Talion V4 diffs and servo saver

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bicketybam

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Arrma RC's
  1. BigRock 4x4
  2. Granite
  3. Infraction
  4. Kraton 8S
  5. Kraton 6s
  6. Kraton 4s
  7. Mojave
  8. Notorious
  9. Talion
  10. Typhon 6s
1. I've been through the front and the center diffs. They are identical to the V3 diffs. If they were supposed to have extra shims or washers, mine do not.

2. I cannot adjust the new servo saver, at least with it out of the truck. It feels like the two halves are cemented together. I went to tighten it because it came like this:
20190415_091800.jpg

I tried holding the top half of the servo saver while turning the bottom. No way. I then held the top half with vice grips and tried turning the bottom. All I did was mangle the top part of the servo saver. Either I'm doing something wrong or Arrma's answer to the servo saver coming loose is to cement the halves together with thread lock.

I'm very disappointed with both issues.
 
1. I've been through the front and the center diffs. They are identical to the V3 diffs. If they were supposed to have extra shims or washers, mine do not.

2. I cannot adjust the new servo saver, at least with it out of the truck. It feels like the two halves are cemented together. I went to tighten it because it came like this:
View attachment 35465
I tried holding the top half of the servo saver while turning the bottom. No way. I then held the top half with vice grips and tried turning the bottom. All I did was mangle the top part of the servo saver. Either I'm doing something wrong or Arrma's answer to the servo saver coming loose is to cement the halves together with thread lock.

I'm very disappointed with both issues.
This is great info @bicketybam. Many of us V3 and older owners, might have thought to upgrade with many of the new V4 parts, but the jury is still out on whether modding the existing or upgrading to new, is going to be worth it. I thought the new servo save used an o-ring to secure the nut, but if they put threadlock, it would defeat the concept. If you heat it up to try and get it off, you're likely to ruin the plastic and o-ring, so this is a real dilemma to deal with.
 
No shim/washer to be found.
I did look it up directly from the manual (ARA10604) available at Horizon Hobby and just confirmed it on Arrma's site as well (ARB200020936). As I mentioned in the OP, I could be wrong but I'm not making any unsupported claims/assumptions/opinions, just pulling numbers directly from the manual w/ 'ARA' prefix.
View attachment 34064

I would assume your Talion V4 was a pre-production unit and was not built to the manual spec with shims for whatever reason (late engineering change, parts availability during PP build, non-standard production procedure, assembly mistake, etc...).

Just my 2 cents on this with a little speculation haha...I think it could have been 1 of 2 things
1. Late change added based on the influence of guys like yourself, RichDuperdash, & others (Jason Dearden confirmed himself in Vaz's interview) who have a large audience and also shim their diffs as preventative measures.
2. Non-advertised change - by advertising adding shims as a "durability improvement" they could open themselves up to questions about whether current design is sufficient (which it is for many like myself) and a flood of differential warranty claims they otherwise wouldn't have received. This is difficult for any manufacturer from a marketing standpoint, you always want to improve design but you don't want make an existing design still in the marketplace appear inferior, insufficient, unsafe, etc... especially a warrantied product.
Looks like there should be a lot of shims, based on this diagram. Even one to go under the planetary, between the pin and the o-rings. I've spec'd all of these before, and the one that covers the o-ring, should be different than the one that goes on the outdrive before the bearing. ARA709057 is 5.4x9.5x0.2. The Mugen shim used by many under the planetary, is 5x18x0.2. You need to contact someone, because it looks like you got a V3 dif. Were the satellite gears shimmed?
 
Looks like there should be a lot of shims, based on this diagram. Even one to go under the planetary, between the pin and the o-rings. I've spec'd all of these before, and the one that covers the o-ring, should be different than the one that goes on the outdrive before the bearing. ARA709057 is 5.4x9.5x0.2. The Mugen shim used by many under the planetary, is 5x18x0.2. You need to contact someone, because it looks like you got a V3 dif. Were the satellite gears shimmed?
Yes. It is identical to every Arrma 6s diff I've had. I'm really not concerned. It's just that they are promoting one thing and doing another.
 
