Slipper clutch gearing advice

[old crusty 3]

Just acquired an xv-01 chassis kit, i have bought all the recommended upgrades, and all the unnecessary ones, and all the totally frivolous ones.

The question I’m asking is, the slipper clutch has a 77t spur gear and I’m wondering if anyone can recommend a pinion gear for general tarmac/grass and some loose gravel surfaces.

motor and esc…..

HOBBYWING COMBO XR10 JUSTOCK G3 ESC/JUSTOCK G2.1 17.5T

 

[Willy iine 18829]

@old crusty

I was wondering when someone would post, but since no one has, I would start with the factory gearing and then touch your motor and ESC heat sink to determine if you can lower the ratio (run larger pinion).

I run a BZ (brushed mod motor) with a Hobbywing 1060 on mine with stock gearing, and while the motor gets hot (within the 3 second rule), I am pretty certain the gearing is quite mild for a brushless setup.  GL!

[Jonathon Gillham 4698]

Thats the same gearbox as the FF04 right?  So the IR is 2.6 from memory.

That 17.5T motor will allow a low FDR.  I was running a 60T spur and 50T pinion (FDR 3.12) I think in my FF04 with a 21.5T.  Given the 4wd and a 17.5T motor then I would aim for FDR of 5 to start, and then check the motor temp.  I suspect you'll end up at an FDR around 4.5, assuming you stick with the onroad sized wheels. 

With a 77T spur then a 40T pinion will give you an FDR of 5.005.  A 45T pinion gives 4.45 so I would suggest a range from 40T - 45T.  If you want really long runtimes then a 36T pinion will give an FDR of 5.56 (as in, you have a big battery and run for 30mins or so, then I would go for a higher FDR)

Does the slipper come with 48p or mod .6 gears?  I assume 48p since Tamiya seem to do that, which is good since 48p pinions are a lot easier to find and mod .6.  You can buy Surpass brand pinions in packs of 6 for not much money which would be a good place to start, and they will no doubt offer a pack which is right around the 40 - 45 that looks to be ideal for this.

And just for completeness, the formula and what the above means...

IR = internal ratio

FDR = final drive ratio

The formula is (spur gear size / pinion gear size) x IR (in your case 2.6)

So in the case of my FF04 it was (60/50) x 2.6 = 3.12

[Pylon80 3742]

On 8/19/2023 at 2:38 PM, old crusty said:

Just acquired an xv-01 chassis kit, i have bought all the recommended upgrades, and all the unnecessary ones, and all the totally frivolous ones.

The question I’m asking is, the slipper clutch has a 77t spur gear and I’m wondering if anyone can recommend a pinion gear for general tarmac/grass and some loose gravel surfaces.

motor and esc…..

HOBBYWING COMBO XR10 JUSTOCK G3 ESC/JUSTOCK G2.1 17.5T

 

Sorry I had misread your post - I did have an XV-01 at some point but have no experience with the slipper clutch. I would suspect that the big 77t spur will seriously limit the largest pinion you can fit. I will let the slipper clutch experts help you instead.

[old crusty 3]

On 8/21/2023 at 5:44 AM, Jonathon Gillham said:

Thats the same gearbox as the FF04 right?  So the IR is 2.6 from memory.

That 17.5T motor will allow a low FDR.  I was running a 60T spur and 50T pinion (FDR 3.12) I think in my FF04 with a 21.5T.  Given the 4wd and a 17.5T motor then I would aim for FDR of 5 to start, and then check the motor temp.  I suspect you'll end up at an FDR around 4.5, assuming you stick with the onroad sized wheels. 

With a 77T spur then a 40T pinion will give you an FDR of 5.005.  A 45T pinion gives 4.45 so I would suggest a range from 40T - 45T.  If you want really long runtimes then a 36T pinion will give an FDR of 5.56 (as in, you have a big battery and run for 30mins or so, then I would go for a higher FDR)

Does the slipper come with 48p or mod .6 gears?  I assume 48p since Tamiya seem to do that, which is good since 48p pinions are a lot easier to find and mod .6.  You can buy Surpass brand pinions in packs of 6 for not much money which would be a good place to start, and they will no doubt offer a pack which is right around the 40 - 45 that looks to be ideal for this.

And just for completeness, the formula and what the above means...

IR = internal ratio

FDR = final drive ratio

The formula is (spur gear size / pinion gear size) x IR (in your case 2.6)

So in the case of my FF04 it was (60/50) x 2.6 = 3.12

 

16 hours ago, Pylon80 said:

Sorry I had misread your post - I did have an XV-01 at some point but have no experience with the slipper clutch. I would suspect that the big 77t spur will seriously limit the largest pinion you can fit. I will let the slipper clutch experts help you instead.

Thanks for all the replies...very informative and helpful, Pylon, your reply before editing was great advice, I have attached the clutch and the pinions that you can use, as no one has actual experience of a 17t with that clutch I think I'll try the 27t.

As you can see.....still in the packets.....along with everything else....so might be a while....got to get the front diff on my SBR 2 sorted out first.

[old crusty 3]

As I said......all still in boxes or packets......can't wait though...last kit(Tamiya) I built was a holiday buggy.

 

My axial deadbolt 1/24th crawler...was a strip and rebuild with carbon and alloy......that was fun.

 

[Pylon80 3742]

6 hours ago, old crusty said:

 

Thanks for all the replies...very informative and helpful, Pylon, your reply before editing was great advice, I have attached the clutch and the pinions that you can use, as no one has actual experience of a 17t with that clutch I think I'll try the 27t.

As you can see.....still in the packets.....along with everything else....so might be a while....got to get the front diff on my SBR 2 sorted out first.

