Track car alignment, Unsettled debate |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Track car alignment, Unsettled debate |
stephenpowless |
Sep 27 2013, 08:42 PM
Post
#1
|
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.
|
brant |
Sep 28 2013, 07:33 AM
Post
#2
|
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 |
stugray |
Apr 22 2016, 04:22 PM
Post
#3
|
Advanced Member Group: Members Posts: 3,825 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
We settled on -2.25 ish for our front setting Brant, I tried your suggestions on my front suspension to get more camber than stock. I removed the kidney shaped "hats" and trimmed the inboard side off with a bandsaw to eliminate interference inside the shock tower. (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1461363731.1.jpg) I also enlarged the bolt holes in the in board direction. Now I can get up to 2.0 degrees camber on that side before the "neck" of the shock top hits the side of the large opening. So I am wondering if I can use the porting tool and remove the inboard lip of that hole to give me another .25 degrees. Can I enlarge the big hole by ~0.25 in without ruining the rigidity? I am sure the lip adds some stiffness in that area, but I dont think it will make much of a difference overall. Here is where I would like to cut back about far enough to remove that lip entirely. (IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1461363732.2.jpg) Thoughts? I could buy the $350 offset billet tops but this costs essentially zero. |
ChrisFoley |
Apr 25 2016, 07:21 AM
Post
#4
|
I am Tangerine Racing Group: Members Posts: 7,934 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
|
Lo-Fi Version | Time is now: 3rd June 2024 - 08:50 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |