Page 1 of 5 12345 LastLast
Results 1 to 25 of 113

Thread: Spring rates for drifting

  1. #1
    SLR is offline Senior Member Supporting Vendor
    Join Date
    Jun 2004
    Location
    Florida, USA
    Posts
    895
    My Cars
    '08 E46, E36,

    Spring rates for drifting

    Here is the new thread to avoid the total hijack of Mike Essa's thread that I caused lol.

    Quote Originally Posted by fishtail View Post
    Mike I'm a big fan, I'm super excited to see this car next year in ATL!

    And not to threadjack, I just figured I'd pick your brain on this matter.

    I have an issue with my e36 being extremely twitchy while drifting, like it will only transfer smoothly if I stay flatfoot pretty much at all times. Do you have any ideas on how I can set my car up to slow down my transfers? (in otherwords, I actually want to be able to pedal off)
    As Mike asked, what is your tire/suspension setup?

    But in general the E36 has a LOT of rear grip, and when you lower these cars they lose front grip, so they become even more rear grip biased. That's why most of the hot setups for roadracing include big rear bars and getting some front roll-center correction.

    The problem is made even worse by cheap coilover companies not knowing ANYTHING about the platform and offering spring rate combos like 8kg/6kg or 8kg/8kg. The rear spring location on E30/E36/E46 means you need a much HIGHER rear rate than front in order to have a balanced feeling car, and it scares me to think these cheap suspension companies are likely valving their shocks inappropriately also considering the shock location.

    Right now pro drifting has been moving toward much more rear grip bias which makes the cars faster while sliding, and they have to stay on throttle for smooth transitions like you mention, but it's very hard to learn from a basic level with a setup like that, and the car needs to be really dialed in to make it all work with the driver too.

    Hope that helps you in the right direction,
    Regards,
    -Sean

    Quote Originally Posted by bennyfizzle View Post
    tl;dr

    go drive more
    .

    Quote Originally Posted by Nisanda View Post
    Soo SLR for rear spring what's your recommendation?
    .

    Quote Originally Posted by bennyfizzle View Post
    with low power and just learning the ropes, start out stiff. When you add power, tire, and angle, go softer.

    mike has a bajillion horsepower and he runs 890lb/in out back which is 16kg/mm.
    .

    Quote Originally Posted by Nisanda View Post
    i ask because i used to run like 16k rear and was ok but to stiff, you can slide the car more easily and if you let go the gas it will keep side ways but not much traction and less smoke.

    recently i have changed to 9k and the grip is great and the smoke two, BUT the car squats and tries to get straight soo no bueno (for me) maybe with more power but im still m5x with mods (for now) what maybe! 200hp, going for some 12k (672lbs) or something in between to balance things up.
    .

    Quote Originally Posted by Jaze View Post
    Who uses those rates? The only time i've seen anyone use an even spring rate is this e30. A few people have ordered 12/10k from me for e36 recently but i've never seen a company offer it that way.

    In any case, i agree about the rear needing higher rates unless you go for a full coilover conversion
    .

    Quote Originally Posted by Jaze View Post
    Who uses those rates? The only time i've seen anyone use an even spring rate is this e30. A few people have ordered 12/10k from me for e36 recently but i've never seen a company offer it that way.

    In any case, i agree about the rear needing higher rates unless you go for a full coilover conversion

    https://www.google.com/search?q=e36+...ient=firefox-a

    Some company I saw a couple years ago was selling 8kg/6kg also. Apparently some "engineers" don't understand "motion ratio" lol.

    12/10 is really whack on an E36, or did you mean 10/12? Explain to people that the rear motion ratio is barely HALF of the front, so generally they need at least 30% stiffer in the rear. Look at PSS9's (very balanced setup) 460lb front, 680lb rear

    Quote Originally Posted by tairyhesticles View Post
    I just ordered my BC's with 10k fronts and 12k rears. What company did you find 16k rears with? I bought the stiffest set I could find.
    .

