Community Forums

noserider · 01-05-2016, 05:37 PM

I have the 3000 MH coupled with my Cummins 5.9ISB. Engine and tranny are running great. Had the tranny serviced at FCCC in Gaffney last June. I plan to change myself next time and change to synthetic with 2 changes. I'm also planning to start testing my fluids annually to include engine and tranny and also engine oil for generator. My tranny runs so cool now it's hard to get it up to temp to use the pad to check fluid level. I was driving today for an hour or so just getting everything loose and it never went over 135F and my coolant temp was around 184F. The outside temps today were in the mid 50's. Sometimes I wonder if changing the tranny oil and filter after 12 months to keep in line with Dino is justified with so little usage. I only put 2500 miles on last year. I know it's cheap insurance and all but seems a little overkill. Once I change over to synthetic I realize it will last a long time especially with testing and just change the filters on schedule and top off with fluid. I also noticed today that my tranny is set up to downshift to second gear with the engagement of the pac brake. I had read others have the same set up and had them programmed for a higher gear (4th) to minimize the hard shift. 2nd does seem a little excessive for freeway driving. I do like the way it works however for downhill runs in the mountains so I will most likely use it less when it's not needed. I was exiting the freeway today at about 65 mph. I waited until I was on the exit ramp and selected the pac brake and observed it drop to 2nd and watched the tach go up to around 2500 RPM's or so. I know the tranny is smart enough to take care of overreving but it seems a little strange to go from 6th gear to 2nd instantly.
If I'm going 75-80MPH and select the pac brake will it also instantly drop to second?? Today was the first time I even noticed the gear selector showing second but I never got over 65ish today.

bluepill · 01-05-2016, 05:47 PM

The RPM that the computer allows for compression braking is usually higher than what it allows for producing power. My MH with a 6.7L ISB and 3000 trans. will never go beyond 2600 RPM under power, but will go as high as 3000 when using engine braking.

If it's a really steep hill and I pick up enough speed to push past the 3000 rpm limit, it will upshift into 3rd gear. The PCM (Powertrain control module) is programmed to protect both the engine and the transmission.

My MH came with a factory fill of Transynd Fluid. I changed the fluid and the filters after 3 years, and the fluid showed no signs of breakdown. It looked and felt just like the new fluid that I put in. Good fluid, Great Transmission!

noserider · 01-05-2016, 05:54 PM

Quote:

Originally Posted by bluepill

The RPM that the computer allows for compression braking is usually higher than what it allows for producing power. My MH with a 6.7L ISB and 3000 trans. will never go beyond 2600 RPM under power, but will go as high as 3000 when using engine braking.

If it's a really steep hill and I pick up enough speed to push past the 3000 rpm limit, it will upshift into 3rd gear. The PCM (Powertrain control module) is programmed to protect both the engine and the transmission.

Good to know. Thanks.

Mr_D · 01-05-2016, 06:10 PM

The transmission will "preselect" a gear, the transmission will NOT downshift to that gear until the RPM's go down enough so the engine won't overrev. The readout only shows what it's target gear is, unless you have the two window control like we do. One window shows the preselect one and the other is the actual "attained" gear.
I had our 2000 Dutch Star reset to preselect 4th, hated it and wanted to have it changed back but we traded the rig off before I got it done.

noserider · 01-05-2016, 06:16 PM

Quote:

Originally Posted by Mr_D

The transmission will "preselect" a gear, the transmission will NOT downshift to that gear until the RPM's go down enough so the engine won't overrev. The readout only shows what it's target gear is, unless you have the two window control like we do.
I had our 2000 Dutch Star reset to preselect 4th, hated it and wanted to have it changed back but we traded the rig off before I got it done.

Nope, just the one window. I always thought the gear showing was the HIGHEST gear selected? So in D 6th is always showing and If I manually downshit to 5 or less then whatever I select is what is shows and is the highest gear available. No???

noserider · 01-05-2016, 08:06 PM

I guess I was applying the logic of the number displayed in the window during normal operating procedures and it's different when the pac brake is on meaning the number now shows the lowest gear selected. That's good to know and makes a lot more sense. I would like to have the 2 window setup to know what gear I'm in. Not sure that would change my driving habits, but I guess I like information.

Mr D when you had yours programmed to 4th when the pac brake was on how did that change your tranny shifting? 4th now becomes the lowest gear available? That also seems strange.

Mr_D · 01-05-2016, 08:26 PM

Quote:

Originally Posted by noserider

I guess I was applying the logic of the number displayed in the window during normal operating procedures and it's different when the pac brake is on meaning the number now shows the lowest gear selected. That's good to know and makes a lot more sense. I would like to have the 2 window setup to know what gear I'm in. Not sure that would change my driving habits, but I guess I like information.

Mr D when you had yours programmed to 4th when the pac brake was on how exactly did that change your tranny shifting? 4th now becomes the lowest gear available? That also seems strange.

The transmission can be programmed to preselect any gear when the pac brake is engaged. It just means that the transmission will aggressively try to downshift to that gear, doesn't mean it will ever make it to that gear. You can still manually select another gear, in fact you could select "R" but nothing would happen since the controls know better. If programmed to preselect 4th you could still manually shift it down to preselect 2nd. All that would do would be to try to downshift to 2nd, nothing more.
Here's a thread on this forum that gives some more info: http://www.irv2.com/forums/f125/alli...es-226982.html
On our rig the preselect is set for 3rd.

noserider · 01-05-2016, 08:53 PM

Quote:

Originally Posted by Mr_D

The transmission can be programmed to preselect any gear when the pac brake is engaged. It just means that the transmission will aggressively try to downshift to that gear, doesn't mean it will ever make it to that gear. You can still manually select another gear, in fact you could select "R" but nothing would happen since the controls know better. If programmed to preselct 4th you could still manually shift it down to preselect 2nd. All that would do would be to try to downshift to 2nd, nothing more.
Here's a thread on this forum that gives some more info: http://www.irv2.com/forums/f125/alli...es-226982.html
On our rig the preselect is set for 3rd.

Good review info in that other thread. The different types of engine brakes, their uses, how they work their magic and how they can be programmed seems to be a widely misunderstood technology. I now have a much better understanding of how MY systems works. Thanks

Mr_D · 01-05-2016, 09:05 PM

Quote:

Originally Posted by noserider

I guess I was applying the logic of the number displayed in the window during normal operating procedures and it's different when the pac brake is on meaning the number now shows the lowest gear selected. That's good to know and makes a lot more sense. I would like to have the 2 window setup to know what gear I'm in. Not sure that would change my driving habits, but I guess I like information.

Mr D when you had yours programmed to 4th when the pac brake was on how did that change your tranny shifting? 4th now becomes the lowest gear available? That also seems strange.

For some years they used the two window unit, then they went to the single window unit, then back to the two window. One of the reasons I went to a VMSpc was to know what gear I was in. Now that we have the Magna it has the two window control, a dash readout and the VMS 440 CL, all of which give the gear attained (the one you're in).