IE hollow 25mm vs uuc swayBarbarian 22mm

[Bothfeetin]

ahhhh i dont know what to do :(

[bimma360]

I mean it really depends on what you want to do with the car. But I think no matter what you'll be happy with the 22/19 setup. I cant imagine you getting into the car and thinking... hmmm this is still too soft. But as i did, get into the 25/22 and think... this feels just too stiff.

[Bothfeetin]

what do you mean by overkill tho like does it affect the cornering does it make the car start to plow?

[nando]

you have body roll because you have really soft springs. going with overly-stiff swaybars is just a bandaid fix for that.

[Bothfeetin]

h&r sports are not the stiffest but their alright

[CorvallisBMW]

I currently have the IE 25/22 sways on the Dinan. On my last e30 I had the Suspension Techniques 22/19 setup. Both cars have H&R Sports, Billy Sports, and e30 m3 control arm bushings. The 22/19 setup just felt worlds better to drive than my current setup. The 25/22 is so overkill to me, and I cant wait to get into something milder.

My sentiments exactly.

[JeffRR]

I mean it really depends on what you want to do with the car. But I think no matter what you'll be happy with the 22/19 setup. I cant imagine you getting into the car and thinking... hmmm this is still too soft. But as i did, get into the 25/22 and think... this feels just too stiff.

Can you explain further?

Based on some rough calcs:

Bars: 22/19
Roll grad w/o tires: 5.0 deg/g
Front roll stiffness dist: 40%

Bars: 25/22
Roll grad: w/o tires: 4.0 deg/g
Front roll stiffness dist: 35%


Looking at these calcs, the total roll grad is reasonable for each bar set-up. Actually I'd prefer closer to 3.0 deg/g w/o tires. But the big issue with both set-ups is the RS (roll stiffness) distribution, (production 325i is closer to 50/50). With such a high RS at the rear I'm thinking you probably had trouble putting down power, and had trouble in steady state corners among other things. The switch to the 22/19 set-up would push you in the right RS direction compared to the 25/22 set-up, by making the car easier to drive (reducing oversteer) and probably speeding up turn-in.
One issue with high RS and low spring rates is head toss, which can be pretty unpleasant, go drive an early FX45.

[Bothfeetin]

i know when im on the track its kinda funny seeing my car flying all over the place

[george graves]

head toss?

[KenC]

I currently have the IE 25/22 sways on the Dinan. On my last e30 I had the Suspension Techniques 22/19 setup. Both cars have H&R Sports, Billy Sports, and e30 m3 control arm bushings. The 22/19 setup just felt worlds better to drive than my current setup. The 25/22 is so overkill to me, and I cant wait to get into something milder.

I too have H&R Sports, Billy Sports, and M3 CABs. I have Urethane everywhere else, and an upper strut bar. Adding the IE 25/22 combo to my car was the best thing that I've ever done for it. I've never thought of it being too stiff. Perhaps it's because I run stock 14s and 195s...

[JeffRR]

head toss?

Head toss is a ride term for a high frequency body roll (very high RS).

Rule of thumb, you don't want more than 50%of the RS coming from the bars (on production cars), honesty I'm trying to think of a non-truck (or high CG vehicle, FX, X5, etc) that I've driven that its an issue. The early (they might have fixed it) FX45's were horrible with head toss, The worst that I can think of, but they are high CG and very stiff. The FX might not be so much of an issue with bounce to roll natural frequency split, but more of an overall high RS (bars and springs) value combined with high damping force.

[JeffRR]

I too have H&R Sports, Billy Sports, and M3 CABs. I have Urethane everywhere else, and an upper strut bar. Adding the IE 25/22 combo to my car was the best thing that I've ever done for it. I've never thought of it being too stiff. Perhaps it's because I run stock 14s and 195s...

That is a pretty aggressive set-up bar wise, its heavily biased to rear RS.

I agree based on some calcs it shouldn't be too "stiff" but I'd be worried about the OS/US balance. I'd think you might have a some trouble keeping her straight with any amount of steering input.

[JeffRR]

To the OP,

As a suggestion I'd look to the IE 25mm front and 19mm rear kit. With one major stipulation, add the M3 front stab mounting bracket to the strut its simple and cheap.

With that set-up you'll be looking at approx:

Roll grad w/o tires: 3.5 deg/g
Front roll stiffness: 55% +/- 3 % (with adjustment on the IE bars)

That'll put you in a good spot if you want to want to add coil-overs later, at that point you could shift RS rearward if you wanted to with spring rate.

[KenC]

That is a pretty aggressive set-up bar wise, its heavily biased to rear RS.

I agree based on some calcs it shouldn't be too "stiff" but I'd be worried about the OS/US balance. I'd think you might have a some trouble keeping her straight with any amount of steering input.

It's pretty balanced right now. It took me a few times driving at the limit to know how to adjust it. It has a little oversteer at the limit.

[bimma360]

I too have H&R Sports, Billy Sports, and M3 CABs. I have Urethane everywhere else, and an upper strut bar. Adding the IE 25/22 combo to my car was the best thing that I've ever done for it. I've never thought of it being too stiff. Perhaps it's because I run stock 14s and 195s...

Yeah, I too have the urethane bushings galore, and a rear strut bar... I guess its just a matter of personal taste, but to me the 25/22 is still too much. But thats just me.