    Quote Originally Posted by Jaze View Post
    I explained that exactly how you've typed it, it's a simple concept really but they said that they liked the rear grip. I suspect one random guy said it was awesome and it made it's way through the grapevine. All were from california too.

    I've never tried such a high difference in rates in the rear, i like to go with a good 100 some odd pound difference or 2k.



    My most popular set up is 15/16-17k or 16/18k. You just weren't looking hard enough google the name in my sig. I don't use those specs for drift though, those are for a stance set up.
    .

    Quote Originally Posted by sdipompo View Post
    My BC's are 10k/14k and revalved.
    .

    Quote Originally Posted by Nisanda View Post
    I run a shock spring setup not a full coilover, bought them of Ebay Hiper coilover spring (900lbs) so maybe 16k?, they are 2.25" inside diameter, so they fit the center hump on the spring base, i trimmed for height cut just like half turn almost nothing just to make it flush.

    http://www.ebay.com/itm/Hyperco-Coil-Over-Spring-2-5-ID-6in-900lbs-HYP186B0900-/380535806522?pt=Motors_Car_Truck_Parts_Accessories &hash=item5899b39a3a&vxp=mtr

    NOte: i bought them of graigslist for 70dlls used for the pair but are the same as the link, worked great! going for 12k now.
    .

    Quote Originally Posted by Nisanda View Post
    Soo SLR for rear spring what's your recommendation?

    Missed this earlier.

    **All advice below is based on stock spring location**
    **For true-coilover rear setups, I have no experience**

    I generally recommend 50% stiffer in the rear than the front, so say youre running a 500 front, then run a 750 rear. Or if 8kg front, then 12kg rear. This is definitely my recommendation for an NA car and/or beginner. The car will have a natural balance and be easy to maintain a slide.

    With 350+hp, and/or more advanced driver I'd say about 20% stiffer in the rear. Especially for competition drifting, where the rear grip will let you open a gap in the lead, and close the gap while following.

    My stock PSS9's stock were a good balance for 190hp with 460lb front and 680 rear (thats 48% stiffer rear). I needed a 60mm front spring for my camber plates, and the closest thing the local shop had in the right length was a 400lb. I wanted to go stiffer, but it felt fine and I never changed it.

    Even with 400lb front and 680lb rear though, (70% stiffer rear) The Z-link just put the power down so well that none of the local cars with more hp could keep up in tandem, and my car was only on 235 Dunlop Z1's

    Now for reference, my E36 weighs 2550lb, and I never drove the car in full weight trim. At it's first event it was 2720lb.

    Also as you lower Any E30-E46, the front loses grip more than the rear (due to roll-center and camber curve), so these cars become even more under-steer prone as you lower them unless you get some front roll-center correction.

    And remember, for street tires, (regulation 140UTQG) high spring rates just do not get the most grip out of the tire. For static drop on stanced cars you need a stiff rate, but for maximum performance on a competition drift car you are probably looking at a 350-400lb front spring and maybe a 450-500 rear.

    For race cars on slicks and R-comps, the tires generate so much more lateral grip that they get much more weight transfer. On soft springs this would cause too much camber change and body-roll, so they run much stiffer rates. Also the sticky slicks with good shocks will hang in there at much higher rates before breaking loose.

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~MERGED POST~~~~~~~~~~~~~~~~~~~~~~~~~~~

    MORE TECH:

    E30/E30/E46 front motion ratio: .94 (the spring moves 94% of whatever distance the wheel moves)

    E36/E46 rear: .65

    E30 rear: .67

    Now to get your effective spring rate, you need to square the motion ratio (because after the spring compresses, it has to push against the lever arm in order to rebound the wheel) and then multiply that times your spring rate.

    The actual force the wheel sees, is called the wheel-rate.

    E30/36/46 front: .94^2 = .88 (1000lb spring gives 880lb wheel-rate)

    E36/46 rear: .65^2 = .423 (1000lb spring gives 423lb wheel rate)

    E30 rear: .67^2 = .45 (1000lb spring gives 450lb wheel rate)

    The rear end has BARELY HALF of the EFFECTIVE spring rate than the front for E30, and LESS THAN HALF on an E36/46 for an identical SPRING rate!

