Suspension & Brakes Theory, alignment, spring rates....

Stiffer rear springs or bigger swaybar?

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Old Apr 25, 2018 | 07:26 PM
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Default Stiffer rear springs or bigger swaybar?

I recently picked up a 93 hatch. I want to get more rotation out of the car. Here's the current setup

Tein Basic Coilovers 10k front 6k Rear
Front sway 1 1/8
Rear sway ITR 23? mm

The 2 ways I was thinking to get more rotation is either downgrade the front sway bar to stock and go bigger in the rear, like ASR 32mm hollow, but I wouldn't know which wall thickness

Or

Get 10k springs for the rear and send the coils to Tein for revalving.

Most track setups have equal or stiffer springs in the rear but people don't usually list their sway bar settings for comparison.

What do you guys think? Pros and cons of either solution? The ride is already a bit stiff so that's already +1 for the sway bar solution

Last edited by VarTheVar; Apr 26, 2018 at 01:01 AM. Reason: Typo
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Old Apr 26, 2018 | 05:16 AM
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Default Re: Stiffer rear springs or bigger swaybar?

Taken into account you want more spring at the rear than in the front:

For track: go with the 'more spring, less bar' option as much as possible, at least at the front.

For street: go with the 'more bar, but not too much, as much spring as you can bear' option, at least in the rear.

Can you bear 10K spring at the rear?
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Old Apr 26, 2018 | 07:28 AM
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Default Re: Stiffer rear springs or bigger swaybar?

Originally Posted by kristo
Taken into account you want more spring at the rear than in the front:

For track: go with the 'more spring, less bar' option as much as possible, at least at the front.

For street: go with the 'more bar, but not too much, as much spring as you can bear' option, at least in the rear.

Can you bear 10K spring at the rear?
I don't know if I could bear it. Never tried it and it would be an expensive mistake if it went poorly. Also my shocks aren't adjustable so it would be one setting for all

What's the reasoning behind your approach? I'm strictly talking about rear setup. I can see a huge front sway being a problem with steering and crosstalk and coupling. But this is my first FF car. The rear setup doesn't seem to be as critical as FR but I don't know for sure
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Old Apr 26, 2018 | 08:10 AM
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Default Re: Stiffer rear springs or bigger swaybar?

What tires front and rear?
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Old Apr 26, 2018 | 10:38 AM
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Default Re: Stiffer rear springs or bigger swaybar?

Originally Posted by Black R
What tires front and rear?
205-50-15 front and rear. Running summer tires right now but going to switch to ra1 or similar
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Old Apr 26, 2018 | 12:13 PM
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Default Re: Stiffer rear springs or bigger swaybar?

if you want to rotate, go with a stiffer rear springs and stiffer rear bar.

track cars with stiffer rear springs always have stiffer rear bars. the fast ones at least.

why do you want to rotate on the street???
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Old Apr 26, 2018 | 12:55 PM
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Default Re: Stiffer rear springs or bigger swaybar?

Originally Posted by Tyson
if you want to rotate, go with a stiffer rear springs and stiffer rear bar.

track cars with stiffer rear springs always have stiffer rear bars. the fast ones at least.

why do you want to rotate on the street???
It's mostly a track and canyon car. I don't need it to rotate on onramps

I already know that stiff rear is better. I need more details.
There's another thread where someone measured the effective maximum spring rate of the thinnest (.095) 32mm ASR bar at 850. I'm guessing the .250 bar is at least 1000lbs stiffer but I don't really know for sure.
Then there's the matter of how you achieve overall spring rate with spring vs sway bar stiffness. I just found the road race forum. I'm gonna ask in there and see if anyone knows. This was my first post. Apologies for wrong subforum
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Old Apr 26, 2018 | 01:36 PM
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Default Re: Stiffer rear springs or bigger swaybar?

reduce the front sway bar to the smallest stock one. theres no benefit to a stiff front swaybar.

the idea is to reduce the rear grip to increase turn in. by increasing the rear sway bars, you are reducing the independent nature of the rear suspension and reducing grip for an over all gain.

