If I were to remove the front & rear Racing Dynamics swaybars off of an E36 M3, what increased spring rate from the present front 500lbs & rear 550lbs would be needed to maintain the overall same wheel rate as before?

In other words approx. how much equivalent in spring rate do the front & rear RD swaybars contribute?

IIRC from previous posts that the rears would have to be over 750lbs to run no rear bar.

for an e36 you are always going to need a front bar. You can do without the rear, but you need to run pretty stiff springs.

If I were to remove the front & rear Racing Dynamics swaybars off of an E36 M3, what increased spring rate from the present front 500lbs & rear 550lbs would be needed to maintain the overall same wheel rate as before?

In other words approx. how much equivalent in spring rate do the front & rear RD swaybars contribute?



Search around, IIRC in an old thread or two there were some numbers thrown
around and rough calculations about sway bar rates.




...

for an e36 you are always going to need a front bar. You can do without the rear, but you need to run pretty stiff springs.

Without the rear bar, how "stiff" would be needed? Archives showed in the 1000lb/in range. Who's actually running that setup now?

Why do you always need a front bar? Is it because springs would need to be so stiff you'd have no compliance, eg. go kart ride? Or for fine tuning?

Search around, IIRC in an old thread or two there were some numbers thrown
around and rough calculations about sway bar rates.

Are front swaybar lb/in. rates or front spring rates equal to wheel rate, i.e. 1:1 ratio?

The back spring rate in the factory location (not coilovers) converts to wheel rate at 1 : 0.46 as I recall.

I run - - - oh shoot, I don't remember. Maybe Steve J will respond to this and remind me of what spring rates I have. He setup my Ohlins Shocks and would remember the spring rates. All I know is that they WORK!! I think they are around 750lb front (with a Ground Control Hollow Infinitely Adjustable Bar) and 400lb rear (no rear sway bar).

I run - - - oh shoot, I don't remember. Maybe Steve J will respond to this and remind me of what spring rates I have. He setup my Ohlins Shocks and would remember the spring rates. All I know is that they WORK!! I think they are around 750lb front (with a Ground Control Hollow Infinitely Adjustable Bar) and 400lb rear (no rear sway bar).

Did you get the Ohlins from RRT?
I sent RRT an email requesting info on OHLINS for my E30, but got no reply.

I tried no rear bar with 750lbs rear springs and that was definitely not enough. So 800lbs minimum

Did you get the Ohlins from RRT?
I sent RRT an email requesting info on OHLINS for my E30, but got no reply.
You would be better served giving them a ring.
I have the RRT JS suspension on my E30 M3 and it completely transformed the car from what it was previously. I do need to run it with fresh rubber but it is more compliant, faster all around and just plain works compared to what was there previously. The prior setup was quite a bit stiffer in spring rate as well.

Did you get the Ohlins from RRT?
I sent RRT an email requesting info on OHLINS for my E30, but got no reply.

I talked to somebody at RRT about the Ohlins. He was going to email me something. Still waiting for that email many many months later. I went with some used ProTracs instead.

If you are interested in RRT products please call on the phone its a lot more efficient than email, as there are a lot of emails, and not many people to read them. if you call and talk to someone it'll be more productive.

Note: You'll be talking to Barry or James if you call inquiring about Ohlins.

Without the rear bar, how "stiff" would be needed? Archives showed in the 1000lb/in range. Who's actually running that setup now?


I'm running 900's with no rear bar and it works for me.

Motion ratios for an e36 are, Front: .94 spring and shock, Rear: 1.05 shock/.65 spring.

wheel rate = spring rate x (motion ratio)^2, wheel rate = spring rate x (.65)^2
or
wheel rate = spring rate x .46

Why do you always need a front bar? Is it because springs would need to be so stiff you'd have no compliance, eg. go kart ride? Or for fine tuning?

In order to control the amount of roll on the front of a lowered E36, you'd need spring rates so high that you wouldn't have any compliance. Further, it's always nice to have a quick way of changing the balance of the car.

Run the bars, reinforce their mounts, buy tools, drink beer, go to touring car races and club race! You'll thank me when it rains.

Run HUGE front and rear bars :)

I think I read 'the' thread on spring rates/sway bay (and many others) but what's the ideal rate with thick bars front and back? Thinner bars...?

I searched, thought I tagged that thread but apparently not.

If I were to remove the front & rear Racing Dynamics swaybars off of an E36 M3, what increased spring rate from the present front 500lbs & rear 550lbs would be needed to maintain the overall same wheel rate as before?

In other words approx. how much equivalent in spring rate do the front & rear RD swaybars contribute?
I assume this is mostly just a "what if" kind of question? I'd be hard to pull off no front bar with an E36.

can you tell us more about the bars? if we know diameter, lever length, and attachment points, the ARB contribution to spring rate in roll can be calculated easily.

In other words approx. how much equivalent in spring rate do the front & rear RD swaybars contribute?

E36 swaybar calc, zip file.
http://forums.***************************************?attachmentid=97330&d=1108677320

RD bars are:
Front bar, 27mm by my cheap ass caliper.

