Rear spring rates!

[e30max]

Just wondering what sort of rear spring rates people are running as I feel mine are way too soft. I have the BC Racing coilover kit while the front is fine, the back feels like it could do with stiffening up. The dampers are on the hardest setting but still not stiff enough. I'm running rotor grid wheels and they are close to the arch so everytime i corner hard or hit a sharp bump the rear scrubbs really bad.
The rate of my rear springs is 12kg (672 ibs) Is this a stiff spring to run for an e30 or not? It was what was recommended when i bought them!
What spring rates are you guys running?

Cheers Max

[e30max]

Anyone any ideas on this?

cheers

[BEMER_LAND]

You could get a straight spring rather than a pigtail one this might be stiffer, i have a 440lbs one in my touring with spax adjustabe shocks on the hardest setting and find it soft enough as it scrubs the tires on harsh bumps. im going changing to a 600-650 lbs spring 5"-6" long, there cheap to buy from faulker springs so easy to change if there wrong. but bear in mind the touring is heavier than a 2 door which is why im going for a stiff spring

[e30max]

There already straight springs on it. 120mm long. Been looking on the faulkner springs website and will probably order some from them but im not quite sure how stiff to get them because theres that much to choose from. lol

[UweM3]

Where is your rear spring?
coil over or in stock location.

You are talking about TWO different things. DAMPING and SPRINGRATE
you can do whatever you want with the damper settings, if your springs are too soft it will ground out.

But you can't seperate the two from each other. Meaning it makes no sense to fit a superhard spring with too soft damper and vice versa.

You are not saying what you are wanting the car for.

680 lbs ish is IMHO hard enough for spirited road driving, deffo not on the soft side.
Have you fitted rear bump stops?

I am not familiar with your susoension kit. Any link to manufacturer?

[e30max]

Sorry I havent explained it very well. I am building the car for track/drift but it will also be my daily. The springs are in the stock position. I'll see if i can put up a link of the kit. Not too good with computers!

[e30max]

http://www.bc-racing.co.uk/c-bci07/bmw- ... -m3-82-94/

Not sure if ive done that right. Doesnt give much info for the rear!

[e30max]

Heres a pick from my project thread. not sure if this will help

[UweM3]

Not familiar with the requirements of drifting. But I can say that in most of the cases two very different requirements (street / drifting) are not really working along side.

I have 1000lbs ish springs on my car for track driving and I can tell you that this is really not suitable for road driving.

why is your rear shock treaded? Is this some sort of height adjuster?

[e30max]

I know what you mean its not ideal having a balls out track/drift setup and using it as a road car too, i'd like to have something else i could plod about in as my daily and just use the e30 for track days but i cant afford to run both so i'll put up with the rough ride. I dont do too many miles in it so its not too bad.

Tbh im not 100% sure why there threaded, pretty sure its nothing to do with the ride height. Was thinking yesterday if it would make any difference to the damping if i wound the bottom down to make the shock longer would this give the piston more force with it being fully open as appose to it being slightly shut like it is now but im not sure it would as that wouldnt make any difference to the damper setting which is on top of the shock and set to the stiffist setting! I need to have a good play with them and see if it makes any difference to how the car feels.

Are your springs in the stock position like mine? And what shocks are you running?

[e30max]

Although making the shock longer would mean i'd have to compress the piston more to bolt it up to the car and would be even more compressed when sat back on its wheels, so cant be anything to do with damper setting. confusing lol

[Black_Potato]

As Uwe said the application matters a lot, for a race car I would generally suggest something like 275 coilover and 550 inbound & thats obviously softer that Uwe likes.

To make it more complex the Diff setup/bushes/damping/tyre etc all come into play as they are either springs or dampers in their own right as well.

I could imagine for drifting you would want a pretty stiff spring rate & lots of damping to keep the rear loose.

[UweM3]

As Uwe said the application matters a lot, for a race car I would generally suggest something like 275 coilover and 550 inbound & thats obviously softer that Uwe likes.

To make it more complex the Diff setup/bushes/damping/tyre etc all come into play as they are either springs or dampers in their own right as well.

I could imagine for drifting you would want a pretty stiff spring rate & lots of damping to keep the rear loose.

550lbs inbound isn't very stiff IMHO for a race car.

These are my rears, shocks are Bilstein Grp N


rear springs left, fronts right

[e30max]

Think i'll try something around 1000lbs and see how i get on!

Thanks for the help/advice. Max

[GeoffBob]

I am building the car for track/drift but it will also be my daily.

If you are specifically interested in setting your suspension up for drifting then you'd do well to get your hands on Paul Morton's book How to Drift: The Art Of Oversteer, published by CarTech books, see here



The book covers all you need to know about setting up both your front and rear suspension in order to get the tail out. Drifting is as much about discouraging understeer at the front as it is about encouraging oversteer at the rear. Your choice of differential is also extremely important, although be warned that much of what makes a good drift car is not well suited to a road car, and could easily see you heading backwards into a ditch at the first sign of damp and frosty weather.

[BadDave]

Heres a pick from my project thread. not sure if this will help

Looks like a locking ring for adjusable spring platform on that rear damper to me.
Is there another one for the spring to sit on?

Did you remove one and leave it in the box?

[BEMER_LAND]

Thats there so you can adjust the height of the shock, so if you have a very short spring it wont come unseated when its jacked up when you shorten the shock housing which i think is an mot failure. It really just take out the need for a helper spring

[e30max]

yes thers was one to adjust the spring but i took it out as the car wasnt low enough even when it was fully closed.