Jocko1960

Hi all.
My car has the stock susp. and shocks. Only piece added is the STB. My problem is when going hard into a turn or getting on the gas hard coming out of a turn it wants to push the front. I would like to eliminate the push. I feel more in control of the car if I can control the rear end more. Question is what do I do to accomplish this. Larger front swaybar or larger back or something else. Don't know how well I've explained my problem, so I'll try to answer any questions you have to help describe what I'm looking for better.
Thanks,
Doug

roy

How about trying a more performance oriented alignment, practice coming off and on the gas before and after cornering. Try no braking during cornering. Addsome sticky tires. That should hold you for a while until your skill level improves abit.

My formula when I started was
-30mins camber +4.5 deg caster
Sticky tires
revalved shocks and springs
-1deg camber +4.5 deg caster
32mm front sway (solid) 21mm 1le rear sway bar

The biggest improvement for me was the sticky tires.

Jocko1960

Well have to admit my driving skills are based on racing go-karts and they pretty much ride on a rail. Though I do have a lot of exp. with fast driving on the curvy roads around the NC mountains. With a rearwheel drive car I like being able to put the rear where I want it in a curve. Previous cars were a 928 and a Opel GT that surprised the heck out of unexpectant drivers <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> . Both handled much better than my Z28.
I just want to know what I need to do to loosen the rear up some, without a lot of experimenting and waste of cash.

BlackBird55

iTrader: (1)

First of all the comment about no braking in the corner is wrong. F-bodies, and cars that push in general, should be trail-braked to counter act the push.

Suspension wise what you can do is to increase the diameter of the rear sway bar, or decrease the front. Play with the tire pressures abit aswell. I usually run 2 psi higher in the front. If you have adjustable shocks you can play with those too, but stick to the basics and see what that yields you. Good Luck!

Jocko1960

Thanks. I was thinking a larger rear swaybar, just wanted someone else to agree with me, lol.
Doug

BlackBird55

iTrader: (1)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by mitchntx:
<strong>
Trailbraking has it's place. But it is on rare occasions under extra-ordinary conditions. Trailbraking to help turn in push is a band-aid for an ill-handling car. It will boil the front tires off. I'm speaking from experience ... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I completely disagree, and ask any of the front runners at the runoffs in T1 and T2. I think you'll find most of them trailbrake, it is NOT done to fix an ill handling car. If you enter a turn by braking in a straight line, release brake, turn in, then accelerate, a car will push to some degree, not matter the set-up. There are many degrees of trailbraking if front tire wear is an issue you need to back off. If done correctly it will yield faster lap times.

mitchntx

iTrader: (14)

Trailbraking is a technique for the not so faint of heart. It's real easy to snap over steer and therefore not the preferred technique for turn in, as instructed to me by one Mike Patterson, T2 driver and multi-year run off veteran.

But this is what makes racing great ... each person has their preferred method of wearing out tires, brakes and rotors ... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

BlackBird55

iTrader: (1)

Ok mitch i won'e be too hard on you for this one, because for beginners that has some merrit. However let me quote from Mr. Carroll Smith's book "Drive to Win"

"The actual technique of straight line braking is pretty simple- you push on the pedal until the tires are not quite locked. You modualte the pedal pressure to keep them in that state as the car loses speed. When you have slowed down enough to enter the corner, you take your foot off the brake pedal and get on with the business of cornering - right? Wrong! The scenario we have just described will indeed get you slowed down enough to get through the corner - but you are very liable to be passed during the process. There is, in fact a lot of technique involved in optimal braking. The basic idea is to build up braking force as rapidly as practical, to maintain maximum straight line retardation for as long as necessary and then to smoothly transition into either trail braking or cornering"

If you don't know who Carroll Smith is goto:
Carroll Smith Bio
I highly recommend all of his books
Straight line braking is what is taught to beginners so they don't over rotate the car. Once past that stage trail-braking, to some degree, is a must to get the front end to turn in. This was taught to me by Multi-time national F-stock Champ Al Chan, FF national champ Gary Gadula, and Multi-time run off champ in SSC & T1 Erich Heuchele.

<small>[ March 24, 2003, 06:11 PM: Message edited by: BlackBird55 ]</small>

mitchntx

iTrader: (14)

Hard on me? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> Sounds like we agree ...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by mitchntx:
<strong> Trailbraking is a technique for the not so faint of heart. It's real easy to snap over steer </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">It's not a technique to be taken lightly.

It appears the point lost here is answering the question Doug asked about some rudamentary suspension tuning, which lead me to believe that he not the obvious expert you are.

