DIY Mullet

[Col_Sanders]

If you are looking to build your own mullet with F10 axles, the problem you will deal with is that the rear and front axles spin in opposite directions. There are a few different ways to resolve this. One is to use a mullet transmission. These typically have some overdrive to the rear and the rear output shaft turns the opposite direction of the front. Several options out there from CL Designs, Deviate Customs, Exo, and others.

Another option is to flip the ring gear over to the opposite side of the pinion gear. This requires reverse cut gears and some grinding. Boom Racing, Ottsix, and some other companies offer these types of gears. For reference, Boom Racing reverse cut on top, Axial standard gears on bottom.



Then you gotta bust out the Dremel on the third member to make clearance for the ring gear. This is some Aliexpress cheapo aluminum third member. The grinding job is not perfect, but it's hidden inside so whatever.


Next is the axle housing. Gotta clearance that for the ring gear as well UNLESS you got one of the newer housings, which vanquish has redesigned to allow the ring gear to be used on either side.



The third option is the cheapest and it's what Vanquish did with their mullet. Clearance the housing and flip the third member upside down. This gives you a low pinion setup, which puts your driveshaft down low. Not really ideal, especially if you're running high clearance links.

 

[JatoTheRipper]

Good tips. Also good to know Vanquish changed their housings. All this because, let's be honest, Vanquish took the cheap way out with their Mullet. It's still a cool rig and I still want to build one, but they knew they were taking a shortcut here.

 

[bgredjeep]

I've built 2 cars now using the "flip the 3rd" method.

The first was my scx10 pro. On that car i could have used a reverse cut gear and kept it high pinion, but i didn't end up keeping that one long enough to even think about it.

The 2nd is my current Phoenix build. So far I haven't found the low pinion to be an issue. Even if the driveshaft does hit, it's basically a smooth ramp to the bottom of the diff. On this car my trans (vrd carbon spec vfd) is a restriction for being able to swap in a reverse cut gear. I mean, I could, I'd just end up with a ridiculous amount of overdrive. As it sits i installed a set of Mues 20% overdrive gears in the rear diff to get a reasonable overdrive ratio.

With a non-od trans, I would probably mod the 3rd and run a reverse cut gear instead of the flipped diff, but I really don't think there's a big impact to performance from the low pinion. If the driveshaft on a low pinion is really going to hang you up, what do you think the bottom half of a high pinion diff would do in the same scenario?

 

[Col_Sanders]

With a non-od trans, I would probably mod the 3rd and run a reverse cut gear instead of the flipped diff, but I really don't think there's a big impact to performance from the low pinion. If the driveshaft on a low pinion is really going to hang you up, what do you think the bottom half of a high pinion diff would do in the same scenario?

With straight rear links I dont think the low pinion would be too much of an issue. The rig I'm building now has very high clearance double bend lower links. Low pinion would definitely hang up and my driveshaft would really get beat up. I had to tilt the axle back a bit to get the driveshaft up out of the way even with a high pinion. I'll try to get better pics of that tonight.

Good tips. Also good to know Vanquish changed their housings. All this because, let's be honest, Vanquish took the cheap way out with their Mullet. It's still a cool rig and I still want to build one, but they knew they were taking a shortcut here.

If they had done a reverse cut ring and pinion and new/redesigned third member, they could have done an underdrive ring and pinion up front and skipped the lightweight OD in the transmission. That would be roughly the same amount of OD, but I guess they are expecting there to be a bigger market for an overdrive ring and pinion than there would be for a reverse cut gear set and third member?

 

[bgredjeep]

With straight rear links I dont think the low pinion would be too much of an issue. The rig I'm building now has very high clearance double bend lower links.

That makes sense on a super high clearance pzoid-ish rear setup. I was speaking more towards the folks that acted like VP did the worst and laziest thing ever in the history of rc by selling a (clutching pearls) low pinion in the mullet. Lol.

Imo, in that scenario it's a non-issue beyond personal preference.

For both mine with typical bent links I just rotated the pinion up a few degrees and the driveshaft is barely below the links at any point, and within the radius of the tires.

 

[JatoTheRipper]

I don't think it's the worst thing ever, but you can't argue that they didn't take the easy way out. I understand why they did it. Parts bin engineering is cheap.

 

[Col_Sanders]

There are also carrier bearings out there with multiple outputs. I didn't find them listed as carrier bearings, but as a gearbox. Only versions I found were no name china stuff so I wasnt willing to try it. I'm sure one of the reputable crawler companies could make one pretty easily. This particular one from ebay also has a 30% underdrive option.