Soft: 8.50"
Med: 7.75"
Firm: 7.00"


Rear measured 24mm

Soft: 10.00"
Firm: 9.25"

I talked to somebody at RRT about the Ohlins. He was going to email me something. Still waiting for that email many many months later. I went with some used ProTracs instead.


Gobuffs,

I appologize for not getting back to you, to be completely honest, I do not know/remember what happened there. Let me know if you need anything, we will be glad to help.



Did you get the Ohlins from RRT?
I sent RRT an email requesting info on OHLINS for my E30, but got no reply.

Mike, we get 100s of emails a day. With busy/broken servers, accidental deletes/overlooks on our part etc... sometimes things get lost. In the future try to re-contact us again via email or simply just give us a buzz. We will be glad to try to help you. I assume this is for your e30, we have done many e30 M3 setups, it would be fun to take on a non M3 setup.

I don't mean to hijack/post off topic on this thread, but thanks guys, once again I appologize, send me a PM or email,

Barry

The rear swaybar on an E36 doesn't do a whole lot when you have stiff springs. The arms are relatively long, and the attachment point is very far in-board on the control arm. When I autox'd an E36 325 in STS, I would often connect/disconnect the rear bar as a fine-tuning adjustment.

I calculated the wheel rate of a 19mm rear sway bar at around 32 lb/in using a motion ratio of 0.45 and an effectiveness of 70% (a guess to account for bushing compliance and other unaccounted-for deflections). That's equivalent to ~70 lb/in of spring (in the stock location).

I used Fred Puhn's formula (same as the spreadsheet posted above) but determined that it had to be multiplied by 2 to account for the fact that one end is moving one way and the other end is moving the opposite way an equal amount. Mr. Puhn didn't do a good job of explaining the formula, but I verified it (and the multiplier) by breaking out my old engineering textbooks.

Don't believe it...just try disconnecting it the next time you're on track/course. You'll probably notice the difference, but it won't be a big difference.

Brian Fitzpatrick

I'm running 900's with no rear bar and it works for me.

SG M3, what front spring rate & swaybar are running with that?

Mild oversteer? No understeer in corner entry under braking?

Thanx!

i have 800's with a UUC bar, for now.

With 800/900 and the uuc front and rear bars the car has tons of oversteer. Rear bar was full soft. With the front bar to medium and rear bar disconnected its neutral, but will rotate well.

wow ive never heard of running such high spring rates w.no anti-roll bars... learn something new everyday. what is the point of this? better racecar-like handling dynamics?

wow ive never heard of running such high spring rates w.no anti-roll bars... learn something new everyday. what is the point of this? better racecar-like handling dynamics?

You obviously waste too much time reading other forums then. :)

The point is better ability to put down power coming out of the turns.

It's lighter (about 10lbs).

Dont have to worry about reinforcing the rear swaybar mount.

In a corner you are unloading the inside tire less.

Would help get the power down earlier on corner exit.

Less wear on the lsd.

Sound kewl telling your friends you have 1000 lb/in rear springs :D

It's lighter (about 10lbs).

Dont have to worry about reinforcing the rear swaybar mount.

In a corner you are unloading the inside tire less.

Would help get the power down earlier on corner exit.

Less wear on the lsd.

Sound kewl telling your friends you have 1000 lb/in rear springs :D

not so cool once you factor in the motion ratio

weaksauce

;)

not so cool once you factor in the motion ratio

My motion ratio greater than 1, so ha. That said, we definitely aren't running 1000 pound springs!

I recently went with a stiffer spring and no-rear bar setup and have been very happy with it so far (3 race weekends and a track day at 4 different tracks). I went with 700 front with a UUC bar on medium and 900 rears with no rear bar. Sean's right, with that type of setup, it is pretty neutral and can be rotated easily when needed. Seems to put power down well. I hope to install a tubular front bar $$ this winter to further save weight, I need to lighten the front of the car up anyway. Brian's right - a few year's ago, I had a rear swaybar bracket break and I honestly hardly noticed it. I don't think the rear sways on E36's really do a ton of work. Ironic that the damn brackets break so often. On a similiar note, a close friend of mine who races an I-class 944 in PCA was surprised and disappointed when he had his totally stock street Audi A4 1.8T up on a rack and noticed that the rear sway was about the thickness of a pencil and had plastic endlinks :lol :lol We gave him quite a bit of abuse about that......

Vern

I don't think the rear sways on E36's really do a ton of work. Ironic that the damn brackets break so often.

It's all about motion ratio.

I recently went with a stiffer spring and no-rear bar setup and have been very happy with it so far (3 race weekends and a track day at 4 different tracks). I went with 700 front with a UUC bar on medium and 900 rears with no rear bar.

Vern

Vern & Sean, how does your car ride on the street? Are they strictly track cars or daily driver or? Do you drive to the track and if so, how's the ride & your butt after 2-3hrs on the freeway? Would you make any adjustment in spring rates from what you have now based on your experience?

Vern & Sean, how does your car ride on the street? Are they strictly track cars or daily driver or? Do you drive to the track and if so, how's the ride & your butt after 2-3hrs on the freeway? Would you make any adjustment in spring rates from what you have now based on your experience?

With no rear bar setups, they are usually for track only car. Remember you are going to need a shock that can control these rates. A custom valved koni DA is about the only streetable shock that can control springs with these rates.