Granite 3s/4s Differential assembly - Is there a particular sequence? Why is it locking up when I try to put the cap on?

[GRC]

I'm assembling a 3s/4s BLX differential. I assembled one previously with minor issue. It locked up at first, but after reassembling, spun properly and I've been running it without issue. I don't know what I did or didn't do right to get it to work.

I ordered the parts for a backup differential. All parts are new. I put in all the gears, o-rings, shims, bearing, and everything spins properly, I add oil it still spins properly, when I put the cap (and gasket) on, it gets locked up. I believe I'm lining up the cap correctly. There's really only one way it will fit all the way down.

I watched a few videos and one mentions that you have to put in the gears in a certain order. Unfortunately that video then proceeds not to show this order. All videos I've found are skipping these steps, they go from empty differential to all gears in and time to fill with oil.

Is there a particular order I should assemble the gears? Could there be another reason the differential is locking up when I try to put the cap on?

 

[MrTitanium]

Check to ensure that small gears are meshing properly. Everything is to slip together nicely one assembled right

 

[Resu]

There is no specific order, but three things that already happened to me:

Screws tighten too hard​

Too much diff oil in the wholes of the sticks​

Seal plate blocks the gears​

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[GRC]

Thanks for the replies.

Check to ensure that small gears are meshing properly. Everything is to slip together nicely one assembled right

Everything is spinning great before the final step of putting the cap on.

There is no specific order, but three things that already happened to me:
Screws tighten too hard

Too much diff oil in the wholes of the sticks​

Seal plate blocks the gears​

Locks up just putting the cap in place, before I can get to using the screws. The gasket getting caught up in the gears is not a problem. However, diff oil in the pin holes might be the problem, I noticed some pins may not be seating fully because they were trapping oil in the hole. I'm cleaning the diff case and pins and will try again. Thanks guys.

 

[MrTitanium]

Oil being trapped in the pin holes shouldn’t be an issue (just need to make sure pins are completed seated by pressing down harder and oil will seep out). Chances are backplate is not mating with diff cup: make sure pins line up with pockets in the backplate.

 

[GRC]

Oil being trapped in the pin holes shouldn’t be an issue (just need to make sure pins are completed seated by pressing down harder and oil will seep out). Chances are backplate is not mating with diff cup: make sure pins line up with pockets in the backplate.

I pushed as hard as possible, trust me. The tolerances are tight enough on this diff cup that diff oil in the holes was not allowing some of the pins to go in completely. 10K diff oil, so it's not like the oil was super thick. After cleaning, the pins went all the way in no problem. Still ran into some resistance while putting the cap on, but some "persuasion" with a pair of pliers got the diff spinning, and everything feels good now. I think the pins not seating fully was the problem. It would cause the pins not mating correctly with the backplate as you mentioned.

 

[jondilly1974]

I’ve had hydro lock on the pin holes with too thick of diff fluid. If you go 50k or higher, the pins won’t seat right. You have to clean the cup 100% and assemble dry before adding fluid. I’ve learned this a few times and had to waste fluid.

 

[razorrc]

It's pretty simple. Stick in the spider gears, push them down all the way so they're seated. Stick the last sun gear into the cup. Don't ever spin anything!
Put the cap on with the pin already lined up with the sun gear, put in the 4 screws.

The secret is to never spin the gears until it is fully assembled. And to place the sun gear into the diff first before putting on the ring gear. It'll never get locked up again.

 

[jondilly1974]

It's pretty simple. Stick in the spider gears, push them down all the way so they're seated. Stick the last sun gear into the cup. Don't ever spin anything!
Put the cap on with the pin already lined up with the sun gear, put in the 4 screws.

The secret is to never spin the gears until it is fully assembled. And to place the sun gear into the diff first before putting on the ring gear. It'll never get locked up again.

The ring gear is molded into the cup. The cap is the gearless side.

 

[razorrc]

The ring gear is molded into the cup. The cap is the gearless side.

Thanks, totally forgot. I need to get me another Granite to refresh my memory.