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Thread: An alternative to hd gear mod

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Old 07-09-2016, 08:32 AM   #1
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Default An alternative to hd gear mod

I remember, when I first started to build this rig, that I tried to do the third bearing mod and it seems it was a complete BS because of the amount of shims needed to make a correct play between pinion and ring, so I just went with a standard self made copper pipe spacer instead of that original crappy plastic one. But a few days ago BHB caught my attention saying the third bearing is not used only as a spacer, but also as reducing the stress on the other two bearings. Obvious, right? But never thought about it this way
You know my opinion about this problem, it not a pinion/ring issue, but mainly a bearing issue being THAT undersized. Here are the original straight cut pinion after 100+ runs. As you can see, they look more than reasonable after all this time, both on 4S and 6S. The only two chipped teeth are like this exactly because bearings failure. Otherwise I would have absolutely no reason to change them




Remembering that stupid amount of shims needed to do the third bearing mod, it strikes me that Axial might have partially resolved this problem by making that edge at the end of the pinion. That almost 1 extra mm might help, considering that the width difference between the spacer and the bearing is 0.9mm. Exactly the length difference between the old pinion and the new one.

So, here is my mod

Shims in order from left (pinion side) to right (drive shaft side). You can use, of course, the standard 0.1mm shims provided by Axial, except you have to use more of them. In total I had to use 0.7mm worth of shims.




In addition to the original 0.1mm shims I also use a 0.5mm shim I bought some time ago. I also used an 0.1mm shim near the pinion which I had to dremel inside in order to have the inner ring of the bearing move freely. But this shim is not mandatory. However, if you use it, you do have to increase the inner diameter to more than 17.5-18.00mm. If you don't install this shim you will have a gap of about 0.1mm between the front bearing and the screw fixing it in place. Not a big deal, but that's me, perfectionist




I have to admit, not being very sure if this mod will work I even make a shaft just to be sure I can make BHB's mod. But after a few runs with my mod I'm pretty sure I don't need to cut down that edge.



Advantages over BHB's mod:
- you now have one extra bearing to keep up with the stress on that poor bearings
- you don't necessarily need a Dremel or a BHB , especially when you don't live in the US.

Disadvantages:
- I don't see any. Maybe you, guys, can find any

Last edited by Tzicul; 03-13-2018 at 05:28 PM.
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Old 07-09-2016, 10:28 AM   #2
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Default Re: An alternative to hd gear mod

? This doesn't move the pinion away from the ring gear.. That is the issue

Stock Depth of the Stock HD Pinion gear


Modified Depth of the BHB Pinion HD mod


This shows how much the pinion NEEDS to recede for Proper Mesh


I completely endorse any mod that helps.. I just don't get how you achieved mesh reduction ?

Last edited by BarHarborBasher; 07-09-2016 at 12:42 PM.
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Old 07-09-2016, 12:44 PM   #3
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Default Re: An alternative to hd gear mod

And its BHB LMAO
J.k You can call me Joshie for all I care lol

I also wanted to add in that the 3rd bearing helps keep things together ( IF ) the outer bearing goes during a run.. That way you notice the outer bearing is Toast (Without) having your gears tell you lol

Last edited by BarHarborBasher; 07-09-2016 at 12:48 PM.
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Old 07-09-2016, 12:45 PM   #4
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Default Re: An alternative to hd gear mod

Trust me, it does. It runs "butter smooth", I just came back from the track. I tried with 0.8mm shims and it was a little notchy. Not very bad, just a little bit. So I went back to 0.7mm
If you ask me this pinion/ring is another proof of poor engineering from Axial. Did you noticed how wide are the pinion's tooth at the end near the diff case? MUCH wider than the corresponding ring's groove. There is no chance to use the entire width of those grooves. This is why you have to pull the pinion away from the ring.
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Old 07-09-2016, 12:59 PM   #5
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Default Re: An alternative to hd gear mod

No the teeth prematurely mesh together because of the protrusion of the pinion.. It's obvious with a Vanquish.. The driveshaft wont even turn!! That's why Jimmy/Dhawk came up with the V2 bulkhead... To recede the pinion ... It took some emails and convincing but I got him to listen... Hens ... V2 bulkhead... and extinction of the Vanquish..

