M931 Bobber Project With Air Ride

[aheilmann68]

So my buddy has been drooling over my bobbed deuce with the dump bed so I sent him a few gl postings for the 5 tons and he was sold.
The past two weeks kin d of spiraled out of control. Last week we visited a reseller a few hours away and got advice and the ability to look at them up close. I had my eye on a few trucks in New castle DE just to see what they were going for but a really nice 931 was up with 500 miles and 50 hours so I put a just for fun bid since I figured I'd be out bid. 5pm rolls around and it ends below my auto limit. Paid that night when I got the invoice and scheduled a load out with great help squeezing me in for Tuesday from Lisa at the new castle yard.
We debated low boying it out on a truck my buddy has access to our making it an adventure, we decided to lowboy for simplicity. We set up a 8:30 meet up at the yard with the lowboy, 8 o'clock rolls around Tuesday and I get a text saying the lowboy went out for a tow and will be back in an hour and a half with a 2.5 hr drive time and a 11:30 pick up, we would not be making it. Make a few scrambled calls to a mutual friend of ours that has a few car dealerships, explain what we are doing and verify that we have insurance and we get a dealer plate. My buddy picks up the plate while I scramble to get tools and equipment ready and we are on the road by 9:15 with another friend of ours that's a great gear head.
We get there do the easy paperwork then are taken to the truck, DOA, get it slaved and it started right up and got it over to the staging area to finish our pre-trip inspection. Everything looked great but when we turned the truck off to check fluid levels we learned that the batteries are 100% dead, Gl hooked us up with another slave and off we went with the truck good to go and the fuel tanks fully filled thanks to uncle sam. Since the batteries were dead we had no lighting but with the chase truck we were ok.
Made a stop half way home at a used truck parts yard and picked out our air ride system from a 2003 freightliner with a likely 20+k gvw rating. The workers stripped the set up from the frame rails and off we went without a hitch. Got the truck home with still no voltage on the batteries so today we are getting new batteries and hoping that that will start the truck since trying to jump it with my deuce was not giving it the extra oommph.

A few odds and ends to fix but we are hoping that since the lighting system worked with the slave connected that the dead batteries are the cause of no lights. I didn't check the alts output voltage but the fan for the heater worked so we are hoping that the alternator is fine.

Plans include possibly a shortened bed, with a dump hoist, but certainly led headlights, the air ride rear suspension, first axle moved back for the bob, drive shaft lengthened, spare tire carrier removed and the truck painted.
Pictures added when I can

 

[Motiracer38]

Pics of the airide are a must please. I'm wondering how well the Kenworth setup clears the airbrake cans.

 

[aheilmann68]

Will do but right now they will not clear, we are hung up on how to move the can pairs and what the small cans even do so it is slow going. Frame is all busted down ready to mount everything but we are figuring out how to move the cans in order to fit the bag and shock

 

[aheilmann68]

2/3) truck in the workshop
4) busting the bogie from the frame
5) removing the bogie comepletely
6) mocking up axle placement

 

[aheilmann68]

1) drilling the hanger holes
2) Spring Hangers bolted on
3) outside view of hanger
4/5) One side Hung
6) Axle on
7/8/9) general pictures of the truck
10) Air ride self leveling valve

 

[aheilmann68]

1) 3rd link mounting
2) general view
3) 3rd link mounted to the axle housing
4/5/6) general pics of the truck
7/ my deuce with the five ton


overall not really that bad to do, only thing was everything was heavy as all heck and the double frame was a pain to drill. Thankfully the mag drill makes it easy with the annular bits to drill. not quite keen on the axle being all the way in the back but my buddy is ecstatic where it is.

 

[bigboy44]

Looks Great! What kind of bed are you going to use? Have you drove it yet and how is the ride compare to the duals? I have had problems drilling the frame also even with a Hogan drill with rotobroch drill bits, I had to use a hardened drill bit and do them by hand (major PITA). Keep up the good work and pics coming! Please let us know it drives and turning radius.

