• Welcome to RCCrawler Forums.

    It looks like you're enjoying RCCrawler's Forums but haven't created an account yet. Why not take a minute to register for your own free account now? As a member you get free access to all of our forums and posts plus the ability to post your own messages, communicate directly with other members, and much more. Register now!

    Already a member? Login at the top of this page to stop seeing this message.

Mini Revo Transmission in Losi MRC

Very cool build.

Do you think gearing the motor up will cause heating issues?

My rig ran very hot with the stock motor plate and a custom 66t spur.

I've since modified and installed an aluminum heat sink mini-t plate which completely fixed the heat issue.

I can't imagine it with an 18t/60t combo.....nuclear....

Anyway, speaking of that spur, check if the Associated 66t for an RC18 (ASC21324) would help you out or not.

It's got a small center hole that may work better than the dual bearing setup.

That should gear you back down to a smaller pinion, buy you some room, and keep the motor from melting.

It seems a perfect fit for your clamping style "slipper" mount you've come up with.

Hope that helps, looking forward to updates.
 
Very cool will be interesting to see what you can come up with. you can also get some hardened gears for the merv if memory serves me right with could make the transmission even more possibly bomb proof.
 
MRCrackhead said:
Very cool build.

Do you think gearing the motor up will cause heating issues?

My rig ran very hot with the stock motor plate and a custom 66t spur.

I've since modified and installed an aluminum heat sink mini-t plate which completely fixed the heat issue.

I can't imagine it with an 18t/60t combo.....nuclear....

Anyway, speaking of that spur, check if the Associated 66t for an RC18 (ASC21324) would help you out or not.

It's got a small center hole that may work better than the dual bearing setup.

That should gear you back down to a smaller pinion, buy you some room, and keep the motor from melting.

It seems a perfect fit for your clamping style "slipper" mount you've come up with.

Hope that helps, looking forward to updates.
Click to expand...

I never mentioned it in the vid, but the biggest you can g in that tranny is a 60t spur because of the case mold, there's stuff in the way

the gearing i think will be fine, a little math, these numbers are stuff i found online, so may or may not be accurate, but in the end the numbers are basically the same.

Based on my research the MRC tranny is 7.59:1 and the flipped merv is 9.721:1

So MRC would be
7.59*(60(s)/14(p))=32.53:1
Merv
9.721*(60/18 )=32.4:1

So that would equate to .13km wide open, basically identical.
 
Last edited:
It will be interesting to see.

I've noticed in my heavier 2.2 crawler, a larger pinion seems to give the car more leverage against the brakes vs a smaller pinion (spurs matched accordingly to maintain similar ratio).

Wonder if you'll experience any of that.

Just looking at the pictures of the transmission, the "stuff" in the way appears to be the mount you used to fix it to the skid.

Maybe that mount could be cut off instead of the rear one.

Then a larger spur would fit, move the motor away (to reduce the excessive shaving of the case), and so on and so forth.

But that's all just speculation from my lazy boy.....lol

You're doing the hands on, what do you think?
 
MRCrackhead said:
It will be interesting to see.

I've noticed in my heavier 2.2 crawler, a larger pinion seems to give the car more leverage against the brakes vs a smaller pinion (spurs matched accordingly to maintain similar ratio).

Wonder if you'll experience any of that.

Just looking at the pictures of the transmission, the "stuff" in the way appears to be the mount you used to fix it to the skid.

Maybe that mount could be cut off instead of the rear one.

Then a larger spur would fit, move the motor away (to reduce the excessive shaving of the case), and so on and so forth.

But that's all just speculation from my lazy boy.....lol

You're doing the hands on, what do you think?
Click to expand...

no, there's some molding that houses one of the bearings for the driveshaft gear that's in the way, could probably clearance the plastic to fit a slightly larger spur, but i don't think it's necessary, as per the math, it's almost identical because the transmission is geared lower.
 
Nice! I've been thinking of putting a transmission in a Kalahari based project and the mini Traxxas looks like it would be a real good fit. And the underdrive option, simple & sweet. Bonus!! "thumbsup" Can't wait to see some performance vids.

Bl-air
 
Just an update, ran my first comp with this transmission this weekend, i have to say, the transmission is working well, too bad i dont have a decent motor, trying to build/find a better motor, had a losi insane in there but it was geared really bad (16/66) so it did not work well, just kept letting the smoke out, not enough torque to even test the transmission... so i ordered some smaller pinions, and once i get a good motor in, i'll get a good torture test in on this thing.
 
Correct me if I'm wrong, but I get 6.64:1 for an internal trans ration for the MRC. 16t top shaft into 34t idler equals 2.125:1. 16t secondary idler into 50t main gear is 3.125:1. 3.125×2.125=6.64:1. I'm not trying to nitpick, I need this info myself as well. Working on a t-case setup with existing parts. I'm almost there now.

Sent from my SCH-I535
 
89redranger said:
Correct me if I'm wrong, but I get 6.64:1 for an internal trans ration for the MRC. 16t top shaft into 34t idler equals 2.125:1. 16t secondary idler into 50t main gear is 3.125:1. 3.125×2.125=6.64:1. I'm not trying to nitpick, I need this info myself as well. Working on a t-case setup with existing parts. I'm almost there now.

Sent from my SCH-I535
Click to expand...

you could be right, as i said, i dont know the ratios, or if the numbers are correct, i just used numbers i sourced online.

EDIT
I cant find anything to verify the tooth counts on the gears, but if your teeth counts are correct, then you're right on the numbers, i'll pull my spare trans apart later and verify..

