Toe Alignment

[Lotusjps]

I'm curious what people are running for toe alignment.  The way my car is currently set up it has great turn in, though is really twitchy at high speeds on the straights.  I'm thinking I'll need to run more toe-in in order to get it to stabilize at higher speeds, though was wondering how much I should be running.  I appreciate any input!

[BDA]

I've never heard any suggestion to use other than the standard alignment. You didn't say what your settings are but some use less rear toe to get better turn in so maybe that's what you've got. I would start by checking toe and camber front and rear and make sure they are within spec. Basically you should never have rear toe out. Too much, and you'll scrub off speed and wear your tires; too little and it starts to get unstable (as you report). If you have the capability to test tire temps, you might use that to play with your camber a bit, but I would plan on staying in the proscribed range unless you had a good reason.

You might also check to make sure that there is no slop in your suspension when it's off the ground. You might have a loose bolt, worn out bush, etc.

From the manual:
Front
Toe: 3/16 - 1/16 in
Camber: 0^o to +30'

Rear
Toe: 1/4 to 1/8 in
Camber: -1^o +/- 30' (between -30' to -1^o 30')

[LotusJoe]

[EuropaTC]

I'm curious what people are running for toe alignment.  The way my car is currently set up it has great turn in, though is really twitchy at high speeds on the straights.  I'm thinking I'll need to run more toe-in in order to get it to stabilize at higher speeds, though was wondering how much I should be running.  I appreciate any input!

Assuming there's no wear in the suspension bushes & dampers then from what I've read high speed instability is, as you say, down to not having enough toe-in.  My car doesn't have standard springs/wheels so it might not relate to your car, but the settings are currently;

Front : 2mm toe in.  I have run it parallel in the past with no major problems but at the last setting I added a bit of toe-in as I was making a few alterations and wanted to edge on the stable side.  Camber is whatever it comes as because the front arms aren't adjustable.  It looks slightly negative and I can measure if it's of interest. (I didn't bother because I couldn't change it anyway    )

Rear : Camber is set to 0.5 degree negative. I have an adjustable lower arm and when I got the car it was something silly (5deg ?) with heavy tyre wear.   With standard tyres I had it set to 1 degree but now with wider, low profile tyres & stiffer springs I've set to the minimum.   I have settled at 2mm per side toe-in, which seems roughly mid-way on the standard spec.

I had quite a lot of head scratching on the rear toe and was uncomfortable with the amount of spacers used but that's how the measurements came out.  The spacer packs weren't identical on either side which I really can't understand but that's what I've got. 

Based on my findings the rear toe had a more noticeable effect.  If you have instability then I'd check overall toe front & rear as starters but also the individual rear wheel toe as you could have one wheel running parallel with all the toe-in coming on the other wheel. That won't be good.... 

Brian

ps - there's a lot of info in the Yahoo Knowledgebase from experienced people like Jay Mitchell, well worth reading for background info even though the S2 & TC need different settings.

[Bainford]

In addition to the great information already offered, I suggest ensuring your tires are properly inflated. I think the tires on my Twin Cam are 17 psi front, 27 psi rear. Good luck, and please report back on your findings. Cheers.

[Lotusjps]

In addition to the great information already offered, I suggest ensuring your tires are properly inflated. I think the tires on my Twin Cam are 17 psi front, 27 psi rear. Good luck, and please report back on your findings. Cheers.

I'm surprised you have that much difference front to rear.  I typically run 22F & 24R (+/- 1 or 2 depending on conditions) for track or autocross.  I've been using a Longacre pyrometer to dial in pressures, and found that the tires started rolling over at lower pressures or started loosing grip at higher ones.

As for alignment, the last time I set it up the car had 1/16 toe in front & 1/8 toe in rear.  Camber is -2.5 front & -2.1 rear (obviously with adjustable arms).  The way it's handling I suspect the front may have toe out now (to change lanes at high speeds you just think about it rather than move the steering wheel).

Think it's time to buy some toe plates or toe bar to be able to check the set up ( use a smartcamber gauge for camber).  Any pros/cons of one over the other (plates vs. bar)?