RS4 3 Sway Bar Install Question

[rossb]

I just got the HPI sway bars for my 18ss. I snapped the bar ends into the suspension arms and the bar ends move around a bit in the arms. This allows the bar to move a bit while it is installed on the car. I can slide it a bit left to right. See the picture below. The bars can be installed on the car with the closed side either angling up or angling down. The instructions did not say which way it goes so I installed them with the closed side angling down because it seemed to run over the suspension arms smoothly that way. I am not sure if I have them installed correctly.

If I simulate body roll manually on the workbench by compressing one side as would happen in a turn the rear bar does not seem to provide any tension on the suspension. I can still easily slide it left and right because the bar ends are allowing too much play and its not wedging against the middle mount on the rear diff. It seems like the rear bar will have no effect on the car. Has anyone else noticed this?

 

[NCNitro]

Ah yes, been there myself. You actually have to loosen the screws in the bottom of the chassis that hold the diffs in, then you will see a small groove that the back end of the sway bar will slide in, this will hold it firmly in place. Let me snap a pic for ya.

 

[Revo Rancher]

Ross:

I am having a hard time seeing your bar set up in the photo, but if my eyes are not playing tricks on me, I have mine the other way around (upside down?) and they put pressure on both sides. Lift one side and within a few millimeters the other side has pressure, trying to move it against that side's suspension.

 

[rossb]

The "closed end" of my bars are angling down. They seemed to clear the suspension arms this way. If I flip them over and install them so that the closed end angles up the angle will hit the suspension arms right near the pivot point screw. I called HPI and they claim that I have them installed correctly. FWIW - I am not even sure if the guy on the phone really understood my question.

Do your bar ends move around in the suspension arms? I wrapped a very small piece of electrical tape around the closed end of the bar where it mounts to the rear diff. This took up the play in the bar and stopped it from sliding back and forth in the rear diff. I also just upgraded my shock springs. My springs were too loose and the car was bottoming out way too much.

 

[Revo Rancher]

Sorry for the delay. Just checked mine. Note that the different color bars are different thicknesses.

My rear one, green, is loose in the diff holder and also at the suspension arms points.

The front one, purple, is not loose at the diff, and barely loose at teh arms.

Both are mounted so the diff section points down, like yours.

 

[rossb]

Thanks. I did realize that the bars are of a different thickness. I used green bars on both sides and only the rear bar was loose in the diff holder. A very small piece of electrical tape wrapped around the rear bar tighened it up. The front one was tight in the diff holder without any help. Do your bar ends move around in the suspension arms?

I went with the Blue 493 gf/mm springs.

 

[Revo Rancher]

Do your bar ends move around in the suspension arms?

Yes.

Are your new springs from HPI? What part number?

 

[rossb]

Here they are:

http://www2.towerhobbies.com/cgi-bin/WTI0001P?&I=LXWB79

Here is a spring rate chart:

http://www.hpiracing.com/graphics/instr/I-6751-2-V8_Color_Outlined.jpg

According to my manual my car was supposed to come with the Yellow linear springs 392 gf/mm part #6753. My stock springs are actually black so I am not sure what they really are. They may be the black medium progressive springs part # 6836 that come with the RS4 RTR EVO.

I went with a linear spring as opposed to a progressive. The 6757 Blue linear 493 gf/mm spring I got is considered a hard linear. The linear springs for the stock shocks are 13x25mm. HPI only makes one linear 13x25mm spring harder than the one I got and that is the 6759 Pink 540 gf/mm. I may also get the Pink springs to experiment with, unless I just decide to build an R40. Stock R40 springs are 580 gf/mm front and 464 gf/mm rear, both linear.

 

[Revo Rancher]

Thanks for the info.

I am surprised that there are not more RS4-3 SS owners out there? Would help if we knew how they set up their suspensions for street or race.

 

[CorradoPsi]

the hpi sway bars suck ass. basically to make them work right you will need to drill and tap the metal holder thats pressed into the arm to accept a set screw. once the bar is locked in with a set screw you should have better swaybar action. i tried them on my super nitro rs4 and had zero affect on handling. every other car i have with swaybars i can notice a difference when adjusting them.

 

[rossb]

I'm not surprised to see this response. The bars do seem to move around too much in the mounts. I am trying them tomorrow on the track.

 

[Revo Rancher]

Put a lock collar on the inside of the bar next to the arm mount when the arm is in the proper droop position.

 

[rossb]

I ran my car on the track today and it seems as though the bars may have helped. The car turned harder than ever and I am pretty sure that the chassis and body were not rubbing around the turns even though I was running a low ride height. The last time I ran at this height I rubbed around the turns. I also ran with a newly installed HPI racing clutch. My stock clutch was destroyed last time at the races when my throttle stuck open after a crash and I had to put the car into the boards with the engine revving wide open. I installed the clutch on the first hole for a low RPM grab. This setup worked very well. The car was rocketing off the line and off every turn.

 

[NCNitro]

I have them on my RS4 3, I have the red ones front and rear. They seemed to help my handling a lot. But since I don't race on road I dont know how much it would help on a track. But they definately seemed to improve my handling.

 

[Revo Rancher]

roos, I don't know of you remember, but I had bought the race clutch from HPI a few weeks back because I was complaining about a late hook up in the clutch and really noticed it in my .12 engine. I set it for the middle spring holes and it helped a lot. Next time I race I plan to drop the mill afterwards for a good cleaning and will move the spring to the outer position for an even quicker hook up.

 

[rossb]

Revo - I remember that you went with the middle hole on the racing clutch. I assume that you trimmed away the first hole to make it work because the instructions said to do so. That means you can only switch to hole 3 which makes it grab at an even higher RPM.

I used the first hole and my clutch engages at a very low RPM, which is ok with me.

 

[Revo Rancher]

Unfortunately you may be right, after looking at your picture. I might have read the directions wrong and presumed the opposite. I am looking for an earlier hook up. Darn it! Well, time to buy another set! At least that way I will have it either way pre-determined!

Thanks for catching that for me.

 

[KillerWabbit]

I have the thick purple bar on the front of my SS and it works.

Put the car on a table so the front wheels hang over the edge and the chassis is flat on the table. Securely hold the chassis down and compress the spring on one side, the other side should go up a tiny bit. I can just hardly tell that the other side goes up, but it does. Try it.

What I'm running now:
Front: Purple springs, purple bar, 40 weight
Rear: Blue springs, red bar, 40 weight

Those purple springs fight the sway bar, so softer springs would allow the sway bars to work more. But the sway bars are pretty much non-beneficial, especially because I run such stiff springs. I actually run the red bar "for color" LOL. I run in a clean, relatively high grip asphalt parking lot, so the stiff suspension handles it pretty well.

 

[rossb]

Revo - Here are the instructions. I did install A and I think you did install B:
http://www.hpiracing.com/graphics/instr/a885.jpg

KW - I think those Purple springs are 670 Progressive? I bought four Blue 493 Linear and four Pink 540 Linear. They are the hardest 13.5x25 Linear springs HPI makes. I will have to experiment to see what combo works best.

 

[Revo Rancher]

Hmmmm, springs, sounds like another trip to the LHS soon for me!

Can you buy a variety of springs from HPI in one package or do you have to buy them in pairs only? And why progressive over linear?