No more underdrive or overdrive gears?

[C_Money]

I notice that rpp doesnt have them or they are just listed different. What gear numbers are the overdrive and underdrive ones?

[Duuuuuuuude]

They're there. Here's one set...

http://www.rpphobby.com/product_p/ax30402.htm

[C_Money]

which ones are those though? The overdrive or underdrive?

It used to say what they were but anot anymore.

[jr104]

I put the 38/14 in mine and the 43/13 in my son's. with stock 55t motor and stock gearing . My son's was a bit slower then mine. The 38/14 seem to do a lttle bit better when a bit more wheel speed was needed. Now we are both running lower turn motors me 35t him 45t on 3s lipo.Now I can't tell any difference at all between the two. Either way you front will turn faster. It just depend if you want crawl slower or have a bit more wheel speed. Hope this helps
Jake

[JeremyH]

Originally Posted by C_Money

which ones are those though? The overdrive or underdrive?

It used to say what they were but anot anymore.

All you have to do is divide the ring gear tooth count by the pinion gear tooth count to get the ratio. A lower value will result in a slower truck...

[CRSMacgyver]

Originally Posted by JeremyH

All you have to do is divide the ring gear tooth count by the pinion gear tooth count to get the ratio. A lower value will result in a slower truck...

Don't you mean a higher numerical value will result in a slower truck? 3.30 gears (43/13) are lower/slower than 2.57 gears (36/14).....

I thought you were a 1:1 guy....

[JeremyH]

Haha....yeah, good catch! I need a cup of coffee....

BTW, it's 36/14 and 43/13.....

[CRSMacgyver]

Yup, I couldn't read this morning.

[JeremyH]

Dont worry...my brain wasnt working then....

[Grizzly4x4]

Originally Posted by C_Money

which ones are those though? The overdrive or underdrive?

It used to say what they were but anot anymore.

Originally Posted by RPP Description

New gear ratios offer a low gear and high gear range
The lower gear range set reduces torque twist (43/13)
The higher gear range offers higher top speed (36/14)

It's all right in the description.

[C_Money]

Ok so would overdrive be the higher one? Or the lower one? This stuff confuses me.

[jr104]

38/14= 2.71:1 taller gear more wheel speed
43/13= 3.23:1 Lower gear less wheel speed

Both gears will give an overdrived front axle

[jr104]

Look, when you put the 38/14 gears in the front and stock in there rear . The front will have a taller ratio than the rear. It also works the same way when you put the lower 43/13 gears in the rear and keep the stock gears in the front. Since the front stock gears are still taller than the rear underdrive gears. So either way the front will end up with a taller gear than the rear. Difference is with 38/14 you will have more wheel speed, and 43/13 you will have less wheel speed. Some people beleive that going with the rear 43/13 will reduces torque twist. For me torque twist wasn't a problem, so neither gear set made much difference other than a slight wheel speed change. Either set you choose will still help with vert climbing because the faster spinning front tires will help pull you up and over certain obsticles.
Jake

[Grizzly4x4]

The 36/14 will make your rig go faster than stock (overdrive), just like shifting your car's transmission into overdrive.

The 43/13 will make your rig go slower than stock (underdrive), just like shifting your transfer case into 4 low.

You can put an overdrive in the front axle and stock in the rear to help climbing and it may reduce torque twist a bit.
You can also put an underdrive in the rear end and leave the stock in the front to accomplish the same thing.
Both cases the front tires spin faster than the rear. Just a little bit though.

[jr104]

Originally Posted by Grizzly4x4

The 36/14 will make your rig go faster than stock (overdrive), just like shifting your car's transmission into overdrive.

The 43/13 will make your rig go slower than stock (underdrive), just like shifting your transfer case into 4 low.

You can put an overdrive in the front axle and stock in the rear to help climbing and it may reduce torque twist a bit.
You can also put an underdrive in the rear end and leave the stock in the front to accomplish the same thing.
Both cases the front tires spin faster than the rear. Just a little bit though.

Exactly. i'm not sold on the notion that the 43/13 reduces torque twist. Just because it looks good on paper doesn't always mean that in the real world it will be that way . Every set-up is different. For me it wasn't , but for someone else it might be. that's why tuning is so important. I have seen it many times where for example, two idenical engines when dyno'n , one will like timing, and the other won't, or one will want fuel and the other won't. There are just to many varibles when it comes to performance tuning.

[JeremyH]

Originally Posted by jr104

i'm not sold on the notion that the 43/13 reduces torque twist. Just because it looks good on paper doesn't always mean that in the real world it will be that way

It doesn't reduce torque twist....it does make it appear to be eliminated. Overdriving the front axle will preload the suspension which will make TT seem to be less. There is not a permanent solution to eliminate TT (unless you go to MOA)....it will always be present when you mount your motor to a sprung chassis.

[jr104]

Originally Posted by JeremyH

It doesn't reduce torque twist....it does make it appear to be eliminated. Overdriving the front axle will preload the suspension which will make TT seem to be less. There is not a permanent solution to eliminate TT (unless you go to MOA)....it will always be present when you mount your motor to a sprung chassis.

There are ways to just about eliminate it though, proper geometry(anti-squat), shock valving, shock volume(hardly hear metion much), shock presure (1.1 example), shock angle , spring presure, a winch sucking down the front axle ,driving with some finess, and so on, so on...

That wasn't my point. My point was just because mathmatically it looks good on paper ,or that it works for Joe Blow, doesn't mean it will always work for you. You gotta try different things and see what works best for you, tune , tune, and tune some more. That's all. Good luck Cmoney

[JeremyH]

Originally Posted by jr104

My point was just because mathmatically it looks good on paper ,or that it works for Joe Blow, doesn't mean it will always work for you.

Yep, I completely agree. I have the overdrive gears in the front of my axial rig and, when driving forward, I dont notice any torque twist. Now, reverse is another story...but that it what I expected out of these gears. I have not tried the underdrive in the rear, but it should affect the truck in the same manner.

[Lobonyc]

HMMMMMM

I put the 43/13's on both front and back axles...

I noticed my truck's take offs to be a little softer and its speed just a tad slower...

but i also noticed that the truck was not leaning to one side or twisting as much.

This allowed me to soften the suspension a bit and allow for smoother articulation.

[PowerCrazy]

It will climb better with a higher ratio in the front and a lower in the rear