Last edited by Tyson; Apr 26, 2018 at 02:04 PM.
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Old Apr 26, 2018 | 05:01 PM
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Default Re: Stiffer rear springs or bigger swaybar?

i would try taking off the front sway bar, if its a track car/canyon car you can go with pretty aggressive camber settings and may benefit from removing it all together..I did with my em1..

if your on just 205 "summer" tires now and going to an ra1 later I wouldnt even bother messing with susp until you get the new rubber as those are a serious tire.
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Old Apr 26, 2018 | 07:14 PM
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Default Re: Stiffer rear springs or bigger swaybar?

Street cars are more about feel and very little about actual result. You want to have the feel of agility and confidence. And you definitely don't want to get tossed around. Usually, this is more damping and softer spring. Body roll and understeer happens...but you don't know its happening...so who cares?

Track cars are more about result and less about feel. Its not supposed to be overly stiff or beat you up...but it should produce MF'ing results. Effective spring rate being high is the only thing that can control the body motion.

A stiffer rear spring and bar is going to shift you into track car territory.

Tein's twin tubes don't do that well with heavier springs. They're all valved to be very lazy at low piston speeds.

Also...

why don't you just get a monotube coilover set that is already valved for a heavy spring and just swap in the heavy springs when you go to a track day. Use softer springs for the street. Dial the damping to suit. Mix and match springs to make the car do whatever you want.

You could do that for under $2K including springs and not have to compromise.
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Old Apr 27, 2018 | 10:57 AM
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Default Re: Stiffer rear springs or bigger swaybar?

I can only tell you what I do on my smf EF:

11k F
16k R
stock front swaybar
ST rear bar on full soft
Hoosier A7 275 F
Hoosier A7 205 R
-2.5 deg camber F
-2deg camber R

I set dampers full soft up front and adjust rear depending on course / conditions.
If that's not enough, I can stiffen up the rear bar between runs.

On the street, I can dial it down a bit by simply running 205's all around and full soft in the rear.

I have debated going with no front bar, 900-1000 Lb springs up front with 550 Lb springs rear, everything else the same - but so far it's close to where I want it to be.

​​​​​​​Ymmv.


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Old Apr 27, 2018 | 11:11 AM
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Default Re: Stiffer rear springs or bigger swaybar?

Oh and I know a national level autoxer who ran a very successful itr like this:

1000lb front/550lb rear with stock ITR sway bars front and rear. 2500lbs race weight.

0* toe front, about -3* of camber. Rear was about 1/16" toe in with around -.75* of camber. Rear camber/toe was where to go for balance changes. Nothing else could affect the balance like a 1/4 degree of camber or 1/16" of toe without negatively impacting other factors.

This is again with 275 F / 205 R Hoosiers, and tire wear + temps were damn near perfect.
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Old Apr 27, 2018 | 11:14 AM
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Default Re: Stiffer rear springs or bigger swaybar?

OP, I see a really cheap (free) way to get more rotation for your setup: try disconnecting one side of your front swaybar and then go for a spirited drive - preferably in a controlled setting like a test and tune Autox or track day.

The difference will be night and day.

​​​​​​​
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Old Apr 27, 2018 | 11:26 AM
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Default Re: Stiffer rear springs or bigger swaybar?

why does anyone even use a larger front sway bar?

put the stock back on, and then do what black r is suggesting. its a tuning device, feel free to tune it.

calculating spring rates vs sway bar rates is kinda pointless because theyre not functionally equivalent.
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Old Apr 27, 2018 | 11:34 AM
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Default Re: Stiffer rear springs or bigger swaybar?

That's all very good info and advice. Thanks

Coming from the RWD world, it's so counterintuitive to have such a crazy oversteer bias in spring rates. And then on top of that, opposite tire stagger and crazy rear sway bar bias. I knew oversteer was favorable but I never expected these kinds of numbers.

Makes you wonder about Tein and their spring rates. They have 10/6 which is understeer bias for Eg and 10/8 which is oversteer bias for Miatas. Both of which are undesirable .

¯\_(ツ)_/¯
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Old Apr 27, 2018 | 02:36 PM
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Default Re: Stiffer rear springs or bigger swaybar?

^ they do it because the popular way to set up an FF for spirited driving is different in Japan; they go with higher front rates and a big rear bar + wider front tires.

Here in the US, the opposite mentality has been popular - higher rear rates and no tire stagger.

There are many ways to get the desired handling, and it's personal preference.

I will say that higher front rates is safer on the street because of the tendency to understeer at the limit - that may have something to do with why tein sells their ots kits with such rates.
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