What do you think of running no rear Sway Bar?

[spork]

now...I'm confused, but partially enlightened...I think...lol. So removing the rear roll bar will increase or decrease the effective spring rate in the back?

[katman]

Removing the rear bar will reduce your rear roll rate, transferring more weight to the ouside front tire.

[260DET]

Removing the rear bar will reduce your rear roll rate, transferring more weight to the ouside front tire.

 

With circuit racing its often the outside front tyre which wears the most on a S30 from what I've seen, mine is presently wearing the outside rear the most, followed by the outside front and then the two insides about the same.

 

Seeing that I did my best lap time ever just the other day by quite a margin with a 18mm rear bar I'm happy

[katman]

My experience jives with yours- the outside rear runs hotter even with no rear bar in our case.

[260DET]

My experience jives with yours- the outside rear runs hotter even with no rear bar in our case.

 

Why do you think that would be in your case? Given that you don't have a rear bar to add to the weight transfer load there.

[briann510]

so what about strictly launching straight line? better to run a rear sway bar or not?

 

also our car is not road raced and generally only used for sheer straight line accelerating and was thinking of also removing the front bar if nothing else to get rid of the weight.

[katman]

Why do you think that would be in your case? Given that you don't have a rear bar to add to the weight transfer load there.

 

Could be several factors including spring rates, roll centers,CG, etc. For whatever reason, your setup with a rear bar has the same result as our setup without one insofar as tire temp trends are concerned. I will say that the difference in temps between the left front and left rear for normal road courses like Roebling and Road Atlanta became very small after we developed the remote reservior double adjustable shocks. In fact, the left side to right side temps also got closer. I'd say we had always been very well balanced but undershocked until a few years ago.

[johnc]

also our car is not road raced and generally only used for sheer straight line accelerating and was thinking of also removing the front bar if nothing else to get rid of the weight.

 

As I've said before, if you get out of shape half way down the track you'll be wishing that front bar was still on the car. I wouldn't run a rear bar on a drag car.

[johnc]

On the Rusty Old Datsun we would always see higher outside rear tire temps even with some nice triple adjustable Penskes. A combination of a Quaife diff, good stick, and lots of horsepower tended to use up the rear tires before the fronts. It was easy to overheat the rears and ruin the session. The car liked to come off corners a little bit tail out (which was pretty easy to overdo) with the inside front wheel off the ground.

 

We did reduce the front anti-roll bar diameter to 23mm and the rear anti-roll bar was either 17 or 18mm depending on what we thought the track needed. Spring rates were 275 to 300 front and 300 to 350 rear again depending on what we though was best for the track. The pressure in the shock cans was adjusted from 175 to 210 and most of the shock settings were fairly close to full soft. It was rare to turn the settings past halfway just because the tracks out here are very bumpy.

[jt1]

On the Rusty Old Datsun we would always see higher outside rear tire temps even with some nice triple adjustable Penskes. A combination of a Quaife diff, good stick, and lots of horsepower tended to use up the rear tires before the fronts. It was easy to overheat the rears and ruin the session. The car liked to come off corners a little bit tail out (which was pretty easy to overdo)

 

That describes my car's handling almost exactly; and I'm not running a rear bar. 250F/275R, Illumina's on 5, 23mm front bar. It amazes me how different setups can yield the same results.

 

John

[briann510]

John, yea i remember your comment on the front bar and heeded that advice and left it on. i had a guy with a V8 z tell me when he took the rear bar off his rear and he got worse traction off the line at the track straight line accelerating. he said it caused one wheel to lift worse and im not sure if thats true or if something else was affecting the launch.

[johnc]

i had a guy with a V8 z tell me when he took the rear bar off his rear and he got worse traction off the line at the track straight line accelerating. he said it caused one wheel to lift worse and im not sure if thats true or if something else was affecting the launch.

 

Like road racers, top contending drag racers are using shocks as their primary tuning tool. Save your money and buy the absolute best adjustable shocks you can afford. I might also have a source for some Z specific drag shocks.

[briann510]

thanks John.

 

i should have at least use adjustables on the rear. once i put the HP's on i realized it, but the old ones were shot and i got a good deal on 4 of the HP's and couldnt pass them up. it didnt take but 45 minutes to replace both rear struts so i may get the adjustables. i dont know about strictly rear drag shocks only as the car is driven on the street as a daily driver also. but if it will greatly help get the car launced maybe...

[260DET]

On the Rusty Old Datsun we would always see higher outside rear tire temps even with some nice triple adjustable Penskes. A combination of a Quaife diff' date=' good stick, and lots of horsepower tended to use up the rear tires before the fronts. It was easy to overheat the rears and ruin the session. The car liked to come off corners a little bit tail out (which was pretty easy to overdo) with the inside front wheel off the ground.

 

....................[/quote']

 

So the front droop was limited in order to get the inside front wheel off the ground?

 

My self appointed wannabe crew chief is nagging me to set mine up so it lifts an inside wheel in corners, my response is two wheels will grip better than one. But they don't, or its not relevant, in that instance?

[johnc]

So the front droop was limited in order to get the inside front wheel off the ground?

 

No, that's an unintended side affect of the Penske setup I had. Some of the stiffer rebound settings would slow the droop of the inside front wheel as weight transferred back under acceleration from the corner apex on tighter corners.

 

 

On longer corners the inside front wheel would still be on the ground.

 

[260DET]

Great pics John

 

Similar attitude here ........

 

http://www.osella.com.au/wayne/2005-sprints-28-5-05/pages/Ose_7963.htm

 

http://www.osella.com.au/wayne/2005-sprints-28-5-05/pages/Ose_7920.htm

 

Keen eyes will have noted the tyre distortion, should go up a few pounds it looks like.

[jeromio]

On my car (high hp LS1), I must be very careful of throttle application when cornering. I want to be able to apply some throttle post-apex, but too much (measured in like 1% increments) or too early and the back squirrels right out. When it's wet, this is all magnified. As it is now, this would make a fantastic drift car (not my intention btw).

 

I have no rear bar. I'm using 150lb/in front, 175 lb/in rear. (BTW, I can't fathom what it's like to ride in a car with stiffer springs - mine's like a freakin' skateboard). I have the stock front bar and no rear bar. I have added front camber (lost my sheet - I think it's like 1.5*) due to relocated pivots (13/16" up and 1/4" out). I have 0 toe in back and about 0.5* toe in up front. Turn in is sharp. It also follows every road irregularity like a hound (235/45/17 Dunlops). It does not (to me) push. the tendency (again, butt dyno) is to oversteer.

 

Overall, the handling is okay, but a bit twitchy. It's not an easy car to drive - requires effort. I'm wondering about this rear sway bar issue. I had a bar and was all set to fab up mounts, but read (on here and elsewhere) at the time some things that seemed to point to no bar as the way to go. Now I'm having second thoughts.

 

I'm a total novice, so stability is the preference over speed. Ease of use is more important to me than corner-exit accel. I'm looking to upgrade the h/w up front, but for the rear, I'm really just trying to figure out the rear sway bar. The outsized power aspect of my car is a big issue. Would adding a rear bar make the situation worse? Adding the mounts will be no small task.

[2126]

Well, I took the rear anti-roll bar off and went for a drive on some of the roads I'm familiar with and frequent when looking to have a bit-O-fun. The results......I like it!!! The rear stays planted better for sure and I did not notice any big difference in front end understeer. I can certainly get back on the gas much sooner and harder, coming out of tight corners, than with the 19mm rear bar in place. Remember, this is just a street car, intended for spirited driving on tight twisty back roads. Thanks for everyones input on this subject matter.

 

Tom