I have a 980F that is used on a farm that has lost 2nd gear in forward and reverse. I would like some advice on possible causes, and the amount of time needed to remove and repair if necessary. Thanks in advance, Pete
If you look on the back side of the transfer gear case (drop box) you'll find a housing that connects to a hose which is the transmission pump suction line. The housing has a screen inside it, check the screen for debris and at the same time check the oil condition. Is it darker than ususual and does it have a burned smell..? Also what is the machine S/N prefix..? There are a number of different types of 980F.
Thanks Nige. S/N is 8CJ00706, transmission is 7TE01169 with A/R 8E4362. Will I be draining all the oil to check the screen? How many gallons?
Simple answer, not sure. You will have to drain some oil because the normal oil level in the drop box has to be above the level of the pump suction line. Try to see if you can figure out where the normal oil level is by using the powertrain oil dipstick down the otuside of the drop box to give you an idea. The total capacity of the transmission is 16-odd gallons, you might end up draining maybe 5 gallons or so. Drain it into something clean so that you can use it again if it's not contaminated but take the opportunity to inspect it ver closely for signs of particles (remember the suction screen is quite coarse) and how it smells.
Here is a drawing of where this magnetic filter is located. Not positive but think it maybe high enough so you won't loose oil, like Nige says judge this by how high the oil is on the dipstick. Standing to the left side center of machine look towards the back from in front of the fuel tank and you should see the approx. 4 inch square cover with 4 3/8 inch bolts or nuts holding it on. Some times the easiest way reach it is to slip between the front of the left rear tire and rear of the fuel tank. This will not work if you are a linebacker on a pro-football team!
It is high enough to check the screen without draining the oil. How is the trans controlled? solenoid? or mechanical linkage? Solenoid failure could be a cheap fix if it has one. Later Bob
It's a good old-fashioned cable-controlled transmission Bob, that's why the first thing I suggested was to have a look in the screen for clutch debris.
Agree, do the zero cost things first. If screen is packed solid with clutch material or metal shavings no sense in doing pressure test which in that case would risk damaging the pressure gauges! If screen is clean or only a very slight bit of crap in it next thing would be to pull filter and cut that open and see what if anything is in it. If both those show little or no crap then look at checking pressures. One question I don't recall seeing asked or answered. Is this something that was working fine one minute and next time it was shifted into second no power to wheels? Or has operator mentioned it acting week in second for the last month?
No history available on when failure occurred. There have been different operators over the last 6 months but nobody seems to know anything. I'll check the screens today and report back.
Pulled screen, it's was nearly plugged with clutch material. Some square shaped pieces about 1/4" X1/4". Other pieces look like the lip of a seal. Maybe from clutch piston. Lots fines on the magnets too. I don't think I can post pictures yet, had to restart my account. Thanks for the help so far. It looks like we will be pulling the transmission.
That can ruin a weekend!
You have 4 posts now, you should be able to post photos. I think you know what the failure us but post a couple of photos and surely someone from here will confirm it for you.
Just checked pressures: P1 - 400psi all gears including neutral. EXCEPT 2F & 2R where it dropped to ZERO P2 - 320psi same as above Lube - 95psi, never below 12psi EXCEPT in 2F & 2r Readings were taken at idle and cold oil. seems to me there is a big leak in the 2nd gear circuit. I'd love to hear from the experts though. I'll try to post pictures tonight from home.
Wiped out clutch pack. Pull it out and rebuild it. Later Bob
EEEEWWWWWW!!!!
TBH I expected far more wear debris than that. With a complete clutch pack failure you normally have to dig the material out of the screens with a screwdriver.
So did I. I drained a little oil off the bottom to see what was there. Not much. Oil was very dirty with visible metal flakes. It was purchased at auction awhile back so perhaps the problem has been developing. I'll be pulling it out Monday.
Got transmission tore down and confirmed that the piston seal in the 2nd gear clutch pack was blow out. We have it reassembled with new seals and friction disks. I am little worried about the 2nd gear clutch pack. When we pressure tested with shop air there is quit a bit of leakage. At first no movement of piston. We tore down and checked seals, all okay. Then we packed grease behind the sealing rings on the shaft and got it to seal up better. I am sure it will work with full oil pressure but would like to hear from someone who rebuilt this transmission before. Thanks for the help so far.
Was the leakage on the 2nd speed clutch pack more than the other 4 clutches in the transmission..? Were there any score marks on either the piston or the housing of the 2nd speed clutch..? Was the 2nd speed clutch piston a looser fit in the housing with no seal in it than the others..? All transmission clutches leak when tested with air, the idea of using air is simply to make sure the clutch piston moves to engage the clutch and retracts when pressure is released to make sure the clutch disengages correctly. I hope you replaced piston seals in the other 4 clutches ........ If it was me I would be fitting new discs/plates in the forward direction and 1st speed clutches while rebuilding because those are the clutches that receive the most abuse.
Yes it leaks a lot more than the others. Yes all new seals and discs through out. Seems to be leaking at the unison rings on the shaft. Minimal scoring on piston an bore. We poured oil in and then pressured without any improvement. With grease packed behind the split seals it did move the piston.
If you fitted all new rotating sealing rings in the transmission I think you need to be inspecting the outside of the rotating hub that carries the clutch piston and/or the housing it runs in for any signs of wear.
It can be very hard to get a good test on this clutch with rotating seals. If you pour enough oil in it you usually get about one application with air. As long as the carrier that the seals run in is good and you have new seals it is probably ok.
I was thinking the same. Been a few years since I was in to one of these Cat transmissions but do recall having to fill some clutches with oil to get them to air operate. Once you have oil flow under say 250 psi things work much better.
Thinking about it that #5 clutch is the most dodgy one in the whole planetary transmission because of the path the oil has to take to reach the clutch piston. If you can't find anything else and you install the transmission I would suggest to immediately perform a full pressure test of P1 & P2 for all four speeds in both forward and reverse to make sure every clutch piston seal is good before putting the loader back into service. All clutch piston seals leak a little, but if one has slightly more internal leakage than the other five a pressure test will show it up right away. The #5 clutch failed - there ought to be a detectable reason why it failed IMO. Generally in a wheel loader the clutches that fail most frequently are the forward direction clutch (#2) and the 1st speed clutch (#6) because of the imposed load on the power train when filling the bucket - unless your operators have a habit of filling the bucket in 2nd speed that is ...........