MM U302 Super Ampli-torc

Jeremy L

Member
Is there anything that would cause the low on the ampli-torc to not work? It was years ago that I was told the low did not work on this tractor but I never did confirm it for myself. The reason I ask is that it seems to me that the low would also work as it is simply driven by the gears on the ampli-torc. I could understand the high not working if the discs were wore or broke as they would not lock the ampli-torc up in high then.

Can someone please explain to me how the ampli-torc actually works and confirm whether I am righ in assuming that the low end should always work as long as there is not a catastrophic failure within it or the transmission?

Thanks in advance for your help.
 
A/T's seem to be misunderstood, there is no direct drive connection to the drive line. On MM's there is either a sprag clutch or a spring/ roller clutch, either way failure there results in a low side slipping, no adjustments, works or not!! On your U 302 Super replacement of the worn parts is the only solution. For more info call @ 920 295 3278, we have the parts and/or can do the rebuild, Dale and Doug, riverdalefarmshop.com
 
High side, multi-disc clutch connects the engine flywheel to the transmission input shaft (direct drive). There's a set of planetary gears between that clutch and the trans input shaft, high side clutch connects everything together as one. When the high side clutch is disengaged, the entire planetary cluster would simply spin IF NOT FOR a odd bearing assembly that stops the planetary cage, causing the drive to travel though the planetary reducing the output speed to the trans. input shaft. That odd bearing is not a bearing but some roller bearings set in ramps, held in the ramp by little leaf springs. Later models used a "sprag" which is essentially the same thing but totally self-contained. Most common to have to replace the rollers and springs or the sprag. Very common and recurring problem. My explanation is not nearly as accurate as a well written manual.
 
Thanks guys for the explanation that makes more sense now. How do I tell if I have the spragg clutch or the spring setup? Can you send me pictures or direct me to the proper location in the parts book that would show these parts?
 
I think you did quite well in explaining it Curt. I was told at one time to always have the tractor in high range when you shut them off, that way if the engine kicks back it doesn't weaken the springs in the ampli-torque.
 
It is highly unlikely that you have the spring, clip and roller setup in your over-running clutch setup. You more then lilely have the "sprag (one way)" clutch setup. It is not all that hard to replace. Not always but sometimes the hub is worn and just replacing the clutch will not help much.
 
If it still has the original setup in it and the serial number is 27601300 or less (LP & gas) it will have the spring and roller type. If newer or diesel or has been updated, it will have the spraug clutch.
 
If the hub is wore, what is the best way to fix it?

Also, to remove the back end of the ampli-torc to get to the spragg clutch/spring and bearing assembly, do I have to drain the rear end oil or is this part ahead of all that and contained within the ampli-torc compartment of the tractors housing?
 
I get that in when it is shot you split the tractor and get in there and replace the parts. I hope Parts are available when and if it ever needs to be done on my 3 tractors.
We have always been told to make sure to make sure the tractor is warmed up before useing it in low range or it will slip and wear out the ampli-torc which I can believe since it does not move so good in low range when first started. Only trouble is shifting gears when in high range which is difficult.
Is it the disc's that wear out or the sprag clutch? I don't quite understand all that but always drive in high range until things are warmed up. On one tractor we had to go help fix the ampli-torc before we could bring it home. Sometimes the lever gets broken from to aggressive use also.I guess it is kind of frustrating when it is suspose to move and doesn't. cleddy
 
I believe most of the time its the sprag clutch. From what I understand, on the older models the springs weakened a lot of times and couldn't push the rollers out far enough to engage the clutch. I agree, it is difficult shifting in high range.
 
I like to remove the Ampli Torq as an assembly. The front compartment (torq) needs to be drained but the rear does not. Now is a good time to drain it and change the oil though.

1. Make sure the torq lever is snapped and tied forward into high range when removing the cover. Then remover the high range clutch pack. Leave the planet carrier pushed into the low side sprag assembly.

Reach through the slots in the carrier with a 9/16" swivel socket and remove the 6 x 3/8" x like 2" bolts that hold the cage to the trans case. then reinstall as an assembly. You can pull the hub (carrier) from the sprag to aid in removal, its not as critical to keep it in with a sprag clutch setup as the roller setup. since you stated you have a 302 super, you'll find that you have the sprag clutch setup.
 
