I’m having issues with my D4d dozer, not sure on the year model I’m thinking late 60s early 70s. Serial is 83j839, 1st gear fwd, and rev always work good. Second gear forward and reverse it will pull its self when cold but will not push dirt. And barely loads the engine. When transmission warms up it won’t even pull itself in second gear fwd or reverse and doesn’t load the engine at all. 3rd gear forward and reverse works cold and hot will pull it’s self but doesn’t have much power either way. Won’t spin tracks to steer in 2nd or 3rd. I’m new to this dozer as my grandpa had it and it sat for 10 plus years. Only gears it will spin tracks in is first gear. And after you work it 4-5 hours the trans temp gets on the line between red and green. Appreciate any help or pointers I can get
How mechanically-minded are you..? Diagnosing the problem might need a bit of wrench-twirling. Does the tractor put out a good puff of black smoke from the chimney when you change direction from fwd to rev and vice versa..? To be pushing a blade full of dirt the tractor really should be in first gear. Fine finishing work with minimum material on the blade could probably be done in 2nd.
I’m aware of How transmissions and hydraulic valves etc work just not this exact transmission, and turn wrenches for a living and run equipment on the side. But it blows a good amount of black smoke when you go from first fwd to first rev, like I think it’s supposed to but the other two gears do not load the engine. Shouldn’t it atleast pull its self in second gear at operating temp?
Sorry about the questions but it's always good to have an idea how mechanically-capable a poster is before starting to offer suggestions that may or may not be fully understood. Here are a couple to start with: - 1. Lift up the floor plate and with the machine up to full operating temperature watch the drive shaft between the converter and the transmission. It will spin in neutral but should stop dead as soon as you engage any gear. Try shifting N->1F->2F->3F, then the same back to neutral. Repeat in reverse and back to neutral. The shaft might turn a few degrees when you shift from one gear to another but generally speaking once you shift out of neutral to any gear the shaft shouldn't turn. A slipping clutch and the shaft will most likely creep in that gear both forward and reverse. 2. Take a look at the illustration below. This is looking at the transmission from the right side of the machine. Item 15 in the illustration is a screen. To get at it will need the transmission oil to be drained, but if you have a clutch starting to let go the first indication should be in that screen. If you find any material in it take a photo with something like a ruler alongside to give an idea of scale and post it here.
Ok Nige, thanks I will drop the belly pan drain the oil, and pull the screen. Just to be clear if you’re setting on the machine, it’s the right side, front, of the transmission on the bottom correct? And the drive shaft between the TC and transmission can’t be seen from the top of the transmission with the floor plate removed I don’t think, I’ve had the floor plate off and all I can remember seeing is the flex drive coupling between the TC and the engine. I work second shift mechanic, I’ll be at the dozer tomorrow to take another look when I drop the pan and take the screen. I’ll let you know what I find
I think you'll find the screen is on the left side lower front corner of the transmission as you sit on the machine. You may be able to access it from above with the floor plate up. It's behind a circular cover with 6 bolts. Here's a view of the complete transmission from the RH Side of the tractor. This machine doesn't have a drive shaft between the TC and the transmission like the larger machines I'm used to. Unless there is some way of seeing the output side of the TC that idea's probably a non-starter.
If you pull that screen you will drain all your oil. I would pull filter under your right foot first. Bob
When you drain the oil have a good look at it. Is it clear or dark, does it appear to be dirty, and more importantly, does it smell burnt..? Do you have any idea what type and grade of oil is in it right now..?
Bob, I changed the oil and the filter at your foot about a month ago and helped the machine quite a bit until it got back in its same old ways, I still have that filter I may cut it open tomorow to see if there’s anything in there. Nige, I also changed the transmission oil when I changed the filter I mentioned above, the fluid didn’t really have a burnt smell that I could recall but it was in fact dark rather then clear. And It has sae 30 oil in it right now, it’s what the service manual said it took.
Ah, you never mentioned that you the oil had been changed recently. Specifically what type of SAE 30 oil does the service manual recommend and what did you put in it..? If you still have the old filter cutting it open and taking a peek at the bottom of the pleats might shed some light on the subject.
