newb gearing question

[Mike McLeod]

i am wondering how to get more wheel speed out of my new jk. i have a wraith as well, is the diff gear ratio and tranny gear ratio the same in the scx as the wraith? both have a 20 tooth pinion and 80 tooth spur, the wraith has a 20 turn, scx a 27 turn. the wraith has alot more wheel speed. could i just put a 20 turn in the scx and get the same wheel speed as the wraith? thanks

[05Fronty4x]

You can put a 20T motor in the SCX10 if you want. The stock AE-2 ESC can handle down to a 19T (assuming that's what you have). Be sure to gear it appropriately. If your motor runs really hot, it may be wise to drop down a couple teeth on the pinion. On the other hand, if your stock 27T motor is running cool with the 20 tooth then you could step up a couple teeth on the pinion for more wheel speed, but you are probably looking for a significant increase, and a motor swap is the only thing that is going to provide that.

If I were in your shoes, having both the Wraith and SCX10, I would dedicate the SCX10 as a slow speed crawler since you have the Wraith for speed.

[BodiBuilt]

Have you considered converting to 3s LiPo?

As John Holmes say's: "Volt Up! Gear Down!"

[05Fronty4x]

Originally Posted by BodiBuilt

Have you considered converting to 3s LiPo?

As John Holmes say's: "Volt Up! Gear Down!"

It's a great thing. My Dingo is a creeper, but on 3s has more than enough wheel speed for any type of crawling, and that's with a 55T motor and 18/87 tooth gearing. 95% of the time I'm only using the first 5-15% throttle and get multiple hours of run time with old 3s Thunder Power 1320mAh LiPos from 2005. I'm loving it.

[Mike McLeod]

currently there are both being run on 2s lipos.......usually when we go, i run the wraith and the jk is the wifes so she runs it. the jeep also has 2.2 mudslingers on it so i was curious if running the bigger tires would heat up my motor more. if i were to run it on a 3s which way should i gear it with a 27 turn and the 2.2's on it in order not to fry my motor?? or would it be smarter to go to a 20 turn and change the gearing? we run on snow covered trails most often and the extra wheel speed of the wraith really seems to make a big difference in the capability of the wraith over the scx. i just want to try and get her rig a little closer to the capability of the wraith. thanks for all the help guys

[BodiBuilt]

When regearing , or using higher voltage (3s), or swapping to any low turn (faster) motor, or any ring/pinion combo change, you will want to keep an eye on motor temp and not allow it to get too hot.

For example, you may be able to go with a lower wind (faster) motor, but you will eventually come to a point where you start to get some high temp reading's (high temps = early death of motor)... to compensate you may need to lower your gear ratio (which makes it slower again!). Smaller pinion and larger spur may be in order... which ratio work's best for you will likely require some trial and error

[05Fronty4x]

Yes those bigger/heavier tires will put more of a load on the motor, and it should be geared lower to compensate. There's no definite answer for what gearing you should use. Feel the motor every few minutes and if it gets pretty hot it may be time to stock up on some various tooth pinions for testing. Chances are the stock 27T isn't up to par to really get those 2.2 tires moving the way you want. Running 3s may be the ticket but that would be a more costly endeavor than simply swapping the motor and regearing (unless you have some 3s packs and a 3s capable ESC already).

A good start would be to get an assortment of pinions and begin doing some testing (you will need them regardless of which road you take whether it be a 3s setup or motor swap). If you switch to a 3s setup with the 27T I would start with something pretty small like a 12 tooth pinion and switch back to the stock(I think) 87 tooth spur gear instead of the 80 tooth you have on there. If the motor seems to make easy work out of everything and doesn't get really hot, you can gradually start putting bigger pinions on until the motor runs a bit too hot, then back off a tooth or two. 3s offers a pretty sizable jump in performance, so be careful or the wife may start blazing right by your wraith =P.