    From corner balancing my own car, I know my weight distribution is 52/48 (it was better stock, but when stripping a car, a lot more tends to come out of the rear)

    Now for a perfectly balanced setup in theory, when we add the front and rear WHEEL RATES the front should account for about 52% and the rear should make up roughly 48%.

    Lets try this for a known setup (PSS9, and no I don't work for Bilstein! lol)
    Wheel rates:
    F: 460*.88 = 405lb
    R: 680*.423 = 287lb

    So even though the 680lb spring rate seems huge, it's really only a 287lb at the TIRE. Lower your wheel offset, and it goes down even more!

    Now lets add them 405+287=692lb and figure out how much of the balance each makes up.

    405/692 = .585 (405lb is 58.5% of 692)

    287/692 = .415 aka 41.5%

    So since the wheel rate is 58.5/41.5 biased to the front, the front is effectively STIFFER than the rear relative to the 52/48 weight distribution which should provide understeer at the limit (logical for an off-the-shelf coilover).

    Here's a few combinations put through the E36/46 calculations above:

    8kg/8kg = wheel rates: 7.04kg/3.4kg (67/33 distribution)

    10kg/12kg = wheel rates: 8.8kg/5.1kg (63/37 distribution)

    12kg/10kg = wheel rates: 10.6kg/4.2kg (72/28 distribution)

    10kg/14kg = wheel rates: 8.8kg/5.9 (60/40 distribution)

    10kg/16kg = wheel rates: 8.8kg/6.8kg (56/44 distribution)
    Last edited by SLR; 01-06-2013 at 08:20 AM. Reason: Automerged Doublepost

  2. #2
    Join Date
    Jul 2012
    Location
    Annapolis, MD
    Posts
    156
    My Cars
    1993 318i L33 Swapped
    Very good info thanks a bunch, was just thinking about changing my spring rates have alot more roll now with the slr setup(especially in the front) which i think is due to not having the sway bar and wider stance. Right now im at 8/10k going to try putting the sway bar on but heard if you mount it to the arms it loses performance and almost need a stiffer sway bar to counter act it.
    1993 318i L33/T56 Swapped Drift Thingy L33 Blew Up Time For LS2

  3. #3
    Join Date
    May 2007
    Location
    fairfax,va, usa
    Posts
    6,563
    My Cars
    2 E30s and a maxima
    For the record, I run 10/18 on the drift E30 and people that didn't know called it "soft"

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  4. #4
    SLR is offline Senior Member Supporting Vendor
    Join Date
    Jun 2004
    Location
    Florida, USA
    Posts
    895
    My Cars
    '08 E46, E36,
    Quote Originally Posted by 4CFEDFD View Post
    Very good info thanks a bunch, was just thinking about changing my spring rates have alot more roll now with the slr setup(especially in the front) which i think is due to not having the sway bar and wider stance. Right now im at 8/10k going to try putting the sway bar on but heard if you mount it to the arms it loses performance and almost need a stiffer sway bar to counter act it.

    I was just looking through a few catalogs seeing if I can find a simple bracket setup. I think I found a panhard bracket that should work, you'll just need heim end links.

    Did you try running your bar strut-mount yet and see what you think? Would still need some kind of heim type end link with end loose to give you full angle.

  5. #5
    Join Date
    Jul 2012
    Location
    Annapolis, MD
    Posts
    156
    My Cars
    1993 318i L33 Swapped
    Na i didnt try it i had it on but around full lock it would bind up so took it off. I found some tabs to weld on but not sure if its going to be strong enough. Think if i had a front sway bar the car would be money if not then go a little stiffer on springs. Once i get may car back from being caged im going to play with it.
    1993 318i L33/T56 Swapped Drift Thingy L33 Blew Up Time For LS2

  6. #6
    Join Date
    Jan 2012
    Location
    Sask, Canada
    Posts
    33
    My Cars
    2000 323ci, e28
    So I have to ask. My e28 has Struts in the rear but due to the semi trailing arm design of the rear suspension does anyone know what the motion ratio would be?