EDIT again
I'll also see if i can verify the numbers for the Merv Trans

Another EDIT
I have not been able to verify the MRC trans gear tooth count, but assuming your numbers are correct, and based on my math (which could very well be wrong), the Merv trans is not nearly as close as i thought it would be, looks like it's
Flipped Gears - (25/18.)*(35/13)=3.74
Stock - (18/25)*(35/13)= 1.94

MRC is
(34/16)*(50/16)=6.64

So the MRC Trans is considerably slower than the merv, even flipped, However, that said, i have been able to fit a 66t spur on the merv, and could likely gear it down to a 9t pinion with that big spur, so i could be at:
Merv- 66/9=7.3333*3.74=27.426
Compared to a stock MRC (i think the stock pinion is 14t?)
MRC- 14/60=4.285*6.64=28.4521
MRC 12t?- 12/60=5*6.64=33.2

(edited to correct math)

So the MERV ends up being similar with the ability to put on the 66t spur, i think i have seen a mod for the MRC trans to fit a 66t spur, so they would be comparable with gearing in the end, both very adjustable with the options for pinion and spur, just hoping the MERV trans is more durable, i have run my MERV with a 5700kv 550 can brushless motor on 3&4s doing standing backflips, doubles and triples off a parking block or curb, so i am confident in the transmission's strength..
 
Last edited:
Based on that website, the MRC transmission would be 4.29:1

R/C Calculations

EDIT: I just opened up my tranny and axles on my Kulak and counted the gears :

Diff : 14/38 (2.71)
Tranny : 14/34-16/51 (7.75)
Motor : 13/60 (4.62)

Which gives me a total ratio of 97:1 ! Wow, talk about gear reduction !
 
Last edited:
daver18qc said:
Based on that website, the MRC transmission would be 4.29:1

R/C Calculations
Click to expand...

based on math, they're incorrect... i'd need to know what numbers they're using to verify it... if it is 4.29, that would bring it a lot closer to the MERV

They do have the correct number for the MERV trans though... like i said, i'll verify the tooth count in the MRC trans when i get home and put the debate to rest "thumbsup"
 
I have HR trans gears with the teeth laser cut in each gear. Top shaft-16t stock, 34t idler, 16t idler, 50t main. Or, 6.64:1. I don't know where they got 4.29. I can take pics...

Sent from my SCH-I535
 
aze3e7em.jpg


ra3u8udy.jpg


na7apasy.jpg


And we all know the top shaft is a 16t.

Sent from my SCH-I535
 
T3rry said:
I have not been able to verify the MRC trans gear tooth count, but assuming your numbers are correct, and based on my math (which could very well be wrong), the Merv trans is not nearly as close as i thought it would be, looks like it's
Flipped Gears - (25/18.)*(35/13)=3.74
Stock - (18/25)*(35/13)= 1.94

MRC is
(34/16)*(50/16)6.64

So the MRC Trans is considerably slower than the merv, even flipped, However, that said, i have been able to fit a 66t spur on the merv, and could likely gear it down to a 9t pinion with that big spur, so i could be at:
Merv- 66/9=7.3333*3.74=27.426
Compared to a stock MRC (i think the stock pinion is 14t?)
MRC- 14/50=3.571*6.64=23.711
MRC 12t?- 14/50=4.166*6.64=27.667

So the MERV ends up being lower with the ability to put on the 66t spur, i think i have seen a mod for the MRC trans to fit a 66t spur, so they would be comparable with gearing in the end, both very adjustable with the options for pinion and spur, just hoping the MERV trans is more durable, i have run my MERV with a 5700kv 550 can brushless motor on 3&4s doing standing backflips, doubles and triples off a parking block or curb, so i am confident in the transmission's strength..
Click to expand...

Your math above shows the MRC with a 14t pinion and 50t spur.

I'm sure the stock spur is 60t (HR makes a 62t, I'm running a modified Associated 66t).

Stock ratio should be:

60/14 = 4.286 x 6.64 = 28.459

Therefore, it's still slower in stock form than the 66/9 flipped merv.

Or am I missing something?
 
MRCrackhead said:
Your math above shows the MRC with a 14t pinion and 50t spur.

I'm sure the stock spur is 60t (HR makes a 62t, I'm running a modified Associated 66t).

Stock ratio should be:

60/14 = 4.286 x 6.64 = 28.459

Therefore, it's still slower in stock form than the 66/9 flipped merv.

Or am I missing something?
Click to expand...

yeah, mybad, but realistically, with some spur/pinion gearing, they have basically the same sweet spot range.

Edit, i went back and fixed the math, MRC is still slower, all depends how i can gear this thing, with a 66t i can probably go as small of a pinion i can find, which looks like a 9T, so that puts me around 27.5:1, which is pretty god, being a 2.3mm bore, they might have some smaller pinions, but i think that would be slow enough. i think i am going to make a new motor mount plate from G10, could even potentially make one to fit a 540 can, with that big 66t spur i should be able to reach with a 540 in there... which would give a lot more motor options, but also add weight up high, so i am not too happy about that idea. ... but i also have another idea for a transmission, so who knows...
 
Last edited:
The 540 motor would be slick, but death for the axles. I can't wait to see what you come up with. The Mini E Revo trans is bombproof!

Sent from my SCH-I535
 
You must log in or register to reply here.

Similar threads

S
Ampd 2
Replies
3
Views
890
durok
durok
tgenial58
Sidobre rise of mudslide
Replies
0
Views
480
tgenial58
tgenial58
S
Ampd
Replies
3
Views
837
WHITE-TRASH
WHITE-TRASH
S
SHERP 10x10 "The Arc"
Replies
2
Views
1K
Greatscott
Greatscott
tgenial58
Foff test
Replies
1
Views
556
tgenial58
tgenial58
Back
Top