I forgot to add, if you stock up on pinions, I'd recommend the heavy steel type vs the lighter materials, they are much quieter. I had an aluminum 16 tooth on my SCX10 and I was starting to think I had some gear mesh or alignment issues in the drive train until I put on a heavy steel pinion on there and all was quiet.

[Mike McLeod]

Wow so much to take in!! lmao thanks alot guys you have given me a few options to try. what temp would i want to watch for on the motor? whats to hot? it gets fairly warm now. when you say "geared lower" to compensate for the bigger tires, should i go with less teeth on the pinion, more on the spur or both? (or do i have it totally backwards?) this gearing stuff still kinda confuses me a bit. i.m leaning towards the gearing and/or motor swap only because we already have several 2s lipos (7 in fact) we can use for now.

thanks again for all your help guys

[05Fronty4x]

I like my motors to never get more than slightly warm to the touch. I'm not sure what they can handle but less heat is always better. My crawler motor never even gets warm, but with a heavy throttle finger some heat is going to be normal. If we had a scale that was: ambient, slightly warm, warm, fairly/pretty warm, very warm, hot (1-6) and you are at 4, I definitely wouldn't suggest trying to get more wheel speed with a larger pinion as this will only create more heat.

You are right about gearing. A smaller pinion or larger spur (lower geared) will increase the number of RPMs per one tire revolution and decrease the load on the motor which results in a cooler operating temperature. Reducing the tire size has the same effect since it travels a shorter distance per revolution vs a larger tire. So, if your motor is running hot you can do one or more of the following: smaller pinion, larger spur or smaller tires.

From the sound of it, you may or may not be geared optimally on the SCX10, and gearing down some may create a bit more punch when you need the power if it's currently geared way too high, but you won't see the significant difference that I think you are looking for. If you will be sticking with 2s packs, I'd give the 20T motor a shot. Since you have one in the Wraith, I'd swap it in and see how it does before buying another. If you still have a standard 87 tooth spur I'd put that on it too because the 20T certainly needs to be geared lower than the 27T (if the 27T is getting pretty warm, the 20T might fry an egg =P). Take note of the motor heat and depending on how it does, order the appropriate pinions for testing (and another 20T motor if you decide to go that route). In the end, a properly geared 20T motor should liven up the JK nicely.

To clear something up, is it actually more top end wheel speed you want, or more "punch"/acceleration to get the wheels spinning quicker?

[Mike McLeod]

Ok so i'm gonna switch to the 87 tooth spur and the 20t motor and try that first. and i'll pick up 18 & 16 tooth pinions and go from there.

thanks again for all your help 05fronty4x

[05Fronty4x]

Originally Posted by Mike McLeod

Ok so i'm gonna switch to the 87 tooth spur and the 20t motor and try that first. and i'll pick up 18 & 16 tooth pinions and go from there.

thanks again for all your help 05fronty4x

Your welcome. Those Mud Slingers you have are smaller compared to a lot of 2.2 tires, but still a bit bigger/heavier than the standard 1.9's (one 2.2 Mud Slinger weighs more than a Trepador+Axial beadlock combined). 16/87 gearing may be pretty good for the 20T on 2s power, but I think you may want to pick up something even smaller just in case. If you end up not using it, it will be there for when you switch to 3s, hehe.

Does the 27T with 20/80 gearing seem like it has decent punch, or can you tell that it's having a hard time ripping the Slingers through the snow?

[Mike McLeod]

it seems like its strugglin just a bit at first (just a little hesitation) but then it gets goin all right, but by then its dug itself into the snow to deep to climb out easily. im hoping to get to where when ya hit the throttle it just picks up and goes!! (like the wraith) i'm also thinkin about a set of ripsaws for the jeep as well. the wraith has them and they seem to be a pretty good tire in the snow. any suggestions on another good tire choice for snow? guess i'll pick up a 14 tooth pinion too

[05Fronty4x]

I hear ya. In the mean time you can swap the 80 for the 87 spur if you have it handy just to see what difference a bit more low end punch makes with the 27T motor. I think the RTR's come with 20/87 gearing and a 27T.

