Need some suspension advice - properly setting it up

[Wicked GT]

I know we have lots of people on here and willing to listen to everyone...

Here is what I currently have:

Koni Sport Adjustables (front and rear) - Front struts are full soft, rear shocks are +1 turn.
Steeda Sport Springs
Addco front swaybar
Whiteline rear swaybar and endlinks (mounts reverse - bolted to rearend) - set to second most outward hole which is not full soft but one step in.
Steeda non-adjustable lower control arms
Steeda adjustable upper control arm
Steeda adjustable Panhard bar (rear end is within and 1/8" of being centered)
Steeda relocation brackets


Here are some pics of how the suspension is set up in case you see something not correct:

If additional pictures will help solve the issue let me know and I will post them up...

So my issue is with handling (obviously)... I didn't really notice it driving around town but I took the car out on the interstate and noticed when I go around a curve the front wheels turn in but the rear of the car feels completely detached. Kind of like a semi with double trailers. The front goes in to the turn, the rear feels like it falls to the outside of the curve for a second and then catches and goes where it is supposed to. If I wiggle the wheel it feels like the rear of the car is flailing around... As mentioned I didn't really notice it doing 35-45mph but was doing 70-80mph on the interstate and it didn't feel right at all. Probably a noob question that has been covered before but couldn't think of a coherent way to search for this... Any advice and things to check
please let me know. Thanks in advance!

 

[skwerl]

Your three points of attachment for the rear axle are the lower control arms and upper arm. I'd start by checking your mounting points for anything obvious, then I'd pull the lower arms to inspect the bushings. Since the movement is more side to side than up and down I'd suspect the lower arm bushings before the upper arm bushings, but if the lower arm bushings check out then move on to the uppers.

Also IMO this is definitely a tech topic.

 

[zeroescape]

Are your lca relocation brackets welded in?

Id check lca relo brackets, lcas, and panhard for play. It could be the uca but its mostly centered and would manifest in clunking on/off throttle than a rear steer issue.

 

[Wicked GT]

Hmmm, thanks guys. So I had a squeak in the rear about a month ago and tore the rear suspension apart to re-grease everything. Everything looked great as far as bushings and having OCD I spent about an hour doing tiny turns on the Panhard bar and then lowering the car to get the rear as centered as possible.

I didn't notice this issue before pulling the old Addco (Mr Squeeky) rear sway bar out and adding the Whiteline but that being said, I generally don't drive the stang on this route as I was headed to the airport. If it will fix it I am happy to tear everything out again but everything looked good and I torqued everything back down properly and rechecked it after a couple days to ensure everything was tight.

Wondering if maybe the front sway bar has more holding power than the rear sway bar and I maybe need to set the rear at a stiffer setting???

 

[Wicked GT]

Are your lca relocation brackets welded in?

Id check lca relo brackets, lcas, and panhard for play. It could be the uca but its mostly centered and would manifest in clunking on/off throttle than a rear steer issue.

Yes brackets are welded and bolted.

 

[Sharad]

What are your tire pressures? (and why so soft on the struts?)

 

[Wicked GT]

What are your tire pressures? (and why so soft on the struts?)

32#'s in all 4 tires. Would a difference in size make a difference? Grasping at straws but I have the factory front tires and 285/35/19's on the rear...

As for the struts, it was bouncy when driving when I had them turned up. My car is a DD so have tried to set it up in a way to provide the best all around set up for everyday driving.

 

[2011/5.0]

Shocks and struts seem way soft, seems like you want stock ride with after marked parts, im sure thats not konis recommended settings for street use. R u on lowering springs?

 

[Wicked GT]

Shocks and struts seem way soft, seems like you want stock ride with after marked parts, im sure thats not konis recommended settings for street use. R u on lowering springs?

Yes, Steeda Sport springs

 

[skwerl]

The Koni adjustables on the softest setting are the same as the Koni non adjustables.

 

[SD07GT]

check pinion angle again!

 

[Whiskey11]

Hmmm, thanks guys. So I had a squeak in the rear about a month ago and tore the rear suspension apart to re-grease everything. Everything looked great as far as bushings and having OCD I spent about an hour doing tiny turns on the Panhard bar and then lowering the car to get the rear as centered as possible.

I didn't notice this issue before pulling the old Addco (Mr Squeeky) rear sway bar out and adding the Whiteline but that being said, I generally don't drive the stang on this route as I was headed to the airport. If it will fix it I am happy to tear everything out again but everything looked good and I torqued everything back down properly and rechecked it after a couple days to ensure everything was tight.

Wondering if maybe the front sway bar has more holding power than the rear sway bar and I maybe need to set the rear at a stiffer setting???

