53 chevy cummins help continued

[spiritjohn]

I made a post about this over a year ago, still working on this bus, decided a new post was a better way to go. This post is both an update on this project and a way to voice many newly found concerns

I've taken a 12 valve with an allison mt643 out of a 1995 bluebird and have put it into my 53 chevy (c4500 I think?). Being someone with absolutely no mechanical experience, this has been hell but it's in and it runs although Theres a fair amount of tinkering I still need to do under the hood. I am right in the middle of swapping the rear axle. The original axle had a 6 37 ratio, very dinky little driveline, primitive rusty brakes widowmaker rims. I'm swapping in a 10 lug 2 spd off a 1971 f700 dumptruck. I do not know the ratios, but my goal is to go atleast 65. Switched the 24 inch tires that came with this axle to 22.5 inch tires to fit my wheel wells better. Either way I am excited to finally be off the 50 year old tires and widowmaker rims. This axle should also support my weight much better as my bus is my house has all my worldly possessions and realllly heavy. The two piece driveline I got with this axle looks to be much more compatible than the one from the 50s.


I'm wondering if anyone here is familiar with or could make an educated guess what the ratios off a 10 lug2spd rear end f700 1971 dump truck might be and what speeds I might expect. At the end of the day I know I need to just use the codes stamped on the axle to find this out but I am feeling lazy right now so I'm asking the internet instead. I do not have the vin for the dump truck as I found it at the local scrapyard and this truck no longer exists. I've googled this as well and found answers ranging from 3.10 to a saddening 7.30. Hoping for anything faster than 6.37 but probably just going for it at this point.

Also posting a picture of an airline coming off my allison mt643. I am wondering what this could have been for. In the bus it came out of this airline led to a junction.
One side of this junction went to the front of the bus(somewhere way up under the dash) the other going to the air accelerator. I have replaced the cummins air compressor with a gear driven vacuum pump for my hydraulic brakes. I am hoping there will be no consequences in removing this airline and what function it would have served.

Keeping original front axle. Had drums resurfaced, new shoes, wheel cylinders, etc on front axle. Replaced single reservoir with dual reservoir with vacuum servo out of some pickup truck from the 90s. I also have a remanufactured hydrovac booster.
For my parking brake I'm going with a very very heavy duty linelock

I am wondering if I should plumb in both the hydrovac with the vacuum servo/what difference that would really make.

[Ronnie]

I was wondering how this build was coming, glad to see you are still at it.

The rear end, well get un lazy and get the numbers off it, and I mean that kindly. There is just no other way(accurately) without counting teeth to find out. I can say my 2 speed has a high of 5.14, and my old International dump truck had a 5.8 in high

I do not like the idea of a line lock for a parking brake. I can see brake fluid very slowly leaking past the wheel cylinder seals over time. Using a line lock till you can get out and block the wheels would be ok, but I would release it after blocking. I carry two blocks for my parking brake. I do have a band brake on the driveshaft for parking but need to reline it.

[spiritjohn]

I dont like the line lock either. I like the band brake idea, first time I've heard of that and seems simple. I've tried finding manual transmission brakes for an allison all over oregon with no luck, also looked into a lock on the pinion of the rear axle which seemed expensive and a little complicated. I'll look into the band brake though. I think I'll be doing a lot of blocking either way.

[Ronnie]

A band brake on the rear of the trans was very common in the 40's and 50's, and is likely what your bus had originally. Here is another brake on the rear of an Allison automatic. It has a drum brake with the shoes inside. this really works great, would even hold the bus on a boat launch ramp. The flange yoke for the driveshaft bolts to the drum.

[ol trunt]

Well, I'm completely confused. You say you are working on '53 Chevy bus but the pictures you have posted (at least the ones I see in your post) are of a 1939 thru 1947 Dodge????
Jack

[spiritjohn]

Only the front end is a dodge

[ol trunt]

Ain't a Chevy, its a Dodge---losa luck!

[spiritjohn]

Nope. It's a chevy. With a dodge front end. Says Chevrolet on the dash inside.

[spiritjohn]

Here's the original tranny, had a brake with a lever that tightened it on the outside. Have been trying to find one for an allison with no luck, sounds like the band brake will be easier to find though

[Ronnie]

Looks like this one had a band around the outside? If so this is what I am refering too. When you shop around for a brake show the picture I put up. By the way the Allison pictured is an MT-40.

I suppect that newer Allisons where in air brake buses and therefore would not have a parking brake. so the older ones for buses/trucks with hydraulic brakes are where you will find them. Might need both trannies side by side to see what parts will fit.

[Ronnie]

Do you have a picture of your trans? Especailly the tail shaft and rear of the trans?

[cadillackid]

there are a lot of allison's in hydraulioc brake busses with that drum on the yoke., my red bus has one and it works great.. when you get one you need to find ojne specific to the MT600 series transmissions , many hydraulic brake busses were smaller and had AT545s, the park brake assembly for an AT545 will not fit an MT643. they can be bought new at a pretty price. but also can be found used.. GMC offered the MT643s on a lot of 8.2 diesel equipped dump trucks of the 80s and 90s, most of them had the driveline park brake.



theres the assembly that mounts to the 4 holes on the trans tailshaft, if your yoke is like mine it already has bolt holes in it for thr drum. the drum mounts to the yoke, then there is a bracket that mounts across 2 of the top mounting holes on the trans..



inside there are 2 types of cable brackets ive seen. there is one that can be mounted to the floor and has a boot and cable goes down through the floor.. my Superior has this type.. and is mounted in the center behind the "mini doughouse",, the other type is one that mountes to the frame of the dashand the cabke goes through the firewall and loops down under the bus.. thats the type my red bus has and its on the left side, when its folded up it doesnt hit my feet or knees..



I like the cable type where the inside end is threaded and the ball handle can be tightened to loosen or tighten the cable tension.. these cables can and do strretch over time.. and its nice to set the tension without having to crawk underneath and do it..

-Christopher

[spiritjohn]

Here's the transmission that's in there

[spiritjohn]

Here are some numbers stamped into the axle housing. Took these numbers to a local shop here and they didn't get far with them. Vin is history.

17221
101263
61547
6-5

Dont know what that all means but I have a feeling I'm gonna have to open this thing to find out what it really is.

[PatrickBaptist]

Awesome swap you got going on there.
I understand about the gearing, my bus is a 6.18 and I'd like something in the 3.73-4.11ish range myself.
Do you have a YouTube? Def would like to see any videos you made

[cadillackid]

transmission is definitely an MT series.. looks like an MT643.
4 speed 1:1 final with Lockup torque converter in 3/4 on upshift and will hold lockup partway into 2nd on decel

-Christopher

[Ronnie]

I do see where there is room for the drum brake, and looks like an easy bolt on.

[whiskey runner]

very cool build.. very muck like mine except i used a 46 white, gillig bus with a 1959 cummins c180 supercharged engine, 10 spd. fuller road ranger trans. with 4:11 gears in the rear.. also air brakes so i dont have a answer for you e-brake problem.. i will hope to see more updates soon...

http://www.skoolie.net/forums/member...ture21575t.jpg

[banman]

Look up a company called Vanco
Vanco Power Brake Supply

Tell them what brake parts you're trying to marry up and they'll give you a solution.

They will talk tech on the phone, or email back to you if you send them a question.