Valve lapping compound to quiet SSD 2spd trans?

[turbodan13]

I recently put the SSD 2 speed trans kit in my Yeti, but I'd guess that this would apply to any/all metal geared transmissions, regardless. Has anyone used valve lapping compound(s), upon initial assembly, to run the gears in & help to quiet them down?

I know that metal gears will always be "louder" than plastic/composite, and over time as the gears wear together they quiet down a bit, but wondered anyone had tried the valve lapping compound before.

Thanks.

(Mods, this was also posted in General Crawlers, but I posted here since my use is Yeti-centric. Feel free to relocate/remove if necessary.)

[DavidH]

I use the axial kit, and it did not appreciably change the noise level of the transmission.

While I understand the lapping of gears to be a real thing, I would only attempt this solution if these kits (axial or otherwise) were both often reported to be noisy and that others had successfully addressed the issue with with the lapping solution. I have seen neither.

I would check for other issues, from assembly to defects in the gears themselves.

Consider removing the kit and see if the noise is something else in the driveline; or, you may be perceiving the tonal change of the lower/higher ratio gears as louder.

I would also contact the manufacturer, to see if they can offer a solution (replacement?).

The 2-speed is an integral part of how I use my truck, so I would encourage you to stick with it. Without knowing how bad it sounds, or your financial situation, its hard to make the call from here (such as, if the noise goes away with the removal of the SSD kit, get the kit from axial).

[turbodan13]

Originally Posted by DavidH

I use the axial kit, and it did not appreciably change the noise level of the transmission.

While I understand the lapping of gears to be a real thing, I would only attempt this solution if these kits (axial or otherwise) were both often reported to be noisy and that others had successfully addressed the issue with with the lapping solution. I have seen neither.

I would check for other issues, from assembly to defects in the gears themselves.

Consider removing the kit and see if the noise is something else in the driveline; or, you may be perceiving the tonal change of the lower/higher ratio gears as louder.

I would also contact the manufacturer, to see if they can offer a solution (replacement?).

The 2-speed is an integral part of how I use my truck, so I would encourage you to stick with it. Without knowing how bad it sounds, or your financial situation, its hard to make the call from here (such as, if the noise goes away with the removal of the SSD kit, get the kit from axial).

The noise, more appropriately the sounds of the gears meshing, was not an issue prior to the 2 speed installation. The transmission is properly greased, and everything turns freely. There's been a couple of missed/slipped shifts, but I'm attributing them to: A. It's new & needs to be run in; B. My getting used to making the shifts. The level of noise isn't horrible, but (as a mechanic) it isn't an ideal sound to listen to. Will it ever be silent? No, it's not supposed to be. But low gear probably shouldn't be as noisy as it is.

My thought behind using lapping compound goes beyond addressing the gear noise, and possibly helping things wear in evenly and improve shifting (again, this could just be error on my part as I learn the shift points).

For the moment though, it's all a moot point. A freshly bent rear axle on today's shakedown trail run will be taking priority over noisy gear issues. With Axialfest around the corner, a functioning rig is more important than a quiet one.

[magic_yeti]

Which servo are u using to shift the gears?
I have the axial 2-speed and it sounds ok (not silent and not that loud), i use a savöx 0231 as shift servo (maybe overpowered ) and it's shifting smooth like butter. I used the plastic shifter inside the trans, instead of the metal version and i use the high speed gear for 2. gear. never had an shift error with this setup.
Important is to set the endpoints correct.

[DavidH]

Originally Posted by turbodan13

The noise, more appropriately the sounds of the gears meshing, was not an issue prior to the 2 speed installation. The transmission is properly greased, and everything turns freely. There's been a couple of missed/slipped shifts, but I'm attributing them to: A. It's new & needs to be run in; B. My getting used to making the shifts. The level of noise isn't horrible, but (as a mechanic) it isn't an ideal sound to listen to. Will it ever be silent? No, it's not supposed to be. But low gear probably shouldn't be as noisy as it is.

My thought behind using lapping compound goes beyond addressing the gear noise, and possibly helping things wear in evenly and improve shifting (again, this could just be error on my part as I learn the shift points).

For the moment though, it's all a moot point. A freshly bent rear axle on today's shakedown trail run will be taking priority over noisy gear issues. With Axialfest around the corner, a functioning rig is more important than a quiet one.

That's a good sign if everything is moving freely.

