450c Transmission issues

[matt1701]

I recently purchased a 450c with some transmission issues. When hot reverse and low will barely move the machine on level ground. High seems to work alright, and reverse works ok when the machine is cold. I did a pressure test on it and the pressure was about 175psi in neutral and when shifted into any range the pressure would drop below 100psi AND stay there. I did the HLR adjustments, however I could not get the 5psi drop when depressing the clutch pedal. Also, it worked best when the nut under the rubber plug was backed way off so that the pressure in neutral was below 150psi.

I took the accumulator/pilot/bypass valve assembly out and clean it. not really any debris. However, the bypass valve seemed to stick at the end closest to the pilot valve. In fact, I had to tap it with a hammer and socket just to get it out. Also cleaned suction screen and changed oil. The oil was a little milky.

The transmission also gets pretty hot, I can only hold my hand on the case for about 1-2 sec. I think the guage is not working as it only gets up about a quarter of the way even when it feels very hot.

Any advice you can give would be very much appreciated

[pondhogvt]

Matt, I would bet pretty good money the problem will be in the manifold inside your tranny on top when you pull the top cover off.

this manifold directs the oil to the range you select with the HLR shifter.your pumps ok because you are developing 175psi then when you shift to reverse the pressure drops,pressure is to low to fully engage clutches but they are trying to engage but are slipping and generating heat because they are slipping,if you keep running it like this you will smoke your clutch pak and end up replacing them as well. the sooner you repair the cheaper it will be.

this manifold is like a cylinder with a polished piston with rings on it, as you move the selector the piston inside moves with piston rings on it and directs the oil to the function you selected.

this is a very precise fit, as everything wears there is to much play inside the manifold cylinder and quite often you will break one or a couple of the piston rings or they get sloppy and score the sides of the cylinder or both . either way they will let oil slip by so it cannot maintain pressure.there is slight chance that the seals inside are the only thing bad, but I have not been that lucky.

these manifolds were about $1000 at Deere as of last year but I see Broken tractor is selling remans for $400 plus your core,I have not used one of their remans so I cannot say how they work. But site administrator Lavoy sells parts and you should atleast give him first shot at it if you need one.

I would read up on how to take this manifold and clutch pak out in your manual,best of luck,Mark.

[Crawlinallover]

ok dont want to hijack the thread but im having a similar issue. I have a JD 450c dozer and it just stopped moving after running in 4th gear. I usually never run in 4th so i thought id try it out. After that i went to 3rd and it engaged but did not move so i went to 1st and 2nd then it would not engage or move. so i checked the fluid level and it was a little low added fluid then it moved but it was very sluggish and took a while to engage the gear. now it will not move again.

Changed the fluid and pulled the filter screen on the right side it was not bad but there was what looked to be golden flakes or pieces of clutch material. so I hooked a pressure gauge up and at idle in neutral i only get about 20 psi. If its up to about 2000rpm and in gear it will rise to about 60psi. I tried tightening the clutch adjuster but no rise or decline in psi. also if I look in the hole i can see the pressure plate spinning but it still spins when the clutch pedal is engaged.

Another thing is sometimes when i would shift to third gear it would not move and grind when shifting out even with HLR lever in neutral. Also it was starting to make a screeching sound when going into high and it always whined a little in reverse. I am thinking maybe there is an internal leak or some debris in a valve somewhere but as of now i'm stuck any ideas where to start would be great.

[matt1701]

Thanks for your reply Mark. Do you know if there is a way to take the manifold out through the top cover without removing the engine? I am guessing no since the clutch shaft runs through it, but the accumulator/bypass/control valve assembly came out through the top fine and the manual said I needed to do the full engine/bell housing removal first.

Also, do you think it would be worth it to replace the clutch packs while everything is apart? I am not sure how long the machine has been running like this, as the previous owner mainly used the backhoe and did not push many loads.

Thanks,
Matt

[pondhogvt]

Matt,

sorry for late reply I don't check site everyday,just read your note.I have a 450 with the engine already out I will look it over tomorrow in the daylight and see if it jogs my old memory,I thought it was possible if that was all that was wrong but I am not sure.I'll try to post an answer tomorrow night,

as far as crawlin guy, sorry don't know your name,sounds like a totally different problem,sounds like your tranny pump went bye bye which means pull motor, pump is in front of tranny or a major leak inside,pull cover off top and start dozer to look for a leak or better yet start a new post with your problem some of the older guys on hear will give you the best advice,good luck,Mark.