I see you have quite a few options for the pinion! My 'concern' was that the largest pinion you can fit will be limited with the larger spur that comes with the slipper clutch. I suspect the instructions for the slipper will come with a gearing chart to confirm the range of pinion 👍

[old crusty 3]

Never even thought of opening the packaging to the slipper clutch......(you must be in management).

I'll have a look...👀

[old crusty 3]

That'll be a NO then....🙄

[old crusty 3]

And yes.......I did turn it over...!

[Jonathon Gillham 4698]

That spur gear looks a lot like the Team Associated ones which come in more sizes and are pretty much a direct swap. You may need new slipper pads though, I'm not 100% sure. @ThunderDragonCy can probably help. Anyway, if I'm right then you'll have any gearing option as you'll be able to fit a much smaller spur

[Pylon80 3742]

4 hours ago, old crusty said:

That'll be a NO then....🙄

I see that this slipper clutch implies switching to 48p pinions (which you have) so fitting the 27t as you were planning shouldn't be a problem

[ThunderDragonCy 8402]

11 hours ago, Jonathon Gillham said:

That spur gear looks a lot like the Team Associated ones which come in more sizes and are pretty much a direct swap. You may need new slipper pads though, I'm not 100% sure. @ThunderDragonCy can probably help. Anyway, if I'm right then you'll have any gearing option as you'll be able to fit a much smaller spur

This is correct. Kimbrough still do a, whole range of spurs for the Associated B4 which are the same fit. No need to change pads, they go straight on. You have options from 69t up to 84t in roughly 3t jumps. Careful anything bigger than the tamiya spur will fit under the cover though. 

You need a, 48dp pinion to go with the 48dp spur on the slipper, so the kit 0.6mod pinion won't work.

[ThunderDragonCy 8402]

Just read from the top. With a buggy you want around 6fdr with 17.5, so accounting for the smaller wheels something around 5.5 or 5

[ThunderDragonCy 8402]

Quick bit of gearing maths suggests your tamiya pinions won't be anywhere near big enough to get 5.5 FDR even with a 69t spur (smallest possible with Kimbrough associated part). With a 69y spure you are going to need a 32t pinion to give 5.6fdr. A 36t pinion will get you 5fdr. RW Racing in the UK do great pinions in all those sizes. Not sure if pinions that big will fit under the gear cover though. 

[old crusty 3]

Again....lots of advice...interesting....if not confusing...still don't know what FDR translates into tooth count for the pinions.

And I don't get why you say I can't use one of the 6 pinions that tamiya say to use with "there" slipper clutch and supplied spur gear that is designed for this chassis. 
What is the point of selling it, if you can't use it.

[Jonathon Gillham 4698]

6 hours ago, old crusty said:

Again....lots of advice...interesting....if not confusing...still don't know what FDR translates into tooth count for the pinions.

And I don't get why you say I can't use one of the 6 pinions that tamiya say to use with "there" slipper clutch and supplied spur gear that is designed for this chassis. 
What is the point of selling it, if you can't use it.

Tamiya usually supply their cars with gearing for brushed motors which need much lower gearing. If you want to run brushless this means the gearing is usually right for low turn mod motors. You've got a 17.5T motir which needs high gearing (low FDR) if you want to make the most of it

[Pylon80 3742]

I really hate to be that guy, but... I am not sure one should use FDR's that low to run on grass with rally block tires. It would however be perfect with semi-slicks on pavement.

[Jonathon Gillham 4698]

4 hours ago, Pylon80 said:

I really hate to be that guy, but... I am not sure one should use FDR's that low to run on grass with rally block tires. It would however be perfect with semi-slicks on pavement.

Good point about the surface and dropping a few teeth on the pinion. 5.5 should be safe though - thats the FDR I run on my 17.5T buggies with bigger wheels, the smaller wheels should make up for the grass

[old crusty 3]

Hey guys,

lots of good feedback again...grass running will be minimal and only when sort , mainly to get from one bit of tarmac/gravel to the next .

seeing as you've got the hang of this FDR thingy, 5.5 equates to which gear, 27t as I originally thought and work down, 26,25,24.....or start higher, 28,29 , and work down.

 

also, on retrospect ....should I have gone for 13.5 instead of 17.5.... ???

[Pylon80 3742]

On 8/24/2023 at 2:22 AM, old crusty said:

Hey guys,

lots of good feedback again...grass running will be minimal and only when sort , mainly to get from one bit of tarmac/gravel to the next .

seeing as you've got the hang of this FDR thingy, 5.5 equates to which gear, 27t as I originally thought and work down, 26,25,24.....or start higher, 28,29 , and work down.

 

also, on retrospect ....should I have gone for 13.5 instead of 17.5.... ???

5.5 will require going with much larger pinion tooth count and therefore down the rabbit hole of converting to 64p with potential issues such as the gear cover no longer fitting as mentioned by other posters. Hence my suggestion to start with the 48p ones you already have, for instance that 27t in the picture

So for 5.5 FDR:

5.5/2.6=2.11 (2.6 being the internal ratio)

Then

77/2.11=36.4 so say 36 teeth! That's a big pinion.

In comparison for 7.5 FDR (my pick):

7.5/2.6=2.88

Then

77/2.88=26.7 so make it 27 teeth.

Hopefully you are following my math above 😐

[Pylon80 3742]

One more thing: you don't have to take guesses and waste money on the parts if you want to know their diameter. You can find the diameters of spurs and pinions with this tool:

https://evolventdesign.com/pages/blank-calc

Choose 1/64" for the 64p gears and a contact angle of 45deg. This way you will know if it fits your gear cover or not by comparing with 0.6mod gears (use 0.6mm for the pitch of these).

[old crusty 3]

Thank you, thank you, thank you.......finally I get how to work out the FDR.....I was having a serious brain fart with those......but with your explanation...and....kerching....I heard the penny drop, and it all fell in to place.