I keep looking at my RPU build and change my mind of how to attach the diff. Building it as a highboy, basically a standard unboxed chassis with reverse eyes both ends. Open diff and hotted up banger. My options are. 1/ use parallel 4 bar setup mounted to inside of rails, bolted and welded and attached to a internal chassis fishplate. Bottom bar to be made from a radius rod 2/ use a long radius rod conversed to trailing arms, mount front using split radius rod kit just behind the centre x member so it looks like this and have the rear of the rod converted to rubber bushing. Could I run a short but parallel upper rod with this setup idea?
Use the lowers [with rear pivots] as lower trailing arms . It will look traditional from a distance. Then add 2 triangulated upper trailing arms so you don't need a panhard. Try and keep them parallel to the ground at "Normal" ride height. GM have been doing this for years , have a look at a Chevelle chassis The advantage of shorter upper is the instant centre shortens when the rear squats, creating more anti squat. The roll centre [behind the rear end] also raises when the rear squats which can make the car induce throttle oversteer when accelerating out of a corner.[fun]
Something like this but with a lot longer bottom? thinking of replicating this type of construction at attachment points But love the long traditional look of radius rods
The roll centre [behind the rear end] also raises when the rear squats which can make the car induce throttle oversteer when accelerating out of a corner.[fun][/QUOTE] Not going to happen with a banger lol
If your trying to build a traditional car use some type of ladder bars,,check out the Pete & Jake set up. HRP
I love that idea make a 3 bar out of it, can use a 4 bar mount at the diff but the top bar will not be visible.
Hod Rods to hell makes truck arm rear suspensions like they use in Nascar and the mid sixties Chevy pickups... Nice functioning set up for all around use,,,
Sir, parallel and converging ladder bars are two different things. I think you are confusing theories. Parallel are a drag race set-up, converging are a street set-up. They are not the same in practice and should not be discussed in the same way. Parallel bars are not appropriate for street use, on the other hand, converging bars a-la Pete & Jakes very well. And I know they work very well from experience. Of course, I am not alone. p.s. I should add that using original converging Ford parts such as 35 or 6 rear radius rods with at least one upper arm added will work just as well.
I know im going to take some fire for this, when I got my RPU it only had the lower split rear arms so I put another set on upside down with an adjustable clevis at the front. I know this acts like a solid sway bar but I have a full spring pack in the rear and the front end can take up any movement that is required. On a a light car like this it not a big issue and it has been done for decades. By using a tube front end as well would put both end in a bind and that's not a good thing but I know of some T bucket people that would argue that point. If you don't box your frame and use a beam axle up front you will have all the flex your RPU will need. JW
I essentially have the same set up (converging bars) in my roadster and it exhibits great road manners and handling. The ride sis very supple and the handling is quite stable and predictable. As long as your bars are relatively long and converge at the center near your transmission output shaft yoke you will be fine.
I have a 46 to 48 rear bars I plan to use, after cutting of the cast end today anyone who uses this cast diff mount as a solid mount better rethink their idea, the cast end is hollow and very lightly constructed. The actual tube is quite solid so that's good. The back will be made into a trailing arm and plan to use bigger bushings in the arm (bigger than normal 4 bar bushings), very similar to what GM used. All the remainder will stay up in the air so will be a 3 or 4 bar Still like the visible bottom side arm/radius arm like in the above pictures. Sorry did not want to start a suspension mounting war here
Richie, Joe Kerr of Jokerr Fabrication has built a number of cars using the package that you propose and I can vouch for the fact that they work extremely well while looking traditional (unless you look closely behind the rear wheels). Roo
Richie, a few things. 1. The ends are forged, not cast. 2. Only the 35/6 radius rods with incorporated spring hangers are normally used as converging 'ladder bars,' preferably with an upper bar added as well. 3. There is another on-going build thread using the type of suspension you're talking about. It's a T RPU. Forget the poster, but it's always near the 1st page. The suspension is way back in the first few pages of the thread.
Four link rear axle set ups are easy to get right. I built one for the rear of my OT jeep. It has close to 12" of suspension travel and over 36" of flex and has NO roll steer, dive and the squat numbers are less than 10%. Street car suspension is so simple a monkey could figure it out.
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