Venture, gearing down, & 550 sized motors discussion

[GA Dawg]

It looks like you removed a lot of material from the motor plate. Was all of that needed in order to get a 13 tooth pinion in there?

[carpetfuzz17]

Originally Posted by GA Dawg

It looks like you removed a lot of material from the motor plate. Was all of that needed in order to get a 13 tooth pinion in there?

I believe he is also using 500 series motor. I believe the diameter is smaller so it won't hit the crossbar. With the removed material on the plate and smaller motor it would get you down to the 13t pinion. I was struggling with a 17t pinion.
I still haven't looked closely at it but I might be able to drop a couple teeth with some sanding.

[HumboldtEF]

Originally Posted by GA Dawg

It looks like you removed a lot of material from the motor plate. Was all of that needed in order to get a 13 tooth pinion in there?

Yeah its slotted much more than needed and the motor is slightly smaller than a 540

[HumboldtEF]

So I revisited the gearing on my SBK and decided to try out a 3:1 GRU/planetary gear unit from Xtra Speed. I'm loving the super low gearing a lot but It did add a lot of extra length and weight to my rig as its a dense little unit. I was trying to keep this rig lightweight but I may just live with the extra mass as I'm really liking the gear ratio I get with it. Lucky for me I hadn't nailed down the body mounting and was able to adjust it to fit the longer motor and GRU.

Its my first time using a GRU but as all of them state they are "Not intended for use with brushless motors", they just arent strong enough.



I think the best starting point for a slow Venture is likely a very slow motor that way you can gear up from there if needed.

[carpetfuzz17]

Originally Posted by HumboldtEF

So I revisited the gearing on my SBK and decided to try out a 3:1 GRU/planetary gear unit from Xtra Speed. I'm loving the super low gearing a lot but It did add a lot of extra length and weight to my rig as its a dense little unit. I was trying to keep this rig lightweight but I may just live with the extra mass as I'm really liking the gear ratio I get with it. Lucky for me I hadn't nailed down the body mounting and was able to adjust it to fit the longer motor and GRU.

Its my first time using a GRU but as all of them state they are "Not intended for use with brushless motors", they just arent strong enough.



I think the best starting point for a slow Venture is likely a very slow motor that way you can gear up from there if needed.

Would you recommend the unit? I have tried my 45T 540 motor and it's still to fast for my liking. So I was considering try the unit that is why I am asking if would recommend it. Also was there a noticeable difference in the speed reduction?

[M1tch]

Looks a good idea, but I am trying to keep the weight down. My Holmes 30t with 14t pinion is a bit fast, but with the MMP esc I can set the throttle curve. A bit more fine tuning and should be fine. I just with the weather would cooperate.

[HumboldtEF]

Originally Posted by carpetfuzz17

Would you recommend the unit? I have tried my 45T 540 motor and it's still to fast for my liking. So I was considering try the unit that is why I am asking if would recommend it. Also was there a noticeable difference in the speed reduction?

Yes this will slow your rig down considerably, top speed is a very slow walking pace (maybe I'll take a short video later). If you are ok with the downsides of the added weight (its like adding an extra motor) and the extra length added to the motor which is 25mm. You'll need to make sure you have room with the body you're using, I'm using Proline's Dodge Power Wagon and it barely fits. I also expect this unit to have a short-ish lifespan so thats another thing to consider.

Originally Posted by M1tch

Looks a good idea, but I am trying to keep the weight down. My Holmes 30t with 14t pinion is a bit fast, but with the MMPesc I can set the throttle curve. A bit more fine tuning and should be fine. I just with the weather would cooperate.

Yeah I'm not super happy with the extra weight, its very nose heavy now as if it wasn't already. I was able to get a nice slow crawl with a throttle curve but found it lacking when going downhill. It really shows the high gear ration when you start to coast down hill.

[carpetfuzz17]

Originally Posted by HumboldtEF

Yes this will slow your rig down considerably, top speed is a very slow walking pace (maybe I'll take a short video later). If you are ok with the downsides of the added weight (its like adding an extra motor) and the extra length added to the motor which is 25mm. You'll need to make sure you have room with the body you're using, I'm using Proline's Dodge Power Wagon and it barely fits. I also expect this unit to have a short-ish lifespan so thats another thing to consider.






Yeah I'm not super happy with the extra weight, its very nose heavy now as if it wasn't already. I was able to get a nice slow crawl with a throttle curve but found it lacking when going downhill. It really shows the high gear ration when you start to coast down hill.

Was there anything special you needed to do to fit the unit on to the motor? Also would running the battery in rear help with balancing it out?

[HumboldtEF]

No nothing special needed, it uses the same length screws to mount the motor to the unit and I cant recall if they provide screws to mount the whole unit to the tranny or not but they're just common M3's. Due to the larger diameter of the GRU I had to use the stock 16T pinion.