This is a serious issue to guys blowing up their rigs ...
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Old 07-09-2016, 01:26 PM   #6
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Default Re: An alternative to hd gear mod

Yes, the protrusions makes the pinion to stay way too close to the diff case in regular configuration bearing-spacer-bearing. But with the spacer being replaced with the third bearing and a few shims you'll get the same result
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Old 07-10-2016, 02:20 PM   #7
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Default Re: An alternative to hd gear mod

Yes, it works!

https://www.youtube.com/watch?v=duepvTooMys
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Old 07-10-2016, 02:47 PM   #8
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Default Re: An alternative to hd gear mod

Would the height of the protrusion change if you put one of the shims behind the 3rd bearing next to the c-clip, my thought was putting a shim there could help prevent mud and dirt from getting inside that 3rd bearing. Last time I read about the 3 bearing mod I recall that the rule of thumb was to increase the height of the pinion put more shims behind the pinion gear teeth, to decrease put more in the back. But that was a long time ago I can't find the thread here in the YXL section maybe I had it backwards, BTW is that a 15.190 mm x 19.928 mm x 0.031" shim, the wider of the 3 shims on the 3rd photo of your first post ??? At any rate please update us with your future findings with this experiment/mod.
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Old 07-10-2016, 03:16 PM   #9
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Default Re: An alternative to hd gear mod

In theory you can install any of the shims wherever you want and I tried to install one of them exactly as you say. But in real life that first shim will be deformed by the c-clip because all that forces are applied only to about half of the circumference of the respective shim. So, unless you can find a very thick shim, I wouldn't recommend this. You can try this, not very beautiful, but it works What bell crank should I choose?. Or you can try a 1/8 nitro air filter
Those are the shims I used. There is no problem narrowing them with a nail scissors, if you need
Vespa ET2 50cc 50IE Variator Shim Speed UP SET 15mm | eBay
You are right about the shimming and now I realise if Axial would have released a narrower shim together with new hd gear, it wouldn't have been all this fuss around this subject.
All you need is to pull back the pinion from the ring because the poor engineering of those teeth, they are way too wide compared to the ring's grooves. Maybe I'll take a picture to explain better, but unfortunately I won't be near my cars for the next two weeks :(

Last edited by Tzicul; 07-10-2016 at 03:21 PM.
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Old 07-10-2016, 03:56 PM   #10
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Default Re: An alternative to hd gear mod

Quote:
Originally Posted by tonyfalkon View Post
Would the height of the protrusion change if you put one of the shims behind the 3rd bearing next to the c-clip
If you use a modified 18x21 shim it wouldn't matter if you install it near the c-clip. But if you use a regular 15x21, yes, you are right, the pinion will be pulled back further more. This was true if you used the standard bearing-spacer-bearing, which has a given length. But if you use three bearings and the right amount of shims this length is whichever you choose.
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Old 07-10-2016, 03:59 PM   #11
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Default Re: An alternative to hd gear mod

!!!! But don't forget, if you choose to use those wide shims near the c-clip, don't forget to dremel it's inside to a minimum of 17mm, otherwise it will block the rotation of the inner ring!!!!
!!!! But if you use it between the bearings you HAVE TO make that "sandwich" for the exactly the same reason!!!! You need that gap between the shim and the outer ring. The only reason I used it instead of regular Axial's shims was because it was much thicker.

Last edited by Tzicul; 07-10-2016 at 04:23 PM.
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Old 07-10-2016, 07:53 PM   #12
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Default Re: An alternative to hd gear mod

Quote:
Originally Posted by Tzicul View Post
!!!! But don't forget, if you choose to use those wide shims near the c-clip, don't forget to dremel it's inside to a minimum of 17mm, otherwise it will block the rotation of the inner ring!!!!
!!!! But if you use it between the bearings you HAVE TO make that "sandwich" for the exactly the same reason!!!! You need that gap between the shim and the outer ring. The only reason I used it instead of regular Axial's shims was because it was much thicker.
Like my friendly PM said... "I'll give it a try my self..." Did and it was the same JUNK AXIAL set-up..

You don't understand the issue... Your just trying to be a Hero...When people try YOUR mod you'll look like a ZERO..
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Old 07-11-2016, 01:02 AM   #13
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Default Re: An alternative to hd gear mod

And why this should be any of your concerns? You should be happy, I'll be a zero and you'll be THE hero. I understand you can't breath if you don't have this feeling. And if you tried this mod and it didn't work is because you didn't wanted to work. Because I know you have the skills to make it right. You are telling me that, even with no shim, the pinion is too far away towards the ring??? Again, in MY case, I needed 0.7mm. Maybe in other cases someone needs less. Or maybe more. All that I know is that this mod is working. And you have the video that show you this. And if it proves it wouldn't, I'll be the first to admit this. But, for the moment, IT WORKS!
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Old 07-11-2016, 04:17 AM   #14
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Default Re: An alternative to hd gear mod

I did this same mod while ago. 3 bearings with shims on an uncut HD pinion. I can't remember the exact placement or how many i used, but it held up great until yesterday when i sold the truck, but I'm sure it'll hold up great for the new owner of the truck too... BHB called me out on the same mod back when i first posted, so don't think your alone in this.
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Old 07-11-2016, 07:07 AM   #15
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Default Re: An alternative to hd gear mod

That's because it doesn't make any common sense...

