BHB MOD, I had to try it

[mtr1514]

So I have jumped into the RC world head first and havent looked back. I am specifically focused on the Yeti XL. I cant get enough and even with all its shortcomings, this rig is fun! A lot of this fun is just trying to make it better and modifying it. With that in mind I have decided to try to do the BHB mod myself. So far running a RTR with only 4S, I have no current issues with my front or rear diffs. But 6S is just around the corner and my driving is definitely becoming more aggressive. Also I definitely want that Vanquish rear axle housing before they become a collectors item so I ordered one. Definitely have to do the mod to use that. Anyway for anyone interested in trying it, this is how I did it.

The first thing to do was to set up my BHB mod equivalent rig. In that I found the hardest part was just finding something to hold the pinion onto the drill. I used a 4MM hex socket 1/4 drive to do the trick. I evenly wrapped the hex side with rubber splicing tape a couple times to give it a bit of that spongy feel to it. Then I wrapped electrical tape over that a few winds so that it would snugly fit into the pinion.




I then used this drill and vise setup. The 1/4 drive side of the socket fits into the drill chuck no problem. The metal piece in the vise had a rounded end to but it is just used to stabilize the pinion so it stays rock steady which is important.



Then using BHB's dremel technique, I shaved the hump down and tried to get the teeth 90 degrees to the shank as BHB states. This is the end result. I didn't have a bearing on me at the time but I used this plate to illustrate how it more or less sits flush with the surface. I think this will work and if not I can shave a bit more off. Think I'll wait until my Vanquish rear axle housing comes in so I can custom fit it. Though I am still having some trouble acquiring shims. Anybody know where you can get more 18x15x0.2mm shims?



I would like to thank BarHarborBasher for putting his videos and knowledge out there as well as everyone else on this site. I am open to any insight, tips or recommendations from the group. Thanks!

[BarHarborBasher]

Great thread

Thanks for the kind words. This is a great thread that will definitely help others out there. Great job improvising looks like you're ready for 6S action. I'll copy and paste some of my technical info on here.

[84yoda]

Awesome idea you came up with.

Axial sells 15x18x0.2 shims.

[mtr1514]

Thanks guys! Yeah Axial does make those shims but you cant find them anywhere right now. I think one website says they are on backorder until May. I will find a way though.

[Tzicul]

Vespa ET2 50cc pre 2000 Variator Shim Speed Up Set 15mm | eBay

However you need to narrows them, as they are wider than 18mm. I don't think this will be a problem for you

[mtr1514]

They definitely look like a viable source if it wasn't for them not shipping to the U.S. and that's where I reside. I did order the Dhawk Spacers which do come with some shims so I might be ok. Thank you Tzicul for the input though!

[pro mod steve]

I got a new pack of 6 shims in my crash box. PM me an address and they are yours.

[mtr1514]

Steve, thank you so much! Actually from going through BarHarborBasher's thread, with the Vanquish Rear Axle, Dhawk Spacer and BHB mod, I shouldn't have to shim. And the Dhawk spacer I ordered comes with some shims if I do have to a little. So I think I'm good but thanks again for the offer!

[84yoda]

You will have to shim. Since you did the mod on the pinion, you have to make up for that with shims.

While your back there, you might as well do the 3rd bearing mod too. Again you will need shims for this as well. But the Dhawk spacer won't be used. Lol

[mtr1514]

BHB said just applicable for the Vanquish rear axle with the Dhawk spacer and pinion mod, no shimming was needed. Everything worked out evenly because of the extra thickness of the fast eddy bearing that comes with the rear axle housing. I guess I'll find out when everything comes in and let everyone know.

[BarHarborBasher]

Originally Posted by mtr1514

BHB said just applicable for the Vanquish rear axle with the Dhawk spacer and pinion mod, no shimming was needed. Everything worked out evenly because of the extra thickness of the fast eddy bearing that comes with the rear axle housing. I guess I'll find out when everything comes in and let everyone know.

Great researching

[mtr1514]

Thanks BHB! I read that entire thread for sure.

84yoda I did read that you have the Vanquish rear axle housing and went with the 3 bearing mod. Do you recall how many shims were needed with that setup? I should do that while I'm opening it all up.

[Tzicul]

You'll need 0.7 to 0.9 mm for a stock axle without bhb mod. Don't know if this help

Sent from my Sony Xperia Z5

[mtr1514]

Yeah that sounds about right. I shouldn't have to shim with a Dhawk spacer and the spacer is 4.82mm wide according to your measurement you posted awhile back. And if a bearing is 4mm wide, it looks like 0.8mm should do it. Thanks for the info Tzicul.

[mtr1514]

Thanks to ProModSteve for donating some shims, I was able to start by BHB mod/3 bearing mod, Vanquish rear axle housing upgrade. The big thing I noticed breaking down the old housing was that the axle was notchy when spun. This was even more noticeable when the new bearing set was in the new housing because it spun "like butter"! No kidding. It was so smooth.

This is a picture showing how the old pinion rested on a bearing versus the new pinion/bearing set. Notice the larger first bearing which is a Fast Eddie bearing, 24x15x5mm. This came with the Vanquish housing which is recessed to fit it perfectly. And because of this bigger bearing, I only had to shim 0.4mm. But I guess the clearances can vary depending on how much you shave off in the BHB mod.



And after securing it down tight, the axle spun effortlessly. And in this pic, I haven't even finished greasing it.



Next I have to retrofit my Hot Racing straight axle adapters to the Vanquish housing. Because as expected, they do not fit. I could go stock plastic, but why. I researched that I will have to do some dremeling to make them fit. Challenge accepted.

[mtr1514]

So the dremeling of the Hot Racing rear axle adapters was successful. Not that hard at all but just tedious. My rear axle is completely aluminum and I have been on 6S for a few battery cycles now. With the new power along with new CI foams, its a whole new ballgame. There is no need or desire to ever go back to 4S. Its fun on a whole new level. I cant recommend it enough.



The only thing left that is not reinforced is my transmission. Installing a Hot Racing aluminum case with Fast Eddy bearings.

[mtr1514]

So I finally got to modding my RTR stock HD pinion gears that I replaced with new ones earlier. I'll keep them in my crashbox if I ever need them. One thing I wanted to pass along is that it's pretty easy to eye it as your grinding down the gear. The goal is to maintain uniformity so I kept measuring the gear to try to meet BHB's numbers that he posted. For the stock pinion he got a measurement of .584 inches which is what I got as well.



Then after shaving the pinion gear he got .618 inches which is what I was shooting for.



Those are proven numbers so if you match those you should be golden.

[BomberYetiXL]

I recently did both my front and rear BHB HD mod and 3 bearing. Unfortunately I wasn't able to find shims but working in a machine shop I was able to make my own and mod the gears on a lathe. But me having no luck whatsoever my front right diff bearing blew causing my HD gear destruction.

Sent from my LG-H872 using Tapatalk

[mtr1514]

Great job on the modded gears! The ultimate BHB mod performed on a lathe.

Tough break on the ring gear. I recommend Fast Eddy bearings on all your future bearing replacements. They are way better than stock.

[Deckard]

mtr1514, is there a thread on what needed to be done to the HR lockouts to get them to fit on the Vanquish axle? I looked before asking but didn't find anything. I'm also very lazy so I only look for a short amount of time.

Thanks