Ok so I got the rest of the ampli-torc out but I still don't fully understand how it is working. The back part which houses the spragg clutch and roller bearings on either side of it, it connects to the housing of the tractor obviously and remains tationary always. Is the spragg clutch supposed to spin in this housing or remain fixed?

The other part with the planetary gears then spins inside the housing one why and the other is the spragg clutch not supposed to grab and lock them together?

Is there anyway to confirm that I have it all working properly prior to putting it all back together once I change the spragg clutch (i.e. should I be able to spin the planetary gear part inside the clutches housing one one and the other way not?

How do I know if where the spragg is supposed to engage the planetary gear housing is wore to much or not?

Lastly, what parts should I be replacing on these pieces when I have it out?

Sorry for all the questions but I want to be sure I have this all right before putting it all back together. The more information the better.
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Yes, the planetary assembly should turn freely within the hub that's in your left hand, in one direction, and not turn at all in the other direction. If you can turn that assembly within the hub in both directions, your sprag is shot. And yes, the marvel of the sprag or springs and rollers, is that they allow free wheel in one direction but lock up in the other.
 
Curt, thank you again very much for all your assistance and knowledge concerning the ampli-torc.

Right now I can spin it in both directions so that explains why the ampli-torc wasn't working. If I get the new spragg and put it in then technically in my hands I should be able to spin the planetary assembly one way freely and the other way it should lock up. If not then my hub is wore and I need to build it back up some correct?

I plan to replace the roller bearings and spragg within the hub but should I be replacing anything else such as the cup and cone bearing at the back of the hub that in next to the transmission housing or anything else for that matter?
 
Also I forgot to confirm, the spragg is fixed to the hub right? It doesn't spin it in like the roller bearing on either side correct?

Lastly, what is the best way to get the roller bearings and spragg out of the hub? They seem to be in there pretty tight so I was thinking I would have to knock them out with a punch and hammer?
 

Find someone whom has a wood lathe, turn down a piece of plastic or if that's not available a piece of wood and remove the snap rings and drive it all out.
 

Also when you reinstall there are oil holes that must be orientated correctly. There are marks of the sun gears of the planetary to aid with the alignment.
 
So will both bearings and the spragg come out one side or the other of the hub (i.e. just remove one clip ring and punch them all out one direction)?

Lastly, what oil holes are you referring too? The ones on the top of the hub that have the oil deflector bolted next to them or are their holes inside the actual hub where the spragg is?

I haven't taken the sun gears out but do they need to be lined up a certain way based on your comment?
 

Usually if both bearings are good, remove both snap rings push out one bearing then the sprag will come out. There isn't a need to remove both bearings if they are good.

Also there is an oil hole in the "cage" that needs to be orientated and holes in the sun gears that are orientated by the lines in the sun gears.
 
Bearing replacement is a subjective thing. Some folks replace them just as matter of principal. I wouldn't as long as they aren't pitted or rusty. If you don't have one, an IT manual would be of great value to you. I've never been in a 302, just M5s and 4Stars. In those models I'm familiar with, there is a thrust bearing, very thin little guy, that I usually replace. The It manual would give you things like pre-load and clearances. Even if you don't have the high tech tools to measure those things, at least you can ball park or get a feel for it. Of course, oil seals and dust shields on the transmission shaft carrier ought to be renewed. Forgive me, going on memory here.
 
The sprag is not fixed to the hub. It is a bunch of dog bone shaped pieces standing almost on end. There are small brass pieces that drag on the inner race when going from high to low and cause the dog bone pieces (that are longer than the distance between the inner & outer races) to stand up straighter locking the outer race to the inner race. What usually happens to the sprag is that the brass pieces wear through or very thin to the point where they don't exert enough pressure on the inner race to stand up the dog bone pieces.
 
Thank you very much for the explanation. All of you have been very helpful.

I believe what has happened in my case is exactly what you have described. The brass pieces have wore and a couple are broke so the sprag is not working properly.

Currently the sprag does not spin (doesn't roll inside like the roller bearings on either side) in the hub it is housed in. Should it or does the internal housing just do the spinning and the sprag stays fixed?

Lastly, which way is best to take the sprag out, towards the front where there is just the clip holding things in or out the back where the bearing race and adapter piece are?
 

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