Snow tires... one area I can't help you with. It doesn't snow anywhere within an hour of me, lol.

[Mike McLeod]

Yeah it snows here for 5 months of the year so......havin a rig that works good in snow is kinda a must if ya wanna wheel in the winter months! lol once people have walked on the trail a bit they get packed down and pretty rough so it makes for some challenging but fun wheelin! i've got a third scx10 i bought as a running rig but it was pretty tired and beat up so i tore it down for a "project truck" i plan on piecing together slowly with all new fancy parts and make it my go to rig eventually, and it has the spur gear you suggested so i'll steal it and throw it in the jk and see how it works. so the 87 tooth should give it a little more "punch" right?

[05Fronty4x]

Yup. 20/80 gearing might even have that 27T bogged down so much with those 2.2's that besides more punch, you may actually gain more wheel speed as well in tough situations with the 87 tooth.

With little or no load (all 4 tires off the ground) higher gearing = more wheel speed, but in realistic situations (climbing a snowy hill for example) there is a point at which the motor simply doesn't have what it takes to handle the load from high gearing and can't reach it's optimal RPM. Switching to the 87 spur will be a good test to see if that's the case. It's like riding a 20 speed mountain bike and trying to take off up hill from a dead stop in 20th gear. If you had some insanely powerful legs that just may work, but chances are 10th gear will get you going much better, and won't be so strenuous. The same concept applies with gearing a motor correctly.

[Mike McLeod]

well i switched the spur up to the 87 tooth, now i just need it to warm up a little to go test it out. woke up this morning to a few inches of fresh snow but it is
-20 degrees celsius out there (brrrrr) think i'll wait for a little warmer weather for a test run! also order up three new pinions, a 14,16 & 18 tooth. another question....do they make larger spur gears? is that even an option or should i just stick with testing the pinions for now?
thanks again

[05Fronty4x]

Stick to pinions. Spur adjustments are for really fine tuning and IMO isn't called for except for those in competitive racing who desire the "perfect" setup and do in-depth testing to acheive it. Those people are changing their gearing for every track and condition though, and we are just building all around trail vehicles where the fine adjustment of going up or down on the spur size really isn't called for (and much easier to just swap a pinion). If you were running 20/87 and you just dropped to a 19 tooth, it would be the equivalent of running 20/92 for the same ratio. For instance, if you came upon a situation where a 20 tooth was too high and a 19 tooth was too low with an 87 spur, then you would mess with spurs to get something inbetween (19/85 or 20/89 for example). One thing I noted when I built my kit, was that with the standard 87 spur, my motor didn't even have room to adjust far enough out to run the supplied 20 tooth pinion. The motor comes in contact with one of the screws holding the sliders on. I reversed the screw to gain some clearance, but I ended up with a smaller pinion which moves the motor inward to clear it anyways. Point is, it won't be necessary to mess with a bigger spur because you should be able to acheive a good gear ratio without doing so, and it may not even fit.

One thing is for sure, you were running 20/80, switching to the 87 and dropping a few teeth on the pinion is a significant difference, and is exactly what you need for the new 20T when you get it =D. Also, it's OK if you end up geared slightly high for the new motor on 2s. Over-gearing is much more detrimental on 3s.

[Mike McLeod]

cool, i'll stick to pinions then. now i just hafta wait for some warmer weather!...lol

[05Fronty4x]

There's a little fresh snow out, perfect testing conditions...what are you waiting for? Lol. Heck, just knit your JK a little sweater, hahaha.

[Mike McLeod]

nevermind the JK its me that'll freeze!! with the wind chill it's -30 out there. i will go out and run it around on the street for a few minutes till i freeze and see if the spur change is noticable however the trails we run on are right beside a river so it will be way to cold there for any testing today. on my way out to go pick up my new pinions as well. the guys at the LHS (hobbyworld) did some lookin for me and they have all three pinions in stock!!