Looking to gather information and feedback from fellow track guys who dont run rear sway bars.

Please include your spring rates, tire size/compound, front bar info, and overall dynamics of the car before/after.

I have been running stock bars with my 12k/10k setup. 275/35/18 hankook rs3's and the lean is just too much. Balance is nice though. I have Tanabe front/REAR sway bars waiting to go on, but will also like to hear what people have to say about running no rear bar.

 

I disconnected the rear bar my last trip to New Hampshire Motor Speedway after swapping my 9kg/7kg Tein SS coilovers for 11kg/11kg Ohlins. I have a massive Speedway front sway bar, btw. Tires were 255/40-17 front 265/40-17 rear Dunlop Z1 StarSpecs.

Basically I felt like I had to do something to put as much power down on corner exit as possible. Disconnecting the rear bar helped a bit, and the balance remained very neutral and tossable.

My car has 463rwhp, a front splitter, and no rear wing, so it is *very* traction-challenged on street tires to say the least!

If I'm you, I'd try just the Tanabe front bar first and see how that suits you before going with a stiffer rear bar.

 

With that much spring rate, you really don't need bigger bars. I wouldn't bother.

 

I am surprised that my car leans so much with these rates. It most certainly is too much and the car will benefit with added stiffness undoubtedly. I am trying to be optimistic believing that stiffer front/rear bars will do the trick, but I am also keeping my mind open to possibly going 14k/12k and ditching the rear bar and keeping the oem front. Thats why I am just looking to hear what ppl have to say.

I did have the tananbe front bar with my 93 oem rear and the car pushed too much. I prefer a bit of oversteer.

 

I'm always puzzled when people have the idea that stiffer springs means you can run softer sway bars, or people who say they prefer "softer springs and stiffer sways".

If you go with stiffer springs, you want stiffer sways as well!

Think about why cars even need sway bars. It is because the wheelbase is typically ~1.5x or more greater than the track width. Without sways, you would get 50% more suspension travel in 1g cornering than you would in 1g braking. Sway bars allow you to have similar suspension travel in cornering as in braking.

If you stiffen up the springs, you should also stiffen sway bars (one or both) to ensure you're in the desired range of suspension travel both in pitch (braking) and roll (cornering).

Stiff springs with soft sways will result in more suspension travel in cornering than in braking, and stiff sways with soft springs could result in excessive pitch under braking relative to roll in cornering.

I would still try the front bar first and see how that goes, and then add the rear bar if you want a bit more oversteer or less understeer.

 

Stiffer doesnt necessarily mean you can run softer sway bars, ur right but many people do think that it is less of a need to run thicker bars with spiffer springs because stiffer springs will resist more weight transfer= flatter cornering. Thats why we see a lot of track guys with various cars not using swaybars w/ superstiff springs.

 

Are you assuming the stock configuration is the optimal sway bar/ spring rate ratio?

 

Me!

I upgraded to the Ohlins last year on my '93, with 11k rates front and back. My front bar is the Tri-point mid size bar. Autocross seemed to work best without a rear bar, and the tri-point bar on it's middle setting. To me, sway bars are a good way to balance the car, and this seemed to give a good neutral handling, and allow some good power on coming out of a corner. This is not too surprising of a setup as the car came with notably stiffer springs in front than in the back. IMO, this is the best my car has handled.

I can still induce oversteer or understeer based on driving, but that is as it should be. I have 18x10's on all 4 corners with 285-30's all around.

 

You may get better traction , but on the slaloms you may suffer because the rear end will not return to position as quickly as before .

I say MAY , because i ran without a rear sway on my Miata and i had that issue .

miatas have the same suspension design as the FD . So thats my only experience , and i didnt like it .

So i'm trying to keep my FD's stock rear . Try upgrading the front if you are NOT getting any signs of understeer . yet if you are getting understeer. then I would remove the rear .

do your shocks have any adjustability? you can play with that to.

 

If they're not using sway bars, then they are using more suspension travel in cornering than under braking, and I would guess they'd be better off with softer springs and a sway bar (or two) for the same roll stiffness but improved mechanical grip.

I would bet that it's close.

I think I might have read some of your posts before I got the Ohlins for my car in September! Freaking AMAZING on the street, smooove as silk

Similar experience for me. 11k/11k spring rates give something like 4k/5k wheel rates front/rear. Disconnecting the rear bar gave me similar balance to what I had with 9k/7k coilovers I had before (~3.4 kg wheel rates all around) with the rear bar connected.

"Normal" staggered spring rates should easily allow use of the stock rear bar but I'd still go with the stiffer front bar only first, and then fit a stiffer rear bar only if I wanted to reduce understeer.

 

Installed the front and rear bars. To my surprise the car now understeers slightly. The high speed stability is much better however.. Not because of the understeer but because the car just feels more planted.

The rear needs to be stiffer. On turns my front inside tire's lift and almost lose complete contact.

 

I had that issue with my 924T, but since it barely got off the ground (90mph turn 10 @ summit point) it really was not an issue.

In your case, it's just too big of a front bar with the big springsthat will not allow much independent front wheel travel. An easy possible fix is to use the oem front, or something in between.

Has anyone modeled the suspension in excel, using like the Puhn method (how to make your car handle) of analysis? I did so for my Mazda 6, and it was very accurate.

an old sway bar link:

Antiroll Bars

.

 

swaybars improve weight transfer, but decrease traction.

I think the stock bars are decent for the 93. I run 12KG front and rear and use 265 front and rear on a 10" wheel.

If you want to put power down, run 17's in the rear and lower PSI, run 18's front. If you have understeer make sure you fit your tires in the front with a stretch, make sure your wheel width is atleast wider than the tread width, optimal is stretching the tire beads outward a little, so a 255/35/18 on a 10" wheel. 265/35/18 on a 10.5" wheel, 285/30/18 on an 11" wheel.

Fit the rear with a slight stretch as well, if you are running a 275/35/18 run an 11" wheel, if you need more traction drop to a 17" wheel and lower PSI to gain more portrait landscape for better front and rear traction.

Stretching the tires allows for the best mechanical grip. We recently dropped from a 225 wide tire to a 205 wide tire on a miata because the guy didn't believe what I was saying. I convinced him to do it on an 8" wide wheel and to his suprise, his grip actually improved, understeer is now gone, and his rear end is much more predictable. It also improved turn in, response.

 

i see your point, and more research is needed. we have found that on FWD cars, where you want to lift a rear wheel, that the interaction between the spring and the sway bar is critical. as you pick the wheel up the spring rate is going down and the bar rate is going up.

we've found this to be true as well, although the tire you pick might matter. a 225 was definitely faster on an 8" wheel than on a 7" wheel

oddly this is Mazda's stock fit...

 

Mazda engineers knew what was going on

Tire tread width matters, some 205's are wider than 225's

gotta check the tread width and section width.

We have played around with a lot of tires since he burns them up every month or so with so much tracking. He usually goes with the extreme sports street tires. You should have seen his face with the 205's, it was like OOOOOOOO.

 

When I went from a 255/35/18 tire to a 265/35/18 tire the in front, I gained traction. Rear was 275 for both.

This was back in the day. Now since I am not going to change my tire size my options are to soften the front or stiffen the rear. I think a stock front swaybar will be too soft.