I don't see how you can adjust the servo saver with the truck assembled like the old one. Have any V4 owners messed with it yet? I may try to find an old style one and ditch this new one.
 
I don't see how you can adjust the servo saver with the truck assembled like the old one. Have any V4 owners messed with it yet? I may try to find an old style one and ditch this new one.
Jennys!
 
I don't see how you can adjust the servo saver with the truck assembled like the old one. Have any V4 owners messed with it yet? I may try to find an old style one and ditch this new one.
Sh!t, they're sold out unless the Senton works
 
Yes. It is identical to every Arrma 6s diff I've had. I'm really not concerned. It's just that they are promoting one thing and doing another.


I took all of mine apart and all 3 had shims behind the pins and on the outdrives. Haven’t messed with the servo saver though, I’ll take a look at it tonight.
 
Yes. It is identical to every Arrma 6s diff I've had. I'm really not concerned. It's just that they are promoting one thing and doing another.

But as far as I can tell, they never actually advertised/promoted shims did they? I never heard official word from arrma, just forum people pointing it out in the manuals before actually owning one. Maybe the manuals were printed and they had to ditch the shims before production release for some reason, and that's why it's not mentioned in the "v4 upgrades" anywhere? Who knows. It is a weird one.

Also wonder if it's a part for one of the other models the manual lists and not talion specific?
 
I seen on YouTube someone that I'm not name dropping doing an inspector on the new Kraton and said the new diffs were shimmed.
 
Never loosen servo saver, is never tighten, never move? Is it even adjustable?
I think you nailed it. I don't think it's adjustable. Look at the diagram here. Instead of it being one threaded piece with a collar nut, it is now 2 halves. Loosening or tightening the two halves would change the overall height of the steering arm. I believe the two halves are tightened all the way and secured with locktite. Good luck getting them apart without destroying the plastic that fits over it.

20190416_080901.jpg
 
I also wondered by looking on the design how it's actually adjustable. you confirm my fears that it's simply not. that's a step back. not good. I guess it's one less thing that can cause failure due to user errors, but don't we have the 4x4 platform for that kind of thinking?

Regarding the shims, i assume the diagram shows where the shims COULD be, but they don't have to be there, only if needed. My hope is during the assembly they add shims only if needed.
 
I also wondered by looking on the design how it's actually adjustable. you confirm my fears that it's simply not. that's a step back. not good.

Regarding the shims, i assume the diagram shows where the shims COULD be, but they don't have to be there, only if needed. My hope is during the assembly they add shims only if needed.
Agree about the servo saver. While it worked fine in my Talion with the smaller and lighter Katars, I don't know how it will do in a Kraton once someone changes to bigger and heavier tires. Or a stronger/faster servo. This is one of those classic "be careful for what you wish for" scenarios. I hope I can find a V3 servo saver hub somewhere. I don't like this at all.

I emailed Horizon about the missing shims. I asked if they could send me 12 of them. Honestly it's not the end of the world. If I had the ones I usually use I would have just put them in, but I was out. These shims are more for the mesh on the internal gears and I've never had an issue with those. I like a shim behind the sun gears to protect the o-ring. But other than that I don't really care
 
I think if you could get the two halves apart you could put some extra washers or a spacer in there to tighten the spring tension, but having to remove the whole assembly to do this would not be ideal. I just ordered a new steering setup for Kraton as I think the old one is slipping under load. I've got the servo saver tightened nearly all the way up, but it still give way when I turn. The one I've got coming is the v3 type.
 
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Happened to me when i (accidentally) sprayed some cow-slick on those parts, it makes them slip much more easily. Only fixed after i took it apart and cleaned them, now i run the SS tighten normally (4-5mm from the chassis) and it doesn't slip.
 
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