Sam Strano

iTrader: (41)

Again if you are in the low 20's, that's an issue no matter what.....

But DeCarbon rears with Koni fronts is about as messed up combination as you could run. Great damping and control up front, junk in the back. The rear will automatically feel a lot less crisp and controlled because you don't have matching junk in the front.

So next step, without question. Rear shocks.

OneMeanZ

iTrader: (2)

Sam how much do you charge for rear Koni's?

Sam Strano

iTrader: (41)

You have a couple of options...

$210 for a pair of 3rd gen Koni Sports. Work very well on the 4th gen, but there are reasons they are less money. Those are the need to remove them from the car for adjustment, and the fact the adjustment has but 4 positions making for coarse changes, and usually no need for the upper two. Making the shock more of a 2 setting shock for most folks (like me). However the change between those bottom settings is 20% more rebound, which is pretty good number most of the time.

Or $310 for the pair of 4th gen Koni Sports. These are always the best choice when money is not the issue. Because you can adjust them right on the car, very easily. And they are a lot more tunable because there are no detent settings, much like the front shocks are. If you have no clicks you don't have to settle for one or the other if you want something, or want to try something else.

OneMeanZ

iTrader: (2)

So it's not because the quaility of the shock is less. It is just because the tunablity isn't as "in depth" as the 4th gens and you have to take them out of the car?

Because right now money is tight and I would most likely be able to get the 3rd gens.

Sam Strano

iTrader: (41)

Exactly right.....

Zepher

Quick question,
I am running the Nitto 555RII's for street and auto-x duty and run them at 36psi all the time. Car handles great and is very predictable.
Is 36 correct for these tires since they have the stiffened sidewalls?

Ssnc4

My suspension on the rear makes the popping sound also when i do the same thins WTF is it i have 315 rear tires PHB i had LCA thinkin that was the problem so took them off and went back to stock and its still doin it the car is also lowerd a inch wtf is makin that noise it sounds like sum thing is going to fall off but every thing is tight

Sam Strano

iTrader: (41)

Front? Back? Both? 36 in the rear might be fine, or may not be that can vary a lot with the tire. For example Hoosier road race tires have extremely stiff sidewalls but need lots of air because the tread part of the construction is not very stiff and needs the air to support the tire under load and with a 245/45-16 was over 40 psi out back and 47 in the front, but that's a rarity. When I ran Toyo RA1's which are reportedly very similar to your 555R2's, I ran about 35 out back and around 41 in the front, which they seemed to like. Then again race tires are pretty stiff all around and a few PSI doesn't change the ride/handling like a few PSI in a softer sidewall street tire.

Pressures... YMMV. Feel is important, response, grip and tire wear are all things that are important on street tires, and all vary with different tires and different pressures. But the front of the car is heavier, and if you are running the same size tire all around, generally you want more pressure in the front to support the greater weight.

OneMeanZ

iTrader: (2)

My tires were at 25psi all the way around. Put some more air in them and the car felt better, but need some rear shocks though.

Sam Strano

iTrader: (41)

Gotta keep those tires properly inflated.... Not to mention 5 psi low will cost you a few MPG's too...

Zepher

I am running 36psi all around.
I'll up the fronts to 40-41 psi and see how that feels.
thanks Sam.

Manny

edit: not sure if you can watch a video of a novice (me) and see if the tires need more air.
this is from my 4th Auto-x event,
http://www.transamws6.com/video/manny-acu4.wmv

Sam Strano

iTrader: (41)

Video isn't clear enough to see the tires and what they are doing. But somethings that have nothing to do with this thread caught my eyes....

You Eaton is toast. One wheel peel EVERYWHERE. Also, 4.10's with the gearing of a T5... not good. Actually 3.42 or even 3.23 is a better gear as you don't wind the engine to tightly, which they don't particularly like.

You could use some more negative camber, 3rd gen's like about -2 for autox, you might not want to go that far if you drive a lot of miles on the road, but it looks like you have none. When you add camber you will get more bite and that will make the car looser, and it looks kind of loose already. This will mean adding grip to the rear. Which will in turn likely mean less tire pressure (and from watching that, I think 36 might be too high as is).

I only know what you sig has listed and there are some things missing, like of course some good dampers. Is the PHB bushed or rod-ended? What size bars are on the car? etc.

DanO

Toasted an Eaton....? How many miles do you have on it! Ive seen them survive 150,000 mile durability tests and still have quite a bit left... Unless you have some really old style unit prior to the paralytic carbon disks...

Sam Strano

iTrader: (41)

Oh yeah, just watch the video. Spins up the right rear a lot, to the point you see smoke off of that tire and even just one black mark....

