simon's learning what to do with the polo thread

[simon k]

other than tyres, it seems like the first place to start is making a stiffening beam for the back-end, and I suppose some poly control arm bushes, maybe make a strut brace for the front too? As I said, I nearly made a rear stiffening beam - I wish I had, I didn't think it'd be as bad as it was...

I like your TT ball joint modification, except that the strut top bearings collapse (right?) can you replace the tops of the standard struts with something that can handle the change in angle? maybe machine an angled plate to sit on top to correct the angle?

oh - and I think I want some 15" wheels - since it's my daily, it might be smarter in the long run for me to get some 15" wheels and cheap-ish track tyres (even 2nd hand race tyres) rather than put expensive tyres on the 16" wheels for the ~25,000km I do each year plus trying to compete. I've always had separate competition and road tyres for the mini

if you were on a (very) limited budget, where adapting or fabricating stuff is easier than buying, where would you start?

[simon k]

You can pick up VR6 wheels 15x6.5 et43 for 200 a set. They are pretty light. Put semis on the front and baldies on the rear. You could put 185 or 195/55/15 on ths back and 205,s on the front. There are some 15mm spacers on the parts forum so id grab them too to get thectrack width up. Id pull the esp fuse because i found it grabs opposire front brakes and funny things like that with the esp active and mucks up handbrake turns. Definitely get the hardest rear bar you can or use an internal bar like gary was talking about. The eibach shims transformed my car so for khanacross youd want a touch of toe out and thst only costs 40 bucks but is a bit of effort. Since you daily your xar you could use spring rubbers or sometimes called blockers. They insert between the coils in the springs, just say 1 full turn, and effectively coil bind them. Tbis will crank up your rear spring rate and then you just pull them out at the end of the day. Summit racing sells them. They sound dodgy but the supercars use them. Yeah the ball joint mod did stress the top mounts a bit, but you don't have to extend the existing slots in the ball joints like i did for extra camber. You can just throw the ball joints in and get the roll centre correction alone.

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[simon k]

For a good street car it might be a bit different. Id just get some koni yellows cos they atleast have some rebound adjustment keep the front springs but throw h and r rears in. Front bar optional without an lsd but definitely a rear bar. The ball joint mod helped. Id rebush everything literally everything. Brakes sre fine if you have good pads so 15,s are perfect. Fexeral rsr are only like 130 a tyre in that size. And i wish id shimmed the rear long ago. One of the best bang for bucks ive done.

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[simon k]

Hi Simon, if you want a priority list for FWD suspension;
#1 Rear swaybar (or beam stiffener) nothing else comes close, bang for buck
#2 Front positive caster, the more the better
#3 Front negative camber for obvious reasons
#4 Rear toe out, ask Sam
#5 Lower the rear roll centre
#6 Dampers, buy the best you can afford
#7 Front roll centre correction and bump steer elimination
#8 LSD
#9 Front swaybar
#10 Rear springs, at least triple the standard rate
#11 Front springs, ~1.5 times the standard rate

Most people are surprised that I put springs so low on the list as it's often the first thing people reach for, when there are things that make far more difference.


Cheers
Gary

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[sambb]

Simon you could ask eddy if his mate is still doing the subframe eccentric bolts. They stop the subframes moving around and give you a tad more caster. When you do the rear LCA bushes buy the offset siperpro ones that you can press in in a position that will get you more caster. The ball joint mod got me a tad more caster too as the ball joints angle forward slightly compared to the stockers. Those things together will get you another degree of pos caster.
For a bolt straight in neg camber adjustable spherical bearing'ed strut top the only thing I know of is the MCA tops as part of the blue or XR series of suspension. You cant get the topes separately - believe me I tried. I think Greg (Kaanage) fitted ground control tops intended for another car so that might be an option if you don't want to go MCA.
For bump steer elimination I had looked at different tie rod ends but couldn't find anything with longer pins. Running the front higher helps with that anyway and raising the rack looks basically impossible to me with packaging constraints.
LSD there is quaife and wavetrac torsens or Kaaz 1.5way or SQS 1 way plate diffs that fit.
I think Gary is dead right re the springs. I'd done most of the above before I stepped up to the stiffer springs. They made me a lot quicker on fast tracks/circuit but on the really tight hillclimbs not the difference you'd think. And a lot of the difference with the MCA kit came from the camber increase that came along with it, but yeah springs alone I don't think are the magic bullet. I think its still debateable if the old setup may even turn out to be quicker in a tight steep wet hillclimb. I have a set of h&R springs you can have cheap and just throw those rears in for now which will get the bum down and stiffer.

