50/50 power split vs. other

Suspension and other discussion

Postby illGT4 » Wed Sep 22, 2004 10:48 pm

AWDios wrote:I notice that, and I don't know if it's a typo, but they say to lessen oversteer you only bring in the front.


Which would be the same as having a wider rear track, no?
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Postby illGT4 » Wed Sep 22, 2004 10:53 pm

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Postby edv-tek » Thu Sep 23, 2004 1:34 am

To reduce nose plow, and make the car handle better in the tighter turns (short course), over steer needs to be induced in the alltrac.


I think you are talking about an anti-lift kit. With a kit on the St165 you can go into a controllable drift with ease. And it has little or no understeer. It was most likely why they used the ST165 for racing right up to 1992.
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Postby CMS-GT4 » Thu Sep 23, 2004 12:40 pm

Please tell us more about this, "Anti-lift kit."
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Postby turbo4wd » Thu Sep 23, 2004 2:05 pm

AWDios wrote:It just seems like with a wider wheel base in the rear it would be harder to cause the rear to break loose. And I've heard from others that they have experienced more understeer, and to me it makes more sense than what you're saying. However I can't argue with results.


This is true and what I experienced myself. Widening the rear track does nothing to help induce oversteer. My rear swaybar did that when I installed that.
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Postby AWDios » Thu Sep 23, 2004 2:07 pm

illGT4 wrote:
AWDios wrote:I notice that, and I don't know if it's a typo, but they say to lessen oversteer you only bring in the front.


Which would be the same as having a wider rear track, no?


Exactly, so in other words to reduce oversteer (we want to increase oversteer) you bring in only the front and leave the rear wide.

I'm just thinking with the DMS, you're able to dial out any understeer that might be caused. I think it would almost have to be a stock vs. stock w/ spacers situation to prove one way or the other.

Either way, I"ll be getting spacers when I get rims again.
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Postby CMS-GT4 » Thu Sep 23, 2004 2:53 pm

That is partially true.

Bringing out the rear wheels to the same as the front with a 25mm spacer will induce oversteer.
The characteristics I experienced was that the car turned in sharper, and coming out of the turn the rear would throtle out and keep the car from going into oversteer.

I thought the front wheels looked to far tucked in so I bought an 8mm spacer. Installed it on the front. (Needed to be more like .5" for looks)
SO I took the car for a test drive. The wider track in the front made the car grip alot better. It took a bit more push to make the front plow. BUT, it was not oversteer. The rear never came around. It just made the car go where you pointed it. It was less pleasing to drive, even though it handled faster. It seemed to jsut drag teh rear around.

So I took it home, and put the 8mm spacers on the rear with the 25mm spacers, thinking that it would increase oversteer. It did not. It actually increased understeer. And I lost the limits that were obtained with the spacer in the front.

So it would seem to me, that the wheels need to be close to equal in track width. Then the car releys on the suspension setup to determine the over/understeer.

Might explain why the TTE car, and other Scca rally gt4's have the same track width. Also the wider the track the better the grip. That is one reason the wheels shouldgo close to the outside of the fenders. That and it looks good too.

http://www.rallycars.com/Cars/Toyota_GT ... ST185.html
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Postby illGT4 » Thu Sep 23, 2004 6:02 pm

AWDios wrote:
I'm just thinking with the DMS, you're able to dial out any understeer that might be caused. I think it would almost have to be a stock vs. stock w/ spacers situation to prove one way or the other.


Fair enough.. But I had the spacers on the car before the DMS.

When I installed the spacers the only other suspension mods I had were the Whiteline STB front and rear.
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Postby illGT4 » Thu Sep 23, 2004 6:04 pm

CMS-GT4 wrote:That is partially true.

Bringing out the rear wheels to the same as the front with a 25mm spacer will induce oversteer.
The characteristics I experienced was that the car turned in sharper, and coming out of the turn the rear would throtle out and keep the car from going into oversteer.

I thought the front wheels looked to far tucked in so I bought an 8mm spacer. Installed it on the front. (Needed to be more like .5" for looks)
SO I took the car for a test drive. The wider track in the front made the car grip alot better. It took a bit more push to make the front plow. BUT, it was not oversteer. The rear never came around. It just made the car go where you pointed it. It was less pleasing to drive, even though it handled faster. It seemed to jsut drag teh rear around.

So I took it home, and put the 8mm spacers on the rear with the 25mm spacers, thinking that it would increase oversteer. It did not. It actually increased understeer. And I lost the limits that were obtained with the spacer in the front.

So it would seem to me, that the wheels need to be close to equal in track width. Then the car releys on the suspension setup to determine the over/understeer.

Might explain why the TTE car, and other Scca rally gt4's have the same track width. Also the wider the track the better the grip. That is one reason the wheels shouldgo close to the outside of the fenders. That and it looks good too.

http://www.rallycars.com/Cars/Toyota_GT ... ST185.html


Excellent. Good post, Josh.
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Postby alltracman78 » Sat Sep 25, 2004 2:10 am

illGT4 wrote:http://www.tckc.net/tips_faqs/chassis/basic_track_adjustments.htm

The Kart does not want to turn into Corners.
Caust = Understeer
too much rear end grip
(Balance is out)

-Move front track out,
-Move rear track out,
-Add rear seat stays,
-add rear torsion bar,
-move set forward,
-remove front torsion bar,
-increase rear tire pressures
-check toe out (start with 1mm out)


Just 'cause it works on a cart doesn't mean it will work on a Alltrac.
I'm not saying it won't, just that it isn't garaunteed.
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Postby illGT4 » Sat Sep 25, 2004 9:22 pm

I hear what you are saying.. But a kart is the same idea. 4 wheels and a chassis. Engine mounted in the rear. The weight distribution for a kart is close to 50/50 (depending on the drivers/course needs)

I believe it's the same principle. I didn't intend on comparing to karts, that's just what all the searches were pointing to.

Either way; I think coldiron said it best in his last post. Thankfully we can dial in oversteer (if that's what you want) with suspension modifications and tuning.

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Postby CMS-GT4 » Fri Oct 01, 2004 8:36 pm

Back to the topic. Changing the f/r split. Reading some of the f/r tire specs in the Hyper Rev mag, and seeing Bob's sucess in autox with his alltrac with a larger rear ratio. I would think there is something to this.

So here is the problem. the fear of burning out a center diff. i will be racing my car so that may not be as much of an issue. Taking into concideration of the center diff, do we really even need the diff for autox and such>? Viscous seems to be better on rally. Too much of a delay for a fast flowwing couse. How much it actully works in autox could be debated. So maybe removing the viscous lock may be the idea in running in autox. Some gt4 gear boxes had no center diff. Or at least that is what some online articles say. I think it may had been some 165 models, and the narrow 185. If the center diff does help, then I would keep it. I am just trying to see if can pull some better driving out of this car by modifying the front to rear ratio.

On that note. The evo has a 50/50 split, and uses the center viscous lock, and rear torsen, and does not seem to have any problems as far as road corses go. So maybe the upgrade of the center diff may not be neccesary, but I think the evo has a better f/r weight dist. So anything to help the front over the rear in the gt4 the better.
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