Hi, working on a 46 Ford pick up cab and front end with a 40's dodge box. Building a new frame from scratch. Has Mustang 2 front suspension with bags on all 4 corners. Front end is done. I set front ride height so arms are level. My question is about welding in the 4 link kit I have. Read many many posts and did so many searches it would make you dizzy. I find all different answers as to how bars should be. What angle. What length bars. Anyone that can give me any advice as how they should be welded in correctly for this type of application? I want to set it on the ground when parked. Thanks in advance.
4 link help
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Old Iron
Well-known member
If we are talking a 4 bar suspension.
The lower bars are level at ride height and parallel to a slight angle in at the front to the frame.
They can be almost any length and the uppers can be the same length or shorter. Of course, the bars length rule is, the longer the better.
The upper bars, on a triangulated setup, can run on an angle of around 30 degrees inward or outward front to back (makes no difference) and around 7 to 10 degrees down in the front at ride height.
You can run upper and lower bars parallel to the frame, with the uppers 7 to 10 degrees down in the front, if you install a panhard bar to keep the rear end centered.
I prefer a triangulated 4 bar setup.
The lower bars are level at ride height and parallel to a slight angle in at the front to the frame.
They can be almost any length and the uppers can be the same length or shorter. Of course, the bars length rule is, the longer the better.
The upper bars, on a triangulated setup, can run on an angle of around 30 degrees inward or outward front to back (makes no difference) and around 7 to 10 degrees down in the front at ride height.
You can run upper and lower bars parallel to the frame, with the uppers 7 to 10 degrees down in the front, if you install a panhard bar to keep the rear end centered.
I prefer a triangulated 4 bar setup.
Thanks, it is a triangulated set up. I have read what your saying about other set ups but didn't know if it was correct for mine. Thanks again
Old Iron
Well-known member
I just put the same setup in a custom framed 51 Ford Bobber last weekend and set it up as a triangulated system with the degrees on the bars as I listed.
It did not have bags is the only difference.
It did not have bags is the only difference.
Old Iron
Well-known member
Nope, you're good with those 
[ [P [P [P
[ [P [P [P
Nope, you're good with those
Thank you.
Bamamav
Well-known member
Back when I was fooling with drag cars, we would use the line from where the top bars and lower bars would intersect to set the lift point for the bars to transplant the body weight to the rear end. Different intersecting points would change the amount of weight transferred from the front to the rear on launch. Probably nothing you wanted to know, just throwing it out there.....
Torch
Extremely dangerous with a torch!!!
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what bamma said
also having the roll axis of the rear suspension out of line with the roll center of the car forces the weight dynamics of the car to fight against the active dynamics of the rear suspension under acceleration limiting body roll on launch.
for cornering you can play with rear suspension dynamics to tweak under and oversteer under braking and acceleration to tune how the car feels going into and coming out of a turn
ADDCO suspension used to have a very fine suspension engineering publication but the information is now online from many sources.
just have to study the science and apply the geometry.
also having the roll axis of the rear suspension out of line with the roll center of the car forces the weight dynamics of the car to fight against the active dynamics of the rear suspension under acceleration limiting body roll on launch.
for cornering you can play with rear suspension dynamics to tweak under and oversteer under braking and acceleration to tune how the car feels going into and coming out of a turn
ADDCO suspension used to have a very fine suspension engineering publication but the information is now online from many sources.
just have to study the science and apply the geometry.
Well I just came in from trying to get the bars on. I am having issues and my brain is fizzled trying to figure out what to do. I am using a Ford 8.8 rear end. The center housing is off set about 2". The lower bars are no problem, but the uppers are messing with me. I can't get the bars the same height on top with them each at 30*. One is high and the other would be going down the side of the housing. Do I build or buy something to go from axle tube over the housing to the opposite axle tube? That way bars could be in the center and the same height on top of rear end. I still have to c notch rear X weld bag mounts also. Thanks guys.
Dr Crankenstein
Rocket Surgeon
Move away from the lump until you can mount to both axle tubes, equal from center, equal height... what's the difference in angle?
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I just re read your post about inward or outward, I will try the other way.that should work if I weld in a cross member.
Here is what I ended up doing. Got a truss for rear end which let me install the upper links in the center of the frame. Thanks for all the help. When my steel arrives tomorrow i can start to fab rear air bag mounts. Thinking of going behind rear axle to keep room for larger tires if I ever go that route.
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Old Iron
Well-known member
That'll work.
Just make sure your pinion angle is around 3 degrees, up in the front, at ride height.
The pinion angle will change as it cycles through drop and lift, which is natural.
Just make sure your pinion angle is around 3 degrees, up in the front, at ride height.
The pinion angle will change as it cycles through drop and lift, which is natural.
Yep, I set it and engine at 3 1/2* . Getting closer, can't wait to drive it. Thanks .
Yep, I set it and engine at 3 1/2* . Do you think i should put a piece behind it back into frame? I don't know what type of pressure that bracket will see. Getting closer, can't wait to drive it. Thanks .
Old Iron
Well-known member
It would probably be alright however, it doesn't hurt to be cautious.
In my shop, if the question is asked then we go ahead and do what ever it is
In my shop, if the question is asked then we go ahead and do what ever it is
Old Iron
Well-known member
Right On.
