simon's learning what to do with the polo thread

[sambb]

hey I remember you said you'd put droop limiting straps in it. If you jack the car at the right rear jacking point to simulate 3 wheeling, its not hanging off the strap is it? Yeah I reckon rear toe out with lots more rear neg camber will really help it rail around corners like that - did with mine. I'm at 2 or 2.5mm (cant remember) total rear toe out and 1.75 neg camber and i'll be going for more of both next stab at it with the shims.
Slicks mean more grip = more lateral G's = more roll angle, needs more spring. My 390lb/in (7kg/mm) fronts = 315lb/in at the wheel can be on the uncomfortable side of fun when commuting but I am from Sydney where goat tracks are frequently called roads so it might not be too bad for you. I guess what I'm trying to say is that despite the fact that more spring than 350lb/in might work better with the slicks, running more than 350-390lb/in on the front at every other time wont be exactly plush.

[Sydneykid]

thanks guys

I've been told where I can get 2nd hand slicks for a good price, and given I'm in the same class as some cars that are basically out-and-out race cars on semi-slicks it doesn't really matter if I put myself into the race car class. I just want to go faster... is 350lb in the right ballpark for them too? does a stickier tyre require a stiffer spring?

Daughter took some really poor photos; this is a reasonably flat corner where the inside rear doesn't pick up as much as the big sweeper. I think it also shows that I do need more rear camber, something I've been putting off

The problem with a full slick is that are very particular about set up, they only operate within narrow windows. For example the spring rate has to be right and will vary from track to track and with conditions. They also have a narrow tolerance level for camber and caster, get outside of that and they will overheat, blister and tear themselves apart fairly rapidly. It takes me almost a full day of testing to get a new car on full slicks in the 95% window. Plus I will kill at least one set getting there.

In comparison semi slicks are far more tolerant, they have much wider window in which they will still operate quite well. I can get a semi slick shod car in the 95% window in a couple of sessions without damaging the tyre at all.

That's with fully adjustable rigid chassis race cars, for a flexing road car with all of the compromises that brings personally I'd stick with the semi slicks.

I'm gradually getting Sam to setting up the rear with 6mm of toe out and 2.5 degrees of neg camber, mm by mm.


Cheers
Gary

[simon k]

That's with fully adjustable rigid chassis race cars, for a flexing road car with all of the compromises that brings personally I'd stick with the semi slicks.

Okie dokie - good advice

I'm gradually getting Sam to setting up the rear with 6mm of toe out and 2.5 degrees of neg camber, mm by mm.

maybe that's a job for this weekend then... it's only 1.5mm and maybe 1.5° neg.

My mini has 12mm toe out at the back, it's a twitchy little thing, especially with a 2.2 turn rack and power steering. I came 5th out of 110 at the mini motorkhana nationals on the long weekend, very happy with that

[sambb]

12mm toe out! I need to man up. I'm ordering another set of the shims tonight.

[simon k]

12mm toe out! I need to man up. I'm ordering another set of the shims tonight.

yep, 12mm, I even checked. I'd adjusted it to give 1° each side but never actually measured how many mm that meant.

It's a lot of fun to drive on dirt, very easy to make it turn, but also very controllable. When doing a khanacross I can basically toss it sideways and get it to drift from one point to the next.

On a straight bit of 100kph road it twitches like it wants to swap ends on every little bump in the road, but it doesn't. You can give the wheel a little tug and it changes direction, then kinda sits at the same attitude. I guess that's what we want our Polos to do hey - not sure I ever put 2 and 2 together...

[Sydneykid]

Minis are always " lively" even when set up correctly, they have a skinny track and very short wheelbase plus it's tricky to get the camber curves (particularly the rear) correct and removing the bump steer isn't easy (hence the twitches over bumps). Overall, that's what you get from 60 year old chassis engineering.

Cheers
Gary

[simon k]

I bought some 6kg springs for the front and spent yesterday afternoon putting them in - a while ago I bought a 36mm socket to undo the CV joints. Taking the whole strut out of the car like the manual says is way easier than f*cking about trying to do it under the mudguard like I did last time

I also cut the domes off the top of the strut tower - did the driver's side first "nah, I don't need to pull that bit of the wiring loom out of the way, I'll be careful" then proceeded to run the angle grinder straight into it, 12 wires cut or damaged... so I was under the bonnet soldering today. I don't think I'll ever truly learn to not be stupid and cut corners

I went for a little drive (also bedding in new front brakes) and ride doesn't seem a lot harsher which is good. I'm getting new tyres tomorrow morning so won't be able to do a "like for like" run around my test corners on the way to/from work but never mind.

[sambb]

ha ha yeah I was worried about doing the same when I did mine. Didn't cut any wires but did manage to nearly set the firewall deadener on fire.
I haven't removed the driveshaft to do it before. Since I got coilovers I just wind the spring collars down until the springs are unseated and then bang the hub off like before except now it just pops off.
Keen to hear how the 6kg/mm springs go. What were your previous fronts?

[simon k]

I haven't removed the driveshaft to do it before. Since I got coilovers I just wind the spring collars down until the springs are unseated and then bang the hub off like before except now it just pops off.

I wonder if your struts are shorter than mine... if I do that, the driveshaft hits the lower control arm before the hub is anywhere close to coming off.

Keen to hear how the 6kg/mm springs go. What were your previous fronts?

the previous fronts were 275lb / 4.91kg, I kinda get the feeling I'll end up on 7kg fronts like you.

hey I remember you said you'd put droop limiting straps in it. If you jack the car at the right rear jacking point to simulate 3 wheeling, its not hanging off the strap is it?

didn't answer this earlier on - pretty sure it's not, the big mother rear bar takes care of that

[sambb]

6kg/mm (335lb/in) will be 271lb/in at the wheel so a decent jump. RE possibly going heavier again, is it still getting over onto the outside front a fair bit or is it just that you feel that ride/comfort-wise you could tolerate stiffer?

edit: oops my comment re getting the struts out wasn't entirely accurate. I remember now that I have damper stroke adjustment on the bottom collar and also ride height adjustment on the spring collar. With BOTH of those backed off the strut isn't hardly pushing into the hub at all and so is easy to get out.