450ES rear differential shim/spacers missing?

[Bman 17]

Took apart my rear diff this last week to inspect. The differential has been pretty noisy at speed.  Running some Lucas oil stabilizer does help it quite some. But not a ton.  Cleaned it  out and inspected the ring and pinion. Ring looks decent the pinion definitely has some teeth wear. No metal In the diff oil oddly enough.   But I did notice after I re-sealed it that I didn't recall seeing any shim/spacers on either side of the ring gear.   So I imagine the ring gear is floating on the axle a bit and it's engagement to the pinion being sloppy is the sound.  

 

Got on the parts breakdown and there's several different options for those shim spacers. Where do I begin? How do I know when I got it right?

[AKATV 822]

Bman,

Spacers are for adjusting the backlash between the gears

They are thin and easy to miss on disassembly, make sure they were not stuck to the bearing or the ring gear front or back

Download the service manual here on the forum, pages 16-7, and 16-8 cover backlash specification and adjustment

Here is the link to download the service manual

https://drive.google.com/drive/folders/15eWwngQ5SdlsIfbgpm5ZJWJYBYx3vJ7s

Let us know how you make out

-AKATV

 

Edited November 18, 2023 by AKATV

[shadetree 5,884]

as akatv ^^^ posted, yeah..those spacers on the ring gear are very easy to miss/over look !. most times in my work, they either stick to the ring gear ?, or stick to the bearings ?..most on ring gears. as for which ones you will need ?, well..this is an open and close case !. all depends on how much wear you have on the pinion gear and ring gear teeth ?. i normally just re-use the spacer washers that are on the differentials as i put them back together. if i have to buy new spacers ?, i just buy stock size, but i always have these spacers when i tear them down. '' if '' i tear one down, and someone '' miss-placed '' them ?..lol. i will round up some spares i keep on hand, do a dry fit. by this, i put the spacers on the ring gear, put it together, spin the pinion gear by hand, rocking it back and forth, i can feel/tell how much space i have before the two teeth hit each other ?, if i feel too much slack before the teeth '' hit '' ?, then i need to locate a thinner spacer washer...this is how i do it. yes.the book says to use a spec tool to '' dial '' in the back lash ( same thing as teeth space ) ?, but i go by feel.

[Bman 17]

I wondered if I just missed them.  But I cleaned everything up by hand and I figured they would have come off it.  The pinion did show some pretty good wear compared to the ring. And it's got some play before I feel the the teeth engage. So I'll probably grab some shims and try shimming it into the pinion a bit more.  It's pretty loud when just spinning it by hand with the wheels up.   

 

Anyone buy any of those non OEM replacement rear diffs? Most of them around 250$. 

[shadetree 5,884]

3 hours ago, Bman said:

I wondered if I just missed them.  But I cleaned everything up by hand and I figured they would have come off it.  The pinion did show some pretty good wear compared to the ring. And it's got some play before I feel the the teeth engage. So I'll probably grab some shims and try shimming it into the pinion a bit more.  It's pretty loud when just spinning it by hand with the wheels up.   

 

Anyone buy any of those non OEM replacement rear diffs? Most of them around 250$. 

i normally just buy the ring gear and pinion gear if its still being sold from honda.

[Bman 17]

Took it apart again. And I was Right. There aren't any shim spacers on the ring gear or stuck to the bearings.   So that's what's going on with the noise. 

[Bman 17]

And upon some closer Inspection the ring and pinion are only engaging at the very tip of the gears. And the ring gear is in so much better shape than the pinion id say someone replaced the ring gear and didn't touch the pinion. Because the teeth on the pinion are worn to fine edges. Where as the ring still had it's flats on the teeth

[AKATV 822]

It makes perfect sense if somebody was in there before and didn’t know about the shims, they were probably stuck to the old ring gear and got tossed

-probably only did half the job because pinion is more difficult to remove than ring gear with the bearing retainer clip removal and the tool/ square tubing needed for disassembly 

 

[Bman 17]

The more I looked at it the more I do want to change out the pinion. Like I say the edges of the teeth are worn down to points instead of them being flat.   But between the gear set, the shims,  and the seals id be right the same as just buying one of those replacement differentials. 

 

Gonna do some research on those diffs and see if they have any good reviews. 

[shadetree 5,884]

9 hours ago, Bman said:

The more I looked at it the more I do want to change out the pinion. Like I say the edges of the teeth are worn down to points instead of them being flat.   But between the gear set, the shims,  and the seals id be right the same as just buying one of those replacement differentials. 

 

Gonna do some research on those diffs and see if they have any good reviews. 

keep in mind, the trx400fm has the same rear diff as the trx450fm. check with power sports nation for a used rear diff before you buy a china rear diff !.

[Bman 17]

From what I can tell the Rubicon 500 and the foreman 500 have the same rear diff as well. 

[Bman 17]

I've got my eye on a parts machine with a rear axle.

 

But in the mean time I took a trip to my local hardware store and grabbed some machine washers with the right inner diameter. Two 18gauge (1.2mm). And two 14 gauge. (2.0mm) 

 

So stock starting point would be 2.0mm on both sides right?.  Tried that. Still sloppy. Audible clunk/clank when rocking the axel back and forth. 

 

Tried 2.0 on the left side and 1.2mm on the right. It got the ring closer and was better, but still a clunk/clank when rocked hard enough.

 

2.0mm left. Nothing on the right was worse all around. 

 

My best combination.  And quietest is both 1.2mm on the left side or 2.4mm and nothing on the right.  Much less clunk and no metal "clank".   Isn't binding. Can turn the hub with one hand relatively easy. So until I can get the other diff or purchase a new ring and pinion im gonna try this. 

 

I'm just doing this all by feel/what I hear. I don't have the tools to measure back lash.  And id say the pinion being worn like it isn't helping. 

[jeepwm69 7,619]

Here's my guess.

 

Previous owner had axle splines strip on the axle and ring gear.  Put in a new axle shaft and new ring gear, minus the shims.

 

These are straight cut (not helical) gears so they don't have to be as precisely set up as something like a 300 or old 350D would have to be.

 

If you have it close enough to have very little play without the teeth grinding against one another, run it.  

 

In the meantime, keep an eye out for a used rear diff.  If you get a used diff, make sure the splines in the ring gear are squres off, and not pointed like a tooth.  When they start to wear, that flat top wears to a point.  Pointy is bad.

[Bman 17]

Yeah pointy is how my pinion is haha. When I got the ATV seller mentioned specifically that the rear end didn't have any striped splines. Which is probably a tell that you're spot on with what was done. 

 

Gonna try it and see.