Hey guys, Years ago i bought a TEREX 7231 BA wheel loader with the two speed allison tt2000 series transmission in it. It has been a good machine for many years. After this past snow storm one of my operators told me that it was very slow in 1st gear and reverse, but 2nd gear seems more normal speed wise. The only thing ive had time to check so far was to verify the complaint and to check the clutch pressure on the dash which appears to be normal in neutral, 1st, 2nd and reverse. Im going to drop the filter and fluid tomorrow to start looking into this but do these symptoms ring a bell as to what the issue might be? Just seems odd that both 1st and reverse are equally slow. Thanks in advance!
The transmission uses the same 1st gear clutch pack for forward and reverse you have range clutches 1st and 2nd and directional clutches forward and reverse
A little update. Today i dumped the oil and cut open the filter. There is very minimal metal both in the sump and in the filter pleats. A stall test showed zero psi converter pressure but im thinking that gauge may have been junk. I will double check tomorrow. When i drained the oil after the test it was very aerated as well.
Today i also dissasembled the main pressure regulating valve in the valve body. According to the manual it says a weak or broken main spring could cause low converter out pressure. The springs look good, trimmer plug looked good. The main regulating valve did have one scuff on the side and it was a bitch to get out of the bore. Any chance this could be the issue? The book also references lube and converter pressure regulating valves. Does anybody know if those are located where they can be cleaned and checked while in the machine?
A few more updates. Today i got a new gauge and verified my converter pressure. It runs between 50 and 65 consistently in any gear. The loader has plenty of torque as it can get into a pile and fill the bucket while spinning the tires while digging. The big issue here is speed, everything it does is at half the speed that it used to do it. The manual states that there is a 1st and 2nd turbine in the torque converter and it shifts automatically between the two. Does anyone have any experience with these??
Just a guess but does your parts book show if the torque convertor can be taken apart? If it is a two-stage convertor, there MAY be an overrunning( sprag) clutch on a stator that is either slipping for the high range turbine or a sprag that is locked up for the low range turbine and not releasing as it tries to switch to high range. If the convertor is a one-piece welded assembly, you may have to find another convertor or a specialized shop that can cut yours apart to fix it
Im going to dig into the manual today to find this info. Im 99 percent sure it shows the converter put together with a ton of bolts so i assume it can be taken apart and repaired. Im hopeful that its something like this as there is no metal in the oil like something came apart.
I have been told the 2 speed sprag will either lock up in low range giving you torque and low speed, ( as your situation) or as mine is locked up in 2 nd range giving me speed and low torque.
Here is the breakdown of my converter. Would i be wrong to assume that the stator (Item15 ) would be the same as a sprag?
No specifics, but in the automotive world the stator is a thing with fins that redirects the oil from the impeller (driven by the engine) to the turbine (driving the rest of the transmission) in such a way as to create torque multiplication at low speeds/high loads. The stator is pushed backwards by the oil flow and it is locked in place by a one way clutch (sprag). After the vehicle begins to gain speed, the stator is just in the way, so it is allowed to rotate freely in the other direction by the same clutch. If the sprag clutch is freewheeling, it will be hard to take off. If it is locked up, the converter will get hot when things are moving at speed.
Ok, im just trying to wrap my head around this so i can go after the correct part. Im not seeing any one way clutch in this parts breakdown. Does the stator control what stage the torque converter is operating on? IE low range ( 1st turbine) vs high range (2nd Turbine)? Im guessing that all of the shaft speed is controlled by the torque converter, meaning other than manually shifting the transmission shifter to low or high gear the shaft speed can be increased or decreased by the converter depending on speed and load conditions?
If the converter is equipped with a sprag clutch and it is not locking then in my experience the machine won't move. All the loader will do when the operator tries to move it is bog the engine down. It's hard to tell from that illustration but it certainly doesn't appear as though the stator has a sprag clutch.