pull the magnetic strainer and see if you have any aluminium in it sounds like a bad torque convertor
Has the problem shown up since the oil change ? It does sound more like a torque converter on the way out rather than the transmission . Too many in the box out at once while only one choice with the inverter covers the lot
Hello guys I have been on vacation since Thursday and haven’t got to dig any deeper into the dozer but will dig deeper tomorrow to let you know what’s in the old filter and in the suction screen. Nige, the oil it specified was sae-30 cd/to-2 oil, and I just used regular sae 30 oil. Maybe that’s an issue as well? Epirbalex, no the problem was existent before the oil change, the problem did get better for a few days and started doing the same thing again. I did do some pressure checks this evening under the top cover of the transmission, my manual said the direction clutch should be 50 +/- 8 lbs In all gears forward and reverse, and the speed clutch should read 275psi in all gears and 75 psi in neutral. The speed clutch specs were right on, but the directional clutches were off really bad. Each gear was over 200lb. 1 fwd - 210psi 2 fwd - 250psi 3 fwd - 275psi. 1 rev - 175psi 2 rev- 225psi 3 rev - 250psi. I don’t think this is right. Maybe a relief valve is stuck closed somewhere? But I didn’t check the machine at operating temp, but even at operating temp I don’t think the psi should vary that much. Also on the overheating I’m gonna pull the cooler off tomorrow while I’m into it to check for blockage.
Hi ,I think you have misunderstood the test spec's. the direction clutch's are 50 psi LESS than the speed clutch's in all forward and reverse ranges did you do these checks at high idle and at operating temperature ? the low side spec is 275 psi and high idle is 305 psi yours seem a bit low Can you also check the lube pressures and the torque convertor outlet pressure as well? Mark
Echo what Mark said above regarding direction clutch pressure is supposed to be 50psi less than the measured speed clutch pressure in any particular gear. Also the importance of having the whole machine (not just the engine coolant) at normal operating temperature before making these checks. They are not supposed to be done cool/cold. Regarding the oil, a regular SAE30 is not the oil for this transmission. The TO-2 specification oil called out in the book has now been replaced by TO-4, so you should be looking for an oil that meets TO-4 spec. These oils have friction modifiers in them designed to work with mulitplate clutches and brakes where straight oils don't. Although I would love to say it so I don't think the oil is the root cause of your problem. Something is wrong somewhere, just need to find out what.
Have you checked the shift linkage for wore out parts and checked the adjustment specs ? Bob
Check the converter inlet pressure I don't know the specs should be around 50 psi. I would think
TC outlet pressure spec....... Test with ALL machine systems at normal operating temperature, transmission lever in 3rd Speed Forward, Brakes applied, and torque converter in a stalled condtion. Governor Control at minimum position - 4psi minimum Governor Control at maximum position - 40+/-10psi.
Mark 250, yes I will check the lube pressures and TC inlet pressures as well. But I did mis understand the manual about the 50 psi less then speed clutch. Nige, I will run the machine until it gets to operating temperature next go around. And regarding the oil, I will try to find some to-4 oil at the local parts house and put that in next time with a new pressure filter. Bluox, I have checked the linkages, the linkages are good and make firm shifts at the shift lever and at the transmission. Dave Neubert, I will check the inlet pressures as well, the book says it should be 110 psi +/- 10 psi.
Spec for converter Inlet pressure P3 (bench test spec for correct operation - no adjustment) 110+/-10psi.
Well if it is low your converter is bypassing and needs rebuilt
The pressure was low on the inlet to the TC compared to the manuals specs. In neutral, 40 psi, 1st fwd 50 psi, 2nd fwd 50 psi, 3rd fwd 75 psi, 1st rev 50 psi, 2nd rev 50 psi, 3rd rev 75 psi. None was as high as the specs, (110 +/-10 psi)
Those pressures you mention, was the complete machine up to operating temp and the throttle wide open..? The only value you need to take note of is the one in 3rd speed converter stall. Your measurement of 75psi is 25psi below the floor of the specification tolerance (100psi). Maybe I missed it, but what was your measured converter outlet pressure..? Now might also be a time to measure Pump Pressure just to get an idea of how much hydraulic grunt it's supplying
Hi, the inlet convertor spec is the maximum oil pressure allowed for the convertor by design. It is a safety valve. the only time you will see that kind of pressure is with very cold or wrong viscosity oil or there is some problem with oil flow within the convertor. the working pressure within the convertor is controlled by the outlet relief valve which in this case is a fixed orifice (welsh plug with a hole in it) in the outlet of the convertor the spec is idle 4 psi min and high idle 40psi +/_ 10 psi this is checked with machine in a stalled condition in third gear Mark
Good catch Mark. You just reminded me that the converter inlet pressure is the ONLY powertrain pressure test that is done with cold oil. In fact looking at a couple of other models the TC Inlet pressure spec is listed as "Xpsi maximum with cold oil".
Actually all the pressure checks are done with oil at normal operating temperature . Bob
Hello guys, sorry I haven’t been on her in a bit, been busy lately. But today I got the dozer up to operating temperature, checked the pump pressure on the filter housing and it was (300psi in 1st fwd) (2nd fwd 110psi) (300psi fwd 3rd) (300 psi 1st rev) (90psi rev 2nd) (300 rev 3rd), so I’m assuming the fluid is bypassing somewhere in second gear. I took the control valves off the top of he transmission to inspect and everything was really clean all springs seemed to be good there. O rings between the directional control and the transmission Were a little flat but wasn’t broke up at all. Any ideas on where the fluid is bypassing?
