Cat 7155 tranny

[Artisan]

OH, Warden you do know where the access panel is to do what
R Racing suggests yes? If you have a new floor mat you need to
look for the access panel then CUT your new floor mat... Basically
it is straight down from your Ratio Selector (Shift Box)

MAKE SURE THAT PUPPY IS CLEAN BEFORE YOU PULL PLUGS DUDE!

 

[Artisan]

PS, I have grounded my trannY temp wire to ground under
the truck and my TRANS TEMP gauge in the cab PEGGED OUT.

To date I have not been able to get any TRANS TEMP either!
I am now wondering if the Teflon tape on the threads of the
trans temp sender ( I even bought a new one) if it is preventing
the temp sender from working right?

Jim what do you think? krap! I forgot I still have that issue of
no tranny temp gauge working!

Warden I think to test the gouge in the cab, I "think" you are suppose
to pull the wire off the tranny and simply ground it out and look at the gauge
in the cab. If you do that, with the key on and maybe the wife sitting in
there watching it, when you ground out that wire that goes to the tranny
temp sender does your gauge peg to the MAX too?

 

[Warden]

I don't even know if I have a trans. Temp gage in the dash , ? I have an over temp light in the pod to the right of drivers seat , I am basing cool oil and trans case by feeling both with my hands ! If the oil smelled at all cooked , or any part of the trans was hot to touch , I would be inclined to call this trans toast ! However it has shown signs of greatness a few times , like pullin thru the maxi brakes with ease in 4th. Or R2 (accidentally ) but then not even trying hard to do the same when I deemed that a test for converter stall ! Then 10 min later it would pull hard again ! Drive 35-40 mph down the road feeling like the engine is well connected and all of a sudden u get the sensation of a fully depressed clutch in a std trans ! And then not ! One thing for sure is the last 4 or 5 gears Barely pull yet I can feel the initial engage and attempt to lock , but very very slight at best , I back shift till I feel a gear that connects and that is what ever gear that is 25-30 mph , what bothers me is the ultra smoothness of all the gears , you can hit 2200rpm in any almost instantly , some jus pull the truck a little better then others ! Yet sometimes it is positive in the lower gears just like power shift in a farm tractor! How do u know if the trans is toast ? Will they smell burnt like every other auto I work on ? They drove it 400 miles last summer 1 way without any issues ( in hot weather ) even tho it's 20 degrees here every thing else on the truck gets warm , and the fan kicks in , and the trans is just a little warmer then the frame rail !

 

[Artisan]

I would take R Racings advice and start pumping some quality O Ring oil
into that puppy and massage it / run it and see if "Use" brings it around...

PS, can you please post up pictures of your truck?

What is this OVER TEMP light you speak of?

I think we need some pics...

Do you have a link to the auction?

 

[Artisan]

PS, I would invite you to peruse my thread "ARTISAN'S M916"

I think it is in post #4 I showNtell how I implemented R Racings
Air Filtering, Pressure Regulating, Oil Misting devices w/ pics no less.


But still we need to se pictures of your rig...

 

[Warden]

View attachment 548476View attachment 548477. I'm not so good at the pics , here is the truck yesterday on my home made poor mans landoll trailer ! It carried super 180 miles home ! The seller suggested I drive it home due to the height which once again leads me to believe that the trans was fine when he last used it , he said it will do 60 mph all day
well , I hit 60 comming down the mountain tonight , but when I hit the jake the engine shut rite off and I had to restart and. Use brakes till I got half way back on the shifter and then the jake would bite but

 

[Artisan]

Pics do not show Warden...

 

[Artisan]

Do NOT use the jake brake under I think it is 1250RPM.

Read the manual to confirm this AND always CONFIRM anything
I say Warden.

 

[Warden]

i just added oil to the air line on the passenger outboard tank rear line .... then drove 50 miles to include steep hills and 60 mph highway the oil seemed to make a big difference but not enough , the transmission is now hot to the touch , everywhere ... the trans oil temp gage that i did not know i had last night came up to approx 150 degrees , ...the oil on the dip stick is cold and just smells like oil ,not burnt ( is there another place for trans oil that i am not aware of ? behind the pass door is what i am assuming is trans check and fill ? ) some facts i found are these , i finally got to feel a little bit of acceleration ( not much ) ...but on flat ground the truck is drivable now , till you hit a hil then your rpm can flat line at 2200 but the speed will drop like a stone to nothing if you let it , my brain won't let me do it !.... i had it in 11th gear pulling the engine down pretty good for a while on steep mountain roads , probably 1400 rpm , and if i was very gentle on the pedal i could keep it connected in 12th , above that i can feel it bite but while under load at 1500 rpm i could slap my foot down and rev 2200 over and over like in neutral ! i descended a few miles of steep grade in 10th and i could use the jake it would stay locked enough for that ! its funny for me because i am driving around trying to make the truck lurch to verify lock up but in my truck driving job the opposite is required ! i feel a deffinate improvement , but what bothers me is the lack of stall speed of the converter ( if this even has a converter ?) in any gear you can step on the brake lightly and pin the throttle for 2 seconds and i don't hit the stall speed , i hit the engine Governor - 2200 , and without much pull at all ! my ass tells me each 4 gears has a mind of their own with 5 thru 7th being the most positive feel .. and i still have to wonder if I'm just so stupid that i have the wrong dip stick and fill for the trans , cause no way can the oil in the tube be that cool with the trans that hot,and this really acts like a low on oil situation , ( as your fairly locked up in 16th at speed on flat , it just looses all drive till you let off the pedal then it seems to take another swing at it ! and this scenario keeps repeating ! i have felt this a thousand times before in other equipment , with probably close to as many causes but mostly low oil , wet oil ,, aerated oil , contaminated filter , ! i strongly prefer to be laughed at and find and fix the problem rather then someone not tell me what a dope i am for checking the wrong oil ? ( i will be checking pressures as suggested asap , ) but that little bit of oil in the air line made too much difference to let go of , above 8th i hear what can easily be mistaken for gear whine but to me it sounds like a suction leak or aeration in oil going thru a pressure relief !? Btw the gear changing sounds fast and consistent up and down thru every gear , with no lag what so ever , ~! I'm hoping my trans is not toast , i would love to hear from someone with a known bad trans or fried clutch packs as to how their trans acted ?. thank you

 

[Artisan]

Is your hand on the shift knob when it acts up?