Autox is completely different than drag racing. An Eaton will last years when it has to just go straight. But ANY clutched LSD wears when you turn and accelerate hard as the same time, just the nature of the way they work.

This is one reason we use those big T2R Torsens for autox/track use. They don't have clutches to wear out.

Zepher

Actually, in the video, I have the SLP Take off Zexel Torsen unit with 3.73 gears.
The Eaton/4.10 rear was installed about a month ago, and is just temporary since it belongs to my friend who recently traded in a 98 Firebird for an 02 WS6 and didn't want to trade in the 98 with the new Eaton/4.10 setup, so we put my dying (gears were whining really loud) 3.73 torsen rear on the 98.
I'll probably have this eaton setup for a couple more months or permanently if I decide to buy it from him. I do want to get the T2R though.

Rear panhard is bushed and the adjustment is at the rod end not the center like the newer bars, stock WS6 Sway bars:36/24, GM Wonder Bar, Stock style Monroe front struts and KYB Gas Adjusts in the rear.

I've recently installed KYB GR2's on the front and new KYB Gas Adjusts on the rear and the new rear shocks seem softer than the ones I replaced, can't really figure that one out since the older ones are 5 years old with about 3 years of use on them. They were on my 86 Trans Am but were replaced with the KYB AGX's.

The car has a lot of negative camber (that is when the top of the tire is tilted inwards, right?), was like that when I bought it. the strut plates are all the way towards the engine. Tires wear evenly and car tracks straight.
I am trying to find a picture showing the angle but can't find one good enough, I'll take some tomorrow, but here is one that you can see a little bit of the camber.
EDIT: here are the new pics,

DanO

I know this, i worked on the latest design (Trailblazer SS). We have test stands that have continous differentiation with large input ring gear torque and they last quite a while. I agree they will wear faster in an Auto X environment, but they should still last for years in occasional auto X use. Dont forget, the Torsens still rely on friction between the gear teeth and as the surfaces of the teeth wear your bias ratio is reduced. So basically, its either clutch packs to wear or gear teeth. I agree though that the torsen type unit is much better suited for an auto x environment.

By the way, the torsen units dont have any static bais. There is no bias unless there is a sufficient amount of input torque. The eaton unit on the other hand has a set amount of "breakaway torque" required to differentiate the unit. but again, this is more beneficial to the drag racer.

dailydriver

Sam, while we're on this subject; are the gears/worm gears in the T2R super-hardened/treated at all? If so, that could address the wear issue, as well as give the occasional drag racer on sticky tires some more confidence in the unit.

jimmyblue

iTrader: (11)

T-2R adds static preload springs specifically along
with more gears as in the T2-HD (no preload). Both
of which are beefier than the "take-out" Torsens
and have more torque bias range. The limited bias
ability is the source of the "one wheel peel", not
preload or the lack, I expect. Though preload is a
bonus it's not going to be sufficient in itself to break
loose a tire. Just enough to get you out of the sand.
Preload has to be low enough not to be a menace to
normal differentiation, after all. Like more than ice and
less than rain, traction-wise.

Sam Strano

iTrader: (41)

Well, now that I was told the video had a stock take-out Torsen it makes more sense. His sig said Eaton, so I assumed the video also included the Eaton it didn't. So I'm happy to say it's probably not burned up.

The teeth are hardened gears. You could say the same about wear on a the teeth of you ring and pinion. Clutches, wear faster than the metal does. And as you mention there is the breakaway torque factor. Clutched diff's that are working are always engaged to some extent, and the better then get power down while turning the tighter they have to be. That wear clutches even when you aren't autoxing. The inside and outside wheels have to rotate @ different RPM, and the clutches have to slip to allow that. Not an issue with a helical diff. Then you have the issue of balance. The tighter a clutched LSD is the more corner exit understeer you have until you are spinning both rear tires. Helicals don't have this issue because any inside wheelspin will just cause more torque to be biased to the outside rear wheel, eliminating the understeer torque of a typical LSD.

NOTE that I'm NOT saying Eaton's (and other clutched units) are junk. They are not, and I sell Eaton and Auburn to name but two as well as helical units. It's horses for courses.

Sam Strano

iTrader: (41)

When you aren't drag racing, what's the use of the car?

I'd not recommend a T2R for a drag car AT ALL because a lot of grip and power and the way those diffs work can break the actually carrier. A modestly powered car that once and while drags.... myabe. If you don't do the things that the T2R is design for then a T2R isn't what you'd ideally want.

In short we'd have to have a conversation regarding your uses, and pick the most suitable unit from there.