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Some info on Cat 7155 Trans

R Racing

Active member
2,767
16
38
Location
St. Leonard, MD
I just finished a repair on a M917 that required a trans swap . I had a rebuilt 1 from a GL auction and swapped it out. Well the rebuilt 1 was sitting in a crate for a # of years and things do get sticky.So after starting the truck and air was up I pushed the air button and all you could hear was air pushing out of the vents in the head. The air pressure dropped from 120 to 90 in about 3 seconds. It was not a good start to a day .I tried the oil in the air line and even after 3 bottles still the same. So I called Cat ( Sugested by Bruce AKA BKubu ) and to my suprise they not only heard of the 16 speed 7155 they new it well and even had a truck with a portable test rig for it !! After several lengthy conversations with them I found out that the cat 7155 was used on I believe he said 4 other model earth movers . He said that they had in just 1 location 3 guys that specialize on the trans, And that parts were still available ! I quized him on it a bit and he himself had worked on the trans and knew it well. So while waiting from a call back from a closer service location, I pulled the umbilical cord off of the ****er ( it coms off with 3 bolts ) and poured air tool oil down the 13 ports and then hooked it back up to the shifter and let it build air ( a quick way to build air in a shop setting was use the air compressor thru a regulator to the red glad hand in the front ;-). after shifting for a bit the big air leaked stopped !! then I had 2 small 1s from the 4th and 7th vent. after repeating adding oil to the umbilical cord 3 or 4 more times the trans was shifting like new and I was driving it around with no air leaks . I did later discover that I still have a problem when the trans is put in neutral, it doesnt want to go back into gear and leaks a bit of air.But another oil in the cord got it going again . So I now have a Cat manual on its way and I made a appointment for cat to take a look at it. So in a way its good news to know that not only the military use this trans but other Cat equipment did as well , And there are still people out there that can fix them :beer:
 

NDT

Well-known member
Steel Soldiers Supporter
10,466
6,547
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Location
Camp Wood/LC, TX
Thanks for the info! Please let us know which cat house has the techs and the parts. Most dealers including Mustang Cat here in Houston do not know this trans.
 

BKubu

Well-known member
Steel Soldiers Supporter
4,763
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Location
Gaithersburg, MD
The CAT dealer in Elkridge, MD and, I believe, Upper Marlboro, MD know this transmission. The former I know to be fact and the latter I believe is what Jim told me this evening on the phone. I am sure Jim will confirm this.
 

R Racing

Active member
2,767
16
38
Location
St. Leonard, MD
Yes at both Elkridge and Upper Marlboro ,Md they work on them. The Manual was $36.00 and the shop superviser said it was a must have and well worth the money .
 

powerhouseduece

Active member
1,440
4
38
Location
Pasadena, Md
Do they have the manual in PDF form? Glad to hear you got it going. I too have done the air tool oil down the shifter cable, it works like a charm. For me, it even sped up the delay between shifts, just a little bit.
 

wreckerman893

Possum Connoisseur
15,629
2,054
113
Location
Akenback acres near Gadsden, AL
I loved the Cat trannys in the Army (drove them in 915's/916's) but have been gunshy of them out here since Cat shop time will eat your lunch.

All the fun of shifting gears without the clutch (I got a knee headed for replacement).

I may have to get a M915 with one in it now.
 
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