D6R shifting hard when changing direction.

[02Dmax]

D6R - 5LN02305

The machine has had an intermittent issue of shifting hard when you change directions. I did the fill calibration and it solved it for about 20 hours.

I knew that there was a newer style modulating valve to put in these older transmissions so we put the newer style in it and serviced the transmission by changing oil and filter. I recalibrated the trans fill and clutch engagement pressures and turned him loose again. This time it lasted 30 hours before shifting hard. Now I can recalibrate the trans fill and it will work perfect for 3 or 4 hours but usually goes to shifting hard again by lunch time.

I'm just wondering if there's a software update I need to upload in to it to solve this or if the calibration process is just masking a valve or seal issue temporarily.

The personality module part number is 1915019-00

Thanks

 

[Cmark]

I guess you have ET? Does the transmission temperature sensor reading look right? Modulation times vary depending on what temperature the ECM thinks the oil is.

 

[02Dmax]

Ya it looks right. I haven't cross checked it with a thermometer but the reading is always within a few degrees of ambient if the machine hasn't been ran yet, then warms as would be expected. About 145-150 F is all the warmer it gets under normal conditions. I usually have to stall it to get it up to the 154 for calibration

 

[Nige]

No software updates. What you have in there now is the latest & greatest.
I assume that when it starts direction shifting hard it's not throwing any codes or such.?

What coolant temp does the machine normally operate at..?
I would've thought 145-150 for the powertrain was way too low.

 

[02Dmax]

No software updates. What you have in there now is the latest & greatest.
I assume that when it starts direction shifting hard it's not throwing any codes or such.?

What coolant temp does the machine normally operate at..?
I would've thought 145-150 for the powertrain was way too low.

Correct, no codes. I'll have to check on what it usually operates at. You might be on to something though. This machine used to run hot all the time. The owner would have to clean the radiator out daily and still have to shut it down sometimes to avoid the buzzer coming on. This spring we replaced the radiator cores and fan blade and he said it doesn't even offer to get hot now. I wonder if all the hours of running hot messed up the thermostat and now the engine isn't warming up enough?

 

[Cmark]

Agree those temps sound low. It should have a 91 deg C thermostat in it and the engine should come up to that temperature fairly quickly. For what it is, I would replace the thermostat anyway.
The million dollar question is, what is the tranny temperature reading when the fault is occurring?

 

[Nige]

91 degC is 196F. If the stat is supposed to open at that temp you can bet that the "normal" coolant temp should be at least a couple of degrees above that. Say 93C/200F. Powertrain temps can easily run up to 120C/250F when the machine is pushing hard.

If you have to stall the transmission to get it up to 154F/68C for calibration then the coolant temp has to be either super-low or a temp sensor(s) has to be on the fritz IMHO.

I agree with Cmark, just throw a new 111-8010 thermostat at it and once that is in watch what the coolant/transmission temps do afterwards.

 

[02Dmax]

Sounds good, I'll do that. The other day when I looked at it, he had been running for 7 hrs in long pushes and the trans temp was 145 F. It was cold outside but that's still low. Thanks guys.

 

[Oldcatpusher]

I have a 6R. 5LN serial number shifting hard but only from forward to reverse. Almost like brakes are applied for a half second. Transmission oil and filters are cat brand. Fresh service. Been waiting on my trusted mechanic to recalibrate trans before I commented or asked advice on here.

 

[Nige]

Sounds good, I'll do that. The other day when I looked at it, he had been running for 7 hrs in long pushes and the trans temp was 145 F. It was cold outside but that's still low. Thanks guys.

Treat it to some genuine ELC coolant at the same time. Doesn't have to be Cat-branded. This is the product that is in a Cat ELC container .......... https://www.peakhd.com/product/final-charge/noat-extended-life-coolant-antifreeze/

Don't be tempted to use nitrite-free ELC in a piece of off-road equipment.

 

[Kiwi Craig]

I dont know about the operating temp, but many years ago I ran a new D7R that had that problem.
Many software updates, discussions from NZ to USA didnt solve the issue.
I found if you dont use the decelerator when shifting from forward to reverse, or vice versa, it is as smooth as silk.
But I know what you mean, it can be very harsh, make sure your seat belt is done up tight in case my idea doesnt work!!!

 

[R.D.G013]

I have been on a D 7 R 2 lgp that had a similar problem for a long time finally they got some one to check the accumulator pressure, supposed to be 250 psi but was in fact over 500 psi, reduced pressure to 250 and the problem went away. Don't know who put it at over 500 as we bought it 2nd hand and was like ever since we had it. Made for a rough old day.

 

[R.D.G013]

I have a 6R. 5LN serial number shifting hard but only from forward to reverse. Almost like brakes are applied for a half second. Transmission oil and filters are cat brand. Fresh service. Been waiting on my trusted mechanic to recalibrate trans before I commented or asked advice on here.

Look at the accumulator pressure.

 

[Cmark]

Look at the accumulator pressure.

Which accumulator?

 

[Mobiltech]

The accumulator on the d6r I have seen is under the fuel tank at the back. It is there to balance out the drop in pressure when you make a shift at low rpm.

 

[Nige]

Which accumulator?

The phantom one .....
The 5LN-prefix D6R doesn't have an accumulator in the power train oil system, although some other S/N prefixes do.

 

[02Dmax]

The phantom one .....
The 5LN-prefix D6R doesn't have an accumulator in the power train oil system, although some other S/N prefixes do.

These 5LN's were the first high track 6 with an electronic power train control system weren't they Nige? And it's a bare bones operating system at that.

 

[Oldcatpusher]

Mine looks identical to my 6H except for the electric plug or 2 protruding from the rear top of the transmission.

Definitely no accumulator on back of either dozer.

 

[Mobiltech]

Might benefit from adding one. It does help with pressure drops for sure.

 

[Nige]

Might benefit from adding one. It does help with pressure drops for sure.

The accumulator in the power train on later D6Rs (PPP, SSS, & TTT-prefix tractors) is a heck of a size for what it is supposed to do.