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Username Post: 4-Link-Rear-Suspension and Diagonal Bar        (Topic#370147)
Posts: 7

Reg: 10-13-09
11-22-22 04:15 PM - Post#2850359    

[image] ckup-Coil-Over-4-Link-Rea r-Suspension-Plain,228452 .html?sku=9105125102&u tm_matchtype={match_type} &msclkid=3fc8baad2cdc 13e1ba6ad9d07e61087[/imag e]

The car being worked on was a purchase from a owner who used it as a quarter mile car, then revamped it for street doing a complete make over. I have had it for 5 years with no issues. I decided to have another drive shaft made as the one done by a supposed "Best" in our large city, botched it badly and I am not getting anywhere with him. The new one will be from out of town. So, while under the car I started to check various
things out much closer.
The image is not the actual unit purchased on the car but will help as to ID the part that I have a question: It concerns the diagonal bar. The urethane bushings were still in tack but under a lot of stress. With the car up on stands, the rear differential (all suspension in place) was dropped to releave some of the tension. It was still tight but the diagonal bar was pulled for the new bushings.
As I believe that the main purpose of this bar is to help keep the differential aligned under hard acceleration:
1. Should this bar have any tension when put into
place? NOTE: The length of the bar can be
2. Should the bar be installed when the entire
car's weight is on all four wheels OR when the
suspension weight is relieved as was done to
remove the bar in the first place?

All input is welcomed.


Frequent Contributor
Posts: 1851

Loc: Orlando Florida
Reg: 07-09-18
11-22-22 05:07 PM - Post#2850363    
    In response to graybeard47

As a general rule, you typically torque the suspension parts to specs when the suspension is loaded with normal weight. That goes for any part that is suspended with bushings that flexes as the suspension travels.

If it is a full floating bushing, it doesn't matter.

People fear change because it threatens what they know, or what they claim to know.

Valued Contributor
Posts: 2799

Loc: Lake George, NY
Reg: 11-11-15
11-22-22 05:57 PM - Post#2850366    
    In response to Tony1963

Sounds like a Panhard bar. This keeps the diff with 4 link suspension centered. On the money, regarding how to set up bushed suspension components, seen tightened control arms done with cars on a 2 post lift, wheels hanging, big mistake. Plenty onfo on the net for setting up that type or rear suspension.

Edited by Shepherd on 11-22-22 06:15 PM. Reason for edit: No reason given.

Site Ambassador
Posts: 15766

Loc: Baltimore, MD
Reg: 11-27-04
11-25-22 03:26 PM - Post#2850502    
    In response to Shepherd

Is it a parallel 4 link or does it just have bars replacing the stock control arms? If it just has bars replacing the stock arms with the stock geometry you can get rid of the diagonal bar since the arms are already triangulated and keep the rear centered. If it’s a parallel 4 link the diagonal bar is a panhard bar that keeps the rear from shifting from side to side. The correct adjustment for the bar should be where it keeps the rear end centered from side to side and has no tension on it when the car is sitting still on it’s wheel weight. And if it has rubber bushings the bolts should be tightened with the weight of the car on it as well. If it has spherical rod ends with steel sleeves it doesn’t matter if the car is in the air or on the ground.

Friends don’t let friends drive Fords.

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Valued Contributor
Posts: 2799

Loc: Lake George, NY
Reg: 11-11-15
11-25-22 04:07 PM - Post#2850506    
    In response to wagonman100

Good info, I can't type that much, so stayed with the basics. Lol


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