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Thread: AST Suspension

  1. #401
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    Quote Originally Posted by clopez95m3 View Post
    Hire more people. Where can I submit my resume?

    Carlos.
    I guess you missed the part about working until 2AM on a regular basis

  2. #402
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    Quote Originally Posted by kenster View Post
    I guess you missed the part about working until 2AM on a regular basis
    He also forgot he doesn't like the Texas heat.
    It's not speed that kills, it's the speed difference that does. Obviously you aren't going fast enough.

    Turning Benjamins into noise since 1997

    I read a list of the 100 things you MUST do before you die. Funny, "Yelling 'HELP'" didn't make the list!

  3. #403
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    Quote Originally Posted by Fair View Post
    Yes, we need more instructions - there's probably not a manufacturer out that that couldn't use more. The videos are easy to access and show more detail than a 1 or 2 page printed instruction sheet. We have a "cheat sheet" for shock tuning as well that needs to be added/link. We'll keep at it!
    Honestly, I thought a blow-up drawing of the entire shock/spring/camber plate assembly along with torque specs is all I really needed. Probably wouldn't be too hard to make and is a nice quick/easy reference. Lets face it, I have a few extra parts that came with the coilovers... still not sure I used everything I should.

  4. #404
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    Quote Originally Posted by Fair View Post
    snip...We have a "cheat sheet" for shock tuning as well that needs to be added/link. We'll keep at it!
    I would love to see that. I'm getting to the point where I need to dial my 4200s in.

  5. #405
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    I agree that more/better instructions would really be good, but understand that you guys are running flat out and if it's a toss-up between getting the suspension and the cornering levels it can achieve versus instructions, I'm quite OK with just the suspension, because it's working for us.

    Quick update. Been very busy - got the engine rebuid completed, installed, and the break-in miles on the car with the 11:1 CP pistons etc., are almost finished (another 100 to do later today), then it's off to a Test-n-Tune tomorrow. Initial A/F looks good. Actually need to lean it out some. I don't know, if we're the first to disprove the myth that one needs 24# injectors with cams, etc., etc., but were running 21.5# injectors, 3.5" HFM, headers, 11:1, etc., and have plenty of injector capacity left. They're not stretching their duty cycle at all.

    I mentioned earlier that we pulled 1.5g's at the last double regional, looking closer at the data last evening showed one run with a 1.54g on cold (first turn out of the start, albeit a long start) 265/35/18 BFG g-Force R1 tires. Now to get some fine-tuning done before Nationals.

    Regards, Alan
    2008 Canadian National AutoSlalom Champion - BSP
    2009 Canadian National SoloSprint Champion - SGT2
    (the car and my co-driver, not me)
    95 M3 3.2L OBDI (M-Perfect ) http://www.cardomain.com/ride/2078238
    was 3.0L (236 RWHP) now 3.2L, well modded - Arrest Me Red
    --------------------------------------------
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    When only the best will do!
    -----------------------------------------

  6. #406
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    Just completed my 2nd autocross with the AST's. Made some alignment adjustments from the first one, and can't believe how well the car did.

    I wanted to get some input on something -- the rear of the car seems to be leaning a LOT in turns. I'm running 515f/625r springs, 1" front sway (on full stiff), and stock rear sway with worn stock links. I did experience understeer, so I'm thinking a rear sway (or go softer on the front) is the way to go, or an increase in spring rates. Any input? Other than the understeer I'd like to correct, does it look fine in the pictures?

    http://bmwchannel.com/pics/072608/IMG_0199.jpg
    http://bmwchannel.com/pics/072608/IMG_0244.jpg
    http://bmwchannel.com/pics/072608/IMG_0270.jpg

  7. #407
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    Your car actually looks to be rolling pretty evenly front and rear as opposed to many E36's that roll a lot more in the front (see Alan's red car in the post above yours).

  8. #408
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    Quote Originally Posted by B.Watts View Post
    Your car actually looks to be rolling pretty evenly front and rear as opposed to many E36's that roll a lot more in the front (see Alan's red car in the post above yours).
    I concur. Seems to be just about right.

  9. #409
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    Alright, just wanted to check. I may just soften the front sway (like move the one sway link a hole "softer" and keep the other where it is) and go from there. Any input on the rear sway? The theory seems to be run a nice big bar in the front and stay stock in the rear - like I said I was experiencing some understeer, especially mid-corner. I have 1/4" total toe in the rear right now, maybe it's too much? Is it sad that I almost have as much fun adjusting the suspension than I do driving it?

    Could have been (probably was) my driving

  10. #410
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    Where was the understeer? Depending on where/when the understeer occurs and what your other settings are (alignment, etc), it may be solved with more front roll stiffness or less.