There is a post a few years ago about Case W24B Allison transmission parts that might interest you
I actually did come across that post. The slow symptom matches up for sure. Yet i dont think my transmission is slipping per se. I can spin the tires while loading the bucket with dirt. Im really torn on this one because the machine isnt worth a huge investment. The torque converter can be dissasembled in the machine as it is divorce mounted and i can access the converter housing by removing a driveshaft then all the accompanying torque converter parts. Getting the actual converter housing off of the trans housing might pose a decent challenge unless i remove the cab.
That is exactly where I am at, but as of right now my engine is out so that makes it easier. And like yourself my machine is not worth the investment, but when fixed I know that part should be ok lol.
So ive done some more reading in my manual and the service manual lists a freewheeling clutch assembly which " locks the 1st or 2nd turbine to the output shaft based on load requirements " per the manual. Im thinking this freewheel clutch (item 14) is the issue.
do you have your transmission open yet?
No not until the weather gets warmer up here in Canada
For what its worth ive done a bunch of digging on this. I have found the parts for my application, about 950 bucks for a complete " freewheel clutch" unit. If your transmission is divorce mounted from your engine you can remove the torque converter housing and get to this part with the transmission stll in the machine. Just food for thought.
Have you taken yours apart yet?
Not yet. Most likely early next week. I habe another project that needs done ahead of this one.
Well I certainly will be following your steps thanks
Update! I got into the converter housing today. I thought i was going after the freewheel clutch but then found the splines for the 2nd turbine completely stripped out. I have a hard time digging any further seeing this issue in front of my eyes. Any thoughts guys?
Oh Boy did not expect to see that, sorry I do not have any thoughts on it, are you going deeper
I didnt either, but honestly this takes an hour or two of extra labor out of this job if it is the issue. Honestly i cant see how it cant be the issue, with the splines stripped out there is no possible way the 2nd turbine was giving any power to the transmission whatsoever. The downside is im sure the torque converter prices are more than the 950 i was quoted for the freewheel clutch. If any guys can chime in who know these two stage converters well that would be great!
You need to remove the transmission. the shaft that is damaged drives the freewheel clutch which i think is locked up,the first stage turbine was fighting with the second stage turbine that caused the splines to strip.being the freewheel clutch locked up. If I were you I buy a rebuild transmission. If the turbine output shaft is damaged than the turbine is damaged. Don't get me wrong it can be rebuild, it'll be close to a rebuilt price. It may be save to say put it back together and use it the way it is,there is no more pressure on the freewheel clutch for it to blow up.
Will either of the turbine shafts be locked up if the freewheel clutch is locked? Just trying to properly diagnose without tearing it completely apart. The 2nd turbine shaft is in perfect shape, only the 2nd turbine female splines are stripped. The odd thing is there is virtually zero metal in the filter or sump of the transmission like this happened over a long period of time.
I guess what i am trying to ask is, how free should the 1st and 2nd turbine shafts spin when the converter is removed? Spin with two fingers? Spin with a pair of pliers? I do know that the first turbine shaft will turn one way but locks when you try to turn it back the other way.
If there's only slow speeds that means that the first turbine is doing its job. For higher speeds the torque must be low ,the freewheel clutch is geared much higher ,it than starts to grab hold of the second turbine shaft witch in your case is missing so there will only be one speed This is a pic of a clutch that blew apart with most parts in the slump, the reason your slump is clean is that the clutch is frozen onto the shaft,there will be nothing wrong with the turbine except the maybe the second drives splines The second pic is of the assembly clutch.
I got ya. How far into the trans is the freewheel clutch after removing the converter housing? I have it in the machine stripped down to an empty converter housing now.
You will understand more once you take the transmission apart you only need to remove input shaft cover
Got it. Once the converter housing is off its basically right there.
Is the sprang clutch the same as freewheel clutch? Also, if freewheel locks up, will it strip one of the splines that drive either of the 2 speed torqueconverter
Yes the "sprag" and "freewheel" are the same assembly. Ive been told that it can wipe out the splines if it locks up because the turbines fight each other. Im trying to get further into this one today to determine if the freewheel is ok or not.
