Strengthening Front Anti Sway Bar Mounts

[S15 200sx owner]

Hey Monster,

 

What is that brake setup on your car, sizes and who's kit?? Looks good.

[MONZTER]

Hey Monster,

 

What is that brake setup on your car, sizes and who's kit?? Looks good.

 

The brakes on my car are AP aluminum 4 piston post mount in front with 13" AP cross drilled rotors. I designed the rotor hat and mounting bracket for the post mount setup myself. Everything is CNC machined from 7075 and hard anodized. I only made 1 set.

The backs are AP 2 piston post mount (same as a lotus Elise front) The rear rotors are cross drilled Z-32 rotors and the backing plate is also custom designed to bolt on and use all of the parking brake hardware from the Z-32. Again only 1 set.

 

 

Thanks Jeff

[S15 200sx owner]

Jeff,

 

Your work is just amaizing!!!!

 

Myself and a engineer friend sat down last night and looked at all your pic's of your fabrication work, rear susp and diff mounting etc.....just beautiful, we are very impressed.....oh to have 1/4 your skills and access to equipment.

 

We do like the look of your diff mount (replacement for moustach bar) couldnt get a good look at your front mount for the diff, what have you done there??

 

Jeff, you are a wizard!

[MONZTER]

Wow, thanks for the comments, much appreciated. I have not finished the front dif mount yet. I am waiting to finish my 3" exhaust routing, and then will build the mount around that. I think somebody else around hear built a mount using the mounting holes for the diff strap. Looks like a good idea, I will probably do something like that.

 

Jeff

[Pop N Wood]

Seems to me if you mounted each end like this then the bar can't twist can it? Normally the bar twists about it's centerline but with the heim joint sticking out away from the centerline they are severly impairing the bar being able to twist - no?

 

Cameron

 

 

Hate to jump so late into such and old thread, especially since the way Jon did it seems to negate the issue, but I agree with Cameron. The center of the bar is acting as a torsion bar. Staking it at both ends will effectively make the bar seem like a heavier bar. Guess it depends a lot how much the ends of the bar can move as the center tries to twist.

[JMortensen]

I think you guys are just plain wrong on this one. The bar can twist just fine. The heims will deal with a good amount of direct twisting of the shaft and a good amount of bending as well before they lock up due to the bearing. After mocking it up and testing on the bench, I was shocked at how little movement there is in the center to move the ends up and down. True, the bar can't twist in any direction (needs to twist in a way that the heims still point at the brackets) but a stock bar with bushings has similar limitations, assuming the bushings aren't worn or too soft. And it is also true that with a stock bar attached with bushings, the farther the brackets are towards the end of the bar, the stiffer the bar will act.

 

I did measure the spring rates on the front and rear bars and was surprised at how low they were. Given the amount of stiction and friction in the poly bushings, I'd venture a guess that in a "normal" setup with teflon tape and whatever grease started out in there long since used up, the poly bushings might drastically affect the spring rate. I'd guess the heims joint setup would probably measure out comparatively light. The front bar had a rate of 105 in/lbs at the lightest setting and 120 at the heaviest. The rear bar had a min rate of 50 and a max of 80. If someone wants to compare to those numbers we'll know for sure.

 

There might be a point if someone were running stock springs and slicks or something similar with grossly excessive body roll where the heims would be an issue. I'm not doing that. I'll be running some very stiff springs, and the swaybars are going to be for tuning the balance, not so much for controlling the roll.

[heavy85]

My assumption is the bar twists about it's center. If you mount the bar off of centerline at both ends then how can it twist? This has nothing to do with stiction or range of motion of the bearings it's a pure mechanical thing. The real effect depends on what part of the bar is bending to begin with. I'm assuming the longer portion that connects the two sides in a 'normal' bar is doing most of the bending. Since you are holding the ends of this portion relative to each other you are forcing the twist to occur in the bend of the bar or the shorter legs that go to the endlinks. There is effectively less bar that can freely twist and therefore leading to my thoughts that the rate would go up.

 

So the real question is when will this thing be on the road! If I get the PCM back I will start the LS1 up for the first time over Christmas.

 

Cameron

[JMortensen]

But it can twist. The bar can twist and the bearings can move independently. This will require a ***slight*** bend in the center of the bar to allow the rod ends to pivot. In practical use I don't see this causing any problems whatsoever and I think a normally installed bar bends in the middle as well, so really not much different going on here.

 

If there were no bearings and the bar was bolted or welded straight to the frame rails, then it wouldn't be able to twist and you'd be relying on the arms to bend. This is just not the case the way my car or the Trans Am car are set up.

[johnc]

I think there's an assumption that an anti-roll bar or torsion bar twists perfectly around the shaft centerline. They don't. Torsion and ARBs warp more then they twist and that's how anti-roll bars with multiple bends and asymentric bends work.

 

[260DET]

I think there's an assumption that an anti-roll bar or torsion bar twists perfectly around the shaft centerline. They don't. Torsion and ARBs warp more then they twist and that's how anti-roll bars with multiple bends and asymentric bends work.

 

 

Yeh and thats so easy to check.

 

With the ARB mounted as usual in the car remove one front wheel and the link that connects that end of the ARB to the lower control arm. With the other wheel firmly on the ground place a suitably sized piece of pipe over the end of the ARB and apply manual force to the end of the pipe, it needs to be long enough so you can apply a fair amount of force. Observe what happens!!!

 

Everything flexes and moves, the thicker the ARB is the more movement and deflection you get in the bushes and mounting brackets and the less the ARB itself bends. Poly bushes don't help that much, they squash out quite easily.

 

Which is why from memory this thread was started, POS stock S30 ARB mounts

[duragg]

And here I sit on a 737 at FL400 reading this thread for the first time with the AHA!!!

I can indeed have adjustable sway bars..

 

Thanks guys.

[gnosez]

Sorry for the late reply but for what its worth, the Bob Sharp race cars had  a pipe welded into the engine bay frame rails and the sway bar was placed inside. I have a few of the solid and hollow core bars that came with a truck load of bits and pieces from the 240, 280 and ZX race cars.

 

That pipe tied the front end together, got the bar out from under the frame and made it easier to work on the suspension and oil pump