29mm exb diffs worth it?

[Garcbomber]

The latest revision has a shim instead of the 3 LSD plates under the sun gears. I’d bet that created a binding situation under certain angle oscillations and caused the teeth to shear. I sent them a photo and they sent another no questions asked.

 

[RCbuzz]

The latest revision has a shim instead of the 3 LSD plates under the sun gears. I’d bet that created a binding situation under certain angle oscillations and caused the teeth to shear. I sent them a photo and they sent another no questions asked.

View attachment 334136

View attachment 334137

Well the diff's sure look like a million bucks! Hope they hold up!

 

[Garcbomber]

The shim is 17.5mm OD, 12mm ID, and 1.9mm thick for RCAWD.

I ordered this to compare while I wait for their engineer’s response.


ARRMA Diff Shim Set (Fits 29mm Diff Case) (3 Diffs), ARA311094 https://a.co/d/dpwrL1j

 

[RCbuzz]

The shim is 17.5mm OD, 12mm ID, and 1.9mm thick for RCAWD.

I ordered this to compare while I wait for their engineer’s response.


ARRMA Diff Shim Set (Fits 29mm Diff Case) (3 Diffs), ARA311094 https://a.co/d/dpwrL1j

I just received mine as well, the build quality looks pretty nice. I am wondering if those shims should be more like 2.0 to tighten them up a little. Please report back!

 

[Lil Dylan]

The shim is 17.5mm OD, 12mm ID, and 1.9mm thick for RCAWD.

I ordered this to compare while I wait for their engineer’s response.


ARRMA Diff Shim Set (Fits 29mm Diff Case) (3 Diffs), ARA311094 https://a.co/d/dpwrL1j

What shims, if any, are being used for the planetary gears? My Mugen shims don't fit into the case? My first time doing this, so maybe I’m doing something wrong...

 

[Garcbomber]

What shims, if any, are being used for the planetary gears? My Mugen shims don't fit into the case? My first time doing this, so maybe I’m doing something wrong...

I shimmed one for fun, had to snip trim flats on each to fit. I would leave planetary set as is and just delete the sun gear plates. That’s where the binding occurs with the arrma ones too.

 

[RCbuzz]

The shim is 17.5mm OD, 12mm ID, and 1.9mm thick for RCAWD.

I ordered this to compare while I wait for their engineer’s response.


ARRMA Diff Shim Set (Fits 29mm Diff Case) (3 Diffs), ARA311094 https://a.co/d/dpwrL1j

How did those Arrma shims look? Was the main sun gear shim also 1.9?

 

[Garcbomber]

How did those Arrma shims look? Was the main sun gear shim also 1.9?

Apologies for the delay, they’re close at 12x17.4x1.8mm

I’ll put it together and see how it feels, should be close enough for the backup girls I date…

 

[Garcbomber]

After a few revisions, these are going to need some investments to hold up on 8S.

Internal planet/sun set and outdrives are failure modes. RCAWD makes a nice case set and ring/pinion, the rest is rubbish. Still cheaper than a parts assembly, and much tougher.

 

[KnowAir]

After a few revisions, these are going to need some investments to hold up on 8S.

Internal planet/sun set and outdrives are failure modes. RCAWD makes a nice case set and ring/pinion, the rest is rubbish. Still cheaper than a parts assembly, and much tougher.

View attachment 345867

Aside from bashing space limited, my biggest concerns with 8s in a 6s rig would be diff failures. Can't handle very well either I wouldn't imagine? Depends on how used I guess.

 

[slick2500]

After a few revisions, these are going to need some investments to hold up on 8S.

Internal planet/sun set and outdrives are failure modes. RCAWD makes a nice case set and ring/pinion, the rest is rubbish. Still cheaper than a parts assembly, and much tougher.

View attachment 345867

Safe to assume that the Arrma internals are better?

 

[Garcbomber]

Safe to assume that the Arrma internals are better?

