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dave45056

Differential Question

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dave45056
I have searched and searched to not avail... I am having a problem with my 3415h differential. It appears to only have 1 wheel drive. If I jack up the right side of the tractor I can spin the right wheel with some resistance and whirring gear noise, but the left wheel does not move. I then removed the right hub to observe the motion. Spinning the differential turns the outer tube, but does not spin the inner shaft. Keys on the inside part of the diff are in place. I have looked in the manual but don't see exactly how this is supposed to work. Do the springs on the planet gears provide the force to the right wheel? Should some surfaces have no grease on them? I read that I can shim the springs by adding washers. Does this sound like the soluton to my problem? I am also wondering if this can be done on the tractor by removing the bolts on the outside of the hub, then removing the bolts the planet gears spin on.

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HubbardRA
Dave, the left and right wheels work together in a differential. If you remove the right hub, you have disconnected the gear from the differential and turning the diff will not move the left side axle because the disconnected gear must be in place to make the axle move. A differential drives both rear wheels together but not independent of each other. If you jack up one rear wheel only and turn the diff, the other wheel should turn, no matter which wheel you jack up. The springs on the spider gears of the diff just provide resistance to rotation. Without the springs, one wheel can easily spin and get the tractor stuck. With the springs, friction is provided and therefore the spider gears cannot turn freely when one wheel loses traction this forces a certain amount of force to be provided to the wheel that still has traction. Yes you can shim the diff to increase this friction. I am the one who came up with this idea and did it in a pulling tractor over 20 years ago. If you need help with doing this, send me a PM and I will walk you through it. You will need to remove the right side hub, then take the large bolts loose and remove the diff from the drive tube. Do not pull the large bolts out of the diff housing or all of the gears and springs will fall out. Lay the diff on its side with the long bolts pointing upward, then remove the 1/4 inch bolts from the outer diameter, then you can remove the upper half of the diff. I used standard washers from a hardware store. I put the washer against the housing where the spring contacts. You will have to grind away part of the outer section of the washer to make it fit within the radius of the diff housing. Make sure you don't mix up the gears in the diff. They need to alternate, one on left, then one on right that mates to the first. If you get two gears together on the same side you will weaken the diff and possibly break some gears from overloading. If you really want both wheels to turn the same speed all the time, there is a way to do that too. Problem with this is that the wheels need to turn at different speeds to make sharp turns. If you lock the diff, the tractor will not make tight turns, it will make the front wheels slide and try to go straight. Rod

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Burntime
Rod, how about a picture tutorial? I would like to shim one of my tractors. Not to full posi but more none the less for winter snow throwing for better traction...

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dave45056
Rod, Thanks for the explanation. I definitely need more traction which is why I posted this question. I think I'll try the shimming method you mentioned. This is not a pulling tractor so I don't want the two wheels to be locked. I have a quetion, though. How does the inner part of the diff come off the tube? Do I need to remove the snap ring? Is a gear puller required? I can take photos when I get this going, but I bet people would believe it more if the DIY came from you:D