 

[aheilmann68]

Ill have to measure the wheel base but to me personally its a land yacht as the turning radius is kind of large. Better than the duals but since the axle was placed in the center of where the duals were, its not that much better than the last axle's placement. the annular cutters IIRC are hardened just since thats what milwaulkee sells or they are possible cobalt. As for the bed he is not in a rush, especially now since he broke his ankle and will be out for about 4 months before being able to put weight on it, but thinking of buying a parts truck and taking the regular dropside and shortening it up and getting rid of the davit crane and that whole mess of stuff and also doing some nice sewer stacks up the back. It rides nice but have not taken it very far since i am still waiting for the title to come and all the legal stuff. We are looking at putting an exhaust brake in it just because letting off the gas does nothing.

On a side note, i just won a cargo truck for myself and am debating what to do to it. Bobbed, crew cab bobbed, origional length with a knuckle boom and dump bed, bobbed with a knuckle boom and dump bed. Im thinking a knuckleboom and 10' dump bed bobbed but a crew cab fully done would be nice, (ac, air ride seats, etc)

 

[tobyS]

Glad to see your progress aheilmann68. Thank you for the great and detailed photo's.

This is my interest also, but I'm looking at a slightly different method that I hope you will consider. While I have a salvage semi trailer axle that has the style you use, I have been looking at the stock mounted 3 link, making a four link and air bag. After removing the intermediate axle and spring, building the top link (making two) and with diagonal support, then installing a bag nearly directly over the axle, with it's mounts as part of the top link weldment. Thus it would be a four link and use a lot of the stock components, including the frame mount that just happens to have holes at the right locations for a proper four link. Looks like (guessing) a 1 1/4" pin at the top, directly in line with the top third link, thus in exactly the right place.

Please look at the parts you removed to see if you think it would work.

I'm not sure about doing a remount, moving the unit forward because I would not necessarily shorten the truck. I may make a rear bed extend farther.

I'll attach a couple of pics of my boomtruck that I may put the crane over on a 5 ton 923A1 or Deuce (which I do not have) after I go take them. I perhaps move the boom to a fresh truck that is not worn out. Got to keep weight low for CDL (with crane), so deuce is desired if new enough (which I would leave 6x6). My problem being that the boomtruck 73 is getting old, tired and needs restored and I need the boomtruck tool.

 

[Motiracer38]

I like it, that was real quick! Did you have to do anything special to get the brakes to clear? Was the leaf spring perch the same Freightliner on, just flipped up on top? What was your ride height like, do you know how much uptravel you have with the bags aired out? Sorry for so many questions, this has peaked my interest. Any plans for the front air ride too?

 

[aheilmann68]

tobys, I think a 4 link is possible may be a pain to bracket it to the axle pumpkin but if you do brackets on the 5x5 and use some of the old mounts for the dogbones you might be in business, the bags on the axle will certainly give a good ride for cruising but im not sure if it would haul well. My buddy wants to be able to still haul goose neck trailers so a hidden 5th wheel will be added. we moved this axle to the center of the tandems so it is split difference in wheelbase. In NJ you only need a CDL for the truck if you are doing for hire work, not to say that i wont get my CDL.

Moti, the whole air ride was from a cut off rear that they disassembled for me so i got all the stock parts. That being said the axle mounts were about 1/8" smaller than the 5 tons width so a little grinding had to occur. Other than that no real modifications were needed. The tits on the axle i had to cut off so it was flush but i just mounted everything under the axle to avoid all clearance issues and get the rake that was desired. Theses are some of the taller bags and i can go up id say easily 8", i have them partially inflated and have about 2" of rake to the front. We may do air ride for the front down the road, the guy the truck is for has a long road ahead for his ankle to heal so there will be no rush on that, i just wanted to get the truck rolling and out of the garage.

