Allison auto box advice

[dmetalmiki]

Well gents, Here's a nifty problem for you (All) to have a go at.
The Diamond T I have now, Is fitted with a four speed auto truck gearbox. Just like some fitted to the Bin (Refuse) wagons. (And buses?).
You can select 1 2 3 4 or R.
You can set of in 4, and it does the Auto thing. up and down
There is a neutral but NO Park selection.
I have the original LOW-DIRECT_OVERDRIVE Aux box working.

How can I fit (something(Anything)) or modify FROM the outside of the gearbox A,
DISCONNECT? Like a fork truck 'shunt' (Clutch)pedal?.
Mechanically OR hydraulically?.
WHY?
I NEED to disconnect/slip/ freewheel When 'SHUNTING My trailer.
Before you yell. "It should freewheel at tickover or low RPMs"), It does. ONLY in overdrive 4th. or Reverse.
But in direct or low, Forget it! the engine easily overcomes the brakes just at the speed I feel is SAFE to shunt.
Allison just say it can't be done, and or don't mess with it due to lubrication failure.
Go to it gents, Prove it CAN be done. Somehow..Anyhow!. Thanks in advance.
There are NO identity plates on the box which is annoying as I wanted to obtain some specifications diagrams schematics or data sheets.."Over".

 

[NDT]

Sounds like your engine idle speed is too high on your DFXE. None of us know what shunting is over here.

 

[dmetalmiki]

Idle is set right.
Shunting is just that, Pushing or pulling stuff into position, (Ah-lah Rail shunting Locomotives(Heavy locomotive actually is what my M.62.wrecker is registered as)).
All other factors being equal. I would like to have a disconnect to be able to use the auxiliary gearbox 'on the fly'. As well as for shunting.
After all, I DO use the clutch on my M.62. When 'shunting'.
And on my fork truck which has a 'Hydraulic release' Pedal. Which is what I am seeking actually.

 

[snowtrac nome]

on the forklift the left pedal applies a brake and declutches the transmission. of all the forklifts I have worked on I have never had to open up a transmission to see how it happens. I suspect its an internal clutch at the output end of the transmission and not inside the torque converter. I suspect what you want to do is not going to be a simple or affordable action

 

[dmetalmiki]

Roger that. I almost already know this option is going to be a ;challenge'. But I am still hoping that a 'Release' can be performed hydraulically. An Allison dealer over here is looking into that for me.
Others have suggested doing it like the 432 A.P.C. Allison Auto box does it.
But that option is for towing only and is a total disconnect mechanically Via a Dog Clutch.
So, The research, and options go on.

 

[Jeff Lakaszcyck]

When I read this thread a few months ago I really didn't understand what you were wanting to do, but after re-reading it I think I get it now. Your Diamond T M20 has an automatic main transmission installed and you want to be able to shift the manual 3 speed aux transmission on the fly. I don't think you need any expensive modifications to your truck to accomplish this, you just need to learn a few techniques. Back in the day when many large trucks has twin stick transmissions most of the old timers shifted them without using the clutch, only using the clutch to start and stop. I have driven a Diamond T 981 with the original transmissions down the road a little and I had no problem shifting the aux transmission without using the clutch. When shifting up in the aux you would let off on the throttle. The instant you let off, the gears will unload and you can then move the aux into neutral. While the aux is in neutral use the throttle to adjust the engine rpm up or down to match the rpm in the two transmissions, while holding slight pressure on the aux lever towards the next gear. When the rpms are matched the aux will side into gear. Downshifting will be similar, you will have to bring the rpms up much higher to make a downshift. Yes, there will probably be lots of gear grinding while you learn all this, but it sounds a lot harder than it really is and eventually you will shift like an old pro.

As far as your engine over running your brakes, maybe the answer to that is to move the main or aux into neutral, as long as your brakes are capable of stopping your truck without relying on the gearing to slow it down. From what I remember the top speed of your Diamond T is only 23 miles per hour !