 

[bgredjeep]

I haven't looked to see if there would be room, but if you could mill out the front 3rd to run reverse cut gears in the front axle, that would solve my underdrive issue. It looks like 2 of the mounting holes might be too close to allow that.

I'll try to take a look this weekend.

 

[bgredjeep]

Fyi. I checked on the possibly of reversing the front axle today. I'm pretty sure it will not work since 2 of the screws that hold the 3rd into the housing will interfere with the ring gear. I'm still going to try it at some point, but I'll pick up another plastic housing before I do since I'm 90% sure it'll ruin the axle housing.

Worth $14 to try, I just don't want to end up with an axle in pieces waiting on replacement parts if what I expect to happen does in fact happen. Lol

 

[justinart24]

Very cool build! I dig the sliders

 

[bgredjeep]

There are also carrier bearings out there with multiple outputs. I didn't find them listed as carrier bearings, but as a gearbox. Only versions I found were no name china stuff so I wasnt willing to try it. I'm sure one of the reputable crawler companies could make one pretty easily. This particular one from ebay also has a 30% underdrive option.

View attachment 514387

So I was looking at these a couple days ago. Of course none of the available options would line up at all with my chassis or generally play nice with the vfd trans I'm using. I took a shot at making my own just for kicks.

I had some leftover transmission parts (vfd slipper input shaft and a couple top gears from the vfd). I also had a 3gear input shaft from a slipper eliminator I ordered. I was successful, but ultimately not successful. The problem in my test is the rear driveshaft is just too short for the amount of travel needed. I could possibly get the case about 5mm shorter, but still not really enough to make it work. It's functional, but the available driveshaft travel in the short shaft limits the suspension travel.

All the same, it was a fun experiment to put together.

 

[Col_Sanders]

If you're wanting to keep the VFD, HTech just released something very interesting....

H-TECH CNC Aluminium Reverse rotation kit for Vanquish VRD MULLET

m.h-techproduct.com

 

[bgredjeep]

Well there we go. That's what I call problem solving. Lol

 

[JatoTheRipper]

If you're wanting to keep the VFD, HTech just released something very interesting....

H-TECH CNC Aluminium Reverse rotation kit for Vanquish VRD MULLET

m.h-techproduct.com

Odd. I can’t see the extra weight being worth it.

 

[Col_Sanders]

Odd. I can’t see the extra weight being worth it.

On the Tuesday livestream a few weeks ago, Brandon had one of his personal mullets up on the desk and it had a high pinion rear. When asked about it, he said it was a kit from Sea Squirrel, which had closed down. The rear portion of the housing was 3d printed but otherwise looked kinda similar.

 

[JatoTheRipper]

On the Tuesday livestream a few weeks ago, Brandon had one of his personal mullets up on the desk and it had a high pinion rear. When asked about it, he said it was a kit from Sea Squirrel, which had closed down. The rear portion of the housing was 3d printed but otherwise looked kinda similar.

Well isn’t that adorable. Vanquish kind of admitting the pinion should be up high! So maybe they’re going to release something like this. I think a flipped third member and accompanying gears would be a better fix, but not holding my breath…

 

[Col_Sanders]

I wonder if it would be possible for them to just have a different gear configuration in the existing case that would eliminate the front overdrive and have a counter rotating rear output.

 

[bgredjeep]

I don't think they could fit that in the trans outside of something like htech did. Better option within their existing designs might be a lightweight gear set with the low od (6.5%). That would allow for using a standard ratio reverse cut gear in the rear and keep about the same underdrive.

The htech part is sold out. I might try one eventually. I guess the weight penalty would be similar to running the standard low od gears in the trans.

 

[bgredjeep]

I wonder if it would be possible for them to just have a different gear configuration in the existing case that would eliminate the front overdrive and have a counter rotating rear output.

Well, now look what you made me do.

After you put that thought out there I took a good look at the manual and realized the center gear in the t-case is the same 23t count as the input shaft gear i used in my failed reverser attempt. I also had an extra rear transfer case half so no real risk in trying.

With the existing ratios this does overdrive the rear output, but with the normal portal ratio I think I'll still be around 20% rear underdrive overall. I could always swap to standard gears in the portal box for more.

I'm heading back to the garage to swap the rear gears and see if my math mathed properly.

 

[Col_Sanders]

Hell yeah! I was thinking it would be possible to do with a new rear case half and relocating the rear output to a different gear. My cad skills and motivation are just not on that level.