 

[Motiracer38]

Good to hear it was so easy. The bags do look a bit lower than they would on a semi, almost out of range for the Firestone spec. The ride height corresponds to the spring rate on airbags so I guess I'm still curious on the ride although I guess anything is better than the dump truck bogeys. Does the 2 inch rake mean it's sitting 2 inches taller? I'm from Socal so our trucks typically rake the other way, prerunner style.

I would have to recommend remounting that panhard bar though. They should sit level at ride height so that the axle doesn't shift side-to-side as the suspension cycles.

 

[tobyS]

Air ride

Here is my boomtruck looking tired...but works fine. Boom is straight and rebuilt.

I'm concerned that because I do commercial work occasionally (not hauling... but setting trusses, placing stuff on roofs, installing machinery) over 26k# will be an issue.

Will you sell a dog a bone cheap? I'll buy one of your dog bones for the fourth member (mount both tops on the frame outside) and only make the diagonal from the extended pins. Can you possibly give a picture of how those dog bone members look at the frame mount after removed?

 

[tobyS]

I have to agree with motiracer about the panhard. But I thought it (panhard link) would go to the side frame, not like a third member in line with the other pivot lines of the bottom members. What keeps it from going sideways?

 

[aheilmann68]

Moti and tobys, you guys are right with that panhard, when it is set at ride height it is true and all but when manually cycling through the different heights it goes out of true. I think i will remount it with a drop bracket off the frame. The way the truck sits it has about a 2" positive rake so the rear is 2" taller in the back. since this is more of a cruising vehicle and not a work truck, the partially inflated bags will act as a damper and it drives so far relatively smooth even without the shock absorbers. We may order shorter bags to control the rake angle and get the bags more inflated but we may do air ride in the front and if thats the case then the tall bags will provide a nice lift.

Tobys, unfortunately i scrapped most of all the bogey components and actually just cut them rather then unbolt everything

 

[tobyS]

Just a suggestion, but google panhard link and look at wiki. Then look at Watt's linkage that is referenced in the panhard description. Especially on panhard, longer (arc) is better.

You do have it mounted at the wrong part of the frame, because it's purpose is to stop sideways movement. Thus it needs to come from the side frame. Find what you want to be your normal cruise height and make it as horizontal as you can. Or go for the watts linkage. Please let us know what you do...thanks.

Poor dog going without a bone. (I remembered that taking the intermediate axle off gives up three (to be dug up later).)

Toby

 

[aheilmann68]

Toby, the way it is mounted now does stop sideways movement when at ride height but i will certainly look it up, the way it was mounted before on the freightliner was different. I will more than likely drop it lower under the frame if i can but the only thing is it is tight down there and the angled way i have it was one of the only ways to get it in there. and yes there were 3 bones

 

[tobyS]

The problem that air bags have that springs do not is a tendency to move sideways. That's why when I describe a four link, I include diagonal bracing. The setup you have needs a panhard link or a Watts link to limit sideways movement. The way it is located (on the cross member) it tries to twist the axle...and shouldn't. It's 90 degree to the direction your needing to limit. This discussion has helped me to realize that a four link, using all 4 dog bones, would also work with a Watts link quite nicely to limit side movement. I do hope you had the time to look at both, as I believe you will need one or the other coming from the side frame, not cross member. I would want a panhard link a lot longer, like from the left frame to the right side of the axle, so the arc is closer to straight. My choice would probably be a Watts link however, from both sides of the frame to the middle and a straight line up and down. The simulation on the wiki for Watts link shows what I mean.

 

[tobyS]

WOA! I made a mistake and thought the link was attached to the crossmember and I reviewed, seeing it is attached to the side frame. Sorry for the mistake and half of what I just said is wrong. My apology!!

 

[tobyS]

Have you finished up this project yet? And if so, have you made any altercations to the panhard link? I really will be interested to hear about the ride. Hope your friend is getting use of his ankle back.