Post
by robin » Thu Apr 28, 2011 1:46 pm
Just my 2p on the above setup to give people an idea what the numbers are about ...
Presumably the fronts are down to zero-shims (or one shim on one side) already so you have no scope for increased front camber (before-and-after are the same here - the minor changes are just noise that's come from toe adjustment/equipment drift over the course of the setup). Ideally you want nearer -1 degrees for "fast road" as it will sharpen the turn in. But that might require taking a mill to the steering plinths.
The rear camber is pretty standard at -2 degrees and is also unchanged before-and-after; people don't tend to go mad on more rear camber and it's debatable whether it adds much to the handling and has some detrimental affects on tyre wear on long straights (you end up melting the inside edge whilst the outside edge is cooling off, I believe - never actually measured any of that, of course).
The front toe must always be set to as close to parallel as you dare, leaving enough margin so that you're sure it's always going to toe out not in. Your front toe was deffo on the high side before and is bang on afterwards. This will make the turn in a wee bit sharper too, as well as making the transition from left-to-right or right-to-left a bit more positive feeling (less of a dead spot in the middle). A lot of that will be dependent on driving style, though.
The rear toe is perhaps the biggest change. Standard geo has quite a lot of toe in on the rear; this helps make the rear end more stable (less likely to oversteer when you turn in a bit optimistically). The downside of this stability is that it compromises turn in, basically the rear end is resisting what the front end is doing; the rear bump steer helps to neutralize this, but only once you've managed to transfer enough weight to the outside to get the rear suspension to roll over a bit. Setting the rear toe closer to neutral will make the turn in quicker, but given the same bump steer characteristics, if you manage to roll over the suspension enough at the rear you might find the car turns in harder than you thought - of course a lot of people like that, but to me that's more track than road. The common use of non-standard rear toe is when you also have much firmer springs (and thus less rear suspension travel in the corners).
A huge change to the handling will come from changing the bushes; tired bushes allow a lot more movement in the wishbones than newer bushes (also you can replace them with anything from stock rubber, enhanced materials like nylatron right up to spherical bearings). Worn bushes under load can easily move more than the small changes you make to the geo when setting it up.
Cheers,
Robin
I is in your loomz nibblin ur wirez
#bemoretut
. However I can't find the post I thought I remembered this stuff being in.
