Is slight overdrive noticeable on pavement?

[TITANIUM94010]

I'm doing a trophy truck build, and my plan is to have it be 4x4, but the only way I can make that happen is having a slight overdrive in the front, because I have to run a Slash type diff in the front while having a TRX4 axle in the rear.

Front diff: 2.846:1

Rear diff: 2.75:1

Or a 3.43% difference.

I'll mostly be doing dirt driving, a lot of 2wd driving too, but I will still be driving it quite a bit on asphalt on 4x4. Truck is estimated to be 10+ lbs when completed, but give a take a few pounds. Other than tire wear, would I notice any extreme handling differences?

It is meant to be a go fast rig, which is why I'm worried.

 

[Goro Majima]

I'd like to think you would notice a difference at higher speed turns. ~3.xx% overdrive is not much at all but in the top end of speeds and turns, I'm just assuming some tweaking in the driving muscle has to be altered barely. If it's what you have to do to achieve your overall goal of the truck, send it.

 

[CODYBOY]

I'm doing a trophy truck build, and my plan is to have it be 4x4, but the only way I can make that happen is having a slight overdrive in the front, because I have to run a Slash type diff in the front while having a TRX4 axle in the rear.

Front diff: 2.846:1

Rear diff: 2.75:1

Or a 3.43% difference.

I'll mostly be doing dirt driving, a lot of 2wd driving too, but I will still be driving it quite a bit on asphalt on 4x4. Truck is estimated to be 10+ lbs when completed, but give a take a few pounds. Other than tire wear, would I notice any extreme handling differences?

It is meant to be a go fast rig, which is why I'm worried.

I'd like to think you would notice a difference at higher speed turns. ~3.xx% overdrive is not much at all but in the top end of speeds and turns, I'm just assuming some tweaking in the driving muscle has to be altered barely. If it's what you have to do to achieve your overall goal of the truck, send it.

Are you running a trx4 portal in the rear? If so I think you are going to have a % of reduction there also. "thumbsup"
Ernie

 

[TITANIUM94010]

Are you running a trx4 portal in the rear? If so I think you are going to have a % of reduction there also. "thumbsup"
Ernie

Oops, forgot to mention, I have a portal delete kit on it.

I'd like to think you would notice a difference at higher speed turns. ~3.xx% overdrive is not much at all but in the top end of speeds and turns, I'm just assuming some tweaking in the driving muscle has to be altered barely. If it's what you have to do to achieve your overall goal of the truck, send it.

I'll try with the slash diff first, plus if I can get the selectable 2wd/4wd thing to worth remotely, I can always just unhook the front drive for high speed runs. Only that's going to take me a while to figure out. Thank you for the reply!

 

[Panther6834]

Honestly, I don't think a 3.43% OD is going to be 'problematic' at higher speeds...the difference is so minimal. For the center, are you using a slipper, or a center diff? If a slipper, just loosen it a little more then you might normally do...and, if a center diff, just go with slightly lighter (ie. lower number) weight diff fluid.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

 

[durok]

Heck, if you get a set of 2 tires worn a fair bit, and throw them up front and keep putting newer (slightly taller) ones out back - you might come out even!

A while back I was thinking of making a slight O/D happen by running TSLs up front & cut Boggers in the rear on a 2.2" bouncer - a bit like Clayton Hollingsworth's Outlaw 1:1 bouncer...

 

[DRED805]

My 36% OD truck does fine on pavement at 10+mph, so I don't think you're gonna notice 3%.

 

[ferp420]

having a slight over drive up front helps keep.the rig going in a straight line
so in my opinion if you notice anything at all it would be a slight bump in the handeling department
you might loose a bit of top speed though

 

[TITANIUM94010]

Thank you all for the replies,

I'm using a RC4WD Ax2 2 speed, so no center diff,

I never thought about tire size differences, after the rear wear's I'll probably swap the rear to the front, but I'm not sure that little of a difference in tire OD would make much of a difference,

But it does sound like it shouldn't effect my build too much.

 

[Njeffs8]

Not with that little of od

 

[OSRC]

I used to run a bit of front OD in my Super Nitro's - helped them pull out of the corners. Might lead to a bit more wear and tear, but never gave me a problem. Tires seemed to wear a bit faster than my non OD car, that's all I ever noticed.

 

[MattH]

I've driven plenty of my crawlers with overdrive on pavement and never noticed a thing let alone saw any binding or "fighting."

Interestingly (kind of), I have had a few full-size off-road rigs that were often daily drivers that had not-exact gearing matches. Less than 1% difference, which, of course, is no where near what strictly off-road only rigs sometimes run or what we run in RC. 1% was said to be allowable and, as someone touched on above, you probably see bigger differences unintentionally due to tire wear or air pressure differences.

 

[lonleycreeper]

Generally, od in a Rc is not a problem.

It is only a problem in full size due to the weight and mass of the rigs, and the fragility of the parts.

 

[MAC FAB]

The "on pavement" statement would concern me, depending on what you consider a go fast rig at the vehicle's scale. 30 mph at your 3% and change gets you over 1 mph. At 20 mph it equates to a little over .6 mph, .5+ mph at 15 mph. With a 10 lb. rig, something is going to tap out. Consider that into your engineering for an easy to replace "fusible link". Something is going to break, be sure its an inexpensive piece as well. It will eat tires at a minimum. Case in point, go watch the rear axles on a 3 axle truck and note the space between the tires' footprint is where they pivot on a turn. You have rears being drug by the front and vice versa. Great in the dirt, my .02 says it will suck on the street.

 

[Ninomaniac]

If you ever turn on pavement, over/under shouldn't worry you.