Clutch pack seals
Agree with Dave. Piston seal failure in the 2nd speed clutch (#4 clutch). Indicated by the red area in the diagram below. The transmission would need to be removed and disassembled to fix it. Attached is the Service Manual for the job.
Got the transmission out of the dozer (was a job) got it all apart un stacked all the clutch packs and started rebuilding the clutch packs from the bottom up, got to the 4th clutch pack and sure enough the inner piston seal was completely gone, nothing left, so that’s my second gear problem. Thanks for leading me in the right direction got it all assembled back together today and going to try to get it back in tomorrow. I’ll let you guys know how it goes when I get it back together
Did you check clutch pack operation with air?
I did not check them, really don’t have the means to do that. I guess I’ll just have to hope everything’s good, everything was clean as new inside and my clutches were like new and everything went back together great so I think everything will be fine
Its just extra insurance. I guilt a Cat skidder trans once it took 30 hrs to get it outso I paid Cat 1100 bucks to dyno it they took my 1100 and did not bother to tell me that 2nd gear was not working I guess since I was considered competition they hung me out to dry
Did you replace the piston seals on all the clutches..? It would be a shame for you to get it back in the tractor and then have the seals on one of the other clutch pistons fail in short order.
Nige, yes we replaced all clutch pack seals, and all seals in the transmission, every o-ring or seal we could find we replaced it. Got everything put back together today and put her to work, worked it hard for 2 hours and it worked flawlessly. Usually within 30 minutes of working it wouldn’t pull itself in second gear. So I think everything is Good, I also put new oil filter and got some Caterpiller transtorq TO-4 oil to put back in it.
Hello guys Ran the dozer for about a week and had no issues whatsoever second gear worked perfect, transmission never got above half way on the temp gauge, everything worked great. Today I was pushing clay up to build up a pond dam and second gear started to act up again(trans temp not even half way), thought maybe the fluid was low, pulled the stick And the fluid was full of bubbles, and second works sometimes and sometimes it don’t now, but still doesn’t have the track power as it did earlier this week. Really stumped don’t know what’s wrong with it now.
If you are working on a steep slope put two more gallons of oil in it and try it. Bob
How much movement are you suppsed to have when you check the clutch packs with air?
I found a piece of the piston seal ring sticking out of the top of the #4 clutch pack today, I guess it’s blew the seal ring out again. Not sure what’s causing this, didn’t see anything else wrong with the transmission when I had it apart. I thought maybe the clutches were wore too much and the piston was sliding out too far to engage, but the clutches looked good so im not sure what’s going on, something not right somewhere, any ideas on what’s going on would be greatly appreciated. Thanks in advance
Did you measure your clutch pack height ? Bob
Bob, I have not checked that, but I definitely will, by height do you mean, the thickness of all the discs and plates in the clutch pack? And what should the height for #4 clutch pack be? It has 2 discs and one plate in the #4 clutch pack, it has the least amount of disks and plates out of all the clutch packs. Which don’t make sense to me.
