Rear end feels 'loose'
11-07-2010, 07:03 AM
#11
5th Gear Member
Join Date: Sep 2006
Posts: 3,401
The sideways movement of the rear end as the suspension is pitty-patter'ing on rough roads is the whole point of ditching a panhard bar.
There are two ways round this, you can either reduce the deflection of the rear end by tying it down with upgraded shocks and/or springs, or you simply eliminate the Panhard bar, replacing it with a Watts linkage.
You could uprade the bushings on and around the Panhard bar all you want which will, to a small degree, reduce the lateral excursions, but you'll never eliminate it fully, it's the nature of the beast
There are two ways round this, you can either reduce the deflection of the rear end by tying it down with upgraded shocks and/or springs, or you simply eliminate the Panhard bar, replacing it with a Watts linkage.
You could uprade the bushings on and around the Panhard bar all you want which will, to a small degree, reduce the lateral excursions, but you'll never eliminate it fully, it's the nature of the beast
11-07-2010, 07:08 AM
#12
5th Gear Member
Join Date: Sep 2006
Posts: 3,401
I would rather suggest you initially poly the bushings that are directly associated with something you want to fix or tighten up and continue on from there monitoring the ride quality as you go
Last edited by marcuskeeler; 11-07-2010 at 07:10 AM.
11-07-2010, 08:41 AM
#13
Cut & Paste Expert
Join Date: May 2007
Location: NW Arkansas
Posts: 13,322
Yea, good point.
I only did the front rear sways and the panhard along with the shifter.
I like the feel of driving her a lot more than driving the cushy Challenger.
Maybe I should retract the 'poly the carp out of her' comment.
But the sway bar polys would be the next item for him.
Then the shifter polys.
I dont suspect the Prothane line gives you any more options
besides the poly engine mounts.
More NVH is not liked by all.
Personally I like it.
Makes me feel in touch with the suspension.
I only did the front rear sways and the panhard along with the shifter.
I like the feel of driving her a lot more than driving the cushy Challenger.
Maybe I should retract the 'poly the carp out of her' comment.
But the sway bar polys would be the next item for him.
Then the shifter polys.
I dont suspect the Prothane line gives you any more options
besides the poly engine mounts.
More NVH is not liked by all.
Personally I like it.
Makes me feel in touch with the suspension.
11-07-2010, 09:30 AM
#14
'Dr. X'
Thread Starter
Join Date: Apr 2008
Location: Toto's Kansas
Posts: 4,388
^^ i read a few articles about the poly bushings and did notice most talked about increased noise/vibrations. i think i'll probably try the bushings for the panhard (can't beat a $16 upgrade 
), then if that doesn't work, i'll go with the shocks/struts (might as well replace them all rather than just the rears 
).
couple more sub-questions if you all don't mind... of all the shock/strut sets i've looked at, i'm leaning for the koni str.t (like koto mentioned, and from what i've read about them, they seem to give the best performance for a dd)... so would anyone else second that? or is there another brand i should look into?
also, for the panhard, would it be worth replacing on a daily driver, or would the upgraded bushings be suitable enough?
), then if that doesn't work, i'll go with the shocks/struts (might as well replace them all rather than just the rears ).couple more sub-questions if you all don't mind... of all the shock/strut sets i've looked at, i'm leaning for the koni str.t (like koto mentioned, and from what i've read about them, they seem to give the best performance for a dd)... so would anyone else second that? or is there another brand i should look into?
also, for the panhard, would it be worth replacing on a daily driver, or would the upgraded bushings be suitable enough?
11-07-2010, 10:10 AM
#15
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
Sneak up on your solution.
Do the Koni STR.T's first and drive it for a while. Koni yellows are another possibility (at a higher price point that buys you the adjustabiliity). Tokico D-specs are another adjustable choice that was probably the preferred option before the Koni yellows became available.
Most times, people replace the PHB in order to gain length adjustability to correct the slight shift in lateral axle location that seems to happen when the car is lowered or to help fit wide tires equally into the two rear wheelwells.
Actually, I'm not even sure whether stiffer PHB bushings would solve this problem or make it worse.
Norm
Do the Koni STR.T's first and drive it for a while. Koni yellows are another possibility (at a higher price point that buys you the adjustabiliity). Tokico D-specs are another adjustable choice that was probably the preferred option before the Koni yellows became available.
Most times, people replace the PHB in order to gain length adjustability to correct the slight shift in lateral axle location that seems to happen when the car is lowered or to help fit wide tires equally into the two rear wheelwells.
Actually, I'm not even sure whether stiffer PHB bushings would solve this problem or make it worse.
Norm
11-08-2010, 10:49 AM
#17
Former Sponsor
Join Date: Sep 2007
Posts: 1,936
Not that Sam needs me backing him up, but this is the right thing. I called Sam up a while ago with the same concerns. I thought something like a Watts Link ($650 part) that kept the axle from shifting while it moved was the way to go. He suggested a pair of Koni STR.Ts ($150) instead. I couldn't have been happier with the results. Before I even got the car out of the driveway I could feel the difference. I don't have that skittish jumpy side to side kick feeling any more, and the car feels much more composed at all times now.
