cummins 12 valve swap help me

[spiritjohn]

Well I got the engine and tranny in and going to keep things simple and just get new parts for the juice brakes. The issue I run into with that is how to park. The original transmission was a manual with a drum brake on it. Now I have an mt643 with no way to park it
I've been able to find the same drum style trans brake for an at545 but have had no luck yet finding one for an mt643.
I can use a line lock on my brakes but something about that just makes me very very nervous. Any advice on parking this thing would be great

[whiskey runner]

Sleddgracer sorry i just now seen your question.. i used some 4x10 sheets of powder coated aluminium i get from the local steel supply yard.. i think it was around 50-60 dollars a sheet.. i know i reduced the weight of my bus quite a bit from the original steel that was on it

[Kubla]

At545 and mt643 use the same parking brake assembly I believe, see if there are 4 bolt holes round the rear yoke

[Elliot Naess]

I agree with you, Spiritjohn, on NOT using a line-lock or anything that relies on pressure -- be it liquid or air -- as parking brake.
Any liquid or gas under pressure WILL leak down eventually. It may take weeks, but one day we WILL leave the vehicle parked longer than usual, and....

This is why air brake systems went to spring-loaded parking brakes ages ago. (Called a Maxi brake, in the day.)
The spring applies the brake at all times, except when air pressure overpowers the spring so the vehicle can move -- "releasing" the brake.

I have both an AT545 and an MT643 here, if you need a comparison.

And yes, thanks, I will keep you and that bumper in mind.

[Ronnie]

Just as a stop gap measure you could use the line lock only long enough to put wheel chocks under it. Not an ideal solution but gets it on the road.

The old trans drum brake, was it an external band on it? The Allison's I believe could be either external band or internal like wheel brakes. My Allison MT-40 has a drum with internal brake shoes.

[Tango]

All I have ever seen on Allisons were internal band. I do know that the 4 bolt pattern on a 545 is slightly different than on a later 2000 series. Those can be found on 2008-2009 GM Medium Trucks, Kodiak C4500 C5500. That is what is on my 2200MH.

[Elliot Naess]

Without crawling under my buses in the mud....
Might the bolt pattern issue be solved with a simple adapter plate? A 1/2 inch steel plate with eight holes?
Come to think of it... with an adapter plate, you could perhaps install "any drum brake on Earth" that has a proper parking brake mechanism in it.
And finally... maybe you could install such brakes in place of your existing parking-brake-less rear brakes?

My mind certainly has no brake on it at all. lol

[Ronnie]

If everything else fits except bolt holes, then drill a new set of holes that would match. Then no adapters would be needed