Rear sway
 

I recently put Hotchkis sways on my car. Front and rear. I did the front about 2 week before the rear. Now that the rear is installed, I notice the car reacts to the road much more than previously. Not sure how to explain. It's like every dip or imperfection in the road affects the car and pushes it around. The imperfection of the road aren't being adsorbed into the suspension, rather they are pushing the car around. I have coil overs and have had them at the same setting for over a year, and don't think that is an issue. I also changed the rear diff bushing, wheels and tires at the same time I did the rear sway. Then took the car for an alignment. The wheels and tires were brand new and road force balanced prior to install.

I've seen several comments that the rear sway should be left stock, so I'm wondering if the stiffer sway in the rear is causing this reaction? What is the down side to having a stiffer rear sway bar? Could it be causing this issue?

I'm having rubbing issues with my exhaust and the rear sway bar also, so I am planning to switch it back to stock anyway, but curious non the less.

Where do you have the rear bar set at?

Sounds like bump steer. See if Firestone will do a free check.

And yes most leave it stock for best handling. I removed it completely because of my spring rates and oversteer issues.

Rear is at the softest setting.

I'm not familiar with bump steer, but after reading up this morning, I think you nailed it. Sounds exactly like my issue. As I understand it, toe changes as the suspension compresses and expands when bump steer is not set correctly.

I have lifetime alignment at Firestone. Probably not the best alignment place, but at least I can take it back as often as needed to get it corrected. I assume that the alignment machine they have will be able to check bump steer and they should be able to fix it. So far, they have worked with me pretty well, considering I'm lowered and have modified parts.

Since I'm taking it back, do you have recommended alignment measurements I should have them aim for? I am lowered about 1". I have SPL rear camber arms with lock out kit. My front has stock arms. Typically, my front camber ends up at -1.7°. They usually get my rear in spec but just on the limit. I think they set rear camber around -2.0°. Since the rear is adjustable, shouldn't they aim for -1.7°? I think they typically set toe at 0.

I just installed wider wheels/tires and have same issue. Car steers left and right on bumps on its own was fine before wit stock 18"s and i have hochkins sway bars front and back.
I will be removing rear sway bar this weekend to see if it will do much difference.

Stillen posted this:

https://blog.stillen.com/2016/04/sti...ide-sway-bars/

on this thread:

http://www.the370z.com/brakes-suspen...ay-bars-3.html

Pretty good read.

Thanks for the links, good info. Further confirms my issue isn't the sway bar.

An example of the issue - On the interstate, traveling about 80, smooth road, when I would hit an overpass or bridge and there were those dips in the transitions, the car would dip and then jerk sideways. First time was pretty startling. Not enough to loose control, but very obvious and uncomforting.

Set the rear camber at -1.7, toe should be in, not zero, or out. Which will give you snap over-steer. :eek:

:iagree: Although, I'd probably shoot for more like -1.0° rear camber.

I stopped and talked to Firestone. They didn't think thier rack could check bump steer. The guy at the counter didn't know what I was talking about, called his manager and set up apt for this evening. Hopefully they can figure out what they did wrong. I'm guessing maybe they tried to adjust front camber and got something out of wack??

I would not be taking it to any wheel works, Firestone, pronouns etc. those places typically employ low level techs and tire changers. The guy not even knowing what bump steer is should be your first sign you are at the wrong place. Those places are set up to do mass production of quick alignment on Oem spec vehicles and tires. Not what you need or want with all the mods to the suspension you did. You need to find yourself a shop that sets up those kind of cars, talk to the guys at the track if any are around you and they will most likely know a shop that is more familiar with that type of work, probably does a lot of porches and those types of cars so pricing will reflect that but having it done right the first time is worth the price rather than dealing with armatures.

I agree with you on this. When I went back for my appointment, they were actually really good to work with. The manager had his "best guy" come out to talk to me about the issues and then he did a full alignment. They let me come out and talk with the tech while he was working. They did not have any way to check bump steer, just ran through the whole alignment again. The tech was telling me that the system they were using isn't the greatest, saying you could get it all dialed in, drive the car around the building and get different numbers. They have a better rack, but my car is too low to fit.

Anyway, he was able to get the rear camber to 1.7 and slight neg toe. Not much he could do with the front, but did have to adjust both sides. Oddly,the right side was much more out than the left. I have a feeling the last tech probably should stick to oil changes and tire rotations. With the new settings, the car feels better. It was just a short 15 mile drive home but I had a chance to take to back roads and have some fun and the car felt better.

I was able to get a good look at the area where the exhaust runs through the rear sway bar. Both side are very close to the bar. Since I don't think the sway bar is the problem, I am going to leave the bar in. I'll get under the car this weekend and adjust the exhaust so that it isn't rubbing on the sway bar.

Yea you really don't want rear neg toe that will cause the rear to want to step out either direction very easily. Probably need to get some of the after market adjustable toe arms. Also depending how low you went spl makes bump steer kits so you can lower you tie rods back to Oem height.

I bet Gator Motorsports could get it dialed in for you.