Stupid 5-Ton Allison Transmission Question

[railroadmike]

Good grief that looks bad, I may be in for similar as my valve sticks for about two three minutes. My air dryer has been out for about 1000 miles and I drained every time I parke. So far not much crud in the system out side a little bit of brown dust in the now failed CITS. A buddy that worked on every type truck in the Army tells me not to worry about the dryer being in the desert. I'm still gonna change it out.

 

[bigsix]

well i got my air problem fixed in the 5 ton, ppv valve was stuck even after i cleaned it so i put some lithium on it . it works good now. horn and wipers come on and work well at 70 pounds. But my trany i think is shot. it spewed oil out of the dipstick tube after i put some fluid in. it locks up in all forward gears. no movement.

 

[Jericho]

Hummmm, check the Tech data , there is a section on fluid blowing from dip stick , Just don't remember what the component call out was for the offender , But do remember it being in there, been a few years .

 

[tobyS]

well i got my air problem fixed in the 5 ton, ppv valve was stuck even after i cleaned it so i put some lithium on it . it works good now. horn and wipers come on and work well at 70 pounds. But my trany i think is shot. it spewed oil out of the dipstick tube after i put some fluid in. it locks up in all forward gears. no movement.

That sounds more like brakes not releasing. Where did your tranny oil register on the dipstick? Could it be overfilled? Are you considering dropping the pan?

 

[tobyS]

The original intention of the thread was to understand why the torque converter does not unlock quick enough when brakes are applied hard during a panic stop and the end result is a stall condition the same as if you locked the brakes on a standard shift vehicle without depressing the clutch pedal.

You know Will, this is a good educational point about driving these trucks. It makes me want to double down on practicing pumping them, even in a panic (requiring some practice)....because as you point out, you can very easily/will kill the engine and go entirely out of control. You make a good point.

As to the higher rpm, is there valve body control for that that can be adjusted??...it would seem logical. Perhaps operator controlled valving by a solenoid (released on braking automatically)?

I think I'm having a releasing problem on my 2011 Chevy half ton, coming to a stop it delays from coming to a full stop and I know I'm slowing the engine down, having to apply more brake pressure. So I'm not sure the issue of releasing the locking torque converter is entirely fixed, even on newer trucks.

 

[bigsix]

I was thinking the torque converter dryer may have been my problem. Like it had fluid locked because of a sticking valve. I am reading g where some people are changing to attend fluid because if you are not loading the truck like it was in service, the thinner fluid helps the converter unlock easier.

 

[bigsix]

Forget the word dryer. I don't know where that came from .

 

[tobyS]

Forget the word dryer. I don't know where that came from .

Transmission has no "dryer". They have an oil cooler.

 

[Suprman]

Transmissions are funny things. Sometimes you have to bite the bullet and pay a visit to your local Allison dealer.

 

[tobyS]

A locking torque converter has friction plates inside of it that are operated by a piston that receives pressure from the valve body. The valve body control has to see a reason to unlock and release pressure to that piston that is within the torque converter. It all takes time and the thicker fluid, will take longer than thinner liquid, resisting movement, especially when cold.

I won't enter the fray of oil v ATF, but used Dextron when we rebuilt the Deuce A3 1545 Allison recently.

 

[tobyS]

Transmissions are funny things. Sometimes you have to bite the bullet and pay a visit to your local Allison dealer.

I don't know where the up vote is, but I'm still setting laughing!

 

[simp5782]

I went up and looked it today. Transmission is toast. Modulator cable is intact and working correctly. It goes in Reverse when the shifter is in neutral. Even tries to go in reverse in 1st. Transfer case in Neutral the jackshaft will spin in reverse very slow but wont spin in any forward gears. Tight to turn the jackshaft with it in Neutral and truck shut off.

 

[dmetalmiki]

Abs pulses the brakes preventing the wheel from becoming locked hence the name anti-lock. Braking force is applied on-off-on-off rapidly. With no abs the driver slams on the brakes the wheels lock up and it's downhill from there. With abs the driver slams on the brakes but they don't lock, the brake application is pulsed to allow some wheel spin along with pulsed brake application. The theory is the vehicle will stop faster and under better control than just fully engaging the brakes and letting the tires drag the vehicle to a stop. In the 929 trucks, in a quick panic stop, the driver would over-apply the brakes and with no abs the wheels would lock. With the wheels locked and the torque converter not yet disengaged, the drivetrain would come to a halt, stalling the engine. No engine power equals no power steering which means basically no steering so panic stop loss of control you see where this is leading. So in comes the military and the add antilock brakes as a bandaid. But if you read about the problem it would appear that the torque converter is the real culprit, if it would unlock then the engine would spin free to idle and no stall. Not that abs is a bad idea it's great to have but retrofitting the converter would seem to have made sense.