  7. #7
    SLR is offline Senior Member Supporting Vendor
    Join Date
    Jun 2004
    Location
    Florida, USA
    Posts
    895
    My Cars
    '08 E46, E36,
    Quote Originally Posted by McGavin View Post
    So I have to ask. My e28 has Struts in the rear but due to the semi trailing arm design of the rear suspension does anyone know what the motion ratio would be?
    Technically it's not a strut, but a coilover shock/spring. Struts are a spindle that is bolted or welded directly to the shock so the shock becomes a load bearing suspension component which maintains camber/caster.

    Technicalities aside though, it's probably very similar to E30 and E36 rear shock motion ratio which is 1.05

    Wheel rate is 1.05^2 which makes 1.1
    Last edited by SLR; 01-06-2013 at 07:58 PM.

  8. #8
    Join Date
    Oct 2009
    Location
    Santo Domingo
    Posts
    18
    My Cars
    E36 325/m50 '95

    Thumbs up

    Good Info... !

    Sean, I have a E36 sedan N/A 228whp, it weights 2,570, I have K-sport 9kg/12kg.


    Q: If I run with out the front Sway bar, I get or loose front grip ?
    also, if the car is lower in the back than in the front , do I get to go faster ?
    Last edited by Juanchy; 01-06-2013 at 09:56 PM.

  9. #9
    Join Date
    Nov 2012
    Location
    Everett, WA
    Posts
    40
    My Cars
    BMW e30m50
    I run 10kg front and 12kg on the rear and i feel i can go i little more little stiffer on the back but at the same time i wondering how the car will react on transitions???

  10. #10
    SLR is offline Senior Member Supporting Vendor
    Join Date
    Jun 2004
    Location
    Florida, USA
    Posts
    895
    My Cars
    '08 E46, E36,
    Quote Originally Posted by Juanchy View Post
    Good Info... !

    Sean, I have a E36 sedan N/A 228whp, it weights 2,570, I have K-sport 9kg/12kg.


    Q: If I run with out the front Sway bar, I get or loose front grip ?
    also, if the car is lower in the back than in the front , do I get to go faster ?

    How much anti-roll bar you need depends on a lot of things. Generally you will lose front grip due to lack of weight transfer and you will lose turn-in feel also. With roll-center correction and wider arms you can get away with less anti-roll bar, but it will always feel soft on turn-in so you have to throw the car into a slide more.

    For ride height, E36's can look lower in the back because of the low fender lip, even when they are perfectly level. Generally the rear should be about 5-20mm higher in back when measured from the bottom of the rocker panel.

  11. #11
    Join Date
    May 2007
    Location
    fairfax,va, usa
    Posts
    6,563
    My Cars
    2 E30s and a maxima

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  12. #12
    Join Date
    Mar 2010
    Location
    Long Island
    Posts
    1,666
    My Cars
    E36
    Bilstein does subscribe to that, but it is worth noting that GC, TCK, and many other only raise the rear rates about 100lbs or roughly 2k. I personally use that bias but have a higher HP car. if it was a little warmer, id set up a trial of a few different combinations, for science.
    Last edited by Jaze; 01-07-2013 at 08:45 AM.

  13. #13
    Join Date
    Nov 2008
    Location
    Baltimore, MD
    Posts
    8,403
    My Cars
    98 540i6
    any decent drift operation has a handful of different spring rates to dial in the car for different surfaces, temperatures, tire sizes, course layouts, etc.

  14. #14
    Join Date
    Apr 2011
    Location
    Naugatuck, CT
    Posts
    339
    My Cars
    '96 328i vert
    I have never known any sort of information on spring rates....ever....and now my mind is blown. I realize now that I have been a terrible car guy/drifter and just slap stuff on without knowing anything about it and just run it.

    I thank you all for giving me such valuable knowledge.

