Makes since and now I understand but it still would be nice to see that awesome quick change rearend.
Another photo dump on the way.... I wanted to build some front shock mounts that placed them a little higher than the typical lower mount off the perch pin. I decided to reinforce the fender braces with some 1/4" steel, which gave me a solid base to weld on some Welder Series upper shock mount brackets. The stock fender brace support rods give some additional stiffness to the braces too. For the lower mount, I welded a threaded bung on the face of the axle web.
I designed a rear torsion bar rack in CAD, and while I waited for the pieces to get laser cut, I moved over to work out some of small details like the pedal return springs and brake light switch. Fortunately for both, I was able to come up with some ideas that worked with the existing bell crank systems: Once I got my pieces from the laser house, I got to welding the rear torsion rack together. It packages two midget bars side by side. The bars are offset 2", so the bar arms will be different in length by that same 2". I also built the upper shock mounts and rear panhard bar attachments into the crossmember, so it handles a lot of tasks. I plan to hang the exhaust off the front of it too.
With the rear bar system squared away, I moved onto the front. The front bars will run parallel and over top of the frame rails. They'll largely package behind the side aprons, so you won't see much of them unless you really lean over the fender with the hood open. I needed to get the engine and trans out so I could work in between the frame rails, but before doing that, I wanted to get the front exhaust sections built. I had already built the mid sections while I was waiting for some parts, so I had a target to hit from the exhaust manifolds. The passenger side was pretty simple, with the drivers side being a little more difficult to clean the steering shaft and the pedals.
Yes...sounds odd, but on the highly swept '33-34 front rails with side aprons, it fits pretty well. I definitely would not do this on a '32 though. It's not my idea - I saw what Jesse Coots did on Lance Sorchik's '33 roadster, and figured I'd give it a shot.
Starting to get the front bar system put together. Like in the rear, I’m using 1” midget bars in the front. The new layout packages the bars parallel, over top of the rails. All of this actually tucks behind the side aprons, so you won’t see much of this at all. Tonight, I welded in hardened chromoly blocks for the torsion stops to ride against. They extend through the boxing plates, against the outer frame rails, to help distribute the suspension loads into the rails. Next up, I’ll be fabbing some mockup bar arms, and building drop links to connect them to the suspension.
I honestly can say I've never seen a torsion bar setup on a straight axle car Sent from my moto z4 using The H.A.M.B. mobile app
I'm not paving any new ground here. Torsion bars on solid axle cars have been around on Indy cars since the '50s, the Odd Rod had bars all around on the cover of HRM in 1949, and most of Moal's chassis today are torsion bar.
every sprint car on the planet, dirt mods in the northeast, about every supermodified in the usa.... torsion has been around a long time ,with lots of applications. given the price and wide availibility of components i'm surprised it isnt used more often in hot rod applications
It's going to be real easy to adjust ride height for sure. Nice work Sent from my XT1585 using The H.A.M.B. mobile app
I would guess due to the work involved getting an old frame reinforced enough to handle the stresses of a torsion bar system such as you see in Corys' chassis.
Been watching the photos pop up on social media but can’t wait to find some time and read threw all the added text you’ve posted with them here pretty good for a garage builder
After seeing the post from @alchemy for replacing the factory swedged studs with pressed in studs, I decided to tackle the task at hand. I picked up a 5/8" hole saw, with a 1/2" ID. That allowed me to cut the swedged part of the factory stud away, separating the pieces. With the hubs degreased and blasted, I chucked them in the lathe to lightly cut and true the face. With that done, I moved onto enlarging the stud holes to 39/64" before pressing in the new studs.
Eventually, I'll make the torsion bar arms out of chromoly, but I wanted to build some mockup arms out of mild steel first just to double check the geomtry. I designed some in CAD, sent it off to the laser house, and got them the other day. For the spline interface, I found some splined collars from Sway Away, allowing me to weld that feature in. Tonight, I got the splined collars welded into the arms, and progressed onto building the drop links for the front. I built some yokes from some laser cut pieces that I also designed in CAD. The yokes fit over the Johnny Joints that I have in the wishbones. They transition to a piece of chromoly tubing that I tapped on the lathe 1/2"-20 for a male rod end. The final arms will have a tab to capture the rod end in double shear, but for mockup, these will do their job in single shear.
How did you go about figuring out the rotational twist you needed in the torsion bar? I understand the arms are adjustable for ride height, but the bar itself has to support a torsional load, kind of like spring rate. How do you get it right the first time without going through a giant pile of trial and error torsion bars? Nice work, as always. -Abone.
Those are the stock hubs that I removed from my '46-48 Lincoln drums. I went with original Lincolns on this car to help narrow up the front wheel track a bit since it's a lowered with fenders.
I worked backwards from deciding what spring rate I wanted, then to the bar arm lengths I could package, to figure out what diameter bar I needed to achieve that target spring rate. What I don't know quite yet (and I think it's part of the question you're asking), is how to get the bar preloaded enough so that you don't sag beyond the ride height you want. I'm guessing it will be trial and error of clocking the bar stop in the correct stop for the rough adjustment, followed by fine tuning it with the adjustment bolt on the bar stop. I hope to have the chassis back on the ground in a couple weeks so I'll let you know then!
I've been working on the park brake system in the rear, which is nothing exciting to show. I did hang a front fender on the frame today to see how things were shaping up though. I'm real happy with the way everything packages together, so it should be pretty inconspicuous when the car is on the ground. The Lincoln hubs also got the tires right in the crowns of the fenders too.
You're a Mechanical Engineer, right? Do you still have your Mechanics of Materials textbook and access to any scales?
I know the torsional rates of the bars....I’ll have 44 course positions to pick from for the bar stops, and the jack bolts to tweak it from there. I’m planning for a ride frequency of 1.5Hz. This should give the car a bit of a sporty feel, and work well with the typically limited suspension travel of a hot rod. I’ve only estimated corners weights at this point, but I’ll definitely weigh the car once it’s fully assembled.
I've been working on the hydraulic lines and park brake system lately. The car is getting a hydraulic clutch, and the plumbing routing is pretty simple. It exits the master cylinder, runs through the x-member via a bulkhead fitting, forward, and back through the x-member via another bulkhead fitting. That bulkhead will be the attachment point for a flexible hose from the frame to the transmission. The brake lines exit the master cylinder, and head over to the right to the residual valves. From there, the front brake line takes a similar path forward to the clutch routing. The rear turns to an anchored bulkhead so that a flexible hose can run to the right wishbone. The hose joins the wishbone at a T fitting, supplying the right rear wheel cylinder and another flexible hose to run over to the left wishbone. Everything articulates smoothly, with no clashing anywhere. Finally, the park brake system is modeled after the stock torque tube arrangement. I drilled the center crossmember, and welded in a sleeve to hold a Lokar park brake cable housing, which will run up to a '40 park brake handle inside. That single cable hooks to an equalizer/horse shoe to a stock early Ford park brake cable. There's a lot going on in a small area, but I think everything turned out well. I'm going to make a "buddy" clip to keep the brake hose in between the wishbones off of the park brake cable. There's clearance at rest, but I'm sure going down the road, there may be some vertical movement that I can keep at bay.
The Jalopy Journal