  11. #411
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    Quote Originally Posted by B.Watts View Post
    Where was the understeer? Depending on where/when the understeer occurs and what your other settings are (alignment, etc), it may be solved with more front roll stiffness or less.
    Corner entry/exit seemed fine, it was mostly mid-corner. Like I said, could just be my driving but I'm fairly confident I can get rid of some of it.

    My alignment was (around) -3.5 degrees camber front and -2.2 rear, and around 1/16" total toe out front, 1/4" total rear.

  12. #412
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    Quote Originally Posted by epj3 View Post
    Corner entry/exit seemed fine, it was mostly mid-corner. Like I said, could just be my driving but I'm fairly confident I can get rid of some of it.

    My alignment was (around) -3.5 degrees camber front and -2.2 rear, and around 1/16" total toe out front, 1/4" total rear.
    I have the exact same setup, and have the exact same problems. Turn in seems weak mid corner seems sloppy. My dads corvette even on stock tires/suspension seems to just beat the shit out of mine on turn in/mid corner.

    I was told by most people on this forum when I brougth my problem up that I should go with less front bar. But then when I was talking to someone at the track, I had him drive my car, and then I drove it with him passenger, and he suggested more front bar.

    Currently have 25.5 front bar and 20mm rear bar.

    I say you put your bar on full soft and report back, and if yours gets worse I'll buy a 28mm bar (if someone will sell me one for NOT 250 dollars), and we'll see whats up.

    BTW it even happens using Khumo 710's, as well as on my street tires azenis 615's. I am just like where is the grip?
    Last edited by Danny318; 07-28-2008 at 07:26 PM.
    '95 318i - DASC Supercharged - 269° Camshafts - 30lb injectors - Ostrich 2.0 tuning - Coil On Plug conversion - 11lb flywheel 228mm clutch - AST 4100's,

  13. #413
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    Quote Originally Posted by epj3 View Post
    ...rear of the car seems to be leaning a LOT in turns. I'm running 515f/625r springs, 1" front sway (on full stiff), and stock rear sway with worn stock links. I did experience understeer, so I'm thinking a rear sway (or go softer on the front) is the way to go, or an increase in spring rates....
    Quote Originally Posted by B.Watts View Post
    Your car actually looks to be rolling pretty evenly front and rear as opposed to many E36's that roll a lot more in the front (see Alan's red car in the post above yours).
    I'd agree. BTW, I should likely change that sig now that I'm running stiffer springs (550#F and 650#R) with the AST 4100s it's pretty hard to get the front wheel up.


    Actually, we're now having the problem of the inside rear getting too light on entry to slalom sections and putting it in the air just enough to stop that wheel and mess up the ABS. Bloody ABS releases some pressure and you feel as though you've don't have brakes for a split second. Anyone know the part # for the E36 Motorsport ABS module?
    Quote Originally Posted by Danny318 View Post
    I have the exact same setup, and have the exact same problems. Turn in seems weak mid corner seems sloppy. My dads corvette even on stock tires/suspension seems to just beat the shit out of mine on turn in...
    Danny a Vette will typically have better turn-in. One area to play with adjusting is slower entry which will allow much quicker exit.
    Quote Originally Posted by Danny318 View Post
    ... I was told by most people on this forum when I brougth my problem up that I should go with less front bar. But then when I was talking to someone at the track, I had him drive my car, and then I drove it with him passenger, and he suggested more front bar.

    Currently have 25.5 front bar and 20mm rear bar.

    I say you put your bar on full soft and report back, and if yours gets worse I'll buy a 28mm bar (if someone will sell me one for NOT 250 dollars), and we'll see whats up.

    BTW it even happens using Khumo 710's, as well as on my street tires azenis 615's. I am just like where is the grip?
    Unfortunately Danny, there are still a ton of people (even here ) quite willing to provide advise that is a very general rule-of-thumb advise to a specific situation without paying sufficient attention to the particular requirements. An E36/E46 does not fit into the general rule-of-thumb fixes, period.

    Just like you need a different setup for a Porsche 911 versus a Honda Civic, the E36/E46 needs to have it's actual suspension geometry addressed, not that of a Mustang, or what-ever else.

    The E36 needs more front bar not less to reduce understeer. It's well documented and is directly a result of the suspension geometry. The front suspension loses camber as it compresses. Sure this can be dealt with via higher spring rates but then you're going to loose grip in other areas.

    You appear to be running a 95 M3 (or 328i sport) front bar with a 96-99 M3 rear bar, this is actually the reverse of where I think you should be going. Run a 28/27mm front bar with your 20mm rear and see how that feels.

