Dublocivic

I have been playing with rear toe a little to try and find the best balance. I am currently a total of 1/4 toe out in the rear and was wanting to work my way back to 0 to see how things felt. Prior to this weekends toe fix (driver rear had slipped 100% toe in at the last event) I had eyeballed it on the adjustment slot to match both sides. Stringing the car this weekend, it was almost 1/2 toe out in the rear and was all over the place when on the brakes. I got it on the string and quicktrick tapes (both sides) 1/8th toe out, 1/4 total. The car still rotates nice and it does pretty good under braking albeit still a little squirrely hard on the brakes. What have you guys found to be optimal for rear toe? I know every car is a little different but what is your preference? What toe settings typically show faster lap times for tight tracks, fast tracks etc..?

Thanks for the input in advance!

ross2004

1/8" toe in required 90* more steering wheel input at Oak Tree compared to 1/8" out, for me. Toe out is a little "dancy" under braking as you've seen; and while I think it most likely faster, for an endurance race & multiple drivers I want it a little more comfortable. Next time I head back out I'm going to run 0* rear toe, I think that will be a happy balance.

*edit* I think rear downforce would compliment rear toe out nicely. With the rear toe out, even coming up the uphill esses at VIR was a little dicey.

Kaan

iTrader: (3)

well its semi complicated... depends on the track, your bushings, and what your suspension compression takes to you with your toe.

I'm on fully sphericals and run 1/16 rear toe at VIR, 1/8 rear toe out at Summit. We keep the "drag" down on the tires there because of the two long straights. after measuring my toe with the suspension compressed... its giving me about 1/8th compressed, slightly more with unknown side load. I would try to run 0 toe but I cant get the PCI rear toe links to go in that far... so I'm going to build my own.

Dilbones

Dublocivic

Steering input is something that I didnt even think about. I did notice with the new PCI spherical UCAs and upper spherical bushings accompanied by the rear toe it takes really small inputs and almost felt a bit touchy with higher speed input under normal driving (I still drive the car on the street occasionally to make sure things feel decent after changes, and the car is tracking straight etc 1993 is a great year for antique plates in VA with self inspections and stuff =-)).

Thanks for the info on OakTree, that is great feedback.


Yeah right now, I am on hardened rubber everywhere except the UCAs/upper bushings. Compliance/RTA control arms are all HardRace so likely more deflection under load. I couldnt seem to get the RTA to set at zero either so I stopped at 1/8th out per side. I didnt want to have the RTA bushing tweaked too much and tear it out at the track. Although that would be a good excuse to replace it with spherical bushings.

boxedfox

1/8" rear toe out on each side is quite a bit. I would back it down to 1/8" total so the car will be stable under hard braking. You can always get the car to rotate around the front end by braking harder later in the braking zone, as long as you have a little bit of rear toe out.

Dublocivic

I did some further straight line hard braking at various speeds and I will go with this recommendation. It still has a bit too much pucker factor set up like this (albeit less than before). I think after a few sessions if I dont get the rotation that I need at 1/8th out overall, I could go up a psi or two in the rear tires to help a little. You are right, it needs less toe. I think Ill try loosening the rta bushing bolts a little to see if I can take a little stress off of the bushing while adjusting it inward, then lock it all down.

killerpenguin21

keep in mind without a good trailing arm bushing (basically spherical), it will toe out under bump. I had this at turn 1 at mid o...not fun when the right rear suddenly toes out mid corner...

the dancing rear under braking is more solved with the front end and a touch of downforce that any actual rear end setting imho/experience.


im at zero rear toe and starting to work on getting the rear tires to "work more".

Dublocivic

I think Ill adjust it inward to an 1/8th total and see how it feels. Aero is in the works over the next couple months so that is good to know some front downforce helped settle your car under braking. The splitter and rear wing should be on the car soon-ish, Id like to have them on for a weekend or two before NasaMa closes up for the season in Nov.

iwannarace

I'm at a 1/16th toe out and have PCI sphericals. Doesn't feel that loose on high-speed turns, or under breaking. No aero other than OE GSR rear wing.

Dublocivic

You know, I think switching to sphericals will also help my issue. I was seeing a ridiculous amount of rear "squirm" under hard braking before with more than a 1/4 total, now being at 1/4 known, its not nearly as bad but is still there. I think that If I can get it in s bit more to an 1/8th overall it should be good to go with hardened rubber in the rear. With the spherical RTAs and LCAs and minimal deflection I should feel pretty stable between 1/8th-1/4th track dependent.

Kaan

iTrader: (3)

i'm on all sphericals... at 1/16th under compression i get out to 1/8

Dublocivic

What could be deflecting under compression if its all spherical? Or is it that it rotates out at the compressed suspension geometry?

Another thought.. any thoughts about leaving the camber adjuster rubber on the rear? Or will it continue to gain negative camber under compression even with sphericals with dw suspension?

Kaan

iTrader: (3)

sphericals have tolerance, smash those tolerances through motion and +1G cornering and you will get more toe.

Dublocivic

Thanks! makes sense.

hispanic panic

What kind of front end work are you talking about? Do you mean toe in at the front? Or stiffer springs??


It might be worth mentioning what spring rates/bar rates people are working with. Stiffer fronts won't see as much rear loading, therefore theoretically the toe out would make less of a difference as the tires will be experiencing less slip angle.

killerpenguin21

not sure what your question is about the front?

im 1000f/600r, 32mm hollow rear bar 0.120 wall, no front bar. i just dropped the rear rate from 700, need to dial in the bump stops/packers before nationals...but it will still toe out under bump and scare me

hispanic panic

I just meant your note here... "the dancing rear under braking is more solved with the front end" Just curious what you mean by solving it via the front end.

Dilbones

he's talking about going from a rubber front compliance bushing to a spherical bushing. It reduces the toe change under braking up front due to rubber deflection, somehow making the rear end more stable.

Other things that help:

*rear wing
*softer rear rebound setting on your shocks

killerpenguin21

ah gotcha now, dilbones nailed it. rear end shimmy can actually be the front end dancing so its important to not chase the wrong end of the car...been there done that.

Dilbones

I'M A FKN HORSE

Dilbones

but fr. the car is a whole picture. it's similar to making a good meal. can't just make good taters and expect the fam to be like damn what a fire meal--gotta have good chicken and green beans and shxt too.

(front and rear matter)

Dublocivic

Got some Chicken and Greenbeans on the way..

Ill let you guys know how much the sphericals help, I have a set of compliance, RTA, FLCA on the way =-) I decided to run the last event at 1/8 out rear total and with the RLCA and front UCA/upper spherical bushings installed and the squirm was still there but it was much more manageable. The rotation was very good set up like this, rear 24mm bar is set to soft and dampers were set in the middle f/r.