WendysOrBust

Is corner exit on an open diff that bad?

tokenride86

iTrader: (1)

psh im about to find out next week when i get my trans in. ill make before/after videos

engifineer

Yeah, its really bad. It is bad enough on a FWD with an LSD, but horrible with an open diff, especially if you run the stiffer front bar.

Think about it this way. When you are turning hard, you are trying to get back in the throttle coming out of the turn. On a FWD you have a number of things working against you:

1) Tires have a maximum amount of grip total, in any direction. When you are exiting a turn, you are asking them to pull you forward as well as steer the car. Look up the "traction circle" for more on that.

2) The cars weight wants to transfer to the outside tire. This leaves less traction overall since you are removing weight from the inside corner.

3) The sway is trying to lift the inside wheel in order to keep the car as flat as possible. This also removes weight from the inside wheel.

4) As you do start to accelerate out of the corner, weight transfers off the front of the car towards the rear, removing more weight (and traction) from the front.

5) With an open diff, issues 2 and 3 are compounded since the power will be delivered to the wheel with less grip, so you end up just spinning the inside tire coming out of the corner.

This hurts in all hard driving situations, but especially so on an autox course since you try to give yourself as many "straights" as you can to carry speed through the course. When .01 seconds can mean a couple of places in standings, every poor exit hurts!

pinoyFMtC

Yeah, I've done #5 plenty of times lol.

Thorium06

iTrader: (5)

I never had issues with the open diff until I went turbo, it sucks

engifineer

Its always an issue the faster you get, but more power will definitely make it worse.

Thorium06

iTrader: (5)

For sure, I always had tire width to mask the issue

Slow_2az

deleting power steering, gives u the best feel for the road

drivinkrn

deleting power steering..?

you'd get so buff from that work out ahah

engifineer

gives you more feel at high speeds, SUCKS for a daily driver and even is not so great for autox.

That was a VERY generalized (and out of place) comment really

RusWolf

iTrader: (3)

want to bring this back to live for a quick question.

What would be the best handling set up as far as spring rates go for handling.
1) 6kg front 11kg rear
2) 7kg front 11kg rear

What do you guys think ?

pinoyFMtC

If my calculations are correct: 7kg/mm is ~391lb/in, 6kg/mm is ~335lb/in and 11kg/mm is ~614lb/in.

Comparing it to this chart, which shows the rates of some OTS coilovers:
http://www.yoursciontc.com/forums/in...pic=16894&st=0

I'd say go for the 7kg, since it's almost identical to the front rates of the SSPs. The ratio front-rear stiffness is about 7% off the SSPs. The 6kg would bring that ratio even further. 7kg is still softer than the front rates on the JIC and the Zeal Function X. If front traction is a big issue, you may benefit more from the 6kg springs on bumps and uneven surfaces (with softer springs there will be a bit more roll, but if there are bumps the tire will be less likely to "skip" and will be more planted), but idk how going softer in the front would affect handling overall, except more roll in the front.

Those rears are hella stiff though, 616lb/in is stiffer than any of those OTS coilovers shown lol.

I'm no expert on suspension though. Still learning. That's my humble opinion.

KCTTC

iTrader: (2)

What brand of coilover do you have? What other suspension modifications do you have?

-Jeremy

RusWolf

iTrader: (3)

^^^ I don't have any coilovers i was picking between DG and Stance coilover's, for now my car is on TRD spring's which will obviously be replaced with coilover's.
The only other suspension mod i have is Hotchkis rear sway bar but it will be swapped with DG sway bar.

KCTTC

iTrader: (2)

I'm running Tein SS-P with EDFC but I swapped out the springs (7/392, 10/559) to 9/504 and 12/672. That is the stiffest you can go on the ssp without re-valving the struts. I rotated the top hats on the struts to achieve max caster. I use 2 camber bolts on each strut to adjust camber. I have the Hotchkis rear camber links, Hotchkis front and rear sway bars with adjustable end links. DC front strut bar and Ingalls rear strut bar. It has been corner balanced and aligned. I'm currently running Rota DPT wheels 18x9.5 +35 with 275/35-17. I'm also running 10mm wheel spacers with arp extended wheel studs. I have not had this setup on the track. I'm currently putting new seats in and building an aluminum roof and roll cage.
This setup is pretty aggressive for the street but I don't mind.

-Jeremy

engifineer

I think that possibly going with the lower front rate is a good choice. Keep the car flat with the the higher rate rears, DG rear bar, etc. The softer fronts will keep it more civil on the street, help it rotate and help to prevent issues with corner exit traction since the front will be more compliant.

However, running the higher rate springs in the rear (11k) than the SSP and the 7k in front will achieve a bit of this on its own. It partly depends on what you want out of the car. Running the SS-Ps for a good while, I am curious how some slightly softer front springs would do with the rears that are on them. Of course, running about 600F/900R would be great... but only on a smooth racetrack

TexasWorldScionTc

Reading through pages...good stuff. I have a few basics to contribute.
Lap times + mods
2:24 + stock,hawk pads
2:22 + hotckis f/r sway bars, rear camber links, stainless steel brake lines, synthetic 450+ fluid
2:15 + magnaflow exhaust with second Cat delete, 18"x7.5" with 225/40/18 street tire
2:11 + Weapon R intake with ram air kit, WR engine dampner, EBC red stuff pads.
Track Texas World Speedway 2.9 mile clockwise
Have a Unichip on the way so I'll have another update next track weekend in September.
Also should contibute that my skill level has improved during these modifications. Hope this helps! I'm leaving out alot of stuff but you get the idea.

RusWolf

iTrader: (3)

thanks for your help guys and especially to Engifineer for some PM help as well.
I've decided that the best set up for me would be 7kg front 11 kg rears paired up with LSD should allow to go into corners faster because of 7kg front and exit corners just as quick with LSD.

Now i just have to wait for coilovers to arrive from japan in september and for me to return home a month after.

can't wait to check it out !