4.10 Ring and Pinion Gear Whine Noise

[Ceelooboob]

Hi all,

I am trying to gauge other people’s experience with 4.10 gear sets and whether or not they are getting noticeable gear whine. I’ve read up a lot and see many people saying their 4.10 gears don’t whine at all while others say they do whine and it’s normal. I recently assembled a 4.10 differential and the gear whine is worrying me that something was setup improperly.

Just for back ground, I put together my diff with a friend who is a BMW tech and pretty familiar with differential assembly. Originally I put in all new pinion and carrier bearings, new seals, new Wavetrac LSD unit and BMW 4.10 gear set. We sourced pinion and carrier shims to properly set pinion depth, carrier shims for back lash, set pinion preload and carrier preload to spec. Pattern looked ok, centered on coast and drive side etc. I already had all 3 AKG poly diff bushings , subframe bushings, motor mounts , trans mounts etc. I Put the 4.10 diff in the car, it whined from the start, drove a few hundred miles, same thing. The poly diff bushings always caused a faint whine with my stock 3.62 diff but nothing like the 4.10’s do. I took the diff back out, checked everything , looked fine, sent the gears for REM finishing to hopefully quiet things down. Put the diff back together with REM treated gears checking everything again, all is within spec again. Differential still whines , slightly quieter , but barely. I’m going to drop it out again and possibly take it to someone for a 2nd opinion, make sure everything is assembled properly and if so just switch to stock diff bushings to quiet the whine (I hate the whine).


What has everyone else experienced with noises and their 4.10 gears?

Anybody know any reputable differential shop in SoCal that could looking things over for me on my diff?

Thanks all!

[heinzboehmer]

Not exactly the answer you're looking for, but my stock gears + AKG poly bushings whine pretty badly. It's most loud at ~70 mph. Had no whine on the stock bushings.

[EthanolTurbo]

Try OEM bushings. Poly has an annoying whine for me on stock diff and OEM didn't.

[bigjae46]

If backlash and gear pattern are good...nothing really to worry about.

Whining with poly and solid bushings is normal.


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[sapote]

How did you set the pinion depth using what tool?
It seems you already calibrated your ears with running poly bushings before, then the sudden louder noise must be from the new setup -- the new pinion/gear mesh.

[bigjae46]

How did you set the pinion depth using what tool?
It seems you already calibrated your ears with running poly bushings before, then the sudden louder noise must be from the new setup -- the new pinion/gear mesh.

Why do you need a tool to set pinion depth? It’s going to be pretty close as long as you use the same pinion shim that came with the case. Might have to go up or down a little bit.


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[siamkazi]

Racewerkz in Burbank work on these diffs (installation etc), Casey is a good resource.

[ATB88]

Replied to your PM with more details about my diff rebuild saga, but for the benefit of anyone else that comes across this thread: Marc at Bavarian Workshop in West Hills was highly recommended to me. I spoke to him on the phone and he sounded very confident in his knowledge and ability. I didn't end up going with him due to my circumstances but if I could do it again I think I would have gone with him.

[Shadytype]

My 4.10 whines a little. Akg bushings in the rear, street/track. Totally tolerable. In comparison, my stock diff did not whine into the cabin at all, same bushings all around except for the rear carrier. I did a full diff swap. I have two, stock and 4.10 for fast gear changes.... lol.. not really. Just 2

[sapote]

Why do you need a tool to set pinion depth? It’s going to be pretty close as long as you use the same pinion shim that came with the case. Might have to go up or down a little bit.

I wouldn't assume that. Most pinion has the pinion depth etched on it. Every pinion/gear come as a set and the depth is unique to each set.

[sc_tr0jan_m3]

Wait until you install solid diff bushings... then you’ll know what whine sounds like


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[Ceelooboob]

Thanks all for the info, I appreciate it. We did use a pinon depth tool to determine the pinon shim since the etched number was different on my 4.10 pinon but we kind of resorted to checking the pattern with different shims to get it as centered as possible. I will still reach out to Racewerkz and Bavarian Workshop to see if I can have one of them go through everything on my 4.10 diff to make sure everything looks alright. I'll probably also go back to stock diff bushings to bring the noise levels back down. I'll post up any updates.

[M3KVU]

Mine whines slightly on over run between 50 and 45 mph but very very slight.

[spnsprt]

If backlash and gear pattern are good...nothing really to worry about.

Whining with poly and solid bushings is normal.


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can you explain what backlash means here? thanks!

[Arith2]

It's the play in the gears. If gears are completely pushed together, no fluid can lubricate them. It also allows for thermal expansion. Basically it's the wiggle room the gears have between the teeth. The pattern should show them touching the middle of the gear teeth fully and flat. You test this with paint.