Using Infraction differential gears for off-road...any input?

[@9G]

I'm going to be starting on a new build soon...just waiting for parts. I want to make an off-road LImitless similar to what Raz Shifrin (video link below) did but with my spin on it. The question I have is does anybody have any experience using the Infraction diffs (15/42 straight cut) for off-road use? I figured these are the fastest diff ratio for on-road cars but would this help an off-road car go faster? Would I loose traction but gain speed? The regular off-road diffs are 10/43 spiral cuts and the Typhon uses 13/43 straight cuts. The 10/43 spirals are proven to be damn near perfect for off-road. At one point I switched the input gear on my TLR Typhon to the 15T Infraction and ran 15/43 but that was for on-road speed (I smoked a few guys with my TLR BTW...LOL) and I was using foam tires. I got the TLR up to 78mph using this setup with 1mil center (46T spur), 500k front and 100K rear. I want to try the Infraction ratio but strictly off-road. Here in Philly 1/5 scale nitro is extremely popular for off road drag racing and I want to compete with that using a 1/7 scale "Limitless type" setup using the fastest gear ratios possible. Is there any advantage/disadvantage to using spiral vs. straight cut off-road? Any thoughts or input would be greatly appreciated.

Link to Raz Shifrin off road build:

He used locked diffs which in my opinion doesn't work well off road since the wheels aren't constantly on the ground like they are on-road. I think you kinda NEED the open diff function for off-road to keep the car balanced over rougher uneven terrain. I also think his build was too narrow and could've benefited from a wider stance (Kraton or Mojave arms). I also think his tire choice could be improved by using a larger diameter to give more ground clearance (I'm thinking belted Katar or even those new Fireteam tires). These are some of the ideas I have to "improve" on his build which I'm definitely borrowing inspiration from. I may even chase the elusive 100mph off-road challenge which I don't think has been done yet.

 

[SrC]

It's not so much the different Ratios of Lim Diffs and Off road diffs. That can be compensated with the spur and pinion sizing at the center diff.
Its more the strength of the Spiral cut off road gears that are more stout than Straight cut . Why Arrma has both types of F/Rmain/diff gears.
Straight gears are better for less load and high rpms.
But I am sure this has been done before.
Give it a try.

 

[ArrmaFreek2022]

I'm going to be starting on a new build soon...just waiting for parts. I want to make an off-road LImitless similar to what Raz Shifrin (video link below) did but with my spin on it. The question I have is does anybody have any experience using the Infraction diffs (15/42 straight cut) for off-road use? I figured these are the fastest diff ratio for on-road cars but would this help an off-road car go faster? Would I loose traction but gain speed? The regular off-road diffs are 10/43 spiral cuts and the Typhon uses 13/43 straight cuts. The 10/43 spirals are proven to be damn near perfect for off-road. At one point I switched the input gear on my TLR Typhon to the 15T Infraction and ran 15/43 but that was for on-road speed (I smoked a few guys with my TLR BTW...LOL) and I was using foam tires. I got the TLR up to 78mph using this setup with 1mil center (46T spur), 500k front and 100K rear. I want to try the Infraction ratio but strictly off-road. Here in Philly 1/5 scale nitro is extremely popular for off road drag racing and I want to compete with that using a 1/7 scale "Limitless type" setup using the fastest gear ratios possible. Is there any advantage/disadvantage to using spiral vs. straight cut off-road? Any thoughts or input would be greatly appreciated.

Link to Raz Shifrin off road build:

He used locked diffs which in my opinion doesn't work well off road since the wheels aren't constantly on the ground like they are on-road. I think you kinda NEED the open diff function for off-road to keep the car balanced over rougher uneven terrain. I also think his build was too narrow and could've benefited from a wider stance (Kraton or Mojave arms). I also think his tire choice could be improved by using a larger diameter to give more ground clearance (I'm thinking belted Katar or even those new Fireteam tires). These are some of the ideas I have to "improve" on his build which I'm definitely borrowing inspiration from. I may even chase the elusive 100mph off-road challenge which I don't think has been done yet.

So what did you end up doing. Also are the Infraction 42/15 diffs spiral?

 

[@9G]

So what did you end up doing. Also are the Infraction 42/15 diffs spiral?

I'm actually still in test mode. The 42/15 are straight cuts. I threw those in my on road Talion with a TP 4070CM 2400KV first and then a Cordova 1445 2300KV. I was having issues with the diffs on road due to build error I'm assuming so I took the Infractions out and used 2 Felony rears (45/14) and did some tire changes and things have been better with those so far. I prefer the longer can higher KV approach as opposed to the fat can lower KV method. I was getting good RPMs with both the TP and Cordova on road but I'm liking the Cordova more (more stable, less heat and seems more efficient overall).

In the meantime I took the modified TLR Typhon with the Talion diffs (43/10) and stretched it on a Talion EXB chassis. Almost done building that and by next week I should have that out for an off road test. I've got a Cordova 1445 2000KV (good for up to 8S) in that. Gonna run 6S through it first. This build serves as my "mini" version of the Raz car. Raz's car uses the JustBashit stretched Talion chassis with is actually 1/7 scale length (same as Limitless). I've got that in waiting. Once I get a feel for the "mini" version on the regular EXB chassis I plan on swapping that over to JBI chassis and moving up to an XLX2 since it'll fit easier and then moving up to 8S. It's kinda hard getting an XLX2 on a regular Talion chassis but the JBI one actually has holes drilled out for an XLX2. If the "mini" version performs well enough I may just leave it and run 8S through that. The plan is once I get to 8S I'll put the 42/15 back in and see how it performs off road. This gives me a chance to get the tuning right as far as shocks, ride height, gearing, etc.

Here is the "Mini" version which was on my TLR Typhon (if you check my page you can see the pics of that). Got Talion EXB chassis, Basherqueen CF Talion towers and diffs with Mojave arms, MMX8S and the Cordova 2000KV. Also Vitavon Kraton hubs/stubs and Vitavon steering rack. Gonna run the belted Katars (ain't really a Talion without the Katars LOL)

This is the JBI chassis in waiting. Once I get the mini version running right I'm gonna swap the motor and arms over to this and run 8S to start going after some real off road speed. The 42/15 Infractions are eventually gonna wind up in this one. XLX2 in waiting as well. Got the TLR Typhon shocks on both cause they're the best shocks Arrma makes IMHO at the moment...very plush and easily tunable to what I'm trying to do.

This is a pic of the JBI chassis sitting next to my on road Talion with the Felony rear diffs (front and back). Got the Cordova 2300KV in this one on some 1/5 GRPs. She runs real good. Got Limitless towers on the M2C Talion Speed Chassis with Mojave arms, Vitavon Kraton hubs/stubs amd steering rack also.

 

[ArrmaFreek2022]

1st WOW nice rigs. They look sick, I'm about to throw up lol. I was interested as i recently built a strecht with Talion Arms, Towers and Springs along with The typhon diffs. I figured if its good enough for the limitless then well. I was thinking of building another or swaping these for the 42/15s like you did figured it would give me more speed, however after all the reading I'm thinking its better to leave those alone, I mean Arrma must know something about what they do. So I'm going for efficiency over speed on the diffs and work with the pinion and spur gears. For you though I maybe the spirals are the way to go, they present more speed but also more power for your offroad rig which you will need. What speeds have you gotten so far?

Also what results have you gotten?