Anti Roll / Sway Bar Thickness

[nuffsaid]

Hi all

I know of a brand that makes sway bars in the following sizes for a R34 GTT

F 31.8mm and R 27.2mm

Now Nismo make em at F 27.2 and R 23.0

and SK's group buy is at F 24 and R 21

Now should I go for the thicker one? it seems like Whiteline gear are the smallest sway bars, Nismo being a step above, and the other brand even bigger.

What do you guys think? are there any downsides to thicker sway bars? (I dont think so but I may be wrong)

Thanks

[Maxx]

the harder the sway bar, the less grip u will get

Edited June 17, 2006 by Maxx

[nuffsaid]

Then what is the point?

Less traction but less body roll with thicker bars?

And more traction and more body roll with thinner bars?

What is the optimum?

Also, who knows what the standard size of the R34 GTT sway bars are?

[r33_racer]

The whiteline bars are blade adjustable, with numerous holes in them to increase the amount of anti sway or decrease. Both front and back are like that. Are the nismo ones adjustable? I know a mate of mine got some cusco ones and they are just plain ole swaybars, but slightly thicker in diameter.

The traction part is debatable, cause it depends on how it is setup:)

[Duncan]

Also, there is a world of difference in stiffness between hollow and solid bars too.

[GTRgeoff]

Mike has it in one.

These would be fine on a super smooth track using slicks, but if you want to drive daily get used to the idea of driving real easy through corners in the wet or over bumps, unless you like the idea of becoming part of the scenery or looking back at oncoming traffic.

I have a 30mm rear bar for my Lynx which transforms the handling, but I've had to reinforce the mounting locations due to the stresses applied as it tears standard mounts apart.

[Roy]

Reading an article from about 18 months ago with regards to touring cars. Two drivers from the same team were lapping about the same, qualified withing poofteenths of one another, and the data showed them having similar consistancy throughout the race...traffic permitting.

One had huge swaybars and soft springs, other had hard springs and bugger all bar. So different strokes for different folks. The chassis were not identicla and its posible one chassis liked one setup more then the other...but odds are it was driver preference.

My thoughts, if you rely too much on bars to control body roll and run too soft a spring, then surely you will have trouble controlling the pitching of the car under brakes and acceleration?!?!?!

Can you put too much bar on a car? I believe you can. Is 31.8mm ec too big for a daily driven car? I dont know. Give it a try, but gut feel is they would be too bigv (Thats assumign that all these cars are solid)

[GTRgeoff]

In the race car they can use brake biasing and other adjustments to account for the pitching, but on slicks it makes a big difference. On road you will be having problems unless you walk in to a good suspension place and let them do a complete and costly setup.

[nuffsaid]

Hmm that leaves the question still unanswered, anybody else have any ideas?

Thanks!!

[blind_elk]

Roll / sway bars have nothing whatsoever to do with traction.

Roll bars stop body roll through corners. As a rule-of-thumb, stiffer front roll bars increase UNDERSTEER, stiffer rear roll bars increase OVERSTEER.

The stiffness of a roll bar is also proportional to the diameter of metal in the bar. So a 27 mm HOLLOW bar may be lighter (less stiff) than a 24 mm solid bar. I found this when I replaced a 25mm (hollow) rear bar on my GTS4 with a 24mm SOLID bar.

You need to check all the properties of the bars in question, and decide what you want the bar to do, before it can be determined which bar is best. That said, Whiteline has done a heap of work working out the best combo of bars (and other suspension components) for these cars under Australian conditions.

[Maxx]

Blind elk

why they have nothing whatsoever to do with traction

but

stiffer front roll bars increase UNDERSTEER, stiffer rear roll bars increase OVERSTEER ?

stiffer front - less traction in the front = UNDERSTEER

stiffer rear - less traction at the rear - OVERSTEER

???

[GTRgeoff]

Actually it's true by the normal definitions in racing.

Traction is a straight line term. Anti-roll bars don't help in a straight line.

Grip is a cornering term. Anti-roll bars contribute to the overall balance of a cars grip when cornering.

The stiffness of a bar is not however proportional to the diameter but to the diameter to the fourth power, so the 27.1mm solid rear bar will be 2.81 times stiffer then the 21mm bar rather than a straight 1.2 times stiffer.

I can bore you with even further detail, but unless you are a race engineer it won't make much difference. Don't buy them unless you are sticking to the race track.

The question has been more than answered.

[Maxx]

thanks for correct me

"grip", not "traction"

english is not my first language

Edited June 17, 2006 by Maxx

[GTRgeoff]

That's ok. Most English as a first language guys have problems with the terminology.

BTW below you can see the amount of roll on a GTR33 with Whiteline blade adjustable bars set to full soft front and rear. I was throwing the car in pretty hard and you can see the outside tyres are in full contact with the tarmac pumped to 40psiF/38psiR. You won't need any more than the Whitelines.

[Sydneykid]

Hi all

I know of a brand that makes sway bars in the following sizes for a R34 GTT

F 31.8mm and R 27.2mm

Now Nismo make em at F 27.2 and R 23.0

and SK's group buy is at F 24 and R 21

Now should I go for the thicker one? it seems like Whiteline gear are the smallest sway bars, Nismo being a step above, and the other brand even bigger.

What do you guys think? are there any downsides to thicker sway bars? (I dont think so but I may be wrong)

Thanks

Hi, let's clear up a the size issue.

1. The Whiteline bars in the Group Buy are selected (by me) to suite that application, they are for a road car with the occasional circuit and drag use. Plus they are matched to the Whiteline spring and Bilstein shock rates.

2. If you have a road car with lots of circuit use, then we would go to the next size up ie; 27 mm front 24 mm rear, both adjustable. This means I can still use the matched to the Whiteline spring and Bilstein shock rates and the car is not uncomfortable to use on the road.

3. The Whiteline adjustable stabiliser bars have bladed ends on the arms, to allow for the adjustment holes. This blading effectively stiffens up the bar as it removes the flex that you get in a round bar. On the Group Buy's softest setting a 24 mm adjustable bar is the same rate as a 24 mm fixed rate bar, and then there are 4 settings siffer than that. So the diameter alone doesn't tell you the whole story.

4. A 27 mm adjustable bar on the full stiffness setting is almost equivalent to a 30 mm fixed rate bar.

So, it's not how thick it is, but how you use it (where have a I heard that before?)

cheers

[Chris Wilson]

Also, there is a world of difference in stiffness between hollow and solid bars too.

Actually there's surprisingly little, as it's the outer "skin" of a solid bar, in torsion, that does most of the torsional resistance. I have the maths for it somewhere.

[R DIRTY 3]

I have 33 Gts-T. I bought the car and it had a solid 31mm bar on the front (brand unknown) Rear was standard. The car understeered BADLY! Got the whiteline adjustable and set it to medium and its so much better in handling. the car is used for local track/events and the times now are a hell of a lot better. I will adjust it to harder later to see what difference that makes but at the moment while its feeling good and other things are being done to the car, i aint going to alter it. (Dont like to change to much suspension at once).

Regards

R Dirty 3