7AT 4.08 gear swap review

brucelidat

I just had the 4.08 gears installed in my 7AT 2011 Z a few days ago. Seb at Specialty Z did the install and did a great job. I had a diff sent directly to their shop so it was all ready and they just had to do a pumpkin swap when I brought my car in. That is definitely the way to do it.

So with the new gears, the engine revs much quicker and smoother. There used to be a lag and sort bogged down revving int he low RPMs until you hit the range where there's actually power. Now the car is always in or very close to that rm range so it's always ready to go. Freeway driving is much nicer now, when I want to accelerate or pass, it just happens, no more laggy revving to the 3k range. Another bonus is that the engine sounds smoother when cruising since I am in the upper 2k to 3k rpm range. I have FI resonated HFCs and CBE and there was a lot more noise when cruising before in the low RPMs. I used to put it in M to raise the RPMs sometimes for the quieter ride. Of all my mods, this is the one I feel the most after install. I had HFCs and CBE installed with a tune all at the same time and the difference in driving feel and fun was less than this.

No review would be complete without stating the negatives as well. Like everyone else has noted, cruise control no longer works (see update below, it is now working) but i rarely ever use that anyway. I'm also losing maybe 2-3 mpg in freeway driving.

A note to those with 2011 and newer models. Mine was the first one newer than 2010 that Seb installed the gears in and I had the Service Engine Soon light come on. The code was p0500 which is Speen Sensor A. Seb chekced I tout and the problem si that there is some kind of miscommunication between the sensor and the ECU. Since theya r enot getting the same reading, it si throwing the light. HOWEVER, this isn't really a problem because it doesn't affect or damage anything. Also, my speedo still works fine and gives me about the same reading as my nav for my speed. Seb can program the ecu to get rid of the light so it's no biggie since it doesn't really affect anything. If I get more info on it form him, I will update this post.

UPDATE:
My cruise control is now working. I guess whatever it was Seb did to fix my Service Engine Soon light also gave me back my cruise control. I tested it to confirm it didn't work right after I had the gears installed. I tried it again tonight for the hell of it and was surprised to find the cruise control was now working. I even turned it off and set it a second time to make sure it wasn't a fluke.

Another UPDATE
I drove from Los Angeles to San Francisco and back this past weekend. I was mostly cruising around 80 and got about 23 or 23.5 mpg for the trip.

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