09-10-2012, 02:55 PM | #1 |
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Geometry - Before and After
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Had my geometry checked last week, by Center Gravity in Warwickshire. Thought it would be interesting to share the results. Chris Franklin at CG in my opinion is unmatched. I had a poor handling 993 transformed by him in the past, and I was intested to see which way the wheels were pointing on the 1M in it's as it left the factory state. He's very well known in Porsche circles, some dont get what he does, some rave about him. I'm in the second group. Chris's service includes a test drive before and after, detailed interview about how you use the car, what you want it to do, what you dont like, etc. Then you get to spend the time stood at his and Pete's shoulder if you wish watching them work, and learning about the car, and suspension set up in general. Very informative. My car always felt a little nervous to me, which I put down to it's character and wheelbase. Anyway heres the before and afters : Intial Rear Axle Camber L -2 deg 09' R -1 deg 39' Toe L +0 deg 02' R +0 deg 16' (+ is toe in) Total Toe +0 deg 18' Setback -0 deg 09' Geometric Axis +0 deg 07' Front Axle Castor L +7 deg 06' R +7 deg 10' KPI L 15 deg 22' R 14 deg 57' Camber L -1 deg 32' R -1 deg 10' Cross Camber -0 deg 23' Toe L +0 deg 05' R +0 deg 03' (+ is toe in) Total Toe + 0 deg 08' Setback -0 deg 06' Included Angle L +13 deg 50' R +13 deg 48' And after (including disasssembling the strut brace and all surrounding plastic bits to remove the factory alignment pins) heres the end result Final Rear Axle Camber L -1 deg 35' R -1 deg 33' Toe L +0 deg 06' R +0 deg 7' (+ is toe in) Total Toe +0 deg 13' Setback +0 deg 01' Geometric Axis +0 deg 00' Front Axle Castor L +7 deg 00' R +7 deg 03' KPI L 15 deg 07' R 15 deg 06' Camber L -1 deg 22' R -1 deg 20' Cross Camber -0 deg 02' Toe L +0 deg 03' R +0 deg 04' (+ is toe in) Total Toe + 0 deg 07' Setback -0 deg 04' Included Angle L +13 deg 45' R +13 deg 46' Its now straighter than a straight thing... Targets were based around an M3's basic set up as we didn't have explicit 1M numbers, although Chris is on the case with BMW to get them and we will compare. Rear cambers aren't very extreme at the moment, as yet I dont track the car. Might increase them when I move to Supersports. The rear axle in particular was a bit out, with cambers and toes fighting each other a little. Car demonstrated "left slip" intially, which was at odds with the initial toes at the rear. The end result is pretty stunning, the car is much more composed and faithful. Steering feel is better and the matched cambers seem to have improved traction as well. Very very pleased with the result. Pete |
09-10-2012, 03:27 PM | #2 |
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Hi Pete
I'm not a suspension expert, but I find high speed stability not that great. Has the changes to your geometry improved the car in this area? Like you I find the car a little nervous especially now that I'm running Evolve's stage 1. Would geometry adjustments improve traction when accelerating hard and keep the car tracking more direct? I've decided not to go down changing the suspension but good to know that improvements can be made to the stock setup!
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09-10-2012, 04:14 PM | #4 |
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The high speed stability feels better to me, not had it to serious leptons since the geo, but it doesn't seem to get deflected as much, just goes where you tell it. My rear axle was fairly wrong though, toe and camber ecentrics were just on nominal as built. I'm sure the tractions better, could be my imagination, but the little yellow light seems an awful lot calmer on full nanny mode. It wasn't putting the same amount of rubber on the road at the back before !
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09-10-2012, 04:29 PM | #5 |
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I am currently running
front axle camber L -1 deg 31' R -1 deg 26' caster L 7 deg 06' R 7 deg 00' toe L 0 deg 07' R 0 deg 05' total toe 0 deg 12' rear axle camber L -1 deg 37' R -1 deg 38' toe L 0 deg 02' R 0 deg 04' total toe 0 deg 05' running KW DDC coilovers...... |
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09-10-2012, 04:30 PM | #6 | |
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09-11-2012, 11:14 PM | #7 |
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Less negative camber and slightly more toe-in will improve stability in most cases.
