Best LSD diff kit rebuild

[Brian65]

Just joined & introduced myself few hours ago Im in need of help. After a couple packs on my EXB Mojave the rear diff l went south. When I turn one wheel the other or both will ratchet or catch. It's essentially a front wheel drive rig now. Ive taken it apart and reassembled with new LSD disks, inspected all gears and still rear does not function correctly. Watched several videos but not sure what shims to use. How good is the RCAWD diff kit? What's the best fix. Would like to do away completely with the disks or LSD. Thanks

 

[Woodentop]

https://www.arrmaforum.com/threads/building-a-stronger-29mm-diff.43971/

This is @HZRDOS work. I'll be using this guide to rebuild my exb diffs this winter and welcome aboard.

 

[parcou]

Just joined & introduced myself few hours ago Im in need of help. After a couple packs on my EXB Mojave the rear diff l went south. When I turn one wheel the other or both will ratchet or catch. It's essentially a front wheel drive rig now. Ive taken it apart and reassembled with new LSD disks, inspected all gears and still rear does not function correctly. Watched several videos but not sure what shims to use. How good is the RCAWD diff kit? What's the best fix. Would like to do away completely with the disks or LSD. Thanks

LSD diffs "should" be a lot better from the first introduction when that fix was introduced. The fix does work, but before you go that direction:

Open the diff and make sure no plates or nothing is missing. Something Horizon Hobby misses the mark. I would make sure the diff in question isn't missing anything and is assembled well. In hand, it turns and feels good. There will be a little bumpy feel due to the LSD plates, but it should be smooth as you twist the outdrives.

Next, shimming. There should be a shim on the ring gear side that pushes the diff close to the input gear in the diff. Make sure there is no side/side movement, add another shim if needed AND it has a good mesh with the input gear in the diff. Sometimes you need a shim on the inner diff input gear. But, I have not needed to do that on any of my rigs with LSD diffs so far compared to some of my open diff rigs.

Check: the diff assembly and check the shimming once the diff is installed. I feel the fix could be simple...even a new purchase can come put together improperly.

Without much info, I think you only need the shims that came with it unless you have pictures showing more details. It is important that all the inner gears and plates for the LSD are installed correct. It has to be exact.

 

[parcou]

Just joined & introduced myself few hours ago Im in need of help. After a couple packs on my EXB Mojave the rear diff l went south. When I turn one wheel the other or both will ratchet or catch. It's essentially a front wheel drive rig now. Ive taken it apart and reassembled with new LSD disks, inspected all gears and still rear does not function correctly. Watched several videos but not sure what shims to use. How good is the RCAWD diff kit? What's the best fix. Would like to do away completely with the disks or LSD. Thanks

I know this is on a new Fireteam that has the same setup similar to the Mojave, but see here good examples of new rigs with issues....

Some good pics of the post below it of the LSD diffs as well

https://www.arrmaforum.com/threads/...scale-speed-assault-vehicle.47731/post-847843

 

[Brian65]

LSD diffs "should" be a lot better from the first introduction when that fix was introduced. The fix does work, but before you go that direction:

Open the diff and make sure no plates or nothing is missing. Something Horizon Hobby misses the mark. I would make sure the diff in question isn't missing anything and is assembled well. In hand, it turns and feels good. There will be a little bumpy feel due to the LSD plates, but it should be smooth as you twist the outdrives.

Next, shimming. There should be a shim on the ring gear side that pushes the diff close to the input gear in the diff. Make sure there is no side/side movement, add another shim if needed AND it has a good mesh with the input gear in the diff. Sometimes you need a shim on the inner diff input gear. But, I have not needed to do that on any of my rigs with LSD diffs so far compared to some of my open diff rigs.

Check: the diff assembly and check the shimming once the diff is installed. I feel the fix could be simple...even a new purchase can come put together improperly.

Without much info, I think you only need the shims that came with it unless you have pictures showing more details. It is important that all the inner gears and plates for the LSD are installed correct. It has to be exact.

I did notice on all 4 inner sides of diff case the plastic looked chaffed. This is where the small square plates fit.

 

[HZRDOS]

I did notice on all 4 inner sides of diff case the plastic looked chaffed. This is where the small square plates fit.

I highly recommend the Arrma 29mm aluminum diff cases. A few reasons for this - but for me, the BIG one is ease of shimming under outdrive pins. The stock plastic cup side is a MAJOR pain to place an extra shim under the pin and still get the pin in place. The aluminum cases have a separate end piece that you can shim and place the pin and outdrive in, then assemble the case.

Also recommend the M2C outdrives and cutting your own pins out of HSS steel blanks. Use a good M35 steel. I feel it has the right amount of cobalt to make it strong, but not so brittle that the shear forces on the pin will snap it (5% versus 8% in M42 steel).

I do not like the LSD plates, but do like the EXP 29mm diffs. The LSD plates I feel generate too much heat, and also place too much force on the outdrive pins under hard throttle when the spider gears are forced towards the sun gear and create the diff locking action.

 

[Brian65]

I highly recommend the Arrma 29mm aluminum diff cases. A few reasons for this - but for me, the BIG one is ease of shimming under outdrive pins. The stock plastic cup side is a MAJOR pain to place an extra shim under the pin and still get the pin in place. The aluminum cases have a separate end piece that you can shim and place the pin and outdrive in, then assemble the case.

Also recommend the M2C outdrives and cutting your own pins out of HSS steel blanks. Use a good M35 steel. I feel it has the right amount of cobalt to make it strong, but not so brittle that the shear forces on the pin will snap it (5% versus 8% in M42 steel).

I do not like the LSD plates, but do like the EXP 29mm diffs. The LSD plates I feel generate too much heat, and also place too much force on the outdrive pins under hard throttle when the spider gears are forced towards the sun gear and create the diff locking action.

Thanks for tips. Any preference on shims to use? I read alot use the Mugen Seiko. I have a local HS that would probably have the Kyosho ones. Would they be worth it? Hate to say it but I have most all Traxxas rigs and this is my first Arrma or anything else. Shimming is sorta new to me. LOL

 

[HZRDOS]

Thanks for tips. Any preference on shims to use? I read alot use the Mugen Seiko. I have a local HS that would probably have the Kyosho ones. Would they be worth it? Hate to say it but I have most all Traxxas rigs and this is my first Arrma or anything else. Shimming is sorta new to me. LOL

I just use Arrma shims. don't see the need to use other ones if I have the size needed. I do special order the shims to to the LSD plate removal. It is listed in my thread that was posted above.

 

[Brian65]

Here's a couple pics of my rear diff which pulls for about 15-30 seconds then quits. Pic of inside diff shows what looks like scuff marks where the square LSD disks go. I bought brand new couple weeks ago so the shims shown is what was in each diff. 1 shim on pinion & 1 shim on outside of ring gear side which I didn't get pic of. I guess this is how they all come? No problems for about first 4 packs.