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brozak
DO NOT release the spring pressure by loosening up the 1/4" bolts around the outside edge of the housing. These small bolts WILL keep everything together but that is NOT their purpose. Removing the small bolts, with the spring pressure still on the inside, will cause the 2 halves of the housing to distort / bend and everything will come flying apart real fast. Remove the differential housing from the axle by removing the 8 nuts from the 8 bolts that go all the way through the differential. Slide the differential assembly off the axle with the bolts still sticking through the differential assembly. After you remove the differential housing from the axle, put nuts back on all 8 bolts, they need to be snug but not super tight. These 8 bolts compress the springs inside and hold everything together. After you have ALL 8 bolts and nuts snug, you can completely remove the smaller 1/4" bolts from the outside edge. Everything is still under spring pressure and held together with the 8 inner bolts. Now, 1 at a time, by only a 1/2 turn each, loosen the 8 bolts. Work your way around all of them, in order, one after the other. On about your 2nd. or 3rd. time around, you'll notice the 2 halves of the housing start to separate. Keep working this process until each nut has reached the end of the thread. The end of the bolt will be flush with the nut. Using the factory bolts, there should still be spring pressure on everything at this point. - If you are able to squeeze the 2 halves together with your hands, the unit is a good candidate for shims or NEW springs because the springs are weak. At this point you need to replace each of the 8 bolts, 1 at a time, with longer bolts that will be snug with the nut almost all the way on the bolt. Repeat the process of slowly releasing the spring pressure until everything is loose and has NO pressure on it. Clean and inspect everything, you may find a few broken springs. If you have 1 or more broken springs, you'll obviously need to replace them but the ones that are not broken are probably ready to break. For the cost of about $2.20 a piece (9/9/2009), I would replace all 8 of them. The parts manual has a good picture of how everything goes together. As mentioned by Rod, above, each set of small gears MUST be assembled in alternating order so they contact the larger axle and hub gears properly. To re-assemble: Lightly grease everything but it will get packed with grease after it is completely together. Clamp the outer hub with large gear in a vise, with the gear facing up. Insert the longer set of bolts (used earlier) through the outside half of the housing. Set this all on the hub you have in your vise, with the bolts sticking up. Assemble the Spacer Rings, springs, and gears in a symmetrical order. - If you have decided to add washers for more tension, I would insert them between the springs and Spacer Rings. After you get the inside half of the housing on the bolts and the nuts on finger tight, all the parts should be in place with 4 of the small gears properly engaged on the hub gear (the part clamped in the vise.) The 4 pairs of small gears may not be touching each other yet. Slowly draw the 2 halves together by tightening each bolt by 1/2 turn, working your way around, the same as in dis-assembly. Watch the pairs of small gears as they come together, you may need to rotate 1 or more of the small gears so that it meshes correctly with its mate. Replace the longer bolts with the shorter bolts, when you run out of thread, and keep drawing everything together, slowly. After both halves are compressed together with the 8 inner bolts, you can put the small outer bolts together and tighten them up. (I think there are 6 of them.) Slowly remove the nuts from the 8 inner bolts. Everything is NOW under spring pressure and the small gears will not move easily. Easily lift the differential assembly off the hub and gear. Slide it back on the tractor axle and the small gears should line up with the larger inner gear just fine, you may need to rotate the inner flange a bit to get the bolt holes to line up, after the assembly is slid into place. Put the 8 bolts back in and tighten to the specifications listed in the manual. NOW pack grease into the differential assembly until you can't get any more to go in. A needle adapter on a grease gun works good but something like a tongue depressor will also work for packing the grease in. Put outer hub and wheel on and you should have a better working tractor. I am not sure about your tractor but on the early style of this differential assembly (I know on the 700, 725) the outer hub had snubber bolts that tightened against a nylon sleeve inside the hub. Properly adjusting these bolts by the Simplicity manual will make a world of difference in traction. - I know this was a long reply but this is the easiest way I know to repair these differential assemblies. - If the 2 halves are drawn together too fast, the small gears can bind and chip. - Assembling the unit on top of the outer hub and gear aligns the smaller gears so they don't need to be rotated when the assembly is placed back on the axle, everything is already lined up. - - - - - I would like to see the fixture or machine that put these together at the Simplicity factory. - -

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landlord2110
Is this the same diff thats in the landlord 2110? I like the breakdown by brozak. That breakdown is for dummies like me who dont do that kind of repairs everyday.

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HubbardRA
Sorry Mike, but I don't really have the time to make the step-by-step drawings that you asked for. All you have to do is insert a washer between the spring and the housing. When you try to put the first one in there you will see it won't fit without grinding the outer edge down some. Just do that and reassemble as outlined in the detailed explanation above. As anyone who had worked on a diff and done detailed assembly drawings knows, I can shim a diff in less than an hour. Doing detailed drawings would take all day or longer with the software that I have on this home computer.

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brozak
I have one in a box, for parts, that I will take pictures of later tonight. I'll try to show normal assembly and shimmed assembly. The landlord 2110 has basically the same differential. The 8 small pinion gears are the same. The 2110 has spacers in place of the springs and I believe the amount of slip between wheels is controlled by the snubber bolts I mentioned. (landlord 2110 information is from looking at the parts diagram.)

