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Macktruckman

Eaton behind maxidyne

Question

I have a 1978 R685ST with a 285 maxidyne and the 2 stick 6 speed with 4.17 rears and tall 24.5’s. Truck is getting a new cab this week and paint job. Old cab is rusted out badly. I have an Eaton RTO14909MLL from a wrecked mixer truck with E7, I think has mounts that will work. Now would be the time to swap transmissions if I want. I was thinking it would help lower my rpm at highway speed and give me a little more top end and maybe help me out on hills. I live in an area with lots of hills. Pull a lowboy to move my equipment and pull an end dump. I like the 2 stick but the gap from 4 to 5 is pretty big with all the hills and I can only get about 60 mph or so on flat ground to the floor tached out. Transmissions look to be within 1”-2” of each other in length. U joints different. Would it be worthwhile to swap? Since the cab is off anyway 

thank you 

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13 hours ago, Macktruckman said:

Thank you 

it seems like it is taking forever 

lol

It's looking good though. Taking the time will be worth it in the end

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Thank you. I hope so. I’m anxious. Lol. I got the new kingpin kits put in it today. Naturally when I pulled the front drums the shoes were pretty much done so I’m off to hunt down new shoes first thing In the morning. May as well get 2 new tie rod ends too. I got a new set of drive tires to put on and I came up with 4 Alcoa’s from a buddy for the outside rears. Need a little polish work but I think I can get them to look well enough. Oh and after putting all that insulation in the cab I’m gonna pick me up a new stereo while I’m in town getting brake shoes...😁

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Tunes make being stuck in traffic not so bad. Sitting in a nice looking truck makes it even better.

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Thank you and I’m hoping I’ll actually be able to hear some tunes now. Mack never went all out for insulation and sound proofing. Lol

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13 hours ago, Macktruckman said:

Thank you and I’m hoping I’ll actually be able to hear some tunes now. Mack never went all out for insulation and sound proofing. Lol

That is because they made their own music.

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You aren’t wrong Rob. Have their own sound

and heat.. lol

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That is a sharp looking tractor. 

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I also think I’ll hunt some Jacobs brakes for it when I heal up a little more. 

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Very sharp!👍👍👍    terry:MackLogo:

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What all did you have to do to convert to air ride cab? I have a 1988 RD I need to convert, rides like a DM right now.

Where did you get parts, what'd you spend?

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Spent less than 200 in parts I believe. I bought two airbags and two shocks for peterbilt cab air suspension and I bought a leveling valve. All off Amazon. Bolted a piece of channel iron across the bottom of the cab with the original rear cab mount bolts. Then, There is a piece of 2x3 rectangular tubing that clamps across the frame and the original cab mount is factory welded to that. I cut the factory mount off of that 2x3 tubing and used good heavy 5x5 or 6x6 angle iron and welded back in place of the cab mount so that it made a dropped shelf for the air bags to sit on and then the channel iron  on the bottom of the cab sit down on top of the bags. Drilled holes in the angle and channel iron first of course for the air bags to bolt to. Then I bolted the shock tops through that channel iron and the bottom I welded a little bracket on the angle for the bottom to bolt to. Level valve bolted through two existing holes in the right truck frame. Was all a straight forward deal for me because the cab was off the truck. So I was able to mock up and mark holes and then take the pieces to the drill press and welding table. Then of course you have to bracket your radiator down to the frame or front shock mount like factory air cab trucks do. And you need roller type hood rests. I also made most of that myself.  But once you have everything loose, you should be able to Jack the back of the cab up fairly high and get at what you’re doing 

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Cabmate wants @ $850 for a kit for the rear. I almost went that road but I figured it wouldn’t be that hard to do myself surely. And it wasn’t 

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I’m not sure but it seems like I remember that rd might already use a roller type hood rest?

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I'll have to double check the radiator mounts, but I know it has 2 hood rollers. Air was an option in 1988, but this truck didn't have it. Or it didn't get transferred over when H&K  put a new frame in the truck.  Square tube/muffler support is a bit rusty, I may just remake the whole bar. It also sits too close to the back of the cab, H&K took a hammer to the back of the cab to keep the diagonal brace from scuffing the cab....

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I was thinking you might already have the rollers, you should be good to go there. Making radiator supports was easy. I would think remaking that bar behind the cab would be pretty straight forward. My exhaust was bracketed to the cross bar originally at the bottom of the stack and the top stack bracket bolted to the cab. I cut that all off and built a headache rack and bolted the new stacks to that. My fuel tanks also hang off of that cross bar.  None of it was complicated. It took a little time of course but it was pretty straight forward. If I can do it about anyone else can. Lol. Btw, we have an 1981 that’s factory air cab. It’s where I got the notion to convert this one. It always rode much better before. 

I have a new problem now. I hadn’t driven it after dark yet. This morning I realized that the headlight relay gets hot after a few minutes and my headlights go off until the breaker resets. And then go a few minutes again. The park lamps all stay on. The headlights quit. I suppose maybe I have a short to chase. That should suck to find. Lol. I haven’t got another breaker to try, naturally the headlight breaker is different than every other breaker in the panel. 

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My dad has always had to split our headlight switch up on our trucks. Headlights and turn signal clearance lights on one switch, cab roof lights another switch, and rear lights a third switch.

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Good to know thank you 

I did swap the old sealed beams out for some new KC hi-lite replacements with halogens. It might help if I stick some led bulbs in those 

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Turned out nice. I put air ride under the cab of the Superliner I just sold. It did make a difference. I got lucky and found everything I needed off another cab. I still had to fab up some things because nothing ever just bolts on. I had to make the brackets for the firewall that the rollers bolt in. After everything you did to it should last you a long time.

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Thank you I hope so. I haven’t worked on the headlights yet, but I’ll figure it out in a day or two. I put a new foot valve on while the cab was off just because they’re hard to get to and I figured it would be smart. It started leaking yesterday. Lol. Parts are so cheesy these days. 

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3 minutes ago, Macktruckman said:

Thank you I hope so. I haven’t worked on the headlights yet, but I’ll figure it out in a day or two. I put a new foot valve on while the cab was off just because they’re hard to get to and I figured it would be smart. It started leaking yesterday. Lol. Parts are so cheesy these days. 

I don't use china brake parts if at all possible. Far too much at stake. B-W new or rebuilt only.

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That air ride cab, the transmission and all that insulation have made a different truck out of it. So much more comfortable. And I may get flamed for this, but my old steering wheel was in bad shape and I couldn’t find a stocker I could afford so I put an aftermarket 18” wheel on and it also is more comfortable. 

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Yes Rob you’re certainly right. This was a Haldex and I thought it would be ok but not so apparently 

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Just now, Macktruckman said:

That air ride cab, the transmission and all that insulation have made a different truck out of it. So much more comfortable. And I may get flamed for this, but my old steering wheel was in bad shape and I couldn’t find a stocker I could afford so I put an aftermarket 18” wheel on and it also is more comfortable. 

Break your "pinky" finger in the wing vent once and you'll think swapping to that smaller wheel is a godsend if you have power steering. I know all about that.....

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