No engineer thought out or tested that piece of' @@@ERR 'equipment' but probably the same team that thought 'let's design a handbrake that the driver can easily knock off, and have the fully loaded truck run away (every time the driver exits the cab!).
ABS, does not judder the brakes on and off. The sensors on EACH wheel have a rotor on them which lets the driver brake at will, But if one wheel 'stops' (starts skidding) the computer measures that differential speed rotation and removes the braking pressure from that ONE(only) wheel. (and) when the rotation becomes equal again, the computer will ALLOW the full braking effort back on that wheel. If it still skids (slips) the computer promptly take the pressure off again. Hence the feeling of a 'judder'. (as this process is happening very rapidly indeed) ABS does NOT prevent skidding. Doubt this? Well visualise 3 wheels on full release! and your trying to turn and stop somewhat quickly..
Like all things safety wise, this is an aid to further assist sensible careful and considerate driving allied to the pertaining road conditions.
New to the hobby drivers of older large trucks in the hobby should be aware also that some of these older 5 tons have very little power steering assist at low rpms in a higher gear. (as in slowing to a stop without changing down..and entering a steep turn to a driveway etc.) My 1/2 penne'th

 

[Jericho]

Push your emergency brake emergency release valve on the dash in after pressure is up. Does the brakes release ?

 

[Csm Davis]

Hey CSM I never got back to you about my data plate. Contract No. DAAE07-86-C-J111 delivery 09/91

Trans oil, MIL . L 2104 GR 10 above 15 degrees F to 40 F
Trans oil, MIL . L 46167 OEA 40 degrees F to 65 F

Any thoughts?

Well 2 years isn't to long to wait it says 10wt so what do think it came with? They all came with 10wt, otherwise they would have a ATF dexitron fluid listed on the data tag. I will never run any ATF in my trucks. I have talked to more than 10 people who changed to a ATF and 7+ have had problems and several lost the trans completely. One thing that aggravates me is guys assuming that it is 15w40 , I would be willing to bet less than 100 trucks ever got a full swap to 15w40 and the odds of those trucks being in private hands is huge against it. The military didn't not automatically drain and refill them when they were shipped overseas, and I know for a fact they were filled at rebuild with 10wt so getting one with 15w40 would be rare not saying it can't have some 15w40 in one but a full trans I doubt it. As was posted earlier these trucks were run hard in Desert Shield/ Desert Storm if they would have had a problem with it they would have changed it, like they added the ABS to prevent wrecks. Y'all can run what ever you want, it is your truck.

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[Csm Davis]

No engineer thought out or tested that piece of' @@@ERR 'equipment' but probably the same team that thought 'let's design a handbrake that the driver can easily knock off, and have the fully loaded truck run away (every time the driver exits the cab!).
ABS, does not judder the brakes on and off. The sensors on EACH wheel have a rotor on them which lets the driver brake at will, But if one wheel 'stops' (starts skidding) the computer measures that differential speed rotation and removes the braking pressure from that ONE(only) wheel. (and) when the rotation becomes equal again, the computer will ALLOW the full braking effort back on that wheel. If it still skids (slips) the computer promptly take the pressure off again. Hence the feeling of a 'judder'. (as this process is happening very rapidly indeed) ABS does NOT prevent skidding. Doubt this? Well visualise 3 wheels on full release! and your trying to turn and stop somewhat quickly..
Like all things safety wise, this is an aid to further assist sensible careful and considerate driving allied to the pertaining road conditions.
New to the hobby drivers of older large trucks in the hobby should be aware also that some of these older 5 tons have very little power steering assist at low rpms in a higher gear. (as in slowing to a stop without changing down..and entering a steep turn to a driveway etc.) My 1/2 penne'th

You are thinking about the 809 series with the emergency brake handle just inside the door they moved it to between the seats in the 939 series.

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[Jericho]

Some Airforce Trucks had a safety chain added with a ring on the end, It was a local option "Safety MOD TCTO" (time compliance Technical Order )When the handle is up just drop the ring over the handle, CANT go down to let brake off, We bought the chain at ace hardware and the ring was a "shim" for the skate disc from a snow plow . simple cheap and works , Ill post a photo when I get time. My M 109A3 had one and I added one to my M931

 

[Jericho]

CSM , I am convinced, No more ATF thoughts here. Compelling argument !!!! Thank you sir

 

[Jericho]

On the tranny locked up and going into reverse in first ect, How did the pan and filter look, I do a fair amount of trans, Mostly trucks , some dozers Was it SLIPPING at all prior to the bad behavior or modulating between gears up and down ?

 

[Jericho]

The more I think about it , if you weren't having problems prior to your air brake issues and adding fluid. What changed. Spent a lot of years rebuilding slush boxes They usually give you lots of hints. Some discreet. Some very bold . Were there any symptoms ?