So i pulled the torque converter housing back about 8 inches off of the transmission today. The freewheel clutch looked in excellent condition and it would allow the 1st turbine driven gear to lock in one direction and freewheel in the other. Knowing how the transmission is supposed to work i was satisfied with this and put it back together. Now i have to wait for my converter parts to come in so i can finish it up.
Looks good glad that was all you found.
Did you get your parts yet?
I did. I ended up getting the 2nd turbine assembly, converter pump, all gaskets, seals and lock tabs from Parts Unlimited in Missouri. Tom Hall is the man to talk to. 1300 bucks for everything shipped to my door. They had used and new offerings for almost every part.
Thank you for sharing the info. Do you have yours up and running again?
I havent had a chance to get the new parts installed. Im shooting for this week, maybe tuesday time frame. Ill keep you updated.
Back in business! I changed out all the parts including seals, gasket, 2nd turbine and splines and lock tabs. Everything works flawlessly now! Fire away if you have any questions!
And more because only 4 files at a time......
That’s good you got it going,
I am gong to get at my transmission this weekend, will have a few questions,
I got torque converter apart today, picture 4 has a piece out of it and picture 1 the bolt holes are a little out of round and 1 broken bolt ( it was still in the bolt hole so it never went through the transmission, going to check spragge but not sure how to,
A couple more pictures
Found the problem ….now to find parts
boom! found it. your 2nd turbine splines are NOT happy. Im 90 percent sure thats how mine looked when the last poor sap took it apart before me, they just happened to last 15 years in my hands. I didnt really get a great look at my sprag but id guess your sump had a bunch of metal in it from that one??
Parts unlimited in Missouri is the place to go. Tom Hall was the guy i dealt with. I think the sprag was around 950 bucks, 2nd turbine was 485 used, 500 something new. How does your ground sleeve look? thats the part that the turbine section bearings mount to in the converter housing.
They’re ok a little mark but I think I can file it out. That is in the converter housingwhere the bearing is in correct
Yes, the ground sleeve is the only part left when the entire converter assembly is removed. The converter pump seal and bearings ride on it.
So with that being said, it should show no signs of marks on it then mine is marked on one side
Yep just file it if you can. Mine was damn near totally destroyed and i was able to make it work.
how are you making out???
Parts are ordered from Tom just waiting on them, then sending the gear/ inner shaft out to machine shop to get it built up of course we need the parts first, so it will be a while before a put it together.
how are you making out???
Oh good I got it going again just like you said, I have another post about it . I thought that’s where I talked to you about it, I followed what you told me and it was a little scary but it all worked out fine, and it works the way it is suppose to. Thanks so much for all the advice.
I'm Digging into a TT in a wheel loader that has a bad suction tube seal. I faintly remember Daddy replacing it 30 some years ago. Can I take the torque converter housing and torque converter off in one piece ?
I had to take torque converter apart so I could take tc housing off. It was trickery still in machine , but we did it, our engine was out of machine at the time. The transmission remained in machine
I'm pulling the engine as well, I am hoping the TC and the housing can be slipped off to get me to the suction tube.
I was not looking for suction line so I was repairing the 2 step clutch,
Pretty sure your converter will have to come out in pieces. Not a big deal just a ton of 5/16 bolts and washers.
Service manual link provided by HEF member Acecadet
Wow, mine manual is a 1979 one we bought when we did the suction tube the first time. It's been so long and now daddy is dead, but I don't remember him making me remove all the torque converter. seems like I took the housing and torque converter in one piece. But I'll probably plan on taking it all to pieces the way zlssefi said.
And he is correct as I did it the way he said.
Hey Rusty - when you did the job this time did you have to replace or reseal the input shaft on the charge pump or was the issue just the suction pipe packing ? - I've got the same problem on a machine in a difficult spot I'm trying to move atm - looks like the charge pump will come off from the outside after removing the aux hyd pump - difficult to get to but may be doable on the machine
My issue was the 2 step clutch. I bought a gasket kit and I replaced the seal on ground sleeve. It is still working fine.
No worries - thanks for the reply