Rochester

iTrader: (9)

I was expecting a more significant uptick in RPM, too. But perhaps that was just anxiety on my part. If you think about the math... the change in final drive is approximately 10%, which is a ratio that speaks to that 300 rpm increase.

This is the point where I meekly claim not-an-engineer. But if you were to ask me to put a number on the new performance gains in the bottom end... 10% is a very realistic number. Insofar as power adds to this car over the last five years (cats, catback, intake ), this mod was hands-down the most impactful. And by a lot... not just another incremental change.

I'm really, really looking forward to driving more today. At the moment I'm up in the middle of the night with another god damn migraine, and probably shouldn't be staring at this iPad because it hurts.

MaQG37

iTrader: (4)

What are the RPMs at 80MPH? I think that's the biggest sticking point, highway cruising RPM's.

Rochester

iTrader: (9)

80MPH? LOL, no, that's not something I care about. But I'll check it out for you anyway next time I'm on a lonely stretch of highway.

The Texas perspective on things is always different. My driving life is 90% suburban, MaQG37. Which was part of my rationale for this particular mod. It fits me. Now, if it were a regular thing for me to have to drive lots of open miles at high speeds... no way would I have done this.

4DRZ

iTrader: (7)

In for RPM's at 75mph

Rochester

iTrader: (9)

Went on another errand with the car, just in time for the sky to go dark and start pouring rain again, dammit. (sigh)

You know, there's a certain kind of thickness to the throttle now in first and second gear, and I really like it. I think what's going on is the time involved to ramp up is shortened, so perceived response time is improved. (Blah blah blah, LOL) Also, I'm driving into the upper RPM range more effortlessly, experiencing mid to upper RPM power more so than I'm used to. Of course, I could have done that before by consciously going into higher revs before shifting.

Anyway, I'm starting to think the car drives better with these gears. Didn't expect that.

Rochester

iTrader: (9)

Assuming I'm actually driving 80mph, it sure looked like 3300 RPM in 6th. But that's eyeballing the gauge.

I need to borrow the wife's Garmin and check my GPS-calculated speed. You would think the built-in NAV system on the G would show my GPS speed, but it doesn't. Or at least, I can't find it.

Rochester

iTrader: (9)

Drove the car around today on dry pavement, first time since getting the car back. One of the things that's clear: it's effortless to spin the rear tires now. Turn off the TC, spin the tires into a corner, and the car will slide around on butter. Don't get me wrong... by no means do I drive like that, except in the winter when it's normal. I'm just checking out where I am with the car now.

Because of this, getting a good launch is more difficult. Really have to walk it out of the hole. Not every 1st gear launch is good, but to be honest, it's always that way. I suppose an automatic transmission would make this all a lot easier... but much less fun.

2GoRNot2G

iTrader: (5)

Assuming you have a smartphone you should just download a free GPS Speed app to your phone. I use an app called Speed Box to verify the accuracy of my speedo.

Rochester

iTrader: (9)

Apparently there are lots of different speedometer apps. So I downloaded one. Thanks!

They aren't. Comparing my speedometer to a GPS smartphone app, the speed is spot-on. The only variations seem to occur over 60 mph, where the car is actually reporting speeds a few MPH over the GPS speed, in which case I'm actually driving a few ticks slower than the car is telling me. So I'm good.

I just checked earlier this morning, having driven to my mechanic's shop for a follow-up discussion. This gear swap... I have to say this is no incremental mod. And after this weekend, I'm convinced the car is easier to drive now, not harder... for reasons I tried to articulate when I was considering it. Basically, my go-to gear on the highway for hard acceleration is now 4th gear, which is so much less obnoxious than dumping into third at 60 mph. And my casual gear for low speed turns is now 3rd gear, which is so much less obnoxious than dumping it into second and rev-matching into the upper rotations.

Wow. Just... wow. Loving this change. Should have been a factory option, IMO.

4DRZ

iTrader: (7)

Glad to hear you don't have to screw around with the speedo.

For the price, this should be your largest performance enhancer. I think it might be tough to compare for you because I think you did your exhaust and intakes at different times(?). Do you think the improvement in acceleration is similar to intakes and exhaust? Wait, do you have a tune on your car?

Rochester

iTrader: (9)

No tune yet. Getting the car dyno-tuned is planned for Spring 2018. And yes, intake and exhaust mods were done year over year, intermixed with suspension mods, wheels & tires, clutch pedal & STS, etc.

2013 - Intake
2014 - High flow Cats
2015 - Catback

The intake mod was more about noise and engine bay doll-up. There was a butt-dyno response, but really that's because of the noise and high expectations of the first power mod. Without a tune, I can honestly say it doesn't matter. And the filters aren't located for cold-air, so there's that. It's always been my plan for an upgrade to long-tube intakes before the tune. We'll see what happens. The R2C kit is so damn pretty, though.

The cats were a noticeable power gain in the bottom end and throughout, but nothing shocking. Just welcome and appreciated, with a little more rumble.

The catback was another noticeable power gain, but less so than the cats, and primarily in the mid-range. Again, welcome and appreciated, with a LOT more rumble.

The gears, however... insofar as a power mod goes, this is next-level stuff. If you want me to compare it to intake/exhaust mods, then it's very reasonable to say gains from the gears exceed the other mods combined, by a factor of 2x or 3x. It's simply exceeded my expectations. And all my anxiety concerns were empty. I wish I could share it with you, but you're on the wrong Great Lake, buddy.

You're probably asking yourself how this would work for your track days. If you're thinking that, let me address it this way: Do you track your car in 6th gear?

4DRZ

iTrader: (7)

Interesting points. I am surprised you noticed bigger gains from the cats than the entire rest of the exhaust, but then again our butt dynos can mislead us from time to time. Of all the stuff I did to my car- by far my biggest gains came from the tune.

I think the rear diff could be an option for me down the road, albeit a spendy one. I am not sure how well it would work for me for a track day. Probably definitely more shifting, which is slower, but I imagine improved acceleration in each gear. The other disadvantage would probably be lower mileage on the hwy on the way to work due to higher rpms. Not the end of the world because I usually get just over 20mpg with almost exactly 1/2 of my 10 min commute to work in city and the other half hwy.

Sorry I am late to the party here- did you just replace your final drive gears ring and pinion, or did you get a whole new rear diff?

Rochester

iTrader: (9)

I believe the 7AT crowd needs a whole new rear diff. Something about the differential housing that's not the same. I think... don't quote me. All I know is that's not necessary for the 6MT.

So just a gear swap: ring, pinion, bearings and seals.

You know, I'm going to start a thread about this. Just for the heck of it.

4DRZ

iTrader: (7)

I would expect nothing less from you, Rochester. Are you putting it in the sedan forum or somewhere else?

Rochester

iTrader: (9)

https://www.myg37.com/forums/g37-sed...6mt-sedan.html