over drive / under drive ?

[94s10blazin]

i want to crawl and do high speed rolls . will i mess any thing up after
over/under drive mod if i drive fast. other than tire wear

+ with locked trans or not?

[66sprint6]

Just do the overdrive front and leave the rear stock and see if you like it, if not then go with the rear. I did the underdrive rear only and Im perfectly happy with it. Tire wear is tire wear, its not a daily driver 1:1 and you wont notice anything out of the normal.
Matt

[Stormin2u]

Originally Posted by 66sprint6

Just do the overdrive front and leave the rear stock and see if you like it, if not then go with the rear. I did the underdrive rear only and Im perfectly happy with it. Tire wear is tire wear, its not a daily driver 1:1 and you wont notice anything out of the normal.
Matt

X2 just the rear works good for me to.

[indiana mudcat]

Just the rear is the best place to start, it has a much better effect on TT than the front does. That said I run OD in one truck and UD in the other cause I had the gears and didn't wanna buy another set.

The only downside is when trying high speed turns it seems to flip faster like the front is pulling out from under the truck.

[TAT76]

Ok I've been seeing post pop up about this alot and till now really just skipped over them. So what am I missing? What parts are needed to UD the rear? Will doing so mess with downhill?
Thanks guys

[66sprint6]

All you need is the Axial Under or Over drive gear kit...roughly $30. Its simple to do and works really really well...my rig is a climbing monster now, and downhills dont hurt just let the drag brake do its job lol. Underdrive the rear and leave the front stock will slow the truck down some and add some torque, Overdrive the front and leave the rear stock will add some speed and wheelspeed. I like torque personally but most around me do the overdrive instead to gain more wheelspeed.
Matt

[BOWTIE]

http://www.rpphobby.com/ProductDetai...ctCode=AX30401

http://www.rpphobby.com/ProductDetai...ctCode=AX30402



i have both in my truggy.. over in front and under in rear. it gives the front a geared "dig" effect and also if you blip the throttle you can make tighter turns.

i haven't had any issues with any speed runs with them in there.

the opening of this video shows a "speed run"

http://www.youtube.com/watch?v=UDZ0TjuTwsc

[kincer]

Ok so Im confused in 1:1 rigs you should always run the same gear ratio in the diffs so how can you get away with it here without tearing things up?

[BOWTIE]

Originally Posted by kincer

Ok so Im confused in 1:1 rigs you should always run the same gear ratio in the diffs so how can you get away with it here without tearing things up?

just for the fact that these are not 1:1 trucks.


here are some numbers:

stock 38t/13t = 2.92:1*

over 36t/14t = 2.57:1*

under 43t/13t = 3.31:1*

*tranny output revolutions : 1 revolution of the tire.

[fred0000]

Originally Posted by kincer

Ok so Im confused in 1:1 rigs you should always run the same gear ratio in the diffs so how can you get away with it here without tearing things up?

1:1 vehicles are MUCH heavier, so the weight pressing down on the drive wheels is tremendous, so it will drag and bind, if we scaled down properly to 1:10, our rigs would be ~400 pounds, then it might be an issue, no need to worry.

I run overdrive in the front of my sportsman crawler and love it, i'd do it to my scaler just for the better steering aspect, I think I also want to try underdrive in the rear of my crawler.

[94s10blazin]

Thanks for your
thoughts guys

[murky123]

I you just want a little tighter turn? OD front is the way to go?

[indiana mudcat]

Originally Posted by murky123

I you just want a little tighter turn? OD front is the way to go?

IMO you should only OD if your already running UD rear and want more, I've ran both in the same truck at differnt times to test and the OD got yanked after the first run. They each have the same effect on turning alone, however the UD is much better than stock at climbing and TT, OD TT is a little worse than stock. Another reason is I fight to gear down and clear the spur with the driveshaft, why gear back up at the axle when I can get more there and take some strain off the back shaft (lessening the twist), OD will increase the front shaft strain and front twist.

[Locked Up]

Fantastic modification for a crawler.
I put them both in my H2 after seeing how much better it worked in my comp ax10.

Better turning, less tendency to roll on climbs and it creates a drag effect that forces the front tires to pull you up hill a little.


High speed ... may not notice as much difference but there are a lot of 1:1 mud trucks that run mismatched gears because they feel it gives them better turning in the goopy stuff.

[BOBO_XLT]

does it seem to affect sidehilling at all?

[indiana mudcat]

Originally Posted by BOBO_XLT

does it seem to affect sidehilling at all?

If any it would be slightly better, it wouldn't hurt.