I took a few vacation days to get some things done and had an incident on the Cat 977L or K (11K 01133 according to the engine). A friend was running it and yelled on the radio it lost drive. I can hear the machine load lightly when I run it through the gears in forward and reverse, but it won’t budge. First dip of the trans stick was dirty, but the next two were spot on and clean. I’m thinking something broke in the link between the transmission and steering clutch(s). What connects the two?. Any other thoughts? Best
Start by lifting the floor plate and look at the drive shaft between the torque converter and the transmission. With the engine idling in neutral the shaft should be rotating. Engage any gear and it should stop. Shift from one gear to another and the shaft should turn slightly then stop again. Try that in all gears and report back.
Thanks Nige, that's the first thing I checked but incorrectly assumed it should remain rotating. It does NOT stop rotating, and even appeared to speed up as I moved through the gears.
I need to bite the bullet and buy a repair manual for this machine. If anyone could tell me whether this would be a 977K (I think) or an 977L repair manual, or share a service manual part number that would be great? Serial number (only found on the engine): 11k 01133
That means that the transmission clutches are not engaging, usually but not necessarily as a result of low transmission oil pressure. With the floorplate up take a look for the housing containing the magnetic screen. It will have a cover secured by 4 bolts. Get that screen out and post photos of what you find stuck to the magnets (metallic) and to the inside of the screen (non metallic). Do you have pressure gauges capable of measuring up to say 400psi.?
The appropriate Service Manual for 11K01133 is Caterpillar Publication REG00635. See this LINK for one on eBay. There are others if you search under the Publication Number. A new one is priced at $285 BTW, so don't go paying too much.
I'll check it out soon as I have a chance. If I don't have a gauge I can get ahold of one this evening. Does the machine already have provisions to pressure test, or will I need a tee? If so, would you happen to know what thread type/size? Thanks!
@Robert Boggs are you in Washington? I worked with a Boggs a few years back.
No sir, WV.
A machine from that era is not likely to have quick connectors for testing, probably threaded plugs that will most likely be 1/4" either NPT or similar. You'lkl have to whip some of the p;lugs out and take a look. See the attachment. Don't go too far on this just yet, first get into the screen/magnetic filter and see what you find.
You would find it best to use a 0 - 600 psi test gauge on all CAT powershift transmissions.
Very good call Nige on not getting too far trying to prep for fittings, I have trouble in paradise. I’m going to scour the parts manuals to see what I can ID, but assuming I’m into a transmission and full flush if I repair it.
Photo #5
Does look like the trans is coming out
Yep. She fcuked.
You’re also looking at a pump and a transmission cooler in addition to the transmission rebuild if you do it right.
I’m having a hay of a time even trying to locate parts new or used to pull an estimate together. Guessing I’m in the $10k-$15k range? Any suggestions on what would be the safest way to start it so I can get the bucket raised and tow it out of the way without further contamination?
Sure appreciate you holding my hand through another one Nige!
Until you get it torn down I think it's highly unlikely that you will be able to make a definitive parts list. I worry about the metal parts that look as though they came from a bearing cage and what other damage that might have done. Offroad Equipment in Alcoa TN is a good source from what others have posted on this forum. www.offroadeq.com/
Your not going to make it any worst, put screen back in and fire it up and lift the bucket.
Just looking for a budgetary number as it may be worth more dead than alive. It’s a solid machine otherwise, but I’d hate to spend more to repair it than what I paid for it.
Rebuilt one https://www.heavytruckparts.net/item/Caterpillar/3s2706/Transmission/8151399/1/28988
Thanks sir!
Don't strip off the drive shaft and start it up as you will get an oil Bath when the drive shaft blows out of the converter, just start it up and get the Beast raised up at least 9"' on balks of timber.
Thanks much, Nige was kind enough to give me a heads up too. That’s something I certainly may have done.