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01-03-2016, 11:25 AM | #8 |
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I am going to re-awaken this old thread because I found the measurements interesting. The OP balanced out a discrepancy in the camber (more negative on the left front and rear) and ended up pretty close to symmetric. The OP also took camber out of the rear, so I am assuming this is not a track or autocross car. At stock settings, with HPDE days and autocrosses, my rear tires wear evenly across the tread at -1.7 to -1.9 camber.
With recent install of camber plates, I have taken some measurements and corrected my front toe. I am looking for advice on what to do at the rear when I take it to a shop for a custom alignment. I will be looking to dial in the rear, and verify/fine tune my front setup. My car had about 0.2 degrees more negative camber on the LEFT both front and rear from the factory. Another forum member had his alignment checked when new, and had similar findings, see this thread, post #6. http://www.1addicts.com/forums/showt...ight=alignment I corrected that with the camber plates in the front and will also correct the rear. Interestingly, more negative camber on the left is the opposite from what you would want to counteract the imbalance created with only a driver in the car. Has anyone else noted this? Is there any reason to maintain that difference? I am only able to measure Camber and total toe with my method. Current measurements Front Axle Camber -2.7 right and left Total toe 0 I plan to keep this geometry and have the shop fine tune the toe. Rear axle Camber -1.9 L / -1.7 R Total toe 0.2 degrees (0 deg 13') toe OUT This is my factory alignment, has never been adjusted. I am surprised to find toe out, although it is mimimal. In balancing out the camber in the rear, I am thinking of -1.9 on both sides if possible, and I was thinking zero toe or perhaps mimimum spec (0 deg 2' toe IN each side). Any thoughts? Last edited by CarJunkie; 01-03-2016 at 07:58 PM.. |
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01-16-2016, 10:46 AM | #9 |
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UPDATE:
I retook measurements with someone of my weight (about 190lb) sitting in the driver's seat, and it corrected the cross camber in the rear. I then also returned the left front camber plate to its original position (with car empty, camber -2.9 L / -2.7R) and the front is now symmetric with a driver in the car. So, even though lowering the car on one side would increase negative camber relative to the car body, the net effect is an decrease in negative camber relative to the road surface as the tilt of the car has more effect. New measurements with driver in car: Front Camber:-2.8 L -2.8 R Front toe: 5 minutes toe IN (will gradually work this towards 0 toe and see how it feels, waiting for warmer weather for real roadtest and autocross) Rear Camber: -1.8 L -1.8 R Rear Toe: 0 degrees 6 minutes toe OUT I have not adjusted the rear at all, so this is how it came from the factory and a few years of driving. |
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01-16-2016, 11:08 AM | #10 |
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Here is another great thread on alignment:
http://www.1addicts.com/forums/showt...ght=toe&page=2 What I am trying to find now is some input on what to do with the rear when I go to get my alignment confirmed and fine tuned at a good shop (want to see how good my measurements are, and don't want to try adjusting the rear myself for many reasons.) I am pretty sure I read somewhere that a little bit of toe out is desirable in the rear for autocross, but increases instability at high speed. I already seem to have rear toe out, and like the way the car has always felt on the road and at the track, never felt unstable. I autocross frequently, do about 3-4 track days per year, and daily drive the car about 8 months of the year in good weather. My greatest concern is the risk of snap oversteer, especially at the track. I have a HUGE increase in front grip now, which I counterbalanced somewhat by installing the M3 convertible front sway bar, but wonder what I should do with the rear toe to improve stability and maximize grip when powering out of corners. Thoughts? |
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01-16-2016, 11:51 AM | #11 | |
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A little toe out is good in the front for autox since it gives great turn-in. Toe out in the back would be scary bad in almost all situations. Neil |
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01-16-2016, 02:00 PM | #12 |
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I am surprised to see it since the car feels great. I will have to wait and see what the alignment shop gets for measurements, but I am pretty sure I am getting accurate measurements. I had planned to do 0 toe all around, or perhaps minimum toe in per spec at the rear.
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01-25-2016, 03:26 PM | #13 |
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Excellent thread, I've used CentreGravity a few times, and they've worked wonders on my 1er with KW setup.. running -3 camber up front and -2 camber on the rear, with alittle toe.
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01-28-2016, 08:14 PM | #14 | |
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Neil is spot on here. |
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02-03-2016, 03:02 PM | #15 |
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Got to the alignment shop, a place that does custom alignment and allows driver in car, recommended by three guys in my local autocross club.