The oil fill check is on the PS, follow that tube down to the tranny to verify.

That thing has TONS of little O-Rings and other devices that will benefit
MUCH from adding a good O-Ring oil into that tube behind the tank
R Racing told you about. Do it more...


ALSO, does your main air pressur ein both systems fall below 95PSI while driving?

 

[NDT]

7155 has no converter! It has a clutch pack on the input side and a second clutch pack on the output side and in between are conventional gears. One of the two clutch packs is not getting enough air pressure to hold engagement and is slipping. Before long you will ruin the friction material. You will know when as then it will slip in all gears.

 

[R Racing]

My money is on the rear clutch pack as its the only of the 2 that's regulated and also the primary 1 to fail or act up. If your locking up hard up to 10th gear. Than its the regulator in the manifold.

 

[NDT]

Put a boost gauge on your 400 Cummins. At around 15 PSI, you are turning out about 350 hp. At 20 is about 400. If your engine is against the governor and not transmitting power, your boost gauge will read almost nothing. The oil is not heating because no energy is being absorbed by it, like would be the case with a stalled converter.

 

[Floridianson]

I believe they are more worried about the Transmission disconnecting from the engine and you can not use the motor/jake brake to slow down the truck. Could be a bad bad thing if you were on the way down a long bad mountain.
I believe a little oil is not going to hurt the Transmission but you maybe could put too much and blow an Oring or two. Like Jim said good dry clean air is good.

 

[cadillac]

My air

So i hitched up a pressure regulating, air filtering, oil misting today, but with cold cold winters here will only be set up in winter. I do like to keep a little heater going inside in winter and i keep my engine heater on in winter to, so maybe will set up the oil misting and all in cab so no freeze. But i set it for a little better then 95 psi and i think it will be nice. I was going to make the new bed slide off and dump but i think to having to many projects i am going to make it just tilt, as im getting older i love projects just not ones i have a hard time completing. Thanks for all the info on here its nice.

 

[cadillac]

I would take R Racings advice and start pumping some quality O Ring oil
into that puppy and massage it / run it and see if "Use" brings it around...

PS, can you please post up pictures of your truck?

What is this OVER TEMP light you speak of?

I think we need some pics...

Do you have a link to the auction?

What lube are you using for your mister? I see petroleum oil is bad for o rings.

 

[Artisan]

What lube are you using for your mister? I see petroleum oil is bad for o rings.

I think I use McMaster's P/N 1298K54 AIR LUBE AF
Good down to -60F

 

[cadillac]

I think I use McMaster's P/N 1298K54 AIR LUBE AF
Good down to -60F

Where do you get it? and is it oilbased ? Thanks for your info.

 

[Artisan]

www.mcmaster.com Do your research...

 

[Warden]

trans seems to be getting slightly better with use , still not locked in any gear even first , but dam close to it ! reverse seems to be the strongest lock up ,,, after 7th you need to be gentle to not slip,,, after 11th you need to be going down hill to use 12, 13,14,15,16 , someone mentioned boost , i can't load this enough to make much boost at all , i just was slogging around in 20'' of snow out in the fields for a couple of hours and with moderate throttle , its locked up good enough to not make me feel like i can hurt it ! it does quite well in extreme hill and snow conditions BUT every 20 minutes or so i get feeling like its perfect so i add a little brake pedal at 2000RPM and it gives a fair grunt but definately will slip even in the first 4 gears ,( not bad but it should not slip at all ,) I'm in an empty tractor , if i hooked my trailer up it would not do well with it at all , my whole concern is to not beat a dead horse , I'm pretty sure the place this came from had no clue on the proper way to run it , so it could be toast , BUT \in the 300 miles i put on it in the last 2 days it has only improved ! MY experience with powershift and autos and hydros is they get worse in a hurry not a bit better each time you drive them ! I'm trying to wrap my head around this trans and understand a few things , what it is is not what i thought at all ! this was an un planned but well needed purchase , i did no research at all , i never thought i would land one of these trucks , I'm not a military truck nut , but i probably know an M715 more intimately then i do my wife , and i made plenty of pick up trucks out of 1952 duces with 454s and th425s when i was a kid ! So , other then Lube what part does oil play in this trans ? is there any pressure fed oil that has a thing to do with movement and lock up ,? if not then why can't i just plumb air to the clutches externally and have a switch to lock them solid when i need them to ? this trans shifts like lightening and never misses a gear its not the least bit sluggish ! if this had a manual clutch with this shifter i would be putting them in all my trucks ! its beginning to show me that this trans does many things that are not needed , has anyone bypassed items and isolated the front from the rear pack to trouble shoot ,
i do appreciate all the comments and help , I'm hoping for success before my OCD kicks in and then i will have to know everything about this dam transmission and master it , at the expense of fun ! !