    Regards, Alan
    Last edited by Alan Coles; 07-29-2008 at 11:26 AM.
    2008 Canadian National AutoSlalom Champion - BSP
    2009 Canadian National SoloSprint Champion - SGT2
    (the car and my co-driver, not me)
    95 M3 3.2L OBDI (M-Perfect ) http://www.cardomain.com/ride/2078238
    was 3.0L (236 RWHP) now 3.2L, well modded - Arrest Me Red
    --------------------------------------------
    Sponsors: Amsoil, BFGoodrich, BimmerSpecialist.com, Corbeau, Dr. Vanos, StopTech VAC Motorsports, Vorshlag/AST, Zeckhausen Racing, 3M-TrimLine
    When only the best will do!
    -----------------------------------------

  14. #414
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    Quote Originally Posted by Alan Coles View Post
    The front suspension loses camber as it compresses.
    I understand what you're getting at, but this needs to be clarified a bit. The front suspension does not lose camber as it compresses. The camber gain rate is simply slower than the roll rate and the rate of camber continues to slow the "lower" you go. So, when you lower the car, you place the suspension in a less advantageous portion of the camber curve. You also lower the roll center quicker than the center of gravity, so the propensity to roll is increased.

    So, by lowering the car, you now get less camber gain per amount of suspension compression and has a larger tendency towards roll...thus, we run big spring rates and big front bars to fight that roll and large static camber numbers in order to deal with the limited camber gain we get from the suspension compression.

    There would be a point at which continued compression of the front suspension would cause camber loss...but by that point, your front tire would probably be starting to show through the top of our hood.

    At least that's how I've come to understand things. Those smarter than me can surely provide corrections.

  15. #415
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    Very nice Alan, thanks for the suggestions. I'll look at finding a larger front bar.
    '95 318i - DASC Supercharged - 269° Camshafts - 30lb injectors - Ostrich 2.0 tuning - Coil On Plug conversion - 11lb flywheel 228mm clutch - AST 4100's,

  16. #416
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    Quote Originally Posted by epj3 View Post
    Corner entry/exit seemed fine, it was mostly mid-corner. Like I said, could just be my driving but I'm fairly confident I can get rid of some of it.

    My alignment was (around) -3.5 degrees camber front and -2.2 rear, and around 1/16" total toe out front, 1/4" total rear.
    If the issue is mid corner, then it might be spring/sway balance. Mid corner is normally a steady state response (what spring/sways control), where entry exit is a transient response (what dampers control).

    i.e., go find a skid pad to ensure you're spring and sway package is balanced, then mess with dampers to make sure your transient handling is working.
    - Ian
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  17. #417
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    Quote Originally Posted by B.Watts View Post
    ...The front suspension does not lose camber as it compresses. The camber gain rate is simply slower than the roll rate and the rate of camber continues to slow the "lower" you go....
    At least that's how I've come to understand things. Those smarter than me can surely provide corrections.
    Bryan, on my car at least, I actually lose camber with spring compression as it currently sits.

    I'm too old to twist my head around the geometry, used to love math but the older I get the more I want things simple.

    All I did to identify this is to setup the car to -3.55 degrees front camber on the alignment rack. This was for both sides (L&R) and after bouncing the front-end a few times to ensure we had a true reading. I then sat in the car and observed the camber with a 200 lb driver (that's me dressed - not a pretty sight otherwise). This produced -3.3x front driver's side camber and -3.5x front passenger's side camber. The car lost approximately -0.2 degrees front camber on the driver's side with me in it versus without me.

    As we're looking for even handling, we then shimmed the lower driver's side strut to gain back that -0.2 degrees front camber on the driver's side with the camber plates in the same spot on both sides. This way we've already compensated for the driver and aren't having to remember different setting (L to R) for the competition settings. This is especially important for us when we run less front camber in the wet, etc., as we can match L & R camber plate points and still allow for the driver's influence on camber.

    Regards, Alan
    2008 Canadian National AutoSlalom Champion - BSP
    2009 Canadian National SoloSprint Champion - SGT2
    (the car and my co-driver, not me)
    95 M3 3.2L OBDI (M-Perfect ) http://www.cardomain.com/ride/2078238
    was 3.0L (236 RWHP) now 3.2L, well modded - Arrest Me Red
    --------------------------------------------
    Sponsors: Amsoil, BFGoodrich, BimmerSpecialist.com, Corbeau, Dr. Vanos, StopTech VAC Motorsports, Vorshlag/AST, Zeckhausen Racing, 3M-TrimLine
    When only the best will do!
    -----------------------------------------

  18. #418
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    Quote Originally Posted by Alan Coles View Post
    All I did to identify this is to setup the car to -3.55 degrees front camber on the alignment rack. This was for both sides (L&R) and after bouncing the front-end a few times to ensure we had a true reading. I then sat in the car and observed the camber with a 200 lb driver (that's me dressed - not a pretty sight otherwise). This produced -3.3x front driver's side camber and -3.5x front passenger's side camber. The car lost approximately -0.2 degrees front camber on the driver's side with me in it versus without me.
    You loaded the car with weight on one side, so you introduced ROLL into the equation. These cars do generally roll at a greater rate than the camber gain, which would account for you seeing less camber reading on the side of the car onto which you placed the weight.