Yes, if you use the round LSD plate on the bottom to support the cast sun gear ears. I have my light SCT Mojave with that configuration in the rear, not a lot of packs through it but small tire and not a big jumper landing on power will certainly increase longevity. Obviously some have had great results with the OEM EXB diffs and they continue to release new 6S models with them.

 

[slick2500]

Yes, if you use the round LSD plate on the bottom to support the cast sun gear ears. I have my light SCT Mojave with that configuration in the rear, not a lot of packs through it but small tire and not a big jumper landing on power will certainly increase longevity. Obviously some have had great results with the OEM EXB diffs and they continue to release new 6S models with them.

Only issues I have had were the screws loosened up on one of the diffs then shredded the gasket and another time I literally split the diff cup. I just think it's ridiculous the price Arrma wants for all the diff parts or even a complete diff.

 

[SrC]

+!
Feel the same...

Arrma/HH does seems to want to blatantly make profit on those parts. I get that. All brands are this way to some extent.
Almost like they are intentionally designed to be replaced often, IMO.
Arrma could have done better.
Just seems that they make them only barely just "Good enough".

 

[KnowAir]

+2 I ended up just buying a complete blx diff off of JRC instead of rebuilding an exb. I know it's not as strong but for the money, just replace and move on..well, until the blx diffs aren't available anymore.

 

[Garcbomber]

$75 for just the ara310990 gp4 (no input) assembly seems like they're still paying off the original tooling costs for their changes.

You're better off buying a 50T center assembly for $40 and getting the EXB GP4 (43/10) ring/crown and input separately for another $40.

Edit-looks like amzn has a sale
https://www.amazon.com/ARRMA-310990-Limited-Slip-Diff/dp/B08BJ5S64W

 

[SrC]

+2 I ended up just buying a complete blx diff off of JRC instead of rebuilding an exb. I know it's not as strong but for the money, just replace and move on..well, until the blx diffs aren't available anymore.

After 100 + diff rebuilds, I am familiar and Quite comfortable running them. The only main advantage to 29mm Diffs are the stout Input and Main gears. Maybe more important if running 8s setups???
That whole LSD thing was a fail IMHO.
Hence why Arrma now makes them as open diffs for the Front and Rear now.
I honestly don't think Arrma will be dropping the standard open diffs any time soon.

 

[KnowAir]

After 100 + diff rebuilds, I am familiar and Quite comfortable running them. The only main advantage to 29mm Diffs are the stout Input and Main gears. That whole LSD thing was a fail IMHO.
Hence why Arrma now makes them as open diffs for the Front and Rear now.
I honestly don't think Arrma will be dropping the standard open diffs any time soon.

Yeah, the ring gear on mine was misiing a couple teeth. No point in spending $40 without even getting inside the diff I figured. I still have 3 others in operation, maybe one of those will eat it's inards and I can salvage the ring and pinion. Otherwise, I couldn't care less when a complete blx diff can be had w/ housing and bearings for $38. There's just no point in rebuilding them to me.

 

[SrC]

I agree that $38. for a prebuilt drop in is a good option.
I always rebuild mine, new and all. My own oils. I am honestly getting 30-40 packs on my diffs, without a hard failure. Just swapping out oil as needed. They never leak or brick the gears. Just normal wear. If anything the BB's will fail first. Then I get another for $38.
I feel using the Mugen Diff shim kit and building them like a Tekno diff like their manual states , really works. Proper shimming is always a given.

 

[KnowAir]

I agree that $38. for a prebuilt drop in is a good option.
I always rebuild mine, new and all. My own oils. I am honestly getting 30-40 packs on my diffs, without a hard failure. Just swapping out ils as needed. They never leak or brick the gears. Just normal wear. Then I get another for $38.
I feel using the Mugen Diff shim kit and building them like a Tekno diff in their manual, really works. Proper shimming is always a given.

Huh, I can't say I ever kept track of packs but, both my 6s EXB'S went 2 years without even opening them. Ever.