I want to fit a Anti Roll bar to the front suspension. Nothing found searching under Anti roll bar and I deffinately do not want to fit a tortion bar. I have coil overs.

Any suggestions? Sizes, brackets and donars.

I have a standard book chassis and a 1.6 Kent.

Search for antiroll bar instead.

MK made me one up for my Indy. I'm sure they could do the same for you if you give them the size/thickness. I don't think you will find a standard donor as all will be too heavy.

I haven't done the one for my seven yet but I made one for the rear of my grasser, from cold drawn mild steel tube. Approx 17mm od and 4mm wall. I heated and bent it in the vice with no kinking problems, and mounted it in split nylon blocks.

see pic below, it's the grey bit (never did get round to painting it properly!)



grasser rear

[Edited on 26/8/05 by NS Dev]

Wouldn't have thought mild steel would be "springy" enough?

it's fine. I used to think the same, and that I would need to use 4130 steel, but mild steel is fine, it is a long bar(or tube in this case) and the twist per unit length along the bar is very small, so it stays well within the elastic limits of the mild steel.

The was an article in this last months? PPC (Practical Performance Car) magazine that showed how to go about building yourself an anti roll bar. Not sure if it was last months or this months as I don't know when the new one comes out. I bought it on monday.

Is the bar suppose to flex?
My understanding was that it was not suppose to flex so it can reduce the chassis roll, but not to the detriment of having rock hard supring settings.

Who has some close ups of this system in their archive.

My understanding is that it has to flex- but the flex is rotational along the width of the main length of the bar. It does not flex if both wheels are in bump or droop at the same time - only flexes when one wheel moves or both move in oposite directions.

Question - I have a mgb anti roll bar that is too narrow for me to use- could it be cut and sleeved-if the center section is bolted and not welded as I assume that welding the section in would make it britle.
Dale

Why is it then the first thing they do when you have your car's (factory speciment) suspention uprated that they replave the factory fitted antiroll bar with a thicker unit?

HaY kango

You need to read the gospel according to Staniforth. Pop round and I will lend you the books

Cheers

Fred WB

If the anti roll bar didn't twist you'd have no roll at all. You'd also have both wheels rigidly connected so if one hits a bump they'd both bounce up - not good for ride quality.

Fitting a thicker roll bar in a production car reduces roll (cos the thick bar twists less than the standard bar) at a slight cost to ride quality.

Liam

OK Ok Ok Ok
I am convinced it must flex...not too much.

Now for some tips on how to do it to a book chassis.

Bar diameter, type of brackets and where to attach to the chassis.

PLease.....

I'm afraid you are quite likely to be ahead in the anti roll bar research and development phase here, probably as most folk simply havent bothered - manufacturers included...

Have you a particular handling trait that you are looking to cure by fitting an ARB?

http://keith.miata.net/seven/updates.php?from=30&no=0

Have a look here. Keith's Locost utilizes Miata (MX-5) suspension parts, but it may give you some ideas perhaps.


Brian

I am doing one (post sva!) for the front of my 7 and I will use the same as I did on the back of my grasser (as the photo) which was 17.46mm x 4.06mm cold drawn seamless mild steel tube.

Your guess is as good as mine as to the spring rate that it gives in roll, but make it adjustable like I did and you can play and see what it does. 3 races saw mine set up ok.

No handling problems as she is still sitting on drums.
The idea was to weld any brackets to the chassis before I have it blasted and coated.
If I feel I need it, once she is on the road, I can fit it with out any welding to a newly powdercoated frame.

Ok, Anti-Roll bars....
If you're a fan of Milliken and Millikens work, I've put together a little spreadsheet program to play with thats attached. Their formula for installation ratio of an anti-roll bar is:

K1b=(K2b)(I^2)((T^2)/(L^2))
K1b="contribution of anti-roll to total car roll rate (lbft/deg).
K2b=anti-roll bar anguler twist rate (lbft/deg)
L=Anti-roll bar lever arm (ft)
I=linear installtation ratio (inches movement of pickup point to movement of wheel (in/in))
T=Track width (ft)

Then Aird goes on to define torsion bars/anti-roll bars rate as:

K=(G*D^4)/(585*L)
K=torsion rate inlb/deg
G=11,500,000 (modulus constant for steel springs)
D=Bar diameter (in)
L=Bar length (in)

and goes on to include the lever arms:

Kl=(Kt/l)(arctan(1/l))
Kl=linear rate of anti-toll bar system
Kt=torsion rate of the bar itself (calculated above)
l=length of lever arm (in)

Keep in mind while going through these that the millikens tend to work to the unit of (ft) while Aid works in inches, so convert accordingly. Cheers!

Edit: One last thing, hollow torsion bars:
Aird
Kt=(G(D^4-d^4))/(585*L)
Kt=torsion rate (inlb/deg)
G=11,500,000 steel modulus
D=OD of bar(in)
d=ID of bar (in)
L=Length of bar (in)

[Edited on 31/8/05 by crbrlfrost]

quote:

---

Originally posted by kango
No handling problems as she is still sitting on drums.
The idea was to weld any brackets to the chassis before I have it blasted and coated.
If I feel I need it, once she is on the road, I can fit it with out any welding to a newly powdercoated frame.

---

Ok I found some decent pictures of a Fraser from Oz that gives a good idea of how to bend it and attach it. It doesn's spec the material. I know the suggested materila is 4130 but When I asked rorty what he thought he suggested cold drawn seamless tube. I'm going to start with 16mm by a standard heavy wall and see what happens. Any way to all that responded, thanks for the replies.
Kango and Fred; fancy bumping into you guys here in the UK.
All the best,
Ross