his is going to be fun to watch. I'll dig through my other stuff to try to find which fuse is the one to pull to kill esp and then you can do some back to back comparo's with the handbrake to see if you can feel a difference.

sam

[sambb]

actually Signature Sway bars (formerly Selbys I think) at Nowra make custom bars. Until I made my abortive rear beam bracing effort I was going to get them to do a 22mm bar (whiteline is 20 I think). You need to send your bar to them and they make up jigs an knock out fatter copies. That could be a bolt in way of stiffening up the back end without getting all engineer. I'l pass on their details if you want them.

[simon k]

legend... I'll see if I can work out what you mean by the eccentric bolts, it may be something I can make myself. I'll get it up on the hoist again this week.

Thanks for the tip on the spacers, but I was a little too late. The plasma cutter is being delivered this week, so I'll be able to knock some out. I asked you about spacing the stub axles away from the rear bar, you said that the caliper mounts are integral with the bar - I'll have a look, but there shouldn't be any reason not to mount the calipers from the spacer (?) - again, something to look at on the hoist.

I wonder if I can't make a strut top shim out of (say) 6mm plate and mill it to the right angle.

I'll take those springs off you, I agree with what you and Gary are saying about leaving that till last, but if it'll help drop the rear when I make a stiffening bar then all the better.

Running around the track yesterday I went up and down on tyre pressures, I started at 28 which was no good, dropped to 23 which was OK and faster but I scrubbed the lettering off the right front sidewall, so then went up to 34 and it was better... but it was really basically a pointless exercise for those tyres, kinda didn't matter what I did with them.


(the photo has done something weird with the front of the mudguard, there aren't any scratches there - I did lose a wheel centre cap yesterday though )

[simon k]

so this is Eddy's eccentric bolt setup, right?

Tramlining & Excessive Torque Steer.

I'll stick my head under the car and see if I can work out where they go before pestering Eddy...

[sambb]

Yep those are the eccentrics. By the time our cars are at 100,000km they'll all be moving around especially if you are going to lean on it hard at the track. You have to just ream the subframe very slightly to get them to fit, the bolt has to be metric fine and 12.2 tenile because they need 100Nm + 90 degrees or soething big like that.
Yeah re the rear shims you could make a one piece plate that takes in the whole stub and caliper mount for sure. I think RGVLee was looking at doing something similar which is a copy of the whiteline shims (discontinued).
Yeah I was surprised that no one was making a sphericalled topmount, even just a fixed position one. If you could make one with just a single 3 degrees neg/ extra 1 degree caster fixed position top then that would be so good. Have a look through Eddys posts as they made custom strut tops which might give you some ideas.
Re the springs I was using the front springs out of the weitec kit as they were only a 10mm drop but the stiffest of eibach/H&R etc and the rears from the H&R kit. That made the spring F:R ratio similar to what I have now but obviously way stiffer overall now. I still think the car was just as good with the standard springs in the front as they were the same spring rate as H&R and eibach yet had the right ride height for good geometry. So you can have both and do that but I reckon just the H&R rears initially (you can have the whole set though obviously) and see how that goes for now. I think a mutant rear bar would be great. I was going to make up some more of the spherical drop links soon as mine are getting a bit crunchy so i'll let you know when that happens too.

[simon k]

so the trick with the Eddy's eccentric inserts is that you get around 2.5mm of adjustment (I drew it based on Eddy's measurements) at the each end of the lower control arm mounts - 4 needed to do the whole car.... I wonder if it's worth machining the holes in the mounts bigger and moving the holes further out, though from the sounds of it the strut top would be better bang for buck

Spherical jointed front sway bar drop links? sure, why not

I'll PM you about the springs

picture from yesterday...