I've been painting parts and assembling the front and rear suspension on my '32 Ford pickup. I designed this rear parallel 4-bar setup and made everything myself, except I bought the polyurethane-bushed rod ends from MAS. I designed the 4-bar brackets so that they wrap all the way around the axle tubes for extra strength. The brackets continue on back to support the round plates that support the bottoms of the airbags (Firestone 9000s). There are two pieces of DOM tubing that go through both brackets sideways underneath the airbags, and those are there to give me a place to bolt the lower shock mount brackets with two 1/2" bolts on each side. The u-shaped lower shock mounts are cut from rectangular tubing with short stubs of round tubing welded in to close up the gap to fit the width of the shocks. The 4-bar tubes are thick wall DOM steel tubing that I drilled and tapped directly for the rod ends. The shocks are fully extended when the airbags are 1/4" less than than their maximum extension. The axle hits the rubber bumpstops just before the airbags meet their minimum height. I designed everything to give it the correct stance with the airbags at their normal ride height. The only thing I'm not sure I like about this setup is that the panhard bar is pretty short. I've seen lots of T-buckets and stuff like that with panhard bars even shorter though, so hopefully it'll work okay. Both ends of the panhard bar are in double shear. The axle end bracket for the panhard bar is held on by three of the pumpkin studs. The axle housing is centered, so the pinion is off center. So I had to think ahead and install the driveshaft safety loops in the frame off center slightly for driveshaft clearance. The yellow slop you see in some of the holes in the frame is some rust preventive stuff called "Wurth Cavity Wax". I sprayed it inside the frame using an undercoating rustproofing gun I got from J.C. Whitney. The axle is a narrowed 9", originally out of a Ford van. The pumpkin is a 3.50 31-spline trac loc out of an old Bronco.
Nice. Great to see someone post about how they went that little "extra" bit further in thinking out suspension limits, worrying about eventual internal rust etc. The Panhard will be fine I think. Your not getting excess lift with the bags out back of the axle anyway. What do you think of the Wurth product line? It's the only company I've used that consistantly holds a candle to 3M. Theres something about the thought of having your cavities waxed that makes me nervous though...
Thanks everybody! I'll try to take some more pictures of the shock brackets next time I'm out there. The Wurth stuff seems to be pretty good. It was a little too thick to shoot through that J.C. Whitney undercoating gun, so I mixed in just a little mineral spirits and that made it liquid enough to shoot through the gun. It sticks really well to everything. I spilled some on the concrete and it's pretty much impossible to get back off again. I even tried burning it off with a torch and all it did was melt and spread around more. It's a really hard wax, much harder than candle wax. I think it'll probably last for 50 years.
I took a few pics of the lower shock mounts. I cut the U-shaped shock mounts out of a piece of rectangular tubing. I welded a stub of steel tubing on each side through large holes in the brackets to wind up with a gap that's the same width as the serrated steel tubes that come pressed into the rubber bushings of the shocks. When you tighten up the 1/2" through bolt, it locks the serrated tube to the short tube stubs in the shock mount on each side to keep the serrated tube from rotating. The shock brackets bolt to DOM tubing pieces that I welded in place through holes in both plates of my 4-bar/air bag brackets on each side. The shock brackets are held to those tubing stubs by two 1/2" bolts each. I don't think the rubber bushing of the shock will slide sideways on the pressed in serrated steel tubing, but if it does, it won't matter because it can't go anywhere. The shocks and airbags are fully extended in these pictures, and that's why the airbags look kind of funny.
Nice work! I'm about to start working on a similar set-up. Is the idea when mounting the shocks to mount them such that they're fully extended when the bag is also fully extended? Meaning, the shocks would support the rear end when the car is jacked off the ground, instead of the bags? Also, how do you pick your shocks? Are generic oil filled shocks that are the right length OK, or are specific shocks needed with airbag set-ups?
looks good, but are the shocks going to bottom out before the bags do? on an s-10 that i bagged i put the shocks in on an angle so the bags could fully deflate before the shocks were fully compressed
looks great. How far away from the center of the bag are your shocks mounted? It may be just the angel of the picture but it looks like they may rub once the baggs are inflated. The f9000 do bulge out quite a bit. Its been a while since i have use the F9000 but if memory serves me correctly that bag will expand to about 5.5" or 6" diameter when inflated.
Thanks! Right, the shocks are fully extended just before the bags reach their maximum height. That keeps you from tearing the bags up. Some guys use limiting cables or heavy nylon straps if the shocks don't reach their limit before the bags do. I mainly picked my shocks based on the types of ends they had and the compressed and extended length and the amount of extension to work well with the air bags, and then designed the shock mounts around the shocks. They're gas filled Monroe shocks. I think they were made for something like an older Chevy Blazer. They might be a little on the stiff side for this little '32 pickup, but the length of stroke was just right. Monroe has data sheets online that show all their part numbers for shocks with compressed and extended dimensions and details on the types of shock ends.
Thanks. The axle hits polyurethane bumpstops on the frame about 1/4" before the shocks bottom out and also about 1/4" before the bags bottom out. Some bags have internal bumpstops, but I don't think these do. So I made it so the axle hits the bumpstops on the frame just before the airbags completely bottom out -- to save the bags. I bought my bumpstops from a place called "Energy Suspension". They're rectangular polyurethane pads that are held in place by a single 3/8" mounting stud. I think they were only $6 a pair at a swap meet. I welded gusseted brackets for the bumpstops to the outside of the frame rails right over the axle centerline.
Thanks! Yeah, it's the angle of the picture that makes them look close. I mounted them so that there should still be a little clearance even if the bags swell up to about 6-1/2".
Got any pics of where the front connects to the frame? I am in the middle of doing this and haven't made my front brackets. How long are your bars? I was building mine 28". Hopefully that's not too short.
Kind of off subject but I have one question why do some use 2500/2600 bags in the rear and some use sleeves??? Pro/Cons of each??
Here's a picture of the bottom of the frame when it was still in epoxy primer. And here's a side view. Sorry everything's black so it's hard to see. I welded vertical 2x2 tubing posts between the horizontal rectangular tube crossmember tubes at the point where the fronts of the four bars attach to stiffen up the crossmembers there. The front brackets wrap around the top and bottom of the upper and lower crossmember tubes, and two of them have triangle shapes that are also welded along the sides of the square vertical posts, so there's a whole lot of weld area holding those brackets on. I figured I might as well make them as strong as possible. I think your 28" bars will work fine.
I talked to a bunch of guys before I started this, and I wound up using these sleeve type bags because they supposedly have a nicer ride for a lightweight truck like this because they're not as stiff as some of the larger diameter bags. They use the larger diameter bags for heavier cars. It was easier to fit these sleeve type bags in mine too because they're taller and narrower.
Thanks for the info...So if a guy had a 48 chevy 2-dr sedan he would be better off with a 2500/2600 bag....
Yeah, probably. Also, if you use bags in a front end with control arms, the control arms add leverage to the bags, so the bags need to hold more weight than they would in the back of a car where it's more of a direct 1:1 loading. If you measure the length of the lower control arm between the ball joint and the lower control arm bushing, and compare that to the distance between the lower control arm bushing and the center of the airbag, that gives you a ratio. It puts more load on the bag, but you get more suspension travel for less movement of the air bag too. My rear setup has the bags located behind the rear axle, so the bags get a leverage advantage there, so there's even less load on them than if they were on top of the axle or in front of the axle.
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