Notorious First diff service - rear diff problems

[L3phturn]

Finally servicing my diffs and replacing bearings with sealed. This is my first Arrma and my first time opening up a diff. I watched a bunch of YouTube videos on it and got various shims but not everything I need. Looking for advice.

Rear diff has a shattered pin on the crown side. Both out drive shafts are damaged and won’t pull out of the cup and the ring. Gears all look Ok though.

I need diff pins. Should I get new out drives too? They look fine they just won’t come out. Should I set up a jig and tap the out drive shafts out? I have a bunch of different shims but not ones that sit under the pins. Should I get extra shims for under the pins to tighten it a bit, or extra shims for behind the planetary gears? Or both?

 

[RCBro80]

This thread should help: https://www.arrmaforum.com/threads/k6s-diff-setup.29171/page-2#post-405642

As for the outdrives, here is what I do:

 

[jondilly1974]

Take a small file to the burrs on the outdrive shafts to get them out. If they are wallowed out then replace them.

 

[L3phturn]

Take a small file to the burrs on the outdrive shafts to get them out. If they are wallowed out then replace them.

I need to pick up a small file and some emery paper to smooth them out and de-burr them.

LHS did NOT have pins or stock of anything that is similar. I ordered a 12 pack of 2.25 mm black oxide drill bits and a friend is going to lend me her father's old dremel so I can cut them. Should do the trick unless the black oxide bit shafts are too soft or brittle, but they are drill bits so hopefully they won't be crap. I need to find a local fastener place that I can talk to for drill blanks, drill bits and shims plus metric bolts. Any other Canadians (especially in Ontario) have a fastener place or other supplier for these things?

So far the only place I can get the Mugen Seiki or Associated shim kits for the diffs are from AMain hobbies in California. That'll be expensive. Horizon Hobby does not carry them. I don't see them on Amazon Canada - I'll check EBay.

 

[RCBro80]

For shims in Canada, try RCDepot.ca. The owner was kind enough to send them to me free of charge, due to the small size/weight.

As for drill bits, #43 drill bits should be a near perfect fit. Try https://www.kbctools.ca/

 

[L3phturn]

For shims in Canada, try RCDepot.ca. The owner was kind enough to send them to me free of charge, due to the small size/weight.

As for drill bits, #43 drill bits should be a near perfect fit. Try https://www.kbctools.ca/

Awesome thanks so much!

 

[RCBro80]

I should have clarified... RC Depot waived the shipping charge (I paid for the shims )

 

[L3phturn]

Hmmmm - how long are the 2.25mm pins behind the sun gears? 8mm?

 

[Notorious J]

Finally servicing my diffs and replacing bearings with sealed. This is my first Arrma and my first time opening up a diff. I watched a bunch of YouTube videos on it and got various shims but not everything I need. Looking for advice.

Rear diff has a shattered pin on the crown side. Both out drive shafts are damaged and won’t pull out of the cup and the ring. Gears all look Ok though.

I need diff pins. Should I get new out drives too? They look fine they just won’t come out. Should I set up a jig and tap the out drive shafts out? I have a bunch of different shims but not ones that sit under the pins. Should I get extra shims for under the pins to tighten it a bit, or extra shims for behind the planetary gears? Or both?

View attachment 106160
View attachment 106161

As for the outdrives, just sit the cup or spur between two hard objects and tap them out with a punch. As long as you hit dead center, you'll be able to reuse everything.

 

[Spoc85]

Pins behind the Sungears are 9mm length ways.
I’d be using 2.5mm

 

[jondilly1974]

Pins behind the Sungears are 9mm length ways.
I’d be using 2.5mm

2.5 doesn’t fit the V4 diffs. 2.3 maybe.

 

[Spoc85]

2.5 doesn’t fit the V4 diffs. 2.3 maybe.

I got the 2.5s in there.

 

[jondilly1974]

I got the 2.5s in there.

I’ve been unable to the 2.5 pins from the EXB into a V4 sun gear

 

[Spoc85]

I’ve been unable to the 2.5 pins from the EXB into a V4 sun gear

View attachment 107608

It’s been a while but I’m sure these are the pins I used last time I had the diffs opened.

 

[Spoc85]

You might be right........ I just found more pins. Il have to open it up and take a look.

 

[jkflow]

Pins behind the sun gear are 2.2mm, max that will fit is 2.3mm.
I just measured the pins in a spare set and I'm using the 2.3mm in several of mine. I switch them out as I go along.

I used this one, you will need tool steel
https://www.mcmaster.com/2900A241/

2900A241

Hardened Undersized High-Speed M2 Tool Steel Rod, 2.300 mm Diameter, 2-1/4" Long

Note: Drill bits will work but tyou will only get 1 pin out of 1 bit.

 

[3d-rc.myshopify.com]

Stock arrma pin is 2.2 but if you measure them they are between 1.9 and 2.1
You can go to mcmaster carr and get drill blanks. You get 4 out of 1 pin and the biggest you can fit is 2.3 mm and it is very snug. 9.6mm is max length I would use. Cut slightly oversized and grind down to length and DO NOT LET IT GET HOT AT ANY POINT. You will take the hardest out of it. I dip mine in water every couple seconds.

 

[L3phturn]

I ordered this from Amazon:

Stock arrma pin is 2.2 but if you measure them they are between 1.9 and 2.1
You can go to mcmaster carr and get drill blanks. You get 4 out of 1 pin and the biggest you can fit is 2.3 mm and it is very snug. 9.6mm is max length I would use. Cut slightly oversized and grind down to length and DO NOT LET IT GET HOT AT ANY POINT. You will take the hardest out of it. I dip mine in water every couple seconds.

Canada so I can't order blanks from McMaster Carr. Damn, I was told it was 2.25 so ordered this: Bosch BL2633 Black Oxide Drill Bit, 3/32-Inch by 6-Inch

I also have some emery paper coming and will spin the out drive shafts in the drill to de-burr them. Looks like I may have to take a few hundreds of a mm off of the drill bit piece. The good news is that a 6 inch long drill bit will give me quite a few 9.5 mm long pins.

Thanks so much for the tips on cooling, cutting and fitting!

 

[olds97_lss]

I ordered this from Amazon:


Canada so I can't order blanks from McMaster Carr. Damn, I was told it was 2.25 so ordered this: Bosch BL2633 Black Oxide Drill Bit, 3/32-Inch by 6-Inch

I also have some emery paper coming and will spin the out drive shafts in the drill to de-burr them. Looks like I may have to take a few hundreds of a mm off of the drill bit piece. The good news is that a 6 inch long drill bit will give me quite a few 9.5 mm long pins.

Thanks so much for the tips on cooling, cutting and fitting!

When you debur, be careful to only sand where the pin goes through. You don't want to rough up where the o-ring sits at all or you will likely burn through the o-rings at a much higher rate than normal.

 

[L3phturn]

When you debur, be careful to only sand where the pin goes through. You don't want to rough up where the o-ring sits at all or you will likely burn through the o-rings at a much higher rate than normal.

Thanks for that... hey what grit emery/sand paper should I use?