Does anybody know a facility that can do a full stall test on a 980H transmission? Apparently there is two types of dyno test, which was news to me. A lot of shops can only spin them and check pressures and run it through the gears. I need somebody that can load the transmission with a load cell to check if the converter is functioning correctly.
Cat Dealer
Probably your only hope. Even then it would need a pretty large dealer rebuild shop to have a transmission test bench.
We had test benches but not one that would load the transmission they would just turn them
Does Indiana have a trans dyno?
I’m thinking they still have the one we had
Every cat dealer I’ve talked to can only spin them. They are looking into who has a bench that can load the transmission. Not easy to find apparently. Long story short is the transmission was rebuilt and when put back into the machine it won’t pass a stall test. Engine won’t get past 1200rpm. It was pass with old transmission, but tranny was getting hot, which is why it was rebuilt. Engine has power to maintain 1700 rpm when deadheading the hydraulics, which is within specs. When the loader goes into the pile it falls flat. All pressures check out and solenoids calibrated. We sent the transmission back to the rebuild shop so we didn’t avoid warranty saying it’s got to be a torque converter issue. They pulled it apart and said it all looks good. They put it back on their test bench and spun it. Pressures look good, but it doesn’t show me flow rates. I don’t want to put it back in into we have a definitive test to see if we have problem the transmission build or if the problem on my end. I don’t think we have an engine power issue.
The first thing that comes to my mind is wrong wheel are the parts listed on invoice?
Does the converter on that particular machine have a lockup clutch.? If so my first thought would be that the torque converter stator sprag clutch has been reassembled incorrectly. Was the converter overhauled when the transmission was rebuilt.? Why was the transmission removed in the first place.?
Nige, yes it has a freewheel clutch. Our initial thought was the springs were installed backwards and that was creating the low stall. Rebuild shop took it apart and said they were correct. I’m skeptical at this point.
Judging by your described symptoms that is the first place I would be looking. It sounds very much like either the sprag clutch assembly is installed backwards (meaning the ratchet mechanism fails to latch and lock the stator in position) or maybe something more subtle such as the roller return springs installed sideways. Seen that before. Somewhere I have some photos. I’ll try to find them. Stand by.
Study this photo closely of an incorrectly assembled sprag clutch mechanism then compare it with the illustration from the service manual showing how it should be assembled. NOTE that the photo is taken from the opposite side. 1. All the springs are on the wrong side of the rollers. The springs are supposed to push the rollers towards the NARROW end of the ramp, not towards the wide end. 2. Three of the springs (3 o'clock, 8 o'clock and 11 o'clock) are installed SIDEWAYS.
I didn't think about it having a clutch. A long time ago we had some stators that would strip the spline in the aluminum stator and cause low stall speed only other thought is if the guy that built it wrong in the first place looked at he would probably think it was right
That is very helpful to understand. They are supposed to be sending me some photos of when they took it back apart. Thanks
Exactly my point. It's not until you try to ratchet the sprag mechanism that suddenly the penny drops that the stator won't stop turning on the hub whichever direction you rotate it. Say nothing to them initially but upload the photos here first. They may well be quite useful.
I’ll push for the photos on Tuesday. Monday is a holiday
Did the H model 980 have the piston pump hydraulics or were they still using the vane pumps? I've done machine inspections on lots of 980H machine and stall tests are mandatory. Generally as I recall most torque stall at around 1,700 RPM. The hydraulics with the load sensing systems don't drop RPM more than fifty. I have to pick up boom from the ground and do a running read of the RPM drop and then it is usually less than 150 RPM. I do the same when doing full stall against the transmission and the hydraulics at full lift of the boom. Even at that if the engine speed is below 1,500 it is flagged in the report. The lockup should not be engaged at all when doing stall tests. It isn't hard to put a torque converter together wrong. It wasn't long ago that I was involved with a D6T that wouldn't move because someone left out a part of the torque divider. I'm with Nige on this as something is obviously assembled wrong.
I suppose the next logical question would be to ask exactly what parts of the sprag clutch mechanism were replaced when the converter was overhauled.? It is a known weak point and the internal parts should be considered as consumables.
Any update on this.?
Hey nige, I’ve been out of town for the last week. I asked for pictures of the tear down, but of course the guy said he wasn’t there when they took the sprag clutch apart. I just got bunch of pictures of the converter parts. It wasn’t much help. I might just have the cat dealer go through the torque converter and verify it’s correct and reinstall back into the loader. If it works, then I’ll now they put it together incorrectly
Pics
Pics
So he couldn’t or wouldn’t tell you what parts of the sprag clutch they replaced.? I don't have the machine Serial Number so the Part Numbers may be different, but items 27, 38, & 39 on the attached should be mandatory replacements during a torque converter overhaul. The attached is from a JMS-prefix 980H but I see different converter arrangements.
Update: I sent the rebuilt transmission back to the shop and they told me everything looked good. Tried to find something that could do a full stall test, but no luck. They told me they could send that transmission back to me, or they would send me another rebuild that was actually my original core. I choose the ladder. We installed and it worked. All tests were within spec. Obviously something was wrong with the first transmission regardless of what they say. It’s not sounding good they want to cover the labor charges. Any suggestions for recourse? I’m not asking for legal advise just suggestions. Thanks
This is news. In Post #7 you said "Long story short is the transmission was rebuilt". From that I got the impression the same transmission that was taken out of the machine was reinstalled after being overhauled. In view of what you posted now obviously that was not the case. It seems strange that out of two rebuilt transmissions the one that originally came from your machine works fine now it has been overhauled and put back where a recon unit taken from another machine did not. I don't suppose you have any details of the transmission that failed to function do you, such as the Serial Number..? Maybe it is on the supplier's paperwork.? It might be interesting to look at that tranny and compare its configuration to the one from your loader. That would also need your machine Serial Number. I don't think you ever mentioned that. IMHO you paid the supplier for a reconditioned transmission for your 980H that works. If they supply a unit that doesn't work then all subsequent labour costs related to finding out why are on them, up to and including supplying a replacement transmission. Personally I don't think they have a leg to stand on and are what we call "trying it on".