Differential Backlash

[Larsson]

Hello,

 

My 2014 silverado has got a set of brand new bearings but I kept the same pinion and ringgear. But before I took it appart I mesured the backlash and it was 0.020mm. The specs are between 0.0015mm and 0.0025mm. But now I put it back together and the backlash is 0.0030mm. 

 

I want to drive it like this. But what do you guys think?

[Larsson]

The truck has about 100.000 miles on it. And the gear pattern is within specs. The only thing thats a little "out of spec" is the backlash. The backlash now is 0.01181 inch. And it should be between 0.006 and 0.010 inch. 

 

I made a mistake with mm and inches. The specs in mm is between 0.15mm and 0.25mm. And the backlash now is 0.30mm. Sorry about that.

 

All the conversions from inches and mm is a little confusing sometimes.

 

 

[Larsson]

Anyone?

[KARNUT]

1 hour ago, Larsson said:

Anyone?

I’d drive it. I’ve changed a couple a rear gears. I didn’t use gauges. Crude I know. I had one howl a little. I’d eyeball the play. 

Edited May 19, 2024 by KARNUT

[Larsson]

It seems the more backlash you have the louder the gears going to sound. So if you're not a great fan of a noisy differential, keep it as close to specs as possible. But it's better to have a little to much backlash than to little ,I think. Because of the lubrication of the gears. 

I think I'm going to experiment with some different shims. Just to see where that takes me.

 

Thanks for your input

[newdude]

On 5/18/2024 at 5:44 PM, Larsson said:

Hello,

 

My 2014 silverado has got a set of brand new bearings but I kept the same pinion and ringgear. But before I took it appart I mesured the backlash and it was 0.020mm. The specs are between 0.0015mm and 0.0025mm. But now I put it back together and the backlash is 0.0030mm. 

 

I want to drive it like this. But what do you guys think?

 

 

Here's the backlash specs from GM:

 

Backlash, NEW Gear Set	0.08–0.13 mm	0.003–0.005 in
Backlash, Gear Set, General Range	0.08–0.25 mm	0.003–0.010 in
Backlash, Used/Broken-In Gear Set, Preferred	0.13–0.18 mm	0.005–0.007 in

Edited May 20, 2024 by newdude

[Larsson]

From which differential are these specs? Every differential has it own specs. There is no thing as "average" specs that can be used for every gm axle.

 

I've found these specs. 

 

 

[newdude]

7 minutes ago, Larsson said:

From which differential are these specs? Every differential has it own specs. There is no thing as "average" specs that can be used for every gm axle.

 

I've found these specs. 

 

 

 

Straight up right from GM service manual for a 2014 Silverado.  It is listed as spec for the 8.625", 9.5"/9.76" and 10.5"/11.5" axles in the service procedures for each axle.

 

I think I'd trust GM over "crawlpedia".  

 

Axle Preload and Backlash Specifications

Axle Preload and Backlash Specifications

Application	Specification
	Metric	English
Axle Shaft Flange Lateral Runout1	+/- 0.04 mm1	+/- 0.0016 in1
Axle Shaft Endplay/Lash (axial lash) per side, max	0.66 mm	0.026 in
Axle Shaft Radial Lash (up and down)	0.051 mm	0.002–0.003 in
Axle Shaft Wheel Pilot Diameter Tolerance Variation	77.81–77.76 mm	3.063–3.061 in
Backlash, NEW Gear Set	0.08–0.13 mm	0.003–0.005 in
Backlash, Gear Set, General Range	0.08–0.25 mm	0.003–0.010 in
Backlash, Used/Broken-In Gear Set, Preferred	0.13–0.18 mm	0.005–0.007 in
Pinion and Differential Case Bearing Preload, New Bearings	3.4–6.2 Y	30–55 lb in
Pinion and Differential Case Bearing Preload, Used Bearings	2.8–5.1 Y	25–45 lb in
Pinion Bearing Preload, New Bearings (Nut MUST be staked for 9.5/9.76 inch axles)	1.7–3.4 Y	15–30 lb in
Pinion Bearing Preload, Used Bearings (Nut MUST be staked for 9.5/9.76 inch axles)	1.1–2.3 Y	10–20 lb in
1. Measure axle shaft flange machined face while holding axle shaft inboard against differential cross pin.

 

Edited May 20, 2024 by newdude

[Larsson]

But I found some shims laying around here in my garage and got the backlash to 0.20mm now. To be on the safe side it's better to respect the given specs. 

 

 

[Larsson]

Thanks newdude for the service manual specs. If I compare them with the specs I used to set up my differential, I'm in the safe zone. 

I found a couple of specs on the internet but they all have different numbers. So if you average them, it'll be ok I think.