No I already had 4.10s with the 4l60e. As I said, all factors were held equal between the two setups just the transmission change. The 4l80e has a lower OD ratio so RPMs will be a little more. That and other small factors probably led to the MPG decrease. With the 4.10s I usually get about 15 mpg on the highway around 75 mph turning close to 2500 rpms IIRC. With 3.42s I bet I could get 20 no problem.

 

What to do, what to do. The truck will only ever see bolt ons and MAYBE a homemade 70mm turbo kit on 6 pounds. Im not interested in a stall or gears or launching. Its just my DD. Maybe I should just keep running stock 60e's with vette servos to retain my MPG around town. The truck will never be run at the track. (well maybe once heh)

 

If you want MPG just keep it near stock, seriously.

With a stock LQ9, tube, 4l60e, and 3.42s I was getting ridiculously awesome gas mileage. I dont remember city numbers but I was pulling down 23+ MPG on the highway

 

Tube?

I was reading that the vette servo helps prolong the life of the tranny by reducing slip in between each shift. I understand that it will increase the firmness of each shift but I cant exactly find an explanation of how much firmer. I want it to be totally comfortable and near stock, as I let my girl drive the it every once in a while.

What I was going to do however was have my tuner increase the line pressure dramatically at higher RPM so that it barks the tires when im on it, but when I want to ease around it feels stock.

So avoid any type of stall at all when I want to conserve MPG? Even a low stall? The only reason I ask is because I want to get the servo, converter, or any other tranny mods sorted out while the tranny is out.

 

No from what I've read on here I think you can do a mild stall in the 4l60e, like the modded trailblazer stall, and maintain very similar mileage. I had a yank 3600 in my 4l80 and was getting 8-10 mpg city on winter blend gas.

 

Change shift firmness with servos and adding washers in a shift kit, not by turning the line pressure up dramatically. Also, barking the tires at shifts on a stock transmission is just asking to break hard parts.

The vette servo is a fairly easy install and can be done with the transmission still in and not drained (though you will lose a small bit of fluid). It's cheap ($16) and a good mod to make to increase trans life. Do that first, then decide if you want it firmer; if so, look at the Transgo HD2 shift kit.

 

Thanks for the info. Being that I need a new tranny anyway, Ill just do the vette servo before I put the new tranny in. Should I look at 4l65's or anything? Just looking for the best bang for the buck here. And do you personally know anything about the trailblazer converter/stall?

 

I went from 60 with a stock TC to a 80 with a 3600 TC and i only drop 1 MPG with 50/50 city/highway driving. The Rear gears (4.10s) stayed the same. So i went from ~16 to ~15 mpg.

 

OP,
Just making sure you caught the post earlier. 80e's do not have servos. They are talking about 60es when they mention them.

 

Well damn... I drive mostly in the city and a poster earlier said he lost about 3mpg city with the 80. If I could lose 1 mpg in the city by doing an 80 I would love to do the swap. You never know when you get an itch and want to turn the boost up I would love to put in an 80 and get it over with once and for all, I will never see enough power to break one of those... But NOT if im going to lose a precious 3mpg in the city.

A buddy of mine just picked up an 80e for 350 bucks off the boards. Was that an insane steal? It seems like it to me.