Mike-SEiW Posted October 1, 2004 Posted October 1, 2004 Measured wheel alignments last night. First time since I built the car. Eyeballing camber apparently worked pretty good, I had -4,1° and -4.5° camber up front and -2.7 and -3,9 at the rear. At the front, I have turned the top wishbone one revolution. Not measured again, but have made gross estimate that this should reduce camber about 1.5°. Correct? At the rear however, Toe on one side was 1mm and other was 2mm. Does that mean half a turn on the rear rose joint will equalise toe? How much do I turn the top wishbones to get equal camber? One revolution on the one that has 3.9° to get it equal to the 2.7? I think starting points of 0 toe front, 1mm toe-in rear per side and about 2.5-3° camber all around are good starting points for 13" wheels and 205/60 A048 tyres. Comments? Quote
Al Yupright Posted October 1, 2004 Posted October 1, 2004 One full turn of the top wishbone is 0.4degrees. Quote
Blatman Posted October 1, 2004 Posted October 1, 2004 I would have said that you have waaaay too much camber. Unless you are serious track daying, or racing, then maybe a degree or a degree and a half rear camber, and no more than about 2 degrees front.... FWIW, my narrow sprint car runs about 1 degree neg rear, and around 2 degrees neg front... Quote
Al Yupright Posted October 1, 2004 Posted October 1, 2004 Yeah, I'm surprised if you can actually get 4.5degs neg without needing shorter top wishbones or a thinner locknut! Must make braking hard interesting! Quote
Blatman Posted October 1, 2004 Posted October 1, 2004 Maybe mike has really strong arms, or a really big steering wheel... Or both... Quote
Mike-SEiW Posted October 1, 2004 Author Posted October 1, 2004 Actually have not noticed braking to be very "sensitive" or difficult in any way. I've really enjoyed the car so far and don't have to do serious "battles" with it other than highway driving with the ACB10s which was very "nervous" . I have had about 4 turns left on the front top wishbone, so more camber (lots of it) certainly is possible. So maybe I need to do another turn then? What about the rears, similar relationship of turns/camber change? I am a total track junkie, and lots of camber isn't actually negative for tyre wear (within reason of course). It's toe that wears lots of rubber. However, too much camber and braking is hurt, you're absolutely right. So far though, without ARBs I've seen very even tyre wear but I have not experienced these A048 so I just wanted to measure where I was at and set things even between front and rear to get a starting point. However, I can conclude that Seven-type cars generally need less camber than other, more heavy cars, so that definitely speaks in favor of your recommendations. Quote
peterg Posted October 1, 2004 Posted October 1, 2004 FWIW crossply tyres (ie ACB10s and older generation slicks) normally require very little camber at all, my car runs 0.5 degree negative front and none rear IIRC. the newer radial slicks and modern track day tyres like AO48s need between 1 and 2.5 degrees to work correctly this may explain why the car was nervous on ACB10s Quote
Mike-SEiW Posted October 1, 2004 Author Posted October 1, 2004 FWIW crossply tyres (ie ACB10s and older generation slicks) normally require very little camber at all, my car runs 0.5 degree negative front and none rear IIRC. the newer radial slicks and modern track day tyres like AO48s need between 1 and 2.5 degrees to work correctly this may explain why the car was nervous on ACB10s Yep. I have since realised. How can one full turn of the upper wishbone (at the front) be 0.4°? Thread pitch is 1.5mm I think. It's about 230mm (rough estimate) between the lower balljoint and upper. 1.5/230/pi*360=~0,7° Hm...I have to turn at least two more turns to get reasonable camber. Quote
Mike-SEiW Posted October 1, 2004 Author Posted October 1, 2004 I just went out again and put the car flat and re-did my measurements. It seems I made a big mistake, measured camber by the tyre. Re-did it by actually using the rim of the wheel. Camber at the front is now (after one turn)... -1° ! Also didn't use my "approximation" of the angle, used inv tan and there's a discrepancy between using parts of a 360° circle (which I've done). Strange that. Same at the rear. Actually the one of the rears are about 1° camber but the other has positive camber by about 1° That must be remedied. So to all other newbies out there, don't do what I did, use the rim Quote
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