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Rear end is way too tail happy. How do I get more lateral grip?

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  • Alex4130
    replied
    Here is a quick side pic of how she sits now.

    Just a recap.
    BC Coilovers (8k front 12k rear) (Max Height)
    22m Front Sway Bar, No Rear Sway Bar
    95a Poly Bushing everywhere.
    5mm Rear spacers
    -3.5 camber, zero toe front, 0 camber and toe for rear. (or something like that)
    SLR mini kit with e46 control arms with IRP 5 lug conversion kit (Great product)
    Decent tires (200 count)

    Aside from tires, I really think removing the rear sway bar and getting the stiffer rear springs (8k to 12k) was the winning answer to my original question.

    Leave a comment:


  • Fooshe
    replied
    Check Rear subframe bushings and bolts. Disconnect your rear sway bar and increase your rear camber.

    Leave a comment:


  • 4ce30
    replied
    Throw a picture up of it. Side would be ideal

    Leave a comment:


  • Alex4130
    replied
    Okie Dokie guys. My car feels amazing now. Thanks for all the help.

    Yes, all bushing were replaced like 4 years ago to some 95a poly, but solid recommendation.

    I also loved the suggestion about the rake of the car.I don't hard park, so my coils are at max height and the rear does sit a bit higher when static (especially with the new springs).
    Might not look good for the instagrams, but that's what perfection looks like ladies and gentlemen.

    Anyways, what I did was,

    1.) Replace rear springs to 12k (I personally think this was the winning ticket)

    2.) Minor 5mm wheel spacers to rear (don't know if it had an effect, but the ol e30 looks better now)

    3.) And got some nice 200 treadwear rubbers, 225's (in reality, this probably was all I need to do; fuck me right?)

    I'm back on my drift alignment 0 camber and toe as well, and even with this setting, the car has grip for days.

    Moral of the story, is follow your dreams and if at first you don't succeed you should probably just give up because in the end it's going to cost you money and they are just
    jealous that we are smarter than them on the account of the extra bone in our body, but science doesn't want to acknowledge that.

    Amen brothers

    Leave a comment:


  • moatilliatta
    replied
    Originally posted by TobyB View Post
    what is this k you speak of? Degrees Kelvin?

    Last I recall, and it's been a while, I might be 800lbs/in front, 700 rear. It is entirely possible that I've transposed those numbers...
    ...but the car will lap acceptably with the same rate front/rear (and yes, that means a rear wheel rate about 62% of front wheel rate)

    Other things that will affect balance, in addition to the above tire discussion:
    for a track car, you want MORE rear camber. With a 50 series radial R1R, the paddock seems to average about -4 in back.
    Some of the fastest have more- and some of their strongest competition have less. Most of the rest of us vary it a bit
    to get even (ish) loaded tire temps.

    Don't overlook rake- getting the nose down and the ass up has counterintuitive effects on balance- yes, it's quicker to turn
    in, but grip seems to improve in back, despite what one might think. If it's too waggly right on turn in and not unstable in mid-
    corner, take some rake out and see what happens. The roll centers on E30s are.... a fiasco, quite frankly.

    t
    or something
    -4 degrees rear camber and rake will not help keep the rear planted.

    Leave a comment:


  • glnr13
    replied
    Originally posted by TobyB View Post
    what is this k you speak of? Degrees Kelvin?
    LBS(pounds) / inch vs KG(Kilograms) / mm

    Leave a comment:


  • TobyB
    replied
    what is this k you speak of? Degrees Kelvin?

    Last I recall, and it's been a while, I might be 800lbs/in front, 700 rear. It is entirely possible that I've transposed those numbers...
    ...but the car will lap acceptably with the same rate front/rear (and yes, that means a rear wheel rate about 62% of front wheel rate)

    Other things that will affect balance, in addition to the above tire discussion:
    for a track car, you want MORE rear camber. With a 50 series radial R1R, the paddock seems to average about -4 in back.
    Some of the fastest have more- and some of their strongest competition have less. Most of the rest of us vary it a bit
    to get even (ish) loaded tire temps.

    Don't overlook rake- getting the nose down and the ass up has counterintuitive effects on balance- yes, it's quicker to turn
    in, but grip seems to improve in back, despite what one might think. If it's too waggly right on turn in and not unstable in mid-
    corner, take some rake out and see what happens. The roll centers on E30s are.... a fiasco, quite frankly.

    t
    or something

    Leave a comment:


  • Sh3rpak!ng
    replied
    Wow surprised by all the spring rate feedback. I've been sitting on 8k front 10k rear for a while now.

    Tires and alignment (plus worn bushings) definitely the place to start. What is your rear differential situation?

    Leave a comment:


  • bradmer
    replied
    Originally posted by e30davie View Post
    "Cheap Hankook 225x17 tires"

    In the words of Adam Savage - "Well there's your problem"
    17" BFG Rival S tires with 30 lbs of air pressure in the fronts, 28 lbs in the rears. Or get the 15" wheels so your not rubbing because the Apex 17's kept rubbing at the track on our e30.

    Good luck!

    Leave a comment:


  • twright
    replied
    I have a better place to start: Have the rear subframe bushings ever been changed? If these are original, the rear will be all over the place. Change these first.

    Leave a comment:


  • roguetoaster
    replied
    No, springs are a bad place to start. Start with tires, then move on from there.

    Leave a comment:


  • Alex4130
    replied
    Thanks everyone for the responses.

    I know 235's might fit, but one of my rear fenders is filled with bondo. Can't roll it and Im rubbing a decent amount with the 225s. Hence the over fenders.

    Ill be sliding it around this winter season, so it will be a while until I time attack and test these theories on my shitty turd of a car.

    I suppose Northern is right in that springs are a good first place to start.

    Ill left you fellas know.

    Cheers!





    Leave a comment:


  • Victell
    replied
    Tire pressures have an effect too. Lower pressures in the rear for less tail happy.

    Leave a comment:


  • tyeler18
    replied
    My 318IS I run square 245's with a 8k Front/14k rear and a 22mm front sway bar (stock rear) and find the car just on the edge of tail happy. Right where myself (and everyone who drove it the last track day) think it's perfect. -3.5ish front camber, no rear camber adjustment so whatever it ends up at with stock bushings. The car has a very nice controllable amount of oversteer.

    Leave a comment:


  • Northern
    replied
    absolutely increase that rear spring to something 12K. Would contemplate more, but 14k (~800lb/in) is a bit much for that front spring.

    Quality 225s will make a big difference as well, but bang-for-buck, I'd do springs first.

    Leave a comment:

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