Here's the specs. There isn't a spec for piston travel AFAIK, but from memory I would say about 0.050". (1) Torque for bolts ... 80 to 90 lb.ft.(11.1 to 12.4 mkg) (2) Thickness of three new discs and two new plates for No. 3 and No. 5 clutches ... 1.034 to 1.064 in.(26.26 to 27.03 mm) (3) Thickness of four new discs and three new plates for No. 2 clutch ... 1.461 to 1.503 in.(37.11 to 38.18 mm) (4) Thickness of five new discs and four new plates for No. 1 clutch ... 1.888 to 1.942 in.(47.96 to 49.33 mm) Thickness of one new 3S7981 Disc ... .180 to .186 in.(4.57 to 4.72 mm) Thickness of one new 2P2903 or 3P8393 Plate ... .247 to .253 in.(6.27 to 6.43 mm) (5) Torque for bolts (nine) ... 80 to 90 lb.ft.(11.1 to 12.4 mkg) (6) Torque for bolts (two) ... 80 to 90 lb.ft.(11.1 to 12.4 mkg) (7) Thickness of two new discs and one new plate for No. 4 clutch ... .607 to .625 in.(15.42 to 15.88 mm) (8) Diameter of shafts for the planet gears for No. 4 clutch ... .7930 to .7934 in.(20.142 to 20.152 mm) (9) Diameter of shafts for the planet gears for No. 1, No. 2 and No. 3 clutches ... .7930 to .7934 in.(20.142 to 20.152 mm) (10) Torque for carrier to retainer bolt ... 32 to 36 lb.ft.(4.4 to 5.0 mkg) (11) Length of pins (five) ... 2.688 in.(68.27 mm) (12) 7S8553 Springs (ten): Length under test force ... 1.735 in.(44.07 mm) Test force ... 55.2 to 64.8 lb.(25.00 to 29.38 kg) Free length after test ... 1.990 in.(50.55 mm) Outside diameter ... .562 in.(14.27 mm) (13) 4M9592 Springs (ten): Length under test force ... 1.375 in.(34.92 mm) Test force ... 24.9 to 27.5 lb.(11.26 to 12.45 kg) Free length after test ... 1.760 in.(44.70 mm) Outside diameter ... .562 in.(14.27 mm) (14) 9H5537 Springs (ten): Length under test force ... 1.843 in.(46.81 mm) Test force ... 26.45 to 31.05 lb.(11.98 to 14.12 kg) Free length after test ... 2.468 in.(62.69 mm) Outside diameter ... .562 in.(14.27 mm) (15) Length of pins (five) ... 5.00 in.(127.0 mm) (16) Length of pins (five) ... 6.94 in.(176.3 mm) (17) 4M5016 Springs for No. 1 and No. 2 clutches (ten each): Length under test force ... 2.68 in.(68.1 mm) Test force ... 25.76 to 30.24 lb.(11.68 to 13.72 kg) Free length after test ... 3.28 in.(83.3 mm) Outside diameter ... .563 in.(14.30 mm)
Thanks Cmark! Very useful information there! But I definitely have more then .050” travel, I would say more like .200”+ travel closer to 1/4 inch then 1/8 inch. Maybe my clutch discs are worn out and I wasn’t aware. Considering I haven’t seen new discs like the ones in my transmission I may have overlooked worn discs? When I get the transmission took out and disassembled I’ll check the thicknesses of my discs and compare them to the information you gave me
Service manual says to expect 0.080 to 0.200 piston movement.
When you have the transmission out, it might be worth checking out the pinion bearings if you have a winch. The pinion has a dog clutch that you use to disable the tracks when using the winch, and the far end rides on a needle bearing. On our 83J that needle bearing failed and damaged the pinion and ring gear. I'd almost say replacing them regardless of condition is cheap insurance.
Puffie40 my machine doesn’t have a winch, although I wish it did. Would it still have the dog clutch you mentioned? Old Magnet, thanks for those specs, I would assume .200 would be the max, I’m about 100% sure mine has .200 plus, if it goes past the .200 point would it blow the piston seal?
The dog clutch was controlled by a lever that was on the floor near the shifter tower. If you don't have that lever you might be okay. I understand it was a special model of transmission used for winches.
I'd say that travel beyond the 0.200" would put the seal/s at risk.
My D4D doesn't have a winch either but it does have the clutch and lever right behind your left foot.
More than likely it would. I need to apologise at this point. TBH it never even crossed my mind to suggest to you to replace the fristion discs and plates from the #4 clutch as I assumed (wrongly as it turned out) that they would have been so torn up as a result of the clutch slipping that you would have taken one look at them and replaced them anyway.
Nige, I’m removing the transmission again tomorrow and I will definitely take a closer look at #4 clutch friction discs and will replace them all regardless this go around, but they didn’t appear burnt or damaged when I had it out last time but didn’t check thickness. But any idea why clutch pack #4 only has 1 plate and 2 friction discs? This seems like it wouldn’t be enough to support second gear. Beings all the other clutch packs have 3 discs +?
Do not just replace the friction discs, replace the separator plate as well. In the case of a clutch that slips for whatever reason the heat generated is usually enough to warp the separator plates. If the plate is not completely flat then when the clutch is released it may be rubbing on the friction discs, leading to them failing prematurely. Make sure that you replace everything in the #4 clutch this time around. I don't have an answer for why the 2nd speed clutch has only 2 discs where the others have 3. However be aware that in general terms 2nd gear is not supposed to be used for dozing, unless it's for very light blade loads. Whenever you have a fair amount of material on the blade you should be in 1st gear.
I'd say it's in the gearing. Apparently Cat thought the 2nd speed clutch was adequate for the gear arrangement.
Hello guys, waiting on parts for the dozer, plates, friction discs, and piston seals. Was wondering if I should rebuild the torque this go around as well. Was curious as to how much work goes into rebuilding the torque?
its not a lot of work a few bearings some seal rings but you need to look at the aluminium parts wear on the fins and wear where the parts fit together stator and turbine you can see if the edges where they go together have reduced clearance