11-08-2010, 01:22 PM
#18
'Dr. X'
Thread Starter
Join Date: Apr 2008
Location: Toto's Kansas
Posts: 4,388
gotcha; i've been considering changing shocks for a while but never really had a 'good' reason to... and now i do .
i usually like to 'upgrade' when whatever part i'm changing is worn out; due to a lack of 'extra' income, i'm never able to bring myself to upgrade a part that still works fine... since it sounds like mine need replaced, i don't feel like it'll 'hurt my wallet' as bad
thanks for the help guys
. i usually like to 'upgrade' when whatever part i'm changing is worn out; due to a lack of 'extra' income, i'm never able to bring myself to upgrade a part that still works fine... since it sounds like mine need replaced, i don't feel like it'll 'hurt my wallet' as bad
thanks for the help guys
11-10-2010, 12:14 PM
#19
5th Gear Member
Join Date: Sep 2006
Posts: 3,401
It's all good but keep in mind that there is a big difference between something that's not performing properly (worn out) and something which is less than perfect 'by design'.
Changing the spring rates and/or shock damping levels will reduce the rear end compression/rebound which will have a resultant positive effect on the lateral instability but understand what's happening - You are merely reducing the sideways travel by limiting the up/down travel which may or may not be to your liking.
With a Panhard bar you cannot eliminate the swing-arm effect unless you replace the rear suspension with blocks, it's impossible. If the rear end goes up or down, the rear end is moving laterally - Fact
It doesn't have to move much either, the sharper/quicker the suspension compression the more pronounced the effect of the lateral shift will be. Like when you run over a big crack in the road and you feel the rear skip one way or the other, or you're dragging away at the lights and as you grab 2nd and the rear squats causing the car to be squirrel'y, it's the rear end momentarily hopping to the right/left.
A Watts isn't cheap but in many ways it's a vice free mod. You don't have to compromise your ride heights or suspension compliance, especially if you go with a setup with bushings rather than heim joints...
The only reason things like watts setups are not factory fitted is cost.
Changing the spring rates and/or shock damping levels will reduce the rear end compression/rebound which will have a resultant positive effect on the lateral instability but understand what's happening - You are merely reducing the sideways travel by limiting the up/down travel which may or may not be to your liking.
With a Panhard bar you cannot eliminate the swing-arm effect unless you replace the rear suspension with blocks, it's impossible. If the rear end goes up or down, the rear end is moving laterally - Fact
It doesn't have to move much either, the sharper/quicker the suspension compression the more pronounced the effect of the lateral shift will be. Like when you run over a big crack in the road and you feel the rear skip one way or the other, or you're dragging away at the lights and as you grab 2nd and the rear squats causing the car to be squirrel'y, it's the rear end momentarily hopping to the right/left.
A Watts isn't cheap but in many ways it's a vice free mod. You don't have to compromise your ride heights or suspension compliance, especially if you go with a setup with bushings rather than heim joints...
The only reason things like watts setups are not factory fitted is cost.
11-10-2010, 12:23 PM
#20
Former Sponsor
Join Date: Sep 2007
Posts: 1,936
There are two issues here, what a Watts link does and what better shocks do are not the same thing.
There are a number of reasons to start with shocks first. They cost less. They almost universally make the car much better in both ride and handling. You'll notice that the complaint is more over bumps then all the time.... and a PHB is always swinging in an arc. Shocks aren't always working in the same piston speed range.
Hey I'm a big believer in Watts links being better than PHB's. But I'm also practical, and having had numerous cars with both Watts and PHB's and various shocks I'll tell you without doubt if I could only change the shocks OR the PHB, it's would everytime be the shocks first. That's the bigger issue, and the poor damping control is the primary reason these things hop and skip and jump around so much. Better dampers settle the back down a lot, especially where small, sharp, high piston speed impacts are concerned.
A Watts link is a better lateral control device to be sure, but the problems come first and foremost from the dampers.
There are a number of reasons to start with shocks first. They cost less. They almost universally make the car much better in both ride and handling. You'll notice that the complaint is more over bumps then all the time.... and a PHB is always swinging in an arc. Shocks aren't always working in the same piston speed range.
Hey I'm a big believer in Watts links being better than PHB's. But I'm also practical, and having had numerous cars with both Watts and PHB's and various shocks I'll tell you without doubt if I could only change the shocks OR the PHB, it's would everytime be the shocks first. That's the bigger issue, and the poor damping control is the primary reason these things hop and skip and jump around so much. Better dampers settle the back down a lot, especially where small, sharp, high piston speed impacts are concerned.
A Watts link is a better lateral control device to be sure, but the problems come first and foremost from the dampers.