Hello all,

Just wanted to share my experience with the 4.363 final drive gears in my 2013 G37 Convertible Sport 6MT. When planning this mod, there were very few first-hand accounts of the 4.36 across the entire G & Z community, with even fewer objective opinions or bits of constructive input. By sharing this review, I hope that it helps someone out!

In the sport convertibles, the final drive is a 3.916. The more aggressive gearing is meant to offset the lesser acceleration of the heavier vert vs. the coupe. That being the case, a 4.08 swap didn't seem like a big enough increase in multiplied wheel torque (4%) vs the 4.36 (11%).

After months of research, (undue) worrying, and great deal on a complete 4.36 rear end w/VLSD (sadly, all verts are open diff), I finally bit the bullet. In a month of daily driving through the city, some lengthy drives on the highway, and an SCCA driving school & autocross event, my impressions are as follows:

Acceleration:

Much improved. Haven't had the opportunity to precisely measure the difference, but the car pulls like I added all my breather mods on top of all my breather mods. In my research, I calculated that the 4.36 vs the 3.91 should provide an increase of 11.4% more wheel torque in every gear, at every rpm. With my current setup, that translates to a simulated increase of ~40hp. It definitely feels like it. If I had to describe the sensation, I'd say it was now as if each gear were 1 lower. The pull in 3rd feels like 2nd, and so on. Will follow up once benchmarked, but I suspect forward motivation is up by 0.2 - O.3 G

Drivability:

Fantastic. No real issues with traction, but 1st and 2nd gear go in a hurry. If made to, tires will spin, but the car's never gotten away from me in normal driving, even in the wet. Chirping 3rd is no problem. I still hit 60 in 2nd, and 6th gear becomes usable around town (35-45mph). While my highway mileage is down, city mileage is up noticeably.

The more aggressive rear end makes for near effortless starts from a stop. It almost feels like a V8, in the sense that I can often get going without any throttle. In a pinch, you could easily start from 2nd. Hill-starts are also much less of a hassle. In 1st, I can crawl so slow at idle that it barely registers on the speedometer. Definitely cuts down on clutching in and out during traffic.

At any given speed I'm up roughly 300 rpm. After a month, I hardly notice. At highway speeds, revs and mileage aren't terrible. At 80 mph, I'm just under 3500 rpm. At 70, ~3100. With cruise on, I still manage mpgs in the low 20s. Passing in 6th is easy, and downshifting at all is only necessary for the most aggressive passes.

For the motorsport enthusiasts, the gears seem perfect for autocross. I ran the entire course in 2nd, and my best run came within 3s of an '18 Camaro SS 1LE at Atlanta Motor Speedway. Will follow up on gearing once I've made it to a track day, hopefully Road Atlanta or Atlanta Motorsports Park this summer/fall.

Cons:

Not many, to be honest. Lots of talk on the forums about the 4.36 being too aggressive, or only meant for towing. That simply isn't true. The feel of the car hasn't changed at all, it just accelerates with much more enthusiasm.

Revs are up and mileage is down, but I knew this from the beginning, and my calculations matched my observations, exactly. The acceleration and drivability are most certainly worth the minor trade-offs, in my opinion.

Hearing a bit more gear whine, but that's to be expected when adding more gear teeth. My polyurethane diff bushings are probably magnifying the sound. The whine is noticeable, but not significant, similar to driving in reverse.

Summary:

In short, the experience has been overwhelmingly positive. As other members have mentioned, the final drive swap isn't an incremental upgrade, but rather a boost in acceleration equal or greater than nearly every basic bolt-on combined, especially with the 4.36. Great bang-for-buck mod, and one of my favorites so far. If I had to do it all again, I'd skip bolt-ons entirely, get a 4.36, sway bars, and an UpRev tune to further improve drivability and raise the redline a touch.

 

 

It's a great mod, I'm glad that our experiences are similarly positive. I'm also glad you were able to find the post. This is quite literally the first time I've seen it online since posting back in May. Hopefully it's as useful to others as your review was for me!

 

So I'm driving an X. This would be awesome to do as I mostly drive city, so it would a) make stop lights more fun and b) bring my fuel consumption down (I think??) The only thing I would run into is having to change both diffs. Also, I wonder if anyone has taken to the transmission and messed with 6th and 7th to make the less of an overdrive and more of a drive gear. I feel like this would be a good idea to keep the engine speed down at higher speeds, say on the highway.

 

 

Yeah, definitely an awesome mod. Couldn't imagine running without it at this point. Great acceleration around town or through traffic. Stoplights are definitely more fun. I put a few car lengths on a 2016+ Camaro V6 with the 8-speed auto. Fuel consumption is definitely up, but around town it's offset by making the higher gears more accessible. If I'm doing more than 30, I'm normally in 5th and 6th. I'm not sure how well a more aggressive rear final drive would play with the rest of the AWD system, but adjusting the overdrive ratios would certainly be interesting. I wouldn't mind a 7th gear exclusively for highway cruising. Drove the G up to Pigeon Forge, TN over the holidays (~300 miles each way) and averaged 20.5 mpg using cruise control set to 80.

Glad it proved useful to you! I traded rear ends (haha) with an employee at Z1 who had one laying around. All in, it cost just under $900 installed. That included flushing the fluids, and changing out the stub axles and diff bushings. If you had a rear end built from scratch, I'd say it'd be closer to $2K installed, depending on your choice of LSD.