Doug, don't trailbrake till you qualify for Joe Stud status ... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

BlackBird55

iTrader: (1)

My point was, Mitch, not to mislead him. The majority of racers, both autox and road race, do trail brake. Trail-braking is not as near as dangerous as your making it out to be. Why not learn correctly from the begining, you should have no problem practicing trailbraking on an autox course.

As for trying different things i think we covered that. Sorry for the long post I just think there is too much misinformation and unproven opinion that gets passed off as fact on the internet.

mitchntx

iTrader: (14)

And I don't believe I am guilty of misleading anyone. It IS a technique not to be taken lightly. The driver needs to have a firm grip on his abilities and know his car's handling characteristics before tackling this technique.

If Doug has that, then he should by all means go for it, when the corner calls for it ...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BlackBird55:
<strong> I just think there is too much misinformation and unproven opinion that gets passed off as fact on the internet. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Again, we agree.

On an AX courese where one is driving by one's self, practicing is a grreat idea.

Practicing this kind of technique with other cars on the track is an awefully big risk, assuming one is inexperienced, for not only the driver but all those other drivers out there.

But I'm not as aggressive a driver as some ...

<small>[ March 24, 2003, 08:39 PM: Message edited by: mitchntx ]</small>

trackbird

iTrader: (4)

Just a quick thought. A car with a torque biassing differential will try to accelerate the tire with the lowest wheel speed first. WHen turning, the inside wheel is turning slower than the outside wheel (duh???)...a torque biasing diff will see the outside wheel as "spinning" and transfer power to the inside wheel which will tend to push the car (due to a thrust imbalance) until you begin to spin the inside wheel (or both of them). This may be part of the true origin of your push off corners. My main clue was....

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif"> when going hard into a turn or getting on the gas hard coming out of a turn it wants to push the front </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">That may be as much the fault of your differential as the cars setup (not that the setup can't be improved over stock). Just thought I'd throw that out to everyone....

Jocko1960

Now things are getting interesting <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Anyhow I'm glad it's started a conversation because that's the problem I'm working on at the moment. The thing is fast enough (well pretty much so) I just want the control I feel like I have when I can work the back of the car and put it where I want it to be in relation to where I want to go.
Thanks for the input all and I'm still listening.
Doug

mitchntx

iTrader: (14)

With stock munted LCAs, the bigger rear bar will have a minimal affect due to binding of the LCA mounts.

When the body rolls and the rear axle stays flat, the LCAs will twist in their mounts. This twisting binds them and adds effective spring rate.

I suggest 2 things ...
A max camber, max caster and zero toe alignment to help turn in;

A pair of G2 poly/rod LCAs to help corner exit.

That did wonders for my car.

I would like to comment on trailbraking to help turn in ...

Trailbraking has it's place. But it is on rare occasions under extra-ordinary conditions. Trailbraking to help turn in push is a band-aid for an ill-handling car. It will boil the front tires off. I'm speaking from experience ... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

<small>[ March 24, 2003, 12:51 PM: Message edited by: mitchntx ]</small>

BlackBird55

iTrader: (1)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by trackbird:
<strong> A car with a torque biassing differential will try to accelerate the tire with the lowest wheel speed first. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">A torque biasing diff works on torque not on wheel speed. A torque biasing, or torque sensing, diff will transfer power to the wheel with the most grip. The more grip it has the more torque it can take without causing wheel spin. In a turn your outside wheel has more grip, therefore the diff biases the torque to that wheel helping your car turn in. You should be able to fell this. When in a turn if you depress the gas the car should take a tighter line, let off and the car should walk back out. So in short a torsen diff helps with cornering.

trackbird

iTrader: (4)

Ok....here are links to the Torsen home page and the tech information.

http://www.torsen.com/general/genera...rential%20work

http://www.torsen.com/Traction_Control_Article.pdf


In the PDF file section 5.2 Torsen states:

"In turning situations, the outside wheels of a vehicle travel over more distance than the inside wheels. Accordingly, the inside adn outside drive wheels must rotate at slightly different speeds to maintain rolling traction with the road. A torque difision between drive axles at the bias ratio is a brecondition for differentiation under all circumstances of operation. Essentially, in otder for one drive wheel to rotate faster than the other, the driev wheel hving greater resistance to rotation slows with respect to the differentail case and transfers torque to the other wheel contributing to it's faster rotation. The Torsen differential resists transfers ot torque between drive wheels in proportion ot the torque applied to the differential housing, and this results in a larger proportion of the applied torque being delivered to the slower rotating drive wheel. Therefore, bias ratio should be selected to provide the maximum traction advantage that will still allow both drive wheels to deliver signifigant portions of engine torque in turns."

trackbird

iTrader: (4)

Guess I should have read over that again first and corrected my typos (and there are lots of them....). Anyway, the inside wheel is the slower rotating drive wheel and therefore gets more drive energy (even per torsen). Those are good tech articles, but the .PDF file gets a little detailed (adn heavy in math, if you want to go through it....but you don't have to do the math). Let the arguements begin.......(just kidding!)

