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Simp's Cat 7155 Swap into a M923A1

simp5782

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Welp got the transmission back in today and did some small nick nack stuff on it like vents and other places that needed plugs. Then I went to work on the air dryer and regulator mister combo bracket. I am going to run a air pressure comparison gauge I got from swampdonkey and mount it to the shifter so I can see the transmission tank pressures as well as the regulator pressure. I read to set it at 95psi. I also thought about a dual digital gauge setup I found on amazon for $100 with both sending units. Didn't seem too bad of a price. Also installed the driveshaft to the front tandem.
 

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simp5782

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After I tried to make the stock cross member work and just make a lift block for the cab to sit on I gave up. Just to much cutting and forcing that thing in to try to adapt it. I got some 1/2" x 8" flatbar and got to work. Used some 2"x3" angle iron from my old semi elliptical ramps. leaves about a 1 7/8" space between the lower mount and the transmission. So I will have to cut some rubber for that. So the cab will sit around 1 1/8" higher than stock. I will redrill the front mounts to make them work as well. I also got some air fittings picked up today as well as the oil for the transmission. Lucas Synthetic 15w40. One of the vertical bars is slightly cocked to clear the air fittings down on top of the spring brake tank. It is much lower than the original mount for added support to it.

I thought about just welding the whole thing together but decided to bolt and angle iron it in case I need to take it back apart I can pull that whole horizontal beam without much trouble than having to take the whole thing apart.
 

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simp5782

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Ok so back to doing transmission work. It was able to use a tractor shaft just fine as a jackshaft replacement. It does have an angle but I think it will work.

Got distracted with some cab stuff after the forklift wouldn't get it up high enough and broke some straps so I had some cab damage I decided to rip the floor and do all that. This was during my time that i ran out of Adderall. With my script refilled it is back to it.

I threw the cab back on and ran into my first issue I knew I was going to have to address. the trans manifold is pretty tall and by having to use the SAE1 bellhousing with new mounts I knew raising the body an inch or 1.5 was gonna have to happen. Well with the floor out it lets you have good visibility. I can see that the cross beam is hitting the manifold. I believe I can raise that with no problem and reinforce it. This is a given also in that area since I am going to be using some pretty good steel to hold that shifter up so it can be adjustable. This also helps with air ride seat stability I believe. So I am looking at a 1/2inch space between the front cab support and the top of the bellhousing. CSMDavis mentioned a tunnel for that but it isn't missing by much and plus the front beam is close to the upper engine mount anyways on the outside of the frame. The rear mount I made will work perfectly as level.

So I tried cutting the stock frame perches for the body but that got old pretty quick as to their weird angle. I will be getting some 3/8 or maybe 1/2" plate together and just do a L shaped bracket like i did for the engine and add some gussets. Should be stronger than the stock by far. I know I will have to raise the hood on its frame mount as well.

I don't think it will look too goofy being raised that much. I will end up raising the bed as well but I plan on using a Battery Relocation box to fill in the passengers side gap and use the stock mounts from the toolbox and on the drivers side I will may able to cram another air tank in there mounted to the bottom of the cab. Then just raise the spare tire carrier as well.
 

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silverstate55

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Well now you're set up to extend that cab for more room, or even make it a crew cab! :)

Great work Wes, looking fantastic so far! Keep at it, it will be done before you know it! [thumbzup]
 

simp5782

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Well now you're set up to extend that cab for more room, or even make it a crew cab! :)

Great work Wes, looking fantastic so far! Keep at it, it will be done before you know it! [thumbzup]

I thought about cutting the rear of the cab and squaring it up and adding 5 inches to it for a lil more seat room but I don't like that 12 to 18inch add on "extended cab" I think it and a crew cab look goofy on a 923 chassis. I think the square look will go well with a nice hard top to square in. I may go raid the steel pile here in a bit.
 

simp5782

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Got new floor braces installed. Floor down. I decided to do mine in several pieces and put it together inside the truck rather than trying to fight with the large steel plate. Used some pruning seal spray that Profo recommended to spray at the places seams. Underneath I used spray foam to fill in the channel plates and gaps I could see. Then added a whole coat of the pruning sealer to the bottom of the floor then 3 coats of Lizard skin and a insulation/heat mat.