As for shifting, I treat the yeti like I did my 4x4 car (Mazda GTX) and truck (Chevy) from the 80's - stopped, or near stopped, wheels straight, then shift the transfer case, then roll forward.

I use a traxxas 2075 servo as it is cheap, waterproof, quick, and the potato chip gears won't be stressed in this application.

Have fun at Axialfest.

[CoolRunning]

I have just done a 2 so install in a Bomber which has the Yeti gearbox.

My gearbox has always sounded like it was crushing rocks. I've replaced all the bearings which were all perfect and it sounds the same. It's had a hundred kilometres of driving through it and runs great apart from the noise.

First thing I noticed was you cannot shift when stationary. Just try to shift it with your finger and you'll quickly notice that it often cannot engage the gear as it's out of alignment so you'll end up stressing your servo. Move slowly forward or backward and shift and it'll be perfect every time if you have your end points perfectly set. You will definitely burn out the servo and damage gears if not. Servo needs to have good torque over speed.

I have to say that mine has not missed a shift so far and is a fantastic addition.

[turbodan13]

Originally Posted by magic_yeti

Which servo are u using to shift the gears?
I have the axial 2-speed and it sounds ok (not silent and not that loud), i use a savöx 0231 as shift servo (maybe overpowered ) and it's shifting smooth like butter. I used the plastic shifter inside the trans, instead of the metal version and i use the high speed gear for 2. gear. never had an shift error with this setup.
Important is to set the endpoints correct.

@magic_yeti I'm using a Savox SC0252 servo. It's nothing fancy, just the basic $20 unit. I figure it doesn't need to be a high torque/high voltage servo if it's just being used for shifting. It works well enough, so I have no complaints.

Update: I've since pulled, disassembled, cleaned & re-greased the entire transmission. All bearings were in perfect condition, and there was no sign of adverse wear. Everything went back together with a healthy packing of Mobile1 Synthetic Grease. The top shaft was put into a small cordless drill, and I gave the whole unit a good 15 minutes of FWD/REV, at various speeds & making shifts by hand. All seems smooth & quiet(ish).

The larger servo saver I was using was swapped out for a smaller one, which helped to put the shift linkage more in line with the selector fork input shaft. Bench testing seemed to be smooth and precise enough. Replacement axles should arrive today, so I'll be able to do some runs under it's own weight.

My "theory" on the noise is that it seems to be from the pinion/spur engagement. It was never an issue prior to the 2 speed install. In high range, it's only minimally louder than stock, barely. My thought is that when the transmission is in low range, there may be enough mechanical torque load that the slight gap between pinion & spur, for proper gear mesh, is giving enough free play between them to make for the added racket. I think that the transmission load is slowing the spur gear just enough that it is ever so slightly not perfectly timed to the pinion rpm's... if any of that makes sense.

Either way, it works, and it runs, so that's all that matters.

[project-c2]

I came across this thread while searching for noise from SSD 2 speed. I have just installed the kit in my Bomber and 1st gear is hella noisy, like a pinion and spur too tight mesh kinda noise. I also have the SSD kit in my SCX10 II and it was noisy, but has since "broken in" and noise is not as loud. I was going to hit first gears in the trans with a steel wire wheel to take down the gears just a hair to see if that works. But the lapping compoud idea is awesome. Just worried about the compund getting in and on the bearings.

[Voodoobrew]

Originally Posted by project-c2

I came across this thread while searching for noise from SSD 2 speed. I have just installed the kit in my Bomber and 1st gear is hella noisy, like a pinion and spur too tight mesh kinda noise. I also have the SSD kit in my SCX10 II and it was noisy, but has since "broken in" and noise is not as loud. I was going to hit first gears in the trans with a steel wire wheel to take down the gears just a hair to see if that works. But the lapping compoud idea is awesome. Just worried about the compund getting in and on the bearings.

I have used car polish and people i know like to use tooth paste as it washes off easy in water. the idea is that it doesn't get into the bearing as centrifugal force keeps it out at the teeth except what flings off.

I haven't had incredible luck quieting down noisy drive trains though. I can make them maybe 30% quieter. but by the time they bug me enough to lap them seems there Isn't much to do but deal.

I have what i think is a cloned rc4wd ax2 transmission and the bearings seem to have a sloppy fit. I shimmed them with aluminum foil which quieted them down temporarily, but i think since the foil has shifted.