BlackBird55

iTrader: (1)

You've taken that statement out of context. What that is describing is when loss of traction at one of the driven wheels occures.

From the same webpage
"It multiplies what torque is available from the wheel that is starting to spin-up or lose traction and sends that available torque, multiplied by the TBR, to the slower turning wheel with the better traction."

Under the section on torque bias ratio
"The provision of the bias ratio significantly affects the operative connection between drive axles and represents a careful choice for controling torque transfers between drive axles to achieve optimum traction A "4:1" bias ratio design means that the torsen diff is capable of delivering to the drive wheel with better traction, four times the amount that can be supported by the lower traction wheel.

Your outside wheel has better traction in a turn than you inside therefore will get more torque applied to it and aid in turn in. Again a torque sensing, or Torsen, diff is dependent on TORQUE not SPEED.

<small>[ March 25, 2003, 10:40 PM: Message edited by: BlackBird55 ]</small>

trackbird

iTrader: (4)

Ok, heres the deal. A torsen differential can't measure actual torque. It can detect a difference in wheel speed. If you are sitting still and you stand on the gas, you will start to spin the right rear wheel. Once that wheel begins to spin (a spinning wheel is still putting down power, just not an optimal amount) the diff will transfer power to the left rear wheel which is turning slower since it has more available traction. At this point, the differential has not measured any torque, it simply is trying to even out the power distribution and it assumes (the math is in the website) that the slower wheel has more traction and will try to equalize the wheel speed. Explain this one:

Put a jack under one side of the rear axle of your car and lift one wheel off the ground...what happens? If you were correct that is sensed torque, the car would drive off the jack....IT WON'T!!! In this case (an extreme case though it may be) we are putting exactly no power to the wheel with traction.....(It really won't drive off the jack. But, while still sitting on the same jack with one wheel spinning in the air, gently pull the emergency brake....you will now drive off the jack. Now, this also does not quite agree with my "slower wheel" in corners....but I'll explain.

A torsen diff is capable of putting 2.3 times the amount of torque to the wheel with traction as it is to the wheel with out (some of the diffs go up to 5:1 or higher, but the F-body type stay around 2.3 or so). Now, if we have one wheel spinning and putting 100 ft lbs of torque to the asphalt, the other wheel could receive 230 ft lbs of "drive torque". Now, if I am putting 100 ft lbs of power down with a wheel that is spinning (the faster wheel) and 230 with the wheel that has traction (the slower wheel), this car is not going to go exactly straight, the slower wheel that is putting down more power is going to turn that car due to an imbalance of thrust. This is why most cars turn right when you hammer 2nd gear (turn right, or the drivers side swings left....either way). I have managed to do a one wheel burnout in my car....I just put enough power down to spin one wheel, and the other managed to hook up with what power was left. The diff allowed a differential of wheel speed, and transfered power to the slower wheel (that had traction). If anyone has taken the time to actually read all of this....thanks, and congratulations (and, why are you still reading way more info than anyone cares to know about the rear of an f-body....get some air, go outside....drive....lol). Did I lose anyone?

2001CamaroGuy

iTrader: (6)

I agree on the LCAs but I also think a really good panhard rod should be the first upgrade. I feel this for two reasons:

1) it sets you up for everything that will probubly come later (lowering springs, wider tires, etc...)

2) the stiffer panhard rod will keep the rear better located and thus improve handling.

Any of my posts, you will see that I always advocate for rod ends (both ends). They perform far better than anything else and the noise is not as bad as people make it out to be (I think...).

With my current setup, I have a little over steer when cruising. When coming into curves, a little heal-toe down shift and a light breaking (mostly let engine do the breaking) at the entrance makes the car really turn fast (more over steer). By the time I am half way through the curve, I have already started to accelerate. The addition of power brings the car to a neutral steer and puts weight on the rear end. I reach full throttle just after I exit (straighten out). Its repeatable and precise allowing me to push corners faster than I ever dreamed.

Chris

<small>[ March 25, 2003, 11:03 PM: Message edited by: 2001CamaroGuy ]</small>