  15. #15
    Join Date
    Nov 2008
    Location
    Baltimore, MD
    Posts
    8,403
    My Cars
    98 540i6
    get an alignment, it will change your life.


    so tired of drift kids throwing on parts, and never actually aligning anything, ever.

  16. #16
    Join Date
    Apr 2011
    Location
    Naugatuck, CT
    Posts
    339
    My Cars
    '96 328i vert
    Yea I held off on getting one on my last car because I kept damaging suspension components/shell from dirt drops and wall hits.

    Once I finish building the new car it is the first thing on my list

  17. #17
    Join Date
    Aug 2005
    Location
    518
    Posts
    12,720
    My Cars
    Dicktone Limo
    I wouldn't even bother until you upgrade from those dumpy racelands

  18. #18
    Join Date
    May 2007
    Location
    fairfax,va, usa
    Posts
    6,563
    My Cars
    2 E30s and a maxima
    I got a laser alignment then broke a tie rod the next week lol. Now I mainly use measuring tapes between alignment sessions.

    Status: Someone put glitter in my oil. Wait. Why's all my oil outside the engine? What's that knocking?

  19. #19
    Join Date
    Oct 2009
    Location
    Santo Domingo
    Posts
    18
    My Cars
    E36 325/m50 '95
    Quote Originally Posted by SLR View Post
    How much anti-roll bar you need depends on a lot of things. Generally you will lose front grip due to lack of weight transfer and you will lose turn-in feel also. With roll-center correction and wider arms you can get away with less anti-roll bar, but it will always feel soft on turn-in so you have to throw the car into a slide more.

    For ride height, E36's can look lower in the back because of the low fender lip, even when they are perfectly level. Generally the rear should be about 5-20mm higher in back when measured from the bottom of the rocker panel.
    ok, Thnx.

    I forgot to tell U I'm using E46 arms and fixed knuckles. I run NO front sway bar because when full lock the sway bar links were touching the side of the chock and making the steering felt inaccurate and weird. I wanted to know wish way was better, thats why I asked.
    *sorry for my bad english, I speak spanish ;-)

  20. #20
    Join Date
    Aug 2005
    Location
    518
    Posts
    12,720
    My Cars
    Dicktone Limo
    Hmm, what do you mean by chock?

  21. #21
    Join Date
    Oct 2009
    Location
    Santo Domingo
    Posts
    18
    My Cars
    E36 325/m50 '95
    Quote Originally Posted by bennyfizzle View Post
    Hmm, what do you mean by chock?
    Sorry : SHOCK ABSORBER

  22. #22
    Join Date
    Aug 2005
    Location
    518
    Posts
    12,720
    My Cars
    Dicktone Limo
    gotcha!

    You cars only have non-m listed, but do your endlinks connect to the control arm or the strut housing (m3 struts)?

  23. #23
    Join Date
    Oct 2009
    Location
    Santo Domingo
    Posts
    18
    My Cars
    E36 325/m50 '95
    Quote Originally Posted by bennyfizzle View Post
    gotcha!

    You cars only have non-m listed, but do your endlinks connect to the control arm or the strut housing (m3 struts)?
    Yes, my car its a non-M , and my endlinks connects to the strut housing (they are M3 struts)

  24. #24
    Join Date
    Mar 2010
    Location
    Long Island
    Posts
    1,666
    My Cars
    E36
    Juanchy, por que no usas la Non M sway bar end links? Yo no se si tu lo quiere por razones de preferencia pero a mi me da lo mismo. El sway bar non M es mas grueso, tu esta usando el non M sway bar con los M3 end links? por que eso me ha dado problema en el pasado con ruido de la suspension.
    Last edited by Jaze; 01-07-2013 at 05:57 PM.

  25. #25
    Join Date
    Oct 2012
    Location
    Regina, Sask, Canada
    Posts
    209
    My Cars
    1998 328is Coupe
    Yo no hablaba nada de espaņol, pero utilizando un traductor me hace ver como un puto genio.

    '98 328 S/C'd Driftorito

Page 1 of 5 12345 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •