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01-31-2014, 07:42 PM | #1 |
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More Camber in Rear?
Just picked up the car after getting rollbar and harnesses installed. I also replaced front left wheel bearings both front control arms (ball joints exhibited a lot of play) and FCAB's. The shop is pretty well known, owner does a lot of coaching for Ferrari challenge. I left the spec sheet at home but I remember being surprised they dialed in more camber for the rears, approx -3.0 in rear and -2.6 in front. I don't necessarily require more camber up front but I would think fronts would relatively be more negative than rears. Is this not surprising to anyone else?
I do have a picture of the corner balance specs, told him to assume 165lbs for driver. I'll post the alignment sheet later. How it sat initially Dialed in with driver weight Last edited by 3002 tii; 01-31-2014 at 09:35 PM.. |
01-31-2014, 08:11 PM | #2 |
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Have they set up a Z4 before?????
I find the rear camber very surprising
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01-31-2014, 08:33 PM | #3 |
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Mostly e30/36/46's but these settings were based in his actual seat time driving a Z4 in Grand AM. He said he recommends more camber in the rear due to the short wheel base and if anything he would up the camber in the front after seeing how the tires wear after doing some lapping.
Last edited by 3002 tii; 02-01-2014 at 08:50 AM.. |
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02-01-2014, 03:17 PM | #5 |
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I would expect the car to push. If I recall, I run about 2.5 in front and 2 in rear. Rears are generally still wearing the inside more than outside.
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02-03-2014, 04:07 AM | #6 |
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I was at -3.6 front and -2.8 rear and it was still understeering. It was really hard to rotate the car but the rear was planted at high speed.
But I also had APR splitter and wing on the car so it might affect the grip. |
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02-03-2014, 03:35 PM | #7 |
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-3.6 in the front
At that point i'm wondering if you are losing contact patch. Has any one checked tire temps following a session? I am currently running -2.5 in the front and -2 in the rear. Tire temps across the tread in the rear are pretty even. The front depends somewhat on the specific track (sweepers vs. a lot of tight turns) but overall it seems to be a good compromise. Also IMHO some of this could also be due to suspension settings (spring stiffness, compression, sway bar, and toe) |
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02-04-2014, 04:52 PM | #8 |
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I suspect that you also had a lot of toe-in at the front. Try a touch of toe-out and the car will become very "pointy". Why do you need so much static camber?
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02-04-2014, 07:18 PM | #9 | |
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-the tires he is running -skill level -spring rates -sway bars -and the track. From a person with a full time track car and a fairly skilled driver, those numbers aren't crazy. 3.5-4 is very common on any bmw. My 2 cents. |
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02-04-2014, 09:35 PM | #10 | |
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I have no camber wear running that much static camber. With -3.2 f, I had camber wear on the outside shoulder ... I have 650f/750r spring rate with KW Clubsport, GC hollow sway bars with adjustable links, Pirelli Dry Hard slicks, APR wing and splitter. I have more toe-out than I usually had on my E46 M3. I don't remember exactly (will need to check) but I think I have 1/16'' total toe out. Things I suspect: -rake/splitter angle under acceleration -APR wing was not set properly, give too much downforce and drag also. -front swaybar adjust too stiff, rear swaybar adjust too soft -too much camber in the rear |
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02-04-2014, 09:42 PM | #11 | |
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02-04-2014, 10:27 PM | #12 |
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So yea.... back to MY original question?
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02-05-2014, 09:18 AM | #13 |
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Don't know if this is of any help, but here are the Dinan alignment specs for their Stage 1, 2, and 3 setups. As mentioned before, springs, bars, shocks... all play a part. Even the Stage 3 which is the most aggressive setup has more rear camber than front. While these are not specs for a track car, they do provide some perspective. Unfortunately, there is no substitute for track time testing.
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02-05-2014, 09:25 AM | #14 | |
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02-05-2014, 11:46 AM | #15 |
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You're at the point where only track time will tell you what you need to know, to many variables to second guess. Keep posting your observations!
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02-05-2014, 02:51 PM | #16 |
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I'm at about 2.7 fr and 1.9 rear. Fr caster is near 8 and toe is close to zero, just a little toe in rear if I recall. Feels pretty balanced front to rear, had it out on street tires past weekend at roebling for the initial shake down of the air setup and it felt great apart from the lack of ultimate grip from the conti dw tires on track of course. Especially after being out in another car with some aero and r comps.
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02-05-2014, 08:00 PM | #17 |
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What It all boils down to, is the best setup for your specific application. ( I know that was a little too general)
In addition to all the above mentioned variables, it also depends on what each driver wants. Even in the pros you can have drivers even on the same team that disagree on specific settings, one wanting the car more "loose" than others. All I'm saying is that one specific setup recommended by anyone isn't going to be perfect for everyone. |
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02-06-2014, 10:35 AM | #18 |
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Are your tires squared up?
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02-06-2014, 01:41 PM | #19 |
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02-06-2014, 03:08 PM | #20 |
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So I find SOME credibility in the suggestion for more camber in the rear based on this fact.
I remember back in 2006 when I first got my car, I asked a friend and a very accomplished club racer to drive the car for a few laps at Willow Springs. He came away impressed, but when I asked him if he thinks I should square up the tires, he said "absolutely not." I was somewhat surprised by his answer, but he said that with comparatively a short chassis like this, he would prefer a staggered set-up to make the rear end more manageable while sacrificing some level of grip up front to make the chassis more predictable in corner exit, and that's where ultimately I will find my speed. And while I spent the next 8 years hunting for more grip up front, what he told me sort of jives with that your shop said. That on a relatively short chassis like this, neutral handling may not be all that ideal because the force required to overcome the pendulum that swings on that fulcrum that's the front tire isn't nearly as big as say, an E36 M3, the king of "more camber up front." So, I'm not entirely sold on having more negative camber in the rear, but back then I wasn't entirely sold on sticking with the staggered tire setup, and it's actually worked out quite well for my chassis and driving style. My only suggestion is, you went to a pro-shop for a reason. Trust their recommendations. Go drive a few hard sessions in current setting, take some measurements, and if you find yourself pushing into the corners way more than you'd like, bring those feedback to the shop and see what they say. A good shop would take your input to heart and find a better baseline for you. And who knows, you may like the additional grip in the rear.
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02-06-2014, 05:37 PM | #21 |
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From my driving experiences/tire wear trends I find that my car likes more camber up front then in the rear.
I had similar experiences up front with tire wear as already mentioned. My major issue with this car initially was major understeer on turn in...I digress sorry! Focusing on the rear I noticed signs of too much camber wear when set higher then ~-2.3 I believe, -1.8 seems to be my current sweet spot. I should add this has been my experience with heavy track and autocross (lately) use on stock suspension/HR springs & front sway bar, e36 shims, dunlop star specs or nitto nt01s. I was running staggered setup too....unfortunately. |
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