I have a machine with a good trans. ser.#11K12?? I pulled the tracks off last fall. Interesteded in a road trip to get it? Or I could buy your's... I'm short of time but possibly open to adding to the fleet ... I want the 977's to flourish... A 977 can't compete with rear engine counter rotating track machine but a good mule in a tough fight.
Definitely, I hate to see a solid classic go to waste. Please pm me for a cell number. Where are you located?
I sent contact info. With us being so far apart exchanges may not be practical. The machine runs so you can warm it up somewhat and test it somewhat but not fully under load. It had other issues so I took its tracks for use on another machine.
I have a 977 with a bad trans, going to try and rebuild it. I’ll definitely do a thread bit maybe that’s a possibility too.
Are you doing only the torque converter, or the range assembly as well?
I’m thinking seriously about pulling the transmission and purchasing a refurb or repairing myself, however the service manual I posted didn’t include an overhaul manual for the 3S2706 transmission, just a generic diagram of all the different range components. Does anyone have info on the specific transmission repair manual, or a part number for the manual. Thanks!
Didn't the manual I directed you to previousy have all the info regarding the R&I and D&A of the transmission.? I assume that you bought it.?
We are planning on doing both. So far the TC is apart and it's really pretty simple but we all know that won't be the hard part... I will do a video on tearing down the trans hopefully before the end of the year
So here are a few documents that might help you. The transmission R&I also covers the D&A for the planetary group.
$8500 for a rebuilt trans. with I assume a warranty doesn't seem too bad to me. Just taking the old one apart and figuring out what all parts you need would be quite the chore.
Thank you sir, certainly something to ponder
Thanks so much, sorry I got side tracked for a few days. The 2-110 manual did not go into that detail, but at a glance this looks to be exactly what I need you if I rip into that machine.
Does anyone recognize this bolt as being from the internals of a 3s2706 transmission or otherwise? 7/8” NCT with a 7/8” head. Thanks!
Where exactly did you find that.? In the screen or somewhere else.?
In the magnetic screen, it appears as if something spent some time in the transfer gears and ended up busting the transfer gear housing.
OUCH!
what do you mean transfer gear housing? Can you post more pictures? That does not look like any bolt I have seen come out of the trans...
I may be wrong but the shape and depth of the head on it gives me the impression it could be some kind of stop. A shame that the photo doesn't show whether or not the head is domed in some way.
I am not saying it is but it could be a bit off a brake band adjuster??? it looks nothing like anything I have seen in a transmission, there is no stop bolts that I can recall on the valve block??? also that is a big thread size at 7/8"?????
Wondering if the other piece in the pic. is related to the bolt? The bolt has a definite groove under the head that might be for a C shaped (fork) piece of metal to fit around. A clip type retainer of some sort that holds something in place like maybe a part of a valve with a spring or spool that can't be directly bolted on?
The ports on the valve body are 1/8 pipe
Operator wanted to knock off early?
Sort of looks like a lock bolt for a shift fork or the like. Its not designed to seat on the head. But 7/8?
See #26 in the illustration below. 2M-7188 Screw. 7/8" NC thread x 6" long. If that's what's in your photo then she done broko, which raises the next question - where's the other piece.?
Nailed it Nige!! I can definitively say that’s it. Now I just need to determine where the other 4 inches is and if it’s been riding in there a while, or the root cause of the current tragedy. Thanks all, you’ve been a huge help!
Thank Tony ( @tctractors ). He was the one who suggested to look in the brake adjuster.
could be a old break down does the machine brakes work if so its parts left over from a old repair
Thanks sir, for making me reread the thread, I was in a hurry and over looked tctractors comments. Thanks Tony, much appreciated!!
Thanks for all the help sir, much appreciated. I’m thinking along the same lines. I plan to jerk the covers over the weekend and hope to see both adjustment bolts intact. Looking good so far, we got the trans stripped down to the drums today and everything looks good except the transfer gear housing area. The lubrication system is a brilliant design for the era IMO and I think it protected the remainder at this point. If anyone has some transfer gear parts available please IM me. Most interested in a 9M2060 case. Thanks!
Hoping to help someone else down the road.