Need a transmission Wizard

[PFTRUKIN]

Just picked up a 1980 JD550 dozer at auction moves FWD/REV in all 3 gears turns as it should just makes an awfull rattle/grind in the trans while in gear. Nothing at idle through full power in neutral. better in FWD worse in reverse. Purchased a jd tech manual but it is still a week away. Is thier any further troubleshooting I can do ? or just start to open it up to find the gernade. What repairs can be made from the top as opposed to splitting the machine? I doubt it would push a pile of dirt kinda afraid to try but climbed onto float no problem. Paul in Ontario

[digitup2]

You may have a bearing or race bad in the trany I would get to a shop ASAP and look into it .I had a bearing lock into a race on my old 550 A and I didn't hurt the race seat[In the trany housing ] but it shure didn't help that I was at the back of the property when it went and I ran the crawler to the front of the property to load .Digitup.

[PFTRUKIN]

I was thinking along the same lines , this crawler stuff is kinda new to me, was this bearing problem that you had fixed from the top? I might tackle a job like that myself anything worse and I might farm the job out. I'am quite handy with the stuff I know, maby the manual will shed some light when it arrives. I'am hoping I can open the trany /powershift up while the machine is still running to pinpoint the damage ( should it not be obvious damage) but with all the oil lines around the tranny that probably is not going to happen. I have been checking a few other post and the refer to a bullgear/ bearing problem with these trannys? Thanks PFTRUKIN

[tizfatboy]

i have a 555 w/tranny problems. i have searched a long time for a little knowgledge, and have learned its as hard to come by as a politicion working for my intrests! you may want to try a form called yesterday tractors, i have found them to be somewhat informative. this is a complicated expencive tranny, some have changed out using a 450. i found rebuilts for around $5500, pull you filter see what kind of trinkets you find?

[PFTRUKIN]

I have checked out yesterdays tractors already, that was just a lot of doom and gloom, this is byfar the better fourm(from what I can tell from some of the other post i have read) its just a matter of getting it into the shop and start the teardown , I was hoping for a clear where to start either pull the trans or go in from the top. pftrukin

[digitup2]

Watch your trans pressure guage and tell us what happens when the sound starts as the clutches enguage .watch to see if the pressure drops or rises when this happens .Digitup .

[PFTRUKIN]

No difference on the gauge (that i can see). I started the machine with the brake on and in gear 2nd and 3rd reverse no noise it just holds aginst the converter , but if you apply both pedal's things start to turn and the noise is back. Pressure on the gauge is bottom green at idle goes up to 50psi at 1/2 throttle+

[digitup2]

Those aren't the most accurate guages in the world . but wach for pressure drop or fluctuation between shifts F to R and H M L as well after things warm up .Digitup.

[Roy Suomi]

In order to repair that transmission.....You have to start from the front and work your way back.....Nose , tin , bellypan , engine , torque converter.....The book will give you the correct disassembly after that..I hope to not have to do any more of these...I've done several over the years only because I was working at the dealership when they came in....If this is doom and gloom , So be it.......It ain't any fun...

[PFTRUKIN]

The Sky is falling!!!!!!!


If that's what it is that is what it is , at least I know where to start, Thanks Roy

[digitup2]

They normaly don't make a noise before they have have power shift problems so check every thing .Before you pannic check the final drives for oil and oil condition check your bullgears and there oil conditions also watch for something else maby making the noise,It may be something small so have patients .I put a lot of hours on those early 550 series and the are still a good dozer to do a days work with .No mater what any one else says !! .When they run right a 450 won't come close to them .Digitup.

[mini kahuna]

digitup,I have to agree,I have a soft spot for the 550 series,they are a great machine,if taken care off and fluid changes are followed you can really run the hours up on them.

[digitup2]

Yah I put 16000 hours each on my first two while my JD repair man said that 550s were no good [He never ran one much though !] .Two weeks after I bought my 550 the contractor that had traded it called and tried to buy it back .No thanks keep your 450D is what I told him .I had my transmission apart and back together while the dealership were still pulling there's apart for Ontario Hydro they had two mechanics working on the 550 in the dealership even . MY 550 was together and working for Ontario hydro long before theirs was running and the parts came in at the same time .I lost a lot of faith in the JD Industrial repair shop then .The 550s are just more machine and have been my main units ever since I would hate to try to count the different 550s I have had since A,B ,G,H and J series all have worked well but the G was the last of the tough machines . word is that Ks are out in the spring of 09 .Digitup .

[PFTRUKIN]

550 up and running output gear went all to hell on the back of the directional clutch, hard to find parts but not a bad job to work on. a lot of wrenching but it was all straight forward. Machine works well just a little concerned about trans pressure. Just doing a little finish grading with it until I get to the bottom of it!

[mini kahuna]

as digitup said,the dash gauges are not accurate,if you tee in a pressure guage you will get a true reading of what is going on.
that trans is notorious for working well when cold,as it warms up you will see the true condition of it.
I had a case backhoe start to slipping on me and I watched the trans temp rise,but I kept going and finished my job,loaded up and got home.
when I disasembled my trans I was greeted with a wasted clutch pack"I expected that",but I also cooked a couple of very expensive hubs in the clutch pack.
I learned my lesson that day about trying to "slip" through a day's work with a sick transmission!!!!!!