Diagonal Link And Panhard bar? (Ladder Car)
11-08-2015, 06:23 PM
#1
Diagonal Link And Panhard bar? (Ladder Car) Is it dangerous in any way to run both?
Little bit of a story...
My car has had a short 16" panhard bar on it for 6 years now. It has worked great until I started running over 150ish mph. At this point the rear wiggles up and down on the pivot point and causes serious vibration that worsens the faster I go. (shake your fillings loose kind of vibration at 160). I've confirmed this is what the rear is doing with gopro video.
Buddy suggested I try a Diagonal Link to tie both ends of the rear together and hopefully eliminate the problem. So I installed a horiz. link and the vibration is gone, but the car shakes side to side around 80 and gets worse at 110. To the point it feels dangerous.
So I installed the panhard bar again, With the intention of removing the diagonal link. Before removing the link, I tested the suspension travel with both installed. I see nothing binding, rear end raises and lowers just fine. Is there any harm in running both? A brief ride seemed fine. I tested it at 120 or so and got no side to side movement. No idea if vibration is gone. I'll wait to try more speed at the track, don't' feel comfortable going 160 on streets around me. (yea I'm a wuss :yay
Hopefully this pic helps.
Here is a video of the side to side movement with just the diag link installed. It would do this at speed. Felt sketchy. Top of the strut mounts would wiggle a ton while the bottom mounts barely moved. With the panhard bar installed it is very solid side to side movement wise.
Little bit of a story...
My car has had a short 16" panhard bar on it for 6 years now. It has worked great until I started running over 150ish mph. At this point the rear wiggles up and down on the pivot point and causes serious vibration that worsens the faster I go. (shake your fillings loose kind of vibration at 160). I've confirmed this is what the rear is doing with gopro video.
Buddy suggested I try a Diagonal Link to tie both ends of the rear together and hopefully eliminate the problem. So I installed a horiz. link and the vibration is gone, but the car shakes side to side around 80 and gets worse at 110. To the point it feels dangerous.
So I installed the panhard bar again, With the intention of removing the diagonal link. Before removing the link, I tested the suspension travel with both installed. I see nothing binding, rear end raises and lowers just fine. Is there any harm in running both? A brief ride seemed fine. I tested it at 120 or so and got no side to side movement. No idea if vibration is gone. I'll wait to try more speed at the track, don't' feel comfortable going 160 on streets around me. (yea I'm a wuss :yay
Hopefully this pic helps.
Here is a video of the side to side movement with just the diag link installed. It would do this at speed. Felt sketchy. Top of the strut mounts would wiggle a ton while the bottom mounts barely moved. With the panhard bar installed it is very solid side to side movement wise.
11-09-2015, 06:51 AM
#2
Have you replaced the heim joints at the front of the ladder bars? Slop in these can allow the axle thrust angle to change... rear steer... shake.
To answer the main question... If you can not detect any binding I don't see an issue if it solves your problem.
To answer the main question... If you can not detect any binding I don't see an issue if it solves your problem.
11-09-2015, 07:01 AM
#3
Heims appear to be good, as long as there's not play in the ball are they considered good? I've never played with ladder suspension parts before. They appear tight with no play in any direction, but the ball moves VERY freely I was assuming there should be some resistance?
Not sure if it solves the high speed vibration but definitely stopped the side-to-side movement at speed.
-thanks
Not sure if it solves the high speed vibration but definitely stopped the side-to-side movement at speed.
-thanks
11-09-2015, 07:25 AM
#4
If the ball is moving very freely the heims are well worn but still fine to use for a bit. On mine I don't check how the pivot ball feels because that would require disassembly/removal. I just visually check for play by grabbing the whole suspension and seeing if anything moves while the car is in the air. If a heim is bad you'll be able to see the play in it.
11-09-2015, 10:08 AM
#5
If the ball is moving very freely the heims are well worn but still fine to use for a bit. On mine I don't check how the pivot ball feels because that would require disassembly/removal. I just visually check for play by grabbing the whole suspension and seeing if anything moves while the car is in the air. If a heim is bad you'll be able to see the play in it.
11-09-2015, 12:01 PM
#6
No all the regular (QA1, AFCO, ALLSTAR) name brands seem to last equally to me.
I've seen some people building big power prostreet cars for the road using heavy duty Evolution Joints, or Curry Johnny Joints. They're expecting to get thousands of miles out of them and hundreds of passes thrown in the mix.
That said if I ever redesign the rear suspension in the dragcar to be more streetable I'm going to get rid of the ladder bars and wishbone. Then I'm going to a 4 bar setup with a watts link and my heims will be some heavy duty offroad type as well.
I've seen some people building big power prostreet cars for the road using heavy duty Evolution Joints, or Curry Johnny Joints. They're expecting to get thousands of miles out of them and hundreds of passes thrown in the mix.
That said if I ever redesign the rear suspension in the dragcar to be more streetable I'm going to get rid of the ladder bars and wishbone. Then I'm going to a 4 bar setup with a watts link and my heims will be some heavy duty offroad type as well.