Felony Felony equal size tyres diff swap - *NO NEED TO BUY ANOTHER DIFF SET*

Yas

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Credit to @Stygian:
https://www.arrmaforum.com/threads/...run-42-100-hoons-all-around.27999/post-406908

Those planning to run same sized tyres in the Felony (like I do) may have been led to believe that you will have to buy another diff set to match each ratio of the front and rear diffs (like I did)

However you can just swap the front GP5 diff with the rear GP6 diff whilst leaving the diff pinion gears where they were originally to get matching ratios. It's that simple!

Ring/pinion
GP5/GP5 (42÷15) = 2.8 ratio (stock front)
GP6/GP6 (45÷14) = 3.2 ratio (stock rear)
GP5/GP6 (42÷14) = 3 ratio (front diff in rear)
GP6/GP5 (45÷15) = 3 ratio (rear diff in front)

Posting this in case nobody has made a thread on this already, and to save anybody from buying and waiting for extra parts when they don't necessarily have to 👍
 

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I wonder if they did that in purpose.. wow that’s crazy..
 

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Just thinking out loud, but do the teeth size still match up? No issues there? I don’t know if both have the same pitch.
 

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Credit to @Stygian:
https://www.arrmaforum.com/threads/...run-42-100-hoons-all-around.27999/post-406908

Those planning to run same sized tyres in the Felony (like I do) may have been led to believe that you will have to buy another diff set to match each ratio of the front and rear diffs (like I did)

However you can just swap the front GP5 diff with the rear GP6 diff whilst leaving the diff pinion gears where they were originally to get matching ratios. It's that simple!

Ring/pinion
GP5/GP5 (42÷15) = 2.8 ratio (stock front)
GP6/GP6 (45÷14) = 3.2 ratio (stock rear)
GP5/GP6 (42÷14) = 3 ratio (front diff in rear)
GP6/GP5 (45÷15) = 3 ratio (rear diff in front)

Posting this in case nobody has made a thread on this already, and to save anybody from buying and waiting for extra parts when they don't necessarily have to 👍
*cheer*👍 thanks for makin this post, and double thanks for credit*Squeal😁*! I'll have to be more outgoing in makin new posts in the future 😝 .

For those lookin for a close to stock Stance in the rear, consider lookin into the offsets from M2C racing, for example: https://m2cracing.net/arrma/567-m2c-3160-arrma-17mm-hub-extenders.html

Don't grab the 10mm hub extenders as the wheels will stick outa the body, I think you need a 4-6mm offset, I haven't measured it yet.

Just thinking out loud, but do the teeth size still match up? No issues there? I don’t know if both have the same pitch.
Yeah they mesh beautifully, mine do anyway, I have roughly 8 *hard* packs on mine and they are still perfect.
 
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Yas

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Just thinking out loud, but do the teeth size still match up? No issues there? I don’t know if both have the same pitch.
I'm 99.9% sure GP5 and GP6 gears have the same pitch, only each set has different ratios. When I pulled both of them out a month ago to fit aluminium cups, I actually test fit one diff with the other pinion to see if they could pair, and they definitely could. @Stygian has said he has tried and tested them too 👍

IMG_20200918_210514.jpg

Edit: you can probably mix and match the Typhon straight cut ring and pinion with GP5 and GP6 gears too - I'm willing to bet they're all the same pitch! (I can't confirm this though)

GP6/Typhon - ring/pinion (45/13) will be the shortest diff gearing. The tallest gearing is the standard GP5 diff set
 
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Stygian

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I'm 99.9% sure GP5 and GP6 gears have the same pitch, only each set has different ratios. When I pulled both of them out a month ago to fit aluminium cups, I actually test fit one diff with the other pinion to see if they could pair, and they definitely could. @Stygian has said he has tried and tested them too 👍

Edit: you can probably mix and match the Typhon straight cut ring and pinion with GP5 and GP6 gears too - I'm willing to bet they're all the same pitch! (I can't confirm this though)

GP6/Typhon - ring/pinion (45/13) will be the shortest diff gearing. The tallest gearing is the standard GP5 diff set

View attachment 106823
Those GPM diff cases are gorgeous! How do they hold up? I have a Hot racing one on my Kraton Center and it seems great so far.

I'd assume Arrma uses the same pitch because in theory it'd save on production costs, can cut everything the same means less bits and specialized machines... I believe. *shrug* who knows... just test test test!
 

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Those GPM diff cases are gorgeous! How do they hold up? I have a Hot racing one on my Kraton Center and it seems great so far.

I'd assume Arrma uses the same pitch because in theory it'd save on production costs, can cut everything the same means less bits and specialized machines... I believe. *shrug* who knows... just test test test!
Thanks! I've had great luck with them in my Noto. I'm hoping GPM make 29mm EXB ones soon. I won't go back to plastic cups. The diff and it's internals seem to last longer using aluminium ones - less flex, fewer leaks and the screws are thread locked. Solid! 💪

Exactly, all 6S diffs including the spiral cut ones are likely the same pitch as well, only they obviously won't mesh with these straight cut gears
 

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Thanks! I've had great luck with them in my Noto. I'm hoping GPM make EXB ones soon. I won't go back to plastic cups. The diff and it's internals seem to last longer using aluminium ones - less flex, fewer leaks and the screws are thread locked. Solid! 💪

Exactly, all 6S gears including the spiral cut ones are likely the same pitch as well, only they obviously won't mesh with these straight cut ones
I'd love if they made the EXB spiral cut in different sizes, those look tough as hell and like they run smooth too. Hot racing has some of the steel spiral cut for the 3s blx kits but I didn't see anything for 6s, though I didn't look too hard for it.
 

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Wow this is fantastic info. So you can just swap the diffs and then run basically any 1/8 on road wheels and tires?
yeah, super simple, you'll have to shim them a tad different due to the different sized input gears though, IIRC one (crown side) shim in the rear and no shims in the front. The front was meshed tight enough that I almost considered putting a shim on the opposite side of the crown gear, but it all runs/spins so smooth I didn't worry about it.
 

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Sorry, I don't have a lot of experience with shimming diffs. What do you mean by crown side?
 

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Sorry, I don't have a lot of experience with shimming diffs. What do you mean by crown side?
Arrma calls the big gear on the outside of the Diff housing the crown gear. the 43ish tooth gear. I hope that helps, are you good with shimming?
 

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Arrma calls the big gear on the outside of the Diff housing the crown gear. the 43ish tooth gear. I hope that helps, are you good with shimming?
I'm the opposite of whatever good with shimming means LOL.

I don't even know it works, to be honest. The extent of my differential knowledge/experience is changing fluids. I hear people talking about them all the time, but it's never made sense to me.
 

Yas

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My two LHS and horizon hobby has fronts abound... Just no rears... 😭😭😭😭😭😭
You can buy mine. $200 a pair 😂
What tyre shortage 🤩 you can have mine at a discount price... of $195 👌😏😂

PXL_20201030_142735656.PORTRAIT-02.ORIGINAL~2.jpg
I'm the opposite of whatever good with shimming means LOL.

I don't even know it works, to be honest. The extent of my differential knowledge/experience is changing fluids. I hear people talking about them all the time, but it's never made sense to me.
Shimming just pushes the teeth of the gears closer together for more contact and durability, or further away if they're too tight 👍
 

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