Z4C...attempting to go from write-off to race car

Thrustyjust · Post by **Thrustyjust** » Sun Jan 17, 2021 6:21 pm

Could be up for the boot nets if you do

Toppy · Post by **Toppy** » Sun Jan 17, 2021 6:29 pm

Only got a brief bit of time on the car this weekend, which was spent trying to do my first DIY alignment/camber setting. Having changed both steering tie rods to go straight meant having the steering wheel 90 degrees to the right

I bought a cheapo camber gauge from Amazon, then got some string going front to back. Its a massively unscientific approach given my driveway isn't flat, but I was just hoping to get it somewhere close so it felt OK to drive somewhere for a proper geo.

To sort the camber meant taking both front struts off to get at the adjustable top mounts, but was then relatively simple to sort - I've managed to get both sides around 2 degrees negative camber now.

On the alignment, the passenger side wasn't too bad - just toeing out by a couple of mm. The driver's side was another story - it was toeing in by a whopping 73mm! No wonder it felt a bit pissed.

Managed to get them to a point where they are toeing out by 1 - 2mm on each side and took it around the block - hey presto it'll actually drive straight with the steering wheel centred now. It's not perfect, but at least it feels safe enough to drive somewhere to get the geo done properly.

Next up, hopefully the brakes - I've got new discs, lines and fluid, just waiting for the Pagid RS29 pads to arrive and it'll all be good to go.

Toppy · Post by **Toppy** » Sun Jan 17, 2021 6:58 pm

Thrustyjust wrote: ↑Sun Jan 17, 2021 6:21 pm Could be up for the boot nets if you do

They've come out already...let me find where I've put them and I'll let you know!

Thrustyjust · Post by **Thrustyjust** » Sun Jan 17, 2021 8:04 pm

Thanks Toppy, let me know what you want for them

Z4C_er · Post by **Z4C_er** » Mon Jan 18, 2021 12:51 am

Toppy wrote: ↑Sun Jan 17, 2021 6:18 pm
Z4C_er wrote: ↑Mon Jan 11, 2021 6:04 pm I may have asked you this before, but if you have subwoofers and are going to strip out the interior, could you let me know when you'd like to sell the grilles please?
Sure thing. Are there different audio system specs? There are 2 speakers with round grilles behind the seats...does that sound like what you're after? If so, I reckon I'll be doing full interior strip in 3 - 6 months depending on how the year pans out

Thanks Toppy, but no, I'm after two large rectangular grilles. Sounds like you don't have the subbies. Thanks anyway!

Toppy · Post by **Toppy** » Sun Mar 21, 2021 3:37 pm

Been quite a while since the last update...progress has been slow due to bad weather, work, lockdown and general laziness.

Finally, I got round to sorting out the brakes - I have swpapped lines for HEL braided ones, new OEM discs and Pagid RS29 pads, followed by a full flush of RBF660 brake fluid.

After this I wanted to do the water pump and thermostat as there was no history of them having been done previously. I managed to get some these delivered from Poland at a decent price <£300 for both, including the Pierburg OEM pump. The swap was easy, but I did struggle to get the system filled again without airlocks to allow the bleeding process to happen. A good bit of faffing later and a fair bit of coolant split on the driveway got it going.

The car has now spent the last week at Abbey Motorsport. I managed to shear one of the ARB bracket studs a while back and depsite my attempts to resolve using a rivnut, couldn't get it sorted to my liking. Abbey have now welded in a nut, and then done a full geo setup for me - ride heights, alignment, camber and droplink lengths to get the suspension pre-load done.

I've just had a set of Nankang AR1s delivered, so next up is an attempt at refurbing the front 2 spare set of MV1s I've got and getting them fitted.

Hopefully, all in time to get out on track at Donington Park in April!

Liam22 · Post by **Liam22** » Sun Mar 21, 2021 10:38 pm

Good progress. I'd be interested to know what length your front ARB drop links ended up at.

Did you run the water pump auto-bleed cycle? I've found it to be pretty reliable. Ign pos II, WOT for 10s.

Toppy · Post by **Toppy** » Mon Mar 22, 2021 9:18 am

I got the auto-bleed to run, my issue was getting the new coolant far enough around the circuit first for that to work...got there in the end.

I'll take a wheel off and have a measure of the droplinks for you next weekend.

Liam22 · Post by **Liam22** » Mon Mar 22, 2021 9:38 am

Thanks! FWIW, after starting out too short, I've now ended up with 200mm drop links from a Proton!

https://www.ebay.co.uk/itm/233715926533

Tanel · Post by **Tanel** » Tue Mar 23, 2021 3:55 pm

Toppy wrote: ↑Sun Dec 20, 2020 4:36 pm

What are the advantages of an offset bushing?

TomK · Post by **TomK** » Tue Mar 23, 2021 4:13 pm

Tanel wrote: ↑Tue Mar 23, 2021 3:55 pm What are the advantages of an offset bushing?

More caster angle. The Z4M comes like that from the factory.

Tanel · Post by **Tanel** » Tue Mar 23, 2021 4:31 pm

TomK wrote: ↑Tue Mar 23, 2021 4:13 pm
Tanel wrote: ↑Tue Mar 23, 2021 3:55 pm What are the advantages of an offset bushing?
More caster angle. The Z4M comes like that from the factory.

And how does it translate to the steering feel?
My car is annoyingly twitchy on uneven roads. Does this fix that or makes it even worse?

TomK · Post by **TomK** » Tue Mar 23, 2021 4:53 pm

Tanel wrote: ↑Tue Mar 23, 2021 4:31 pm
TomK wrote: ↑Tue Mar 23, 2021 4:13 pm
Tanel wrote: ↑Tue Mar 23, 2021 3:55 pm What are the advantages of an offset bushing?
More caster angle. The Z4M comes like that from the factory.
And how does it translate to the steering feel?
My car is annoyingly twitchy on uneven roads. Does this fix that or makes it even worse?

It's a fairly complex subject that I don't fully understand, however one possibility is that a higher caster angle will allow you to run less static camber (as there will be more negative camber applied as more lock is applied).
High static camber is often a cause of tramlining or the feeling of the wheel being pulled about in your hands on a bumpy road say.
What camber are you running at the front?

Liam22 · Post by **Liam22** » Tue Mar 23, 2021 5:28 pm

Simple version: more caster provides better braking stability and stronger self-centring

The affect on camber is mostly negligible.

Twitchiness on bumpy roads is more likely related to front wheel alignment and/or worn components. Increase toe-in to compensate.

Toppy · Post by **Toppy** » Fri Apr 02, 2021 1:44 pm

The final stages before the first track day next week are now done...giving the spare set of MV1's a little refurb. Not tried that before, but was too difficult - just a bit of a slow and dull process. The finish isn't perfect but good enough for use as a track set of wheels.

These have now got a set of Nankang AR1s fitted ready to go for what could be a cold and damp Donington track day next week.

I took it out for a test run today...there's an annoying loud squeal from the rear brakes when coming to a stop (<10mph only), regardless of whether I'm on the brakes or not. I assume it's something to do with the handbrake, but any ideas much appreciated!

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