I have considered switching back to the stock battery mount in the name of balance but I think I may try a much slower motor in the mean time.

I've also changed my tune about not making a new front crossmember that allows lower gearing as it really is seeming to be something worth doing.

[M1tch]

I'm tempted to try a lower turn motor, but the wheel speed with the 30t is good for getting over roots and ledges. I might get a cheap 45t just to try, but I have my Land Rover with a 30t Tekin in and it's fine now I have set up the FXR esc and tx to suit it. My K10 Ascender has a 21t 550in, but that is a heavier motor which I don't want in the Venture.

[HumboldtEF]

I think this will allow for the lowest gearing. You will need to slot the holes on the motor mount to get down below a certain tooth count (the slotted mount hole as well as the center hole for the motor/bearing housing).



I'm just waiting on another print to finish so I can test this out.

[GA Dawg]

Are you going to make that STL file available?

[HumboldtEF]

thats the plan

[M1tch]

Great idea there. Could the stock one not be modified though? I haven't had a look as I'm busy doing boring stuff at home that's has to be done :(

[GA Dawg]

Originally Posted by M1tch

Great idea there. Could the stock one not be modified though? I haven't had a look as I'm busy doing boring stuff at home that's has to be done :(

From my perspective, I don't want to modify and potentially ruin any stock parts until I'm sure I can get replacements if needed. I'd rather 3D print something and keep the stock part as a backup.

[HumboldtEF]

Originally Posted by M1tch

Great idea there. Could the stock one not be modified though? I haven't had a look as I'm busy doing boring stuff at home that's has to be done :(

I'm sure you could gain a bit more room by just carving up the stock mount, I have a feeling you'd only be able to get so low gearing wise before you need to fully cut through the bottom of it.

I'm still waiting to reassemble my Venture, Its torn apart right now so I could make this mount and paint the rock sliders and bumpers. It does look like the mount will work fine, there doesnt seem to be any clearance or interference issues but I'm waiting on final assembly to confirm that.

Here's the first print.




a few of the holes have so little meat around them that I was afraid of splitting them open so I tapped the holes. After a test fit I found that tapping the holes for the servo was not a great idea as I was able to strip 2 of the holes. so I'm only going to recommend tapping the one hole, and even that one will likely split but it can be glued up with some CA while a screw is left in place.
One of the button head screws needs to be replaced with a socket head (they have a smaller diameter head) because its so tight.



I should have the final verdict tonight but I was able to get my smallest pinion to fit, a 10T pinion. Once I'm confident the model is good I'll be posting it up on Thingiverse so anyone can download it for free.

I'm still wondering what the smallest pinion is in 48 pitch, so far the smallest I've found is a 9T. Though with these smaller pinions I do worry they wont be stout enough since its metal on metal and these 9T and 10T pinions have so little material in the center of them. If you check out this picture below you can see how little material there is between teeth (in the center).


So what I'm getting at is that I think I'll call it good at 10T as the 9T looks so fragile I doubt many will use it. let me know if you think otherwise.

[GA Dawg]

I have never seen a 9T 48 pitch pinion before. I have a 12T pinion new in the package that I'd like to get on my Venture.

[M1tch]

I see what you mean about modifying the stock mount now. I have seen aluminum ones, but assume they would be difficult to modify if they could be at all.

The smaller the pinion, I think might need more precise the mesh would need to be, even with the steel gears. As for the screw holes. Would it be possible to put spacers between the motor mount and chassis rails to give a bit more room? Only 1mm or so, but enough to allow for more material. You could space the cross member as well.

[HumboldtEF]

Originally Posted by M1tch

As for the screw holes. Would it be possible to put spacers between the motor mount and chassis rails to give a bit more room? Only 1mm or so, but enough to allow for more material. You could space the cross member as well.

Unfortunately the holes that need more material are too close to the motor and servo to add any more material, though I did add .5mm to the material around the servo. I did consider making one of them too big so they would hit the motor with the plan being to install the screw and then file or shave off the excess or whatever is in the way. My thinking being that the hole might have more strength this way even thought they'll likely be the same dimensions afterwards.

I suppose I have plenty of space to make the hole longer and get more thread engagement.

I think it will likely be fine but like any plastic you'll need to be careful not to over tighten. Really I would have been fine to ignore the stripped holes but as a sort of test I went a bit farther just to make sure they were actually stripping out which they were. But as I said above i had tapped these holes, I printed another and didn't tap those holes and its holding very firm.

[M1tch]

I have done some plastic work, but only delrin, not 3D printed. I don't tap the holes as the plastic is soft enough that the screw will cut the thread. Tapping will give a clearance fit, and that would cause the stripping. I have used helicoil type inserts on stripped threads in plastic, but they can strip as well.

Hope it works out ok in the end.