Took a little bit to get all the height and mount situations figured out. The cab was raised exactly 2 inches from the stock height. Used some 3/4" thick bushings on the rear and I think I will be using the stock bushings on the front. I am not sure yet. I used hockey pucks for the bushings on the transmission to its cross member.

Got all the air system for the transmission figured out with the lubricator and regulator installed. Hoses ran where they need to go as well. I will be adding a bracket there for the air tank drains somewhere in that location. With the height of the cab I may even install another air tank on the bottom side of the cab to fill in some of the space.
 

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patracy

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Thanks for all the pics. But looking at how tall that transmission is in the frame, I'm thinking I'll just have to watch this one from the sideline. :(
 

simp5782

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Thanks for all the pics. But looking at how tall that transmission is in the frame, I'm thinking I'll just have to watch this one from the sideline. :(
It is 10" to the highest part of the manifold above the frame. Bottom of the cab on a 939 is a hair under 9 inches off the frame. it is about 10.25 to the bottom of the floor. Those channels for the cab braces is what caught me up by hitting the manifold.
 
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Swamp Donkey

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So, your worried about the cab growing new branches since you modified it???
He never had to take potty breaks during his travels because of the trap door in the floor. The new floor doesn't have a door, so think of the pruning tar as a form of rubber sheets....in case he forgets.
 

simp5782

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So, your worried about the cab growing new branches since you modified it???
It is in honor of those RRAD SEE trucks with trees growing thru them. It is thin and seals up holes much like flex seal would and its waterproof. Marty said it gets into cracks a lot better than like bedliner would. He is the fabrication guru. Just taking notes.
 

simp5782

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He never had to take potty breaks during his travels because of the trap door in the floor. The new floor doesn't have a door, so think of the pruning tar as a form of rubber sheets....in case he forgets.

Don't let your trailer pull a gimpy as it gets off my trailer.
 

simp5782

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Cab is back on. mounts on and it is all bolted down. 1/2" plate for the L bracket. Should hold fine. I used the stock front bushings on the top of the mount and I used hockey pucks I squared off on the lower half to fit snug in the mount. Used 3/4" rubber bushings in the rear. The drivers side cab mount is sitting off center for a reason as that I was able to utilized 2 bolt holes that were already in the frame instead of drilling others. At Stock the cab sits 10 1/8" from the top of the toolbox (not the tread plate) to the bottom of the door sill on the passengers side. I am sitting at 13-5/8". So it went up quite a bit. Transmission clears just fine. I did put in two Street elbows to hook the vents to for the transmission so that I could run the air line to the drivers side and keep it away from the cab and any rubbing. Seemed more practical to me.

I threw one fender on to see what it was going to be like. I will probably add a small mud flap strip below the fender. I am also going to make a inside fender section since my stock ones got torn up and I don't need the hole for the air cleaner. The cab seems to be a lil bit further forward than before. I can't tell from pics really but the fender kinda shows it compared to a stock pic. That is the furthest back the cab can go cause the front cab perch is right close to the engine mounting bracket. the hood is gonna have to go up anyway and if I need to I can slot the bolt holes for it to go forward a slight bit.

Tomorrow I am going to try to tackle the exhaust. I am looking at a 5" pipe. 90 Degree off the manifold itll drop down to just below the frame like and go back thru the front U cross member to the back of the transmission. THEN I have to figure out how to get it up to the existing stack side. I may be able to snake it under the cab. Not sure yet. Pretty tight space. I am going with a 5" pipe in the event I swap over to a big cam it is already there and suitable.


I am also going to use a battery relocation box or cut down another toolbox in order for it to hold two 8D's The battery box is ideal though since it will fit without using the drop brackets.
 

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simp5782

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Test ran the installed transmission.had trouble getting it into any gear at first then it wouldnt get past 12th.

Pulled it out and put the spare one in. Test ran it. Checked out good. Engine run later on.

https://youtu.be/Sl13jKvU_io

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