Where To Get New Swaybar D Bushes And Brackets?

[V28VX37]

Hi all,

I just got a set of second hand ARC (Auto Refine Company) R33 GTS-T swaybars that I'm planning on installing on my R34 GTT - fingers crossed they fit.

These swaybars are hollow and measurements are as follows:

• Front 28mm, non-adjustable (stock bar = 22mm)
• Rear 25mm, three point adjustable (stock bar = 18.5mm)

The rear bar uses spherical end links (see photo below) and apparently the front uses the standard end links.

I'd like to clarify a couple of things before attempting to install these:

1. I'm missing some D brackets and bushes and was planning on replacing them anyway. Any idea where to buy a set (2 x 28mm, 2 x 25mm)?
2. With the rear adjustment, what's the most "understeery" setting I should start with (= closest to stock behaviour)?
3. I read somewhere that the spherical end links may not be ideal in a road car - can they be easily replaced with something else?
4. These bars don't have the "lateral locks" like in the M35 Stagea thread, I assume that's ok?

Thanks guys!

I've found some good installation instructions by Sydneykid here: M35 Stagea Suspension and R33: Installing Whiteline Swaybars.

Photos of my swaybars:

And some more pics of different ARC swaybars here: arc pipe stabilizer for s13 and Arc Auto Refine Company 30mm Pipe Swaybar Rear Bnr32.

[ARTZ]

you can get universal d bush..I found them on ebay the other day from Eagle auto in dandy but imagine lots of places could have them..have you asked around bursons etc..

Will post a link when i get home..

[GTSBoy]

Spherical links are absolutely ideal on the end of swaybars. They have zero influence on NVH, but make the bar react instantly to any body roll, which is excatly what you want. The only problem is that they wear as they get dirt in them, so at some stage you may have to work out how to recondition them (ie find suitable replacements).

The most "understeery" setting will be the one that gives the most grip at the rear, which is the softest setting. The softest setting is the hole closest to the end of the bar. Having said that, the front bar might be quite a bit stiffer than the rear, so I would start with the middle or stiffest settings rather than the most understeery. Understeer is the very devil, and you'll probably have more than enough as it is. Try the middle, see if you like it, then you only have to make one change either way depending on how it feels. If you start at one end, you may end up changing it twice to get the same result (of course you may not need to change it at all......but then you almost certainly will, just to fiddle!)

As for the D bushes....because they are so large you may not be able to find them easily. You might be able to, but if you can't you could always get someone to machine some out of a block of PU or similar material.

Edited October 24, 2011 by GTSBoy

[V28VX37]

Spherical links are absolutely ideal on the end of swaybars. They have zero influence on NVH, but make the bar react instantly to any body roll, which is excatly what you want. The only problem is that they wear as they get dirt in them, so at some stage you may have to work out how to recondition them (ie find suitable replacements).

The most "understeery" setting will be the one that gives the most grip at the rear, which is the softest setting. The softest setting is the hole closest to the end of the bar. Having said that, the front bar might be quite a bit stiffer than the rear, so I would start with the middle or stiffest settings rather than the most understeery. Understeer is the very devil, and you'll probably have more than enough as it is. Try the middle, see if you like it, then you only have to make one change either way depending on how it feels. If you start at one end, you may end up changing it twice to get the same result (of course you may not need to change it at all......but then you almost certainly will, just to fiddle!)

As for the D bushes....because they are so large you may not be able to find them easily. You might be able to, but if you can't you could always get someone to machine some out of a block of PU or similar material.

Thanks GTSBoy, brilliant response!

Good idea about starting with the middle setting in the rear. You're right, the stock setup has mad understeer as it is, I'd much prefer something more neutral/balanced.

I might have a look through the Whiteline catalogue for the D brackets & bushes... I wonder who else manufactures these kind of items?

[ARTZ]

http://www.ebay.com.au/itm/Universal-Swaybar-Mount-Bushes-All-Swaybar-Mount-28mm-/120793677341?pt=AU_Car_Parts_Accessories&hash=item1c1fdd3e1d

http://www.ebay.com.au/itm/Universal-Swaybar-Mount-Bracket-All-Swaybar-Bracket-/190544495369?pt=AU_Car_Parts_Accessories&hash=item2c5d564309

[V28VX37]

http://www.ebay.com....=item1c1fdd3e1d

http://www.ebay.com....=item2c5d564309

Thanks Artz!

[89CAL]

Super pro do the d-bushes just need to know the size

[V28VX37]

Super pro do the d-bushes just need to know the size

Thanks mate, ordering some as we speak.

I've been in touch with Fulcrum and these bushes should be compatible with the OEM brackets, so no need to get new D brackets either.

[89CAL]

Yep spot on. as long as you know the sway bar OD they will fit fine

[R.3.2.G.T.R]

hit up sponsor gslrallysport

[V28VX37]

I just got a set of second hand ARC (Auto Refine Company) R33 GTS-T swaybars that I'm planning on installing on my R34 GTT - fingers crossed they fit.

These swaybars are hollow and measurements are as follows:

• Front 28mm, non-adjustable (stock bar = 22mm)
• Rear 25mm, three point adjustable (stock bar = 18.5mm)

All rightie, I finally got around trying to install these puppies and more questions popped up:

Looks like the ARC 28mm front swaybar is about 35mm longer than the OEM item and the end shape is slightly different too, see pics below. Could this be a GT-R item?