Well... a few things. Your front bar is larger than most rear bars are and has a significantly higher rate than the rear bar does. Suffice to say it definitely has a lot more spring tension in it than the rear bar does. Total wheel rate on the S197 chassis' front is going to be a lot higher than the rear. There is a number of reasons for that but it has to do with the car being RWD and having struts up front.

I would say you have a few things going against you:

1.) Big front bar, rear bar in a soft position.

2.) Staggered wheels and tires... this hurts front end performance, a lot believe it or not. By ensuring that your rear tires always have a larger contact patch you've ensured that the front end will lose grip quicker than the rears. This can create a "lazy" rear axle feeling in the driving since the car "turns in" but the rear wants to stay going straight ahead. You can tune this out with more rear bar and more rear rebound but really there will always be more mechanical grip at the rear due to the larger contact patch.

3.) Soft damper settings. If you really want the rear end to track with the front better, up your rear rebound adjustment a half turn at a time and see if that fixes it. On the Koni Sports, it's the only adjustment. This is going to transfer weight side to side and to the front quicker which will make the car's rear more lively. Up the fronts some too. I've found that the fronts will generally be stiffer than the rears to get the right transitional feel for the car but you have adjustments, start messing with them!

4.) Panhard bars... I hate them with a passion. Watts linkages do so much for these cars in a handling environment I think you are only hurting yourself with a PHB. They are more expensive but by eliminating the lateral play in the rear axle the only lagging the rear will do in corners is due to the sidewall flex of the tires which is super quick compared to the axle moving. It's also a lot more consistent. There is a night and day difference between the two in a handling environment and they are worth EVERY penny.

 

[Wicked GT]

Thanks Whiskey!!! I will do some trial and error runs this weekend... I will start with the turning the rear shocks up a bit and then will move the rear swaybar to a stiffer setting and see if that helps. I will be putting matching tires on the front in the near future, just didn't have the funds for all 4 at once.

A Watts Link is not in my near future so will have to make do with the PHB for the time being. This is a DD that as of yet has never seen a track. I know I am asking for a "Unicorn" when I want it to handle like a go-cart but still ride nice... just trying to get it to where it handles well and doesn't crush my spleen or bounce down the road like a 16 year olds Accord when I hit bumps or potholes.

 

[stang389]

i run my white line bars at neutral in the front and second closest to the axle in the rear- adding more rear bar will help the car get through the corner but to much can cause the car to over rotate

 

[BMR Tech]

This does not have a whole lot to do with "set up" - but, is that a tear I see on the left side poly bushing on the UCA?

 

[Wicked GT]

Thanks Stang, I debated on which of the two middle settings to go with and chose the softer... thought the stiffer would be too much but sounds like that is where I should have started.

 

[Wicked GT]

This does not have a whole lot to do with "set up" - but, is that a tear I see on the left side poly bushing on the UCA?

Good eye, I will have to go research that... I noticed it in the pic but brushed it off as everything was fine a month ago. Better make sure!

 

[Sharad]

32#'s in all 4 tires. Would a difference in size make a difference? Grasping at straws but I have the factory front tires and 285/35/19's on the rear...

As for the struts, it was bouncy when driving when I had them turned up. My car is a DD so have tried to set it up in a way to provide the best all around set up for everyday driving.

IMO, 285s squeezed onto stock wheels and set at 32# would feel mushy. It would be interesting to see if your rear end wiggle went away if you borrowed a pair of stock brembo wheels/tires from a friend to put on your rear end.

 

[Wicked GT]

Okay, been messing with the suspension all weekend and it doesn't seem to be getting any better? First, let me start by calling myself a "Ratard"! I thought I had the shocks 1 turn off soft... I had them 1 turn off full hard. Reset them to one off full soft and moved the struts to one turn off full soft so they were matched. Didn't seem to do anything.

Moved the endlinks on the swaybar one step stiffer. Didn't seem to do anything. I then shortened the end links as much as I could which made me have to put the jack under it to force it upwards so I could put the bolt through... didn't seem to do anything. Aired the tires up to 36# on all 4 corners to see if that would help, didn't seem to do anything either.

At a complete loss... what should I try next, unhooking the front end links and see if it is the front one overloading the rear???

Let me know your thoughts guys, thanks!

 

[Wicked GT]

IMO, 285s squeezed onto stock wheels and set at 32# would feel mushy. It would be interesting to see if your rear end wiggle went away if you borrowed a pair of stock brembo wheels/tires from a friend to put on your rear end.

Don't have anyone to borrow some wheels from... thoughts on me putting the front ones on back and the bigger ones on the front? I assume that would just make things worse???