2001 Int'l 4700 DT530 3000 Allison

When shifting from neutral to drive, or reverse, with a cold trans, the shift is so hard that the whole truck lurches.

When parking, and applying the hand brake, shifting to neutral first, the truck drifts, regardless if the trans was put in neutral before the hand brake or after the hand brake.

Is anyone else experiencing this - I'm trying to determine if it's normal.

I purchased the truck in March, with 131k miles, and it has been performing the same since I purchased it.

The fluid levels are okay, both from the selector and the dip stick, with truck at operating temp and engine at idle.

Thanks.
Al

Al: When you say your truck is cold, is it cold enough that the low idle is above 700 RPM, if so, could that explain some of the lurching?

As to the "drifting" even with the P/brake engaged, I can't help you as mine is a manual 10spd and with those air spring-brakes engaged on mine, she's NOT moving!

Thanks, bstartk.

The idle is at 700, according to the tach, not above it. I would imagine, that with the indicator right at 700, it might be a little under.

The truck has hydrolic brakes, and they stop okay.

Would adjusting the knop on the top of the hand brake make a difference? I have it tight and that didn't make any difference.

Would the speed of applying the hand brake make a difference?

Al

Looks like a Stalick, if so you most likely have the Detroit-Locker rear end. That is a major pain in the neck and that isn't just a figure of speech in this case.

Your parking brake is on the transmission output so that takes the transmission out of the equation for the drifting problem. The only other things that could contribute to it are horribly worn universal joints and the gear mesh being way out of adjustment in the differential. Both of these causes have very obvious and noisy symptoms that you'd surely notice.

The locker give you several inches of free rotation on the rear wheels that is very frustrating. You can see this on flat ground, set the brake and push the truck forward and back. About all you can do is to try to take up the slack before engaging the parking brake. If the truck looks to roll back put it in drive, if it looks to roll forward put it in reverse, that way most of the slack will be gone when you apply the brake and rolling about will be minimized.

The knob on top of the brake is the "fine" adjustment for the parking brake tension, it should be adjusted to the point the shoes don't drag when the brake is released and it will hold the truck at idle in gear. You might want more braking if you end up on a hill with your fiver. We have been trapped in the truck holding the service brake for a half hour waiting on traffic to clear on a steep downhill. That was not fun but there was no where to go and we had to sit and wait.

The "coarse" adjustment for the parking brake is on the shoe activation lever under the truck and has a lot greater range of adjustment. Best to set the fine adjustment to about 75% loose then do the coarse adjustment as close as you can get it. This is a real pain and goes best with two people, one working the brake and one under the truck.

An added gotcha is that if you have the brake snugged down near the maximum you or the wife may not be able to apply the brake because the lever is just too hard to pull. We added on a PVC extension that was as long as possible so Trudy could pry the brake on when she drove.

That covered the brake and drifting issue leaving the lurching when going into gear. Again all fingers point to the Detroit-Locker and its free play. The Allison has a bunch of heavy metal inside and when you shift into gear all that starts spinning, the free spin before the locker's slack is taken up is a big part of the lurch adding to the engine's torque, no good workaround for this like there is for the drifting though.

You can do two things to make it a bit less of a problem but nothing but a differential swap for an air-locker is a real solution. I priced one of them and decided to train myself to set my coffee down before punching the D button instead.

First switch to synthetic transmission fluid and Allison Gold series filters. The gold filters are needed for maximum life on the synthetic and since it is expensive and there is a lot of it lifetime is important. IH recommends TranSynd that is really expensive, Allison lists several other fluids that work as well or better. You want to select one that has the best flow rate in cold weather, that will give you the smoothest possible shifts when the transmission is cold. It has been a while but I used Mobile-1 and was quite happy with it. Do read up on the conversion process to synthetic and make sure to get it done correctly and mark your owner's manual with the new filter and fluid change intervals.

Second and a continuing operation, make sure to reprogram your transmission when switching from towing to bob-tail operation. If you don't do the reprogram properly and with the transmission warm you might not be able to do it. The transmission has to be above 140 (?) degrees to reprogram and on our truck in the winter there was just no way to get it up there without putting the fiver behind the truck or letting it idle in gear for a long time.

Reprogramming is easy if the transmission is warm but varies based on how you have the internal settings of the transmission configured. Both follow the same steps but the number of repetitions varies. Unhook and before things cool off shift to neutral, drive under light throttle until you shift to third, brake gently until you come back to 1st, the converter unlocks and you stop.

Don't confuse the 1st gear converter lock-unlock with a shift, older Allisons showed the actual gear as well as the desired gear, new ones only show the desired gear. You can be sure you are in third by forcing a downshift to second with the transmission controller. If you punch it down to 3 and then go to 2 at low RPMs you should feel a shift. If you go from 3 to 2 and don't feel a shift you were still in second.

If your Allison is in "fast-adapt" mode you should do this three times and the new shift schedule will be activated. If you are in "normal-adapt" I believe you need to do it six times to get the reprogram.

Remember you are wasting your time if the transmission is not above 140 degrees.

Getting the reprogram works to reduce the lurching because it causes the internal clutches to engage with less pressure and that gives a bit more cushion to the drive line during shifts.

Going the other way the truck will warm up and reprogram fairly quickly with the fiver behind it in most conditions. In really cold weather it might not want to warm up and you'd need to block the radiator and drive slowly with the torque converter unlocked to build up enough heat to make it happy. We only had that happen one time and we just lived with the softer shifts until we got down off the mountain and into warmer temperatures.

If you get a chance to compare try out a truck with an Allison and an air-locker and see how much difference it makes, might be worth the money to you.

Al
Stan has provided excellent information. As for me, I just set on my truck brake before shifting from neutral to drive or reverse. Part of the reason for the lurch is the high torque of the truck.
I also have the drift problem, especially when leveling, but I have learned to live with it by doing exactly as Stan suggests.
Jerry

I have found my Allison starts lurching / jerking when the filters are needing to be changed.

Filters are a big deal in the Allison, I've seen two mechanically (non-electrical faults) broken ones over the years and both could be traced back to bad filters. Both had collapsed filters that blocked proper oil flow and caused expensive damage.

quote:

Originally posted by Stanley P. Miller:
Filters are a big deal in the Allison, I've seen two mechanically (non-electrical faults) broken ones over the years and both could be traced back to bad filters. Both had collapsed filters that blocked proper oil flow and caused expensive damage.

I'm wondering how quickly you'll see an increase in tranny temp is this happens? Probably not enough response time to avoid damage.

Just sounds to me like the filter people owes them a tranney.

Don't know what the end result was, both trucks were parked waiting for the legal types to sort things out.