JD 550 B trans problems

heavyhorse · Post by **heavyhorse** » Sun Mar 30, 2008 11:40 am

Hello All, i just bought this 1980 JD 550 this winter, it slips in reverse and is slow to engage, once it does engage however there is full power going to the tracks. If i am trying to back up a slight incline i may have to pull forward first to get going and then it will climb no problem, again with full power going to the tracks. There are none of these problems in forward. if i try to shift into 2nd or 3rd in reverse power doesn't get to the tracks. At an idle the gage for trans pressure on the dash reads on the low side of the green and when revved up it climbs to the middle or a little higher. Am i looking at needing to replace the reverse clutch pack? I haven't done any pressure checks yet on the valve body, i'll try to get to that monday. Maybe the trans pump is worn out? if i need to pull the powershift do i remove the motor, torque converter and then the powershift? Thanks John

digitup2 · Post by **digitup2** » Sun Mar 30, 2008 4:56 pm

Check your pressure guage if you see pressure build up after the shift as it is starting to move then your seal on the piston of that direction is bad Fuel tank and battery box come off first then the hydraulic oil tank .Always go in through the top if you have pressure problems Replace the seals in the clutch packs you will notice that the pistons are made of white metal or cast aluminum this is what goes first taking the friction plates out .Replace all seals in the pack units and all friction plates in clutch packs . You may have to replace the pistons .Then look into the pump after if you have no pressure in system.Digitup.

heavyhorse · Post by **heavyhorse** » Sun Mar 30, 2008 8:03 pm

OK i'm not doubting your expertise here but nowhere in the manual does it say that the clutch packs can be accessed from the top, can they really be removed without taking out the entire powershift housing? John

heavyhorse · Post by **heavyhorse** » Sun Mar 30, 2008 8:14 pm

I paid $18500 for the old crawler, its a huge step up from my '55 D4 CAT with a pony motor! If i have to go in and do this work do you think i would be out of line asking the guy who sold it to me, who said everything was good to go on it, for the winch and ripper that he wanted to sell me separately. This in my mind would make up for the trans problems if i can fix it. John

pdmech08 · Post by **pdmech08** » Mon Mar 31, 2008 7:29 am

heavyhorse: Are you certain it is a 550? If so then to the best of my knowledge you have to remove the transmission assy.. The components can not be removed from the top. The 450 series can be serviced from the top but not the 550. Some pressure tests before tearing into it would be a good idea. Best advice anyone can give is to get yourself a service manual if you don't already have one. If you have any other questions feel free to email me directly. Good luck. Steve

RANDY Fay · Post by **RANDY Fay** » Tue Apr 01, 2008 7:15 am

550 clutch packs have to come out through the front--remove eng. and converter housing 450 clutch pack comes out the top but you have to remove eng. and bellhousing to get them loose--newer 550G and 450G transmission all comes out back in one piece trany in a draw nice have fun Randy

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