450C drive lagging then nothing

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slabguy
420 crawler
420 crawler
Posts: 40
Joined: Mon Aug 19, 2019 12:56 pm
Location: West TN

450C drive lagging then nothing

Post by slabguy » Sun Jul 05, 2020 1:43 pm

Over the past few weeks my dozer has been lagging for a few seconds after putting shifter in gear before it starts pulling. This happens regardless of rpm. Maybe worse at lower rpms but hard to tell. I checked trans fluid a week ago and it was low. Filled it back up to within tolerance and it didn’t make a difference. For some reason (and maybe it’s just in my head) sometime tugging on a stick or jiggling the blade lever would seem to get it moving. Sometime in 3rd and 4th it wouldn’t move at all if on an incline. Once engaged and pulling it pushes strong. I was climbing a fairly steep incline today and it gave out like the clutch fully disengaged or something. I rolled back to the bottom of the hill and tried all gears and forward and reverse. Wouldn’t move at all. It sounds like the winch drive is still spinning when I release the clutch. It also sounds like the engine loads slightly when I fully release the clutch as if it is trying to engage but won’t. After shutting down, I looked underneath to see if I had dumped fluid and it had not. Any suggestions on what to check? It is back in the woods and will be a few days before I can get back to it just FYI.

Jim B
350 crawler
350 crawler
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Location: western Maine

Re: 450C drive lagging then nothing

Post by Jim B » Tue Jul 07, 2020 6:46 am

These things never seem to happen in a good location. In my mind it is not likely to be related to the steering clutches as both sides are affected at the same time from reading your description. Steering clutches are more likely to go one at a time and your C will have wet clutches which normally don't give the problems dry clutches do. I guess pulling a lever might cause a change in oil pressure or flow and cause a valve for the HLR to move that was hanging, but don't know how likely that is. The only other thing I think pulling a steering lever might do is allow a weak clutch in the HLR to make up when the that steering clutch is disengaged, but I would expect both levers would need to be pulled to do that. That heads me towards the engine clutch and HLR.

You need to get your manual (TM1102 for the 450C) out and check all the adjustments and pressures. Proper diagnostics can save money and time, without it is just guessing. Some things to consider are the engine clutch adjustment (how is the free play?) and clutch valve, valve that controls the shift speed, pressures, and worn linkages. The transmission section of the manual has the info to do all those checks. They should be done in order and using the book is a better start than trying to post it all here. First, have you checked/cleaned the transmission sump screen since you got it? Have you changed the transmission filter? They may not be the problem but if restricted will affect pressures and flows. If you changed transmission fluid what did you use for fluid? Keep notes of what you find and adjustments you make, as questions will be asked about what you found if/when you get back here with questions. Just my thoughts, others may differ.

slabguy
420 crawler
420 crawler
Posts: 40
Joined: Mon Aug 19, 2019 12:56 pm
Location: West TN

Re: 450C drive lagging then nothing

Post by slabguy » Tue Jul 07, 2020 7:38 am

Thanks Jim. I will take the book with me and start running through the checks next time I go. I did replace the transmission screen and filter last summer when I changed all fluids and filters. The sump screen wasn't very dirty then but I put a new one in anyway. If I'm remembering correctly I used hydraulic fluid that meets the specs called for in the book.

JWB Contracting
2010 crawler
2010 crawler
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Joined: Thu Aug 27, 2009 10:08 pm
Location: Edmonton, Alberta

Re: 450C drive lagging then nothing

Post by JWB Contracting » Tue Jul 07, 2020 9:28 am

A C is more difficult to diagnosis vs a B as the steering clutches are operated by the same pump as the transmission.

We start by checking the transmission operating pressures and adjust first. If pressures are poor can be many causes but we check the steering clutches for leaks first. From there we block the machine up, remove the tracks, side tanks, fuel tanks and hydraulic pump, clutch covers and block the pressure lines going to the clutches. If pressures return to normal it’s one of the clutches. If not then we pull the cover on the tranny and see if we can find the leak. I plan to use an external 12V pump next time to introduce pressure to precisely determine where the leaks is. Could be the manifold, clutch packs, internal plumbing etc.
Jason Benesch

John Deere 420, 430, 440 & 350C With 3 Point Hitch
John Deere 400G With Winch
John Deere 2010 Crawler Dozer
John Deere 420, 430, 435 & 440 Wheel Tractors

slabguy
420 crawler
420 crawler
Posts: 40
Joined: Mon Aug 19, 2019 12:56 pm
Location: West TN

Re: 450C drive lagging then nothing

Post by slabguy » Thu Aug 13, 2020 11:02 am

Wanted to post a quick follow up to this. Got the lever linkages adjusted per spec and the clutch and hydraulic pressure per spec and all is well. Snappy shifts. Thanks for the info

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77 Ford
1010 crawler
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Joined: Tue Nov 22, 2011 7:52 pm
Location: Missouri

Re: 450C drive lagging then nothing

Post by 77 Ford » Fri Aug 14, 2020 7:36 am

That's good to know and thanks for following up.
JD- 450C track loader
Serial #208336T

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