So YOU TWO.... THREE ... whatever ... think that Vanquish PULLED their AXIAL because their is a MAGIC shim sequence... And the FN gears don't even fit into a Dhavk V1... God you guys are blind... You guys must work for Axial

I think the best thing for me to do is pull my HD thread and let guys destroy their shit trying out your mod..But I won't..
And J.B ..... You've got a junkMAXX right? Really haw many times did you drive the XL? I bet you ran nothing but 4s as well ... Probably 3-4 times... Thanks for voicing in

So pleases explain why Vanquish and DHAWK recognize this as a problem?
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Old 07-11-2016, 08:01 AM   #16
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Default Re: An alternative to hd gear mod

Because they want to keep bearing-spacer-bearing Axial's original layout. I don't! When you will be capable of understanding there are different lenght of those layouts involved here we will talk again. Until then please keep your opinion about Xmaxx and your fine language for yourself. I'm not here to be named a fool by a nobody!

Sent from my Sony Xperia Z5

Last edited by Tzicul; 07-11-2016 at 08:27 AM.
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Old 07-11-2016, 08:21 AM   #17
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Default Re: An alternative to hd gear mod

How is it not obvious that this mod also improves mesh between the HD gears? The pinion is retained in the bulkhead by the outermost bearing. The whole pinion/bearing assembly just sits a little further back in the bulkhead to compensate for the extra bit of pinion (that is ground away in the BHB mod).

Tzicul, in fact I think your mod is superior because it doesn't involve grinding off metal, and uses minimal shims. Best of both worlds if you plan on running 6s with 100% punch/acceleration

BTW I'm using the HD gears with STOCK front and rear housing on 4s w/ 20t pinion. Temps are great and still get wheelies even though I limit torque to 70%. Speed is high 40s. I've done about 20-30 runs on this setup with NO mods and gear mesh is perfect, maybe I got lucky.
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Old 07-11-2016, 08:54 AM   #18
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Default Re: An alternative to hd gear mod

There is no physical way the bearing can recess any further into the housing without grinding off material behind the teeth, which creates proper 1-1 mesh.

Even if you had NO SHIMS at all, Just the bearing closest to teeth, and the three small screws installed, It still would not be proper mesh.. because the gear does not sit down enough in housing, due to the material behind the teeth creating space between the teeth and bearing.

It may work temporary, but I don't think it will in the long run. I got about 5 hard runs on my HD gears in stock plastic housing before havoc took place. I did the finagling you mentioned, not tightening the rear cover screws all the way also because the gears would bind excessively. It could be different for different peoples rigs though.

The plastic housing can get warped and reemed from previous improper runs, so it may seem "OK" but under 6s it will flex due to improper mesh and cause problems.

Last edited by alibby; 07-11-2016 at 08:58 AM.
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Old 07-11-2016, 09:02 AM   #19
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Default Re: An alternative to hd gear mod

True Statement
I probably would of kept buying plastic housings and running 4 s if it wasn't for the Vanquish that wouldn't even turn that showed me the REAL issue
(No Shims Required) material


Quote:
Originally Posted by alibby View Post
There is no physical way the bearing can recess any further into the housing without grinding off material behind the teeth, which creates proper 1-1 mesh.

Even if you had NO SHIMS at all, Just the bearing closest to teeth, and the three small screws installed, It still would not be proper mesh.. because the gear does not sit down enough in housing, due to the material behind the teeth creating space between the teeth and bearing.

It may work temporary, but I don't think it will in the long run. I got about 5 hard runs on my HD gears in stock plastic housing before havoc took place. I did the finagling you mentioned, not tightening the rear cover screws all the way also because the gears would bind excessively. It could be different for different peoples rigs though.

The plastic housing can get warped and reemed from previous improper runs, so it may seem "OK" but under 6s it will flex due to improper mesh and cause problems.
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Old 07-11-2016, 09:02 AM   #20
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Default Re: An alternative to hd gear mod

I'm not saying it is not possible everything you say but, for the moment, it work really nice. And I tried with both the old axle and a brand new one. Only time will tell, but for the moment I'm on vacation with my family, so no updates for the next two weeks

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