4.10 gears

[x Spades x]

Hey Fellas,

I just purchased this 4.10 diff used. I bought a cover (with bushing pre-installed, so I switch it over and took some pics. Does this look like its REM polished to you? Im not sure what it looks like, so want to reach out to the experts.

[bigjae46]

Hard to tell., better pics would help. From those pics doesn't look like it is.

[Cubieman]

Lol, I feel like an idiot going from 4.10's to stock gearing as everyone is going the other way, my car will feel slow as its all I have ever known since I purchased it. I think some 3.85's or 3.91's would be a nice sweet spot.

In any event enjoy that diff, it definitely feels peppy off the line, just be ready to constantly be shifting between 2nd/3rd when driving in traffic in the 25-45mph range.

[maupineda]

I think the way it will feel is “heavy” off the line. Incremental changes are less perceived than decremental. For sure you will have to get used to.

4.1 does have you shifting more often in town as otherwise revs go high. It gives the car a motorcycle vibe :P

I like how easy it springs off the line, 4 and 5 gears are super useable to gain speed, even 6th is no longer an overdrive and a proper gear.

[oceansize]

I really like the 3.91 (diffs online) in my FI SMG car. I shift more, but its paddles so easy peasy.

[maupineda]

Hey Fellas,

I just purchased this 4.10 diff used. I bought a cover (with bushing pre-installed, so I switch it over and took some pics. Does this look like its REM polished to you? Im not sure what it looks like, so want to reach out to the experts.

OP, can you take photos of your teeth to see how it meshes, from coast and drive sides? I want to compare to mine.

[x Spades x]

OP, can you take photos of your teeth to see how it meshes, from coast and drive sides? I want to compare to mine.

I put it in last night, so apologies as those were the only pics I took. Ill ask my friend if he has any.

I did look at the teeth, as this is a used diff (10k miles), and there was ZERO wear marks. I thought that was weird, but it was also 330am, lol.

Drove this morning for about 45 miles its almost SILENT.
There is a SLIGHT hum when coasting steady on highway... like 1 out of 10 noise (if stock is 0 out of 10). Zero off throttle whine, zero heavy on throttle noise.

I have the receipt from the shop that installed it, but im EXTREMELY happy as whine would have killed me.

Oem bushings everywhere.

[x Spades x]

Lol, I feel like an idiot going from 4.10's to stock gearing as everyone is going the other way, my car will feel slow as its all I have ever known since I purchased it. I think some 3.85's or 3.91's would be a nice sweet spot.

In any event enjoy that diff, it definitely feels peppy off the line, just be ready to constantly be shifting between 2nd/3rd when driving in traffic in the 25-45mph range.

I did 3.91 about 7 years ago on my previous car (stock) and they aren't worth it. You'll get the diff whine (if not perfectly installed) without the benefit feel. Its just not that much of a change to feel worth it with all of the drawbacks from a gear change.

[Cubieman]

I will definitely keep my 4.10 diff in case I want to go back. My M3 may be running in an open road race here in Nebraska where I'll be doing 110-120mph for literally miles on end in some cases. I just want it to he set up for that so I'm not so far up in the RPM's.

Also I never liked how high the RPM's get on the highway, in all reality its probably fine as we are talking about maybe a 500rpm difference.

But all things considered I think the 4.10's are pretty good and I may go back, just wanted to feel the car in stock gearing.
Then maybe at some point I can afford a quality suspension and ditch these embarrassing BC coilovers.

[x Spades x]

I will definitely keep my 4.10 diff in case I want to go back. My M3 may be running in an open road race here in Nebraska where I'll be doing 110-120mph for literally miles on end in some cases. I just want it to he set up for that so I'm not so far up in the RPM's.

Also I never liked how high the RPM's get on the highway, in all reality its probably fine as we are talking about maybe a 500rpm difference.

But all things considered I think the 4.10's are pretty good and I may go back, just wanted to feel the car in stock gearing.
Then maybe at some point I can afford a quality suspension and ditch these embarrassing BC coilovers.

Oh stock gearing is good. Id do that or 4.10. Doing 3.91 aren't worth it i meant.

[Obioban]

Stock gearing ftw.

[maupineda]

I will definitely keep my 4.10 diff in case I want to go back. My M3 may be running in an open road race here in Nebraska where I'll be doing 110-120mph for literally miles on end in some cases. I just want it to he set up for that so I'm not so far up in the RPM's.

Also I never liked how high the RPM's get on the highway, in all reality its probably fine as we are talking about maybe a 500rpm difference.

But all things considered I think the 4.10's are pretty good and I may go back, just wanted to feel the car in stock gearing.
Then maybe at some point I can afford a quality suspension and ditch these embarrassing BC coilovers.

At 120 with 4.1 you would be at 6k, which is a walk in the park for the S54. But I totally see your point.

and yes, it is very much so noticeable, at 75 the stock gears do 3k, 4.1 is 3.4. I have the stock exhaust so I have not yet felt I am in 5th while already in 6th, but with a loud exhaust it will be very annoying.

[siamkazi]

What a timely post, just got a 3.91 in with shims etc, installing in a few weeks, excited to see the difference

[eacmen]

I really like the 3.91 (diffs online) in my FI SMG car. I shift more, but its paddles so easy peasy.

Did you have to code the new gear ratio for the SMG or Engine ECU?

[oceansize]

Did you have to code the new gear ratio for the SMG or Engine ECU?

ECUWorx tool is what I used, setting titled "SMG Final Drive Swap".