My personal measurements are above in prior post. Baseline measurements: Front Camber -2.6 L -3.2 R (didn't think the Vorshlag plates could even get that much) Toe was 0.1 degree toe in, pretty close to my measurements. Rear Camber -2.2 L -1.7 R Toe 0.15 degrees toe OUT, similar to my measurements. Notice that the cross camber was off in opposite directions front to rear. This was with the camber plates in front set to exactly the same hashmark, meaning that the car frame would have to be off that much. My own meausrements were entirely consistent with baseline measurements others have posted on this car. Despite that, I had them go ahead and correct everything. I left with this: Front Camber -2.4 both sides Toe 0 Rear Camber -1.8 both sides Toe 0.1 degree toe in To the naked eye, the right front and left rear obiviously have less negative camber now. I took a level and verified that my garage floor does not have any major issues that could have screwed up my measurements, and it is pretty damn perfect. I think the shop's rack is not level, the only explanation I can think of. Headed to another shop where one of the autocross club members will actually do the work. Should have just gone there the first time, but the first three responses to my request for a recommendation were all for the place I went to. |
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02-03-2016, 04:09 PM | #16 |
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I am now sitting in my driver's seat on a Hunter HawkEye rack (much better equipment than the last shop) and my suspicion is confirmed.
Initial reading here: Front Camber -2.8 L (same as my measurement, not adjusted at the other shop) and -2.0 R Rear Camber -1.2 left -1.8 right. Most of the adjustment done at the first shop was on the left side in the rear. Happily, a fellow autocross club member works at a shop with good equipment and was able to get me in and hook me up today! |
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02-03-2016, 06:10 PM | #17 |
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Final numbers:
Front Camber -2.7 both sides Caster 7.2 L / 7.4 R Toe 0 Rear Camber -1.9 L / -1.8 R Toe 0.05 degrees toe in both sides, 0.1 degree total toe in. Very happy with results so far, and think I was pretty close to this with my own measurements and front adjustments. Once there is warmer weather and a chance to autocross, I'll see how the balance feels at the limit. RE-71R's got delivered today also . . . Last edited by CarJunkie; 02-04-2016 at 09:02 PM.. |
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02-03-2016, 07:07 PM | #18 | |
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Glad you got it "straightened" out. Neil |
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02-03-2016, 07:34 PM | #19 |
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No kidding. There was another thread where a forum member had a terrible alignment that probably resulted from poorly calibrated equipment. As soon as I saw their baseline measurements, I should have trusted my own work (no way I was sloppy enough to be that far off!) and ran from that place. Lesson learned.
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06-20-2016, 09:10 AM | #20 |
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I finally got to the autocross after dialing in my alignment with camber plates. Work schedule and weather have not cooperated until now.
When I installed my Maddad midpipe two years ago, I found myself going from B street to ASP! Needless to say I got PAX'd into the depths of hell and haven't won class in two years. At this point, all I have done is the midpipe and Camber plates with a proper alignment (and a front sway bar which would be allowed in B street) so I am far from a full ASP build. The obvious BIG item would be coilovers and they are going on the car for next year. The understeer has been removed from the car and it rotates really well. I am using RE71R's 255F/275R on stock wheels. I managed to win class by 3/10ths, very excited. Fixing the understeer in this car goes a loooong way! For your viewing pleasure: Last edited by CarJunkie; 06-20-2016 at 09:29 PM.. |
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06-23-2016, 07:16 PM | #21 |
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This is a great thread becuase I just put come MCS/Ground Control coil overs on and need to get an alignment. I was going to post asking about spec's to give to them.
My car is a street car that occasionally sees a track day or two a year. What would you guys advise for an alignment set up? I am running 295/35/18 and 275/35/18 on Apex EC7's. I also have upgraded away bars, subframe and diff bushings, MFactoy LSD, upgraded sway bar end links, etc. essentially the suspension is worked over and I need a good alignment. Thanks for the input! Sam
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06-23-2016, 08:54 PM | #22 |
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It is too early for me to tell how the tires will wear, but it *looks* even so far with the specs I listed above. I have put about 4000 miles on the tires, plus 1 autocross (8 runs) and 1 track day with about 110 minutes of track time.
Having 1 degree more negative camber in the front compared to the rear seems to be a very good balance with my FSB. The understeer/oversteer balance depends on what I am doing with brakes and throttle and is very predictable now that I have gotten used to it. I can't wait to see what better damping does! |
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