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HubbardRA
Be interesting to see what Mr. Brozak comes up with. It has been over 20 years since I shimmed my limited slip diff. Since then, I have not shimmed any of the others that I have. I shimmed that first one for tractor pulling. I had been using it with a locked diff, but the general maneuverability was so poor, that I decided to go with a tighter limited slip. I haven't seen the need for shimming the diffs in my other RBTs since most of the wheel slip has been cured by the larger tires I am using.

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dave45056
WOW... Brozak, your instructions worked like a charm. I have the whole thing apart. I have inspected everything and it looks perfect, though. I was planning on shimming springs. I am confused about using 1/4" or 5/16" washers. It looks like the Pinion Spindles (P/N 121083) fit between the Ring Spacers(P/N 171517) withought a gap. The bolts which go though the diff are 3/8. The pinion spindle is 5/8" OD. The springs are 7/8" OD. In order to shim the springs the washers would need to be 5/8" ID and 7/8" OD. I am not sure how thick to use, but will check how far the spring can be compressed before getting solid. Has anyone done this recently? Rod's recollection may be a little off after 20 years (no offense).

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HubbardRA
Dave, I guess those were 3/8 washers that I used. I did not spend time trying to find washers with only the 5/8 OD like you said. I used the standard washers that I picked up from the bin at the local hardware store. That is why I said that I ground material off one side of the washer so that it would fit inside the housing. I left the material on the other side. That way I could hold it with vice grips and grind it on my 8 inch grinding wheel. Sorry that I stated the wrong size in the earlier post. I was thinking about the 1/4 bolts on the outside instead of the larger ones that held the gears. I used the same shimming technique on a motorcycle clutch setup, rather than buying a new set of disks for a cost of around $300. Washers are cheap compared to that.

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brozak
I'd like to apologize for taking so long to get back here and post these pictures but Rodney is right, I probably could have assembled 2 or 3 of these in the time it took to edit the pictures, make a crude drawing, and type all of this. Dave, I'm glad to hear you didn't find gears that look like the ones in the following pictures. I have never shimmed a differential but I fully understand the concept and had extra parts I could take pictures of. - The following pictures and descriptions should help anyone else that is currently reading this and is trying to envision what is being talked about, or anyone in the future that reads this full topic. -


What I would call 1 set of PINION, SPRING, and SPINDLE, setting on the RING, spacer on the outside COVER. Each of the 4 sets alternate in the same way, around the cover. The outside COVER has a ridge around the center hole, the SEAL fits over the ridge. The inside COVER is flat on the face around the center hole. The pencil is holding the BOLTS up against the outer COVER and everything is setting on top of the outer hub and gear, which is clamped in a small drill press vice. - The PINION (gears) should NOT look like the top one. These pictures of of dead parts I saved and haven't sorted yet. -


Inner RING setting on top. This RING is warped, the COVER is also warped. Somebody assembled the unit too fast and didn't apply even pressure as the springs were bieng compressed.


Standard washer on the SPINDLE. This is how a washer needs to fit around the SPINDLE, to add more tension on the SPRING. A SPRING goes between the PINION and washer.


Inside cover on top of everything. These are original bolts sticking through, with the COVERs not compressed together. The COVERs will bend and warp if only the 6 small 1/4-20 bolts are used to draw everything together. For some reason I remember using longer bolts, as I described previously. It looks like these have enough thread sticking through, to start nuts on them, and compress everything.


Picture of where washers need to be placed to give more SPRING tension. These are just standard washers.


Picture #2 of where washers need to be placed to give more SPRING tension.


Washers would need to go in between the SPRING and RING, spacer. The added washers can not go between the cover and RING, spacer. Adding washers between the cover and RING, spacer would only spread the 2 COVERs apart because everything gets tightened against the SPINDLE, diff. pinions.


As Rodney said, standard washers would need to be trimmed. The RED lines are drawn in where the washers would need to be trimmed just to fit together. The wear marks around the holes on the SPACER are from the SPRING and PINION rubbing on it. The SPACER seems to be a harder metal, it has a different sound when tapped on or dropped on other steel. I didn't have a chance to try grinding on it to see if the sparks were smaller - harder steel. They call it a SPACER but I think it works more like a wear plate. I think the washers shown above would cause problems if they were only trimmed where I drew the RED lines. The un-trimmed part of the washers would rotate into the PINIONs as soon as one wheel traveled more than the other. I think it would have the effect of locking up the differential or making it tight as the washer and PONION grind against themselves. My thoughts about the washers: - Smaller OD washers wouldn't require any trimming. - Larger OD washers could also be used if they were trimmed to clear the PINION, center hole, and a flat spot that locked them against the cover so they wouldn't rotate. - The washers shown could be trimmed as indicated and then welded to the SPACER so they wouldn't rotate. Dave, if you put it together with washers to add more tension, I think you are correct: "In order to shim the springs the washers would need to be 5/8" ID and 7/8" OD." The thickness of the washers can only be equal to or less than: (length of SPINDLE) - (length of PINION + length of compressed SPRING); any thicker, and everything is bound together, with no movement. Stacking washers for more thickness, or more compression of the SPRINGs, may have an opposite effect of what you are trying to do. Even though the SPRINGs and PINIONs will be pressed against each other tighter, there may be less friction between everything. Dave, I hope you got yours back together and working, please post back how it worked out, even if you didn't add washers. I get disappointed when I read a topic like this that just dies with no conclusion of what worked. I hope these pictures and my color drawing have helped.

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dave45056
I put my differential back together using the instructions Mark posted before. Once you get into it you will see why it makes sense to keep the center gear in place while assembling. I flipped over the Ring, Spacer so I had fresh areas to wear in. My gears looked perfect... Hardly any wear at all. The plate I flipped had some scratches around every other hole similar to the pics above, but not as deep. Also mine were very flat. A couple things I found... I think it would be VERY difficult to replace the bolts on a fully assembled unit, even 1 at a time. So if you can use the standard bolts it will be easier even if you have to pre-compress the 2 halves in a vice or press. There is a small hole on each flange on the diff covers. These need to be lined up at assembly. The 3/8-16 nuts on the diff are locking nuts. It's easier to replace these with standard 3/8 nuts for disassembly and reassembly. Since you have to remove them on the last step to put the diff back on the tractor, you can use teh locking nuts at that point. This reduces the number of times the locking nuts get used. I was going to replace the springs (at $2 each) and maybe add shims. Since I had neither of these parts in hand, I convinced myself it's easy enough to take it out again later when I have all the stuff. I was too anxious to get my tractor running again. I have not had a chance to see if the diff is working differently than before, yet. I will check it soon, before buying any new parts.

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brozak
Great to hear you got it back together Dave. Thanks for adding your experience, like using standard nuts instead of the lock nuts, I forgot about that. It has been about 2 years since I had the one apart on my 7014s and about 25 years since I did it on a 725.

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Vassal
Thanks for the effort spent here fellas, this is great info and the pics are priceless! Regarding the flat washer used for shimming, you mention the perfect washer would be 5/8" ID and 7/8" od - this yields a wear surface of only 1/8" wide. That seems a bit narrow no? Maybe an 5/8" SAE washer would be better than the USS style I think you're showing. 5/8" SAE vs USS washer; Slightly smaller ID: 21/32" vs 11/16" - tighter fit on spindle - less chance to walk around Much smaller OD: 1 5/16" VS. 1 3/4" - less grinding for clearance Slightly thinner: 13ga (3/32") vs 10ga (9/64") - maybe too thin?? - maybe just right so diff is not too tight?? I believe the SAE washer is hardened too, but bot sure. Anyway, just my $.02 Thanks for sharing

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rjobkar

I just want to thank everyone that who has contributed to this thread. I was able to rebuild my differential with this information. I was able to use the original bolts, I didn’t not need any longer to assemble or disassemble.

what I did notice with mine was the wear plates on each side were worn 4 on each side most likely where the springs would turn against them. I flipped the wear plates and bought new springs. Put it all back together, used the black permatex to seal, And now I have both wheels gripping again!!!

my springs looked ok and the spring tension felt about the same, but I replaced them anyway. 

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