1978 550 dozer problem with reverse

[1badZ28]

I have a 550 dozer that the reverse hardly works. I have done all pressure tests as per JD manual on trans and was within 5% on all tests. the problem I'm having is the machine works well forward in all gears but hardly backs up in reverse and will stop complety in any gear. If I even touch one of the steering clutches it will stop in reverse. But works fine going forward. I have checked all lines for leaks to find none, trans temp is getting high. I have pulled the valve body to see if any thing got in there and found nothing. All spools are free with no galling or scores. Replaced oil and filter and still nothing. dozer will to move on low idle in reverse but as soon as I give it throttle is loses all movement. But like I said foward works normal. If any one can help give me a call (570) 606-8175 Thanks, Ken

[digitup2]

Ken if you have a pressure gauge on the dash is there much pressure drop from forward to reverse and any hesitation into reverse .If clutches are slipping you probably will notice heat build up > I would suspect the o ring seal in reverse piston is letting pressure off or if pressure is OK then piston is binding and not letting the proper pressure on the plates .Digitup.

[1badZ28]

OK so what is the fix total trans tear down to repair seal? or can it be fixed with out tear down.

[1badZ28]

A mechanic from Cat told me to try seal sweller in it because the machine sat for about 5 or 6yrs before I got it but that is not really a fix just a patch

[digitup2]

That 's the bad news .The good news is you can do it your self.Digitup

[1badZ28]

Does any one know a fix for my 550 insted of stupid anwsers?

[mini kahuna]

digitup knows those 550's in and out,leakage past the reverse piston,or the piston is getting hung up in it's bore and not applying force to the reverse clutch pack,digitup I think you nailed the problem

[CELSESSER]

I don't imagine you get a whole bunch of help with that kind of attitude.
Get your manuals, study them. They have great descriptions and exploded views that show you what you are dealing with and how it comes apart and goes back together. Call Mother deere to see how much the parts are or even how much they would charge to fix it. Digitup (who is probably one of the few members on here that lives day in and day out with that series crawler) has probably pointed out exactly what the problem is. I wouldn't call it a stupid answer. Why would you expect him to help you any further??

Chuck

[OneWelder]

Does any one know a fix for my 550 insted of stupid anwsers?

Digitup spends a lot of time giving good advice on this board. He would certainly missed if he got sick of sarcasm from someone looking for a free handout- After all you call a Dealer they want to send a teck. out, not give away much useful information.

[1badZ28]

My sarcasm was not toward dig it up! It was to some one who sent me a private message. And I did not get there name SORRY FOR THE MISTAKE!!

[digitup2]

Those old 550s are a great machine but can have a weak spot when it comes to the power shift and yes I have rebuilt many of the dam things over the 30 plus years I have had 550s .I counted them up the other day for 550s alone 3-550s ,2-550As,2-550Bs5-550Gs,4-550Hs and so far 4-550Js They are time consuming and some times frustrating to work on I was a transmission mechanic right out of school so multiple plate clutches are second nature.I would rather work on my own machines any day and you could say 550s 550As and 550Bs had this thing about power shift the piston is magnesium and tends to grove after a while this takes out the o ring and the fun begins I will try to phone you as I have your number be patient I normally have been putting in 18 hour days so I may even call from a cell as I am stuck on a darned dump truck all weekend ,No office job for this guy I guess!!. Digitup