've had it happen with one tyre losing pressure but at least it was a cheap fix.

 

[kis]

I think this is generally why people avoid kwik-fit (unless I'm getting confused with another thread!)

 

[MrPT]

The first post explains they couldn't get it to "stock", this was as close as they could get... which isn't a bad thing IMO (M spec for alignment).
Post reads to me, that before adjustment it wasn't anywhere near stock. And now at least it is closer...

Yep but that's half my point in a way - they couldn't get to stock or it can not be returned to stock? Change the people working on it or look for bent/worn components but I'd look at tyre pressures as well - I've had it happen with one tyre losing pressure but at least it was a cheap fix.

It’s quite a common issue on the rear. A little unexpected, given you’d think the natural “sag” in the rear axle due to wear etc would increase -ve camber.

Perhaps a specialist garage might know a trick of the trade or two, but the OP could well be looking at a lot of additional labour to work all the various tolerances in the rear suspension enough to get it back within spec - “spec” being one of the first things that people change when they’re trying to sort out BMW’s overly safe rear geo and improve driving enjoyment (and not something that will help with tramlining at the front).

 

[n1cecupoftea]

Thanks very much for the replies about the rear camber.

When I took it for the first alignment, nothing was a long way out. They couldn't get the rear camber within spec but they got everything else green and with tiny differences between the left and right.

I had never checked the M Roadster alignment check so thanks for pointing that out. So the M should be - 1° 50' ± 25' and I have -1.39 and -1.40, which is within that spec. This can't be a bad thing.

I know there is mixed, mostly negative , opinions on Kwik-Fit but I felt this particular technician knew what he was doing. I have their Geocare package so I have booked it in for a second alignment this Saturday. I will also ask them to make sure they get the steering wheel bang on straight and reset the angle sensor. If this doesn't improve the tramlining, I will either get the alignment done elsewhere by a specialist, or get new front tyres.

 

[Smartbear]

Has your car got wheel spacers fitted? I put them on my si and it was definitely more twitchy afterwards, if they are fitted take them off & try the car.
Rob

 

[Marlon]

Has your car got wheel spacers fitted? I put them on my si and it was definitely more twitchy afterwards, if they are fitted take them off & try the car.
Rob

It has actually (unless removed by OP) - with the style 32s I put 15mm on front and 20mm on rears

 

[n1cecupoftea]

Has your car got wheel spacers fitted? I put them on my si and it was definitely more twitchy afterwards, if they are fitted take them off & try the car.
Rob

It has actually (unless removed by OP) - with the style 32s I put 15mm on front and 20mm on rears

Thanks Rob/Marlon. If the 2nd alignment doesn't reduce the tramlining; I will try without spacers before moving onto the front tyre swap. Would be a shame though because it does look great with the spacers

 

[enuff_zed]

The first post explains they couldn't get it to "stock", this was as close as they could get... which isn't a bad thing IMO (M spec for alignment).
Post reads to me, that before adjustment it wasn't anywhere near stock. And now at least it is closer...

Which could then imply that the tyres had worn unevenly as a result?
As I said before, isn't there anyone close enough who could lend a pair of known good fronts for a quick test run?

 

[n1cecupoftea]

The first post explains they couldn't get it to "stock", this was as close as they could get... which isn't a bad thing IMO (M spec for alignment).
Post reads to me, that before adjustment it wasn't anywhere near stock. And now at least it is closer...

Which could then imply that the tyres had worn unevenly as a result?
As I said before, isn't there anyone close enough who could lend a pair of known good fronts for a quick test run?

Thanks for the suggestion. I would prefer trying different tyres with my wheels but I guess I would then have to pay someone to fit/balance them.

Would it be worth asking Kwik-Fit to swap over the front tyres and rebalance?

 

[kis]

Which could then imply that the tyres had worn unevenly as a result?

OP, originally before you swapped anything (wheel or tyre) were you experiencing any issues?

I say this because I've remembered you're on a square set up. So I believe when the "old" tyres were put on the new alloys the positions have been changed. So you could have a front tyre on the rear alloy, vice versa. This could be causing the problems. As per the above, I'm not so sure the tyres have worn unevenly, just not been put back from the corner they were taken. It's important on the Zed to keep tyres on a particular corner, the swapping wheels thing to improve wear doesn't really apply to us.