    I promise you that as the suspension goes through it's range of motion, under compression, the wheel gains camber relative to the chassis. However, it doesn't gain camber at a rate quick enough to keep up with the roll you introduced so you lose camber relative to the ground. If you placed your weight directly along the centerline of the car, you would see more camber on both front wheels.

    Keep in mind that you've added weight to the car which effects a lot of things rather than just the alignment. Your CoG, weight balance, ride heights, etc, all change. It's not the same thing as measuring the camber gain of the suspension as you put it through it's range of motion. Put the car on the lift which the wheels unsupported, remove the spring and move the suspension through it's entire range of motion. The hub/wheel will gain camber throughout the entire range of motion from full droop of your damper till when your tire hits the top of your fender liner.

    This thread that I started looking for more explanation has some good discussion from a few of the experts around here:
    http://forums.bimmerforums.com/forum...ht=camber+gain
    Last edited by B.Watts; 07-30-2008 at 11:38 AM.

  19. #419
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    Quote Originally Posted by B.Watts View Post
    I promise you that as the suspension goes through it's range of motion, under compression, the wheel gains camber relative to the chassis.

    This thread that I started looking for more explanation has some good discussion from a few of the experts around here:
    http://forums.bimmerforums.com/forum...ht=camber+gain
    This really isn't open to debate as it was an element of suspension design that won BMW an award way back (late 70s?). There's a list of BMW innovations that BMW displays at dealerships on occasion.

  20. #420
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    BMW suspensions are great for the street - but even back then, BMW was messing with suspension geometry on the e9/e30/e28/etc race cars to control roll centers, toe changes and camber curves.
    - Ian
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  21. #421
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    Quote Originally Posted by epj3 View Post
    Corner entry/exit seemed fine, it was mostly mid-corner. Like I said, could just be my driving but I'm fairly confident I can get rid of some of it.

    My alignment was (around) -3.5 degrees camber front and -2.2 rear, and around 1/16" total toe out front, 1/4" total rear.
    My co-driver and my ///Ms are running AST 4200s:
    Springs: 586F 628R and 628F 686R
    Bars: 28mm full soft front, stock rear.
    Tires/wheels: square
    Camber: ~ -3.5 and -2.0
    Toe: 3/16th out and 3/16th in.

    Initially we had the front bar set on full stiff. After skid pad testing we settled on full soft to balance out the steady state understeer. The softer car still has a small bias toward understeer and the stiffer car has a slight bias toward oversteer.

    My suggestion would be to add grip to the front by softening the front bar. Our cars are about where we want them. We'll probably go to a 600-628F and 650R to see if that nets us a balanced car with little to no front wheel lift. Currently the understeer in the softer car is mostly coming from a touch of front wheel lift.

    Rob
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  22. #422
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    so wtf, stiffer front bar or softer for me ?
    '95 318i - DASC Supercharged - 269° Camshafts - 30lb injectors - Ostrich 2.0 tuning - Coil On Plug conversion - 11lb flywheel 228mm clutch - AST 4100's,

  23. #423
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    yes
    - Ian
    2000 M Coupe, stripped and DE prepped

    46mm wheel bearing socket for rent - $30 deposit + $10 fee. PM for details.

  24. #424
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    Quote Originally Posted by Danny318 View Post
    so wtf, stiffer front bar or softer for me ?
    Yes and No. There's rarely an off-the-shelf answer that works for everyone...too many variables from driving style to tires to surface to shock damping to... That's the reason for test & tune days.

  25. #425
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    Quote Originally Posted by B.Watts View Post
    Yes and No. There's rarely an off-the-shelf answer that works for everyone...too many variables from driving style to tires to surface to shock damping to... That's the reason for test & tune days.
    if only alternate parts were provided free of charge on these test and tune days
    '95 318i - DASC Supercharged - 269° Camshafts - 30lb injectors - Ostrich 2.0 tuning - Coil On Plug conversion - 11lb flywheel 228mm clutch - AST 4100's,

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