Track car alignment, Unsettled debate |
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Track car alignment, Unsettled debate |
stephenpowless |
Sep 27 2013, 08:42 PM
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#1
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Newbie Group: Members Posts: 6 Joined: 27-September 13 From: Minneapolis Member No.: 16,444 Region Association: None |
I have a 74 914 tub converted to a track car. Sheridan body kit, 3.6 varioram motor, 915 tranny(which I hate and may convert to G50), 935 front suspension, 944 turbo brakes, bilstein coil overs. On flat straightaways, it's debating which tire to follow and darts left and right, as if there is a strong cross wind. Had it re-aligned as follows; scale, L/F 497. R/F 458, L/RR 638, R/RR 590. Camber : L/F 3.5. R/F 3.6. L/RR 1.8. R/RR 2.0. Toe: L/R front 0, L/RR 1.5. R/RR 1.5. It's still "debating" at speed, which is very unnerving going into turn one at BIR. The questions are; is the alignment the problem or do I need some downforce via a wing? Appreciate any insight. This is my first visit to this forum. Thanks in advance.
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brant |
Sep 28 2013, 07:33 AM
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#2
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914 Wizard Group: Members Posts: 11,632 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
I run about a quarter degree less negative camber in the front than in the back. So up your rear number and straighten out your front. Hoosiers also.
I always set my rear suspension to a balanced number that is close to what I can max the worse side at. And then set my front ratio for a quarter less than I got on the rear. So for example rear at -2.50. And front at -2.25 I think your front end is skating down the straight on a very small corner of contact patch. We noticed significant brake capability loss when we went more than -2.75 or -3 degrees in the front. Even though th Hoosier would like the negative camber in the corners it didn't like the contact patch under breaking. We settled on -2.25 ish for our front setting What suspension bushings do you run in the rear? With a bushing that has no movement like a metal mono ball you can go to zero toe. Otherwise a 16th of toe in. I think you probably should realign. I don't know how often you are realigning but it changes much more than you would expect and frequent re alignments are a necessity on a track 914. Our car weights are different which also has an impact on the tires and their temps so you may have slightly different alignment needs too |
ChrisFoley |
Sep 28 2013, 08:34 AM
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#3
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I am Tangerine Racing Group: Members Posts: 7,934 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
I run about a quarter degree less negative camber in the front than in the back. So up your rear number and straighten out your front. Hoosiers also. I always set my rear suspension to a balanced number that is close to what I can max the worse side at. And then set my front ratio for a quarter less than I got on the rear. So for example rear at -2.50. And front at -2.25 I think your front end is skating down the straight on a very small corner of contact patch. We noticed significant brake capability loss when we went more than -2.75 or -3 degrees in the front. Even though th Hoosier would like the negative camber in the corners it didn't like the contact patch under breaking. We settled on -2.25 ish for our front setting What suspension bushings do you run in the rear? With a bushing that has no movement like a metal mono ball you can go to zero toe. Otherwise a 16th of toe in. I think you probably should realign. I don't know how often you are realigning but it changes much more than you would expect and frequent re alignments are a necessity on a track 914. Our car weights are different which also has an impact on the tires and their temps so you may have slightly different alignment needs too I agree with Brant that you should be running less front camber. You should also check bump steer on all 4 corners. Depending on the how low the car is, the loaded rear tire could be toeing out quickly as you turn in, which means extra rear static toe-in is needed. Without knowing the camber and toe curves of your suspension setup raising the ride height may be the easiest way to improve handling. |
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