I tried putting it on but couldn't quite close the D brackets, and I'm not too sure if the original end links will like that much stretch.

I'm also concerned about the ends fouling the control arm and/or radius rod... I might have another go this weekend, what do youse think?

Also, turns out the OEM bars are solid whereas the ARC ones are hollow so they're not directly comparable. Does anyone have a formula for solid to hollow e.g. 20mm solid ~= 25mm hollow etc.?

The ARC 25mm rear swaybar went on without a hitch along with the spherical end links. I set it to the softest (outermost) setting to dial out some of the original understeer but go into oversteer. Based on a quick drive it seems reasonable but needs some more testing. See pics below.

Oh yeah all bushes are Fulcrum SuperPro ordered through Tuspeed.

Front swaybar

ARC vs OEM front swaybar

ARC vs OEM front swaybar

ARC vs OEM front swaybar length difference

OEM front swaybar and end link

Rear swaybar

ARC vs OEM rear swaybar

ARC rear swaybar and end links installed

[GTSBoy]

There's no easy formula for converting the stiffness of solid and hollow bars. You could knock up a calculator in Excel to do it in a few minutes though.

The rules are simple. Stiffness increases with the 4th power of thickness. So if you want to compare a 22 and a 25 bar, just take the 4th power of each and divide one by the other. 25^4 / 22^4 is 390625/234256 which is 1.67. That means that a 25mm bar is 167% the stiffness of the 22mm bar.

Now, here's where it gets tricky. You can calculate the stiffness of a hollow bar by simply working how how stiff a solid bar of the same OD is, and then subtracting the stiffness of a bar the size of the hole up the centre. It's that easy. But the trick is that if you had, say, a 25mm bar with a 10mm hollow, then the stiffness is 390625 - 100000 = 290625. That makes that bar still stiffer than a solid 22mm bar. Because the stiffness varies with the 4th power, it is really really sensitive to the diameter of the outermost layers of the bar - stiffness goes up massively as diameter increases. What this means is that the smallest diameters don't matter at all. Example. If you take a straight bar 25mm in diameter and bore it out 22mm in the centre, then the thin little wall that you have left (only 1.5mm thick) gives you a hollow bar that is still 67% of the stiffness of the 22mm of material that you bored out of it. A tiny amount of material is nearly as stiff as a solid 22mm bar. In fact, if you start with a 26mm bar and bore 22mm out of it, the remaining 2mm wall thickness bar is about the same stiffness as the 22mm you removed.

FWIW, this is why tailshafts are hollow and really thinwall. You only need the material out at the edges. The material near the centre does little to justify its own weight.

NOTE......this all assumes that the material properties are the same. If there is a different material in one bar than in another, you need to calculate the actual stiffness, rather than just the simple stand-in for stiffness I calculated. Need modulus of elasticity, etc.

[V28VX37]

There's no easy formula for converting the stiffness of solid and hollow bars. You could knock up a calculator in Excel to do it in a few minutes though.

The rules are simple. Stiffness increases with the 4th power of thickness. So if you want to compare a 22 and a 25 bar, just take the 4th power of each and divide one by the other. 25^4 / 22^4 is 390625/234256 which is 1.67. That means that a 25mm bar is 167% the stiffness of the 22mm bar.

...

Thanks GTSBoy - Sounds like there's no easy way to compare unless you know the wall thickness of the hollow bar.

I am basically trying to work our whether there's much difference in stiffness between the 22mm solid OEM bar and the 28mm hollow ARC bar. My guess is 'yes' but exactly how much is anyone's guess...

Any thoughts on whether putting in a 35mm longer swaybar will kill the OEM end links?

What's an acceptable angle for the end links anyway, are they supposed to be pretty much straight up when stationary?

Thanks again!

[GTSBoy]

Yuh, without knowing the bar's internal dimension, you can't calculate it. But......because the 28mm is HUGE compared to the 22mm bar, you can do some simple test calcs to show what wall thicknesses would give what stiffness and compare against the 22.

If the 28mm bar was only 3mm wall thickness (pretty bloody thin for a swaybar) then it's "stiffness" is 28^4 - 22^4 = 614656 - 234256 = 380400, which is much stiffer than the 22mm bar. Given that the wall thickness is likely to be more than 3mm, it should be a lot stiffer.

As to the fitment. I wouldn't try to put the ARC bar on the front. I don't know for sure, but it could well be for a GTR. I had thought that the overall shape of the bar was a bit more different than shown in your picture......but regardless, I don't think that having the end links on such a nasty angle will be good. They really need to be as close to vertical as possible so they don't become part of the bar's stiffness (ie if you load them in beam they will be much much weaker than the bar and so should deflect a lot).

[V28VX37]

Any thoughts on whether putting in a 35mm longer swaybar will kill the OEM end links?

What's an acceptable angle for the end links anyway, are they supposed to be pretty much straight up when stationary?

Just a quick update on this, the front swaybar is now in and works fine. All clearances are good and the end links are actually more straight (vertical) than with the OEM front swaybar, go figure. See pics below.

Now, SuperPro don't make the front bushes in 28mm and supplied me with 27mm items. Therefore there's a bit more material around the bar than there'd be with the correct size bushes, which means that the D brackets wouldn't close properly and you couldn't get the rear nuts on. I ended up grinding 1-2mm off the top of each bush (the tapering bit) and voilà, in it went!

Thanks again for the input everyone, I hope this helps somebody else.