Thread: F150 MPG Blues
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Old 07-17-2013, 02:19 PM   #8 (permalink)
EcoModding Lurker
Join Date: Jul 2013
Location: San Diego
Posts: 18

Goldy II - '94 Saturn SC2
Last 3: 26.24 mpg (US)

The Beast - '88 Ford F150 XLT Lariat, Supercab, Long Bed
90 day: 13.61 mpg (US)

Domo - '89 Honda Civic Wagovan
90 day: 30.49 mpg (US)
Thanks: 2
Thanked 1 Time in 1 Post
First Mod Done!

I got the ZF transmission installed! I had to make a custom-length driveshaft and a couple of things didn't exactly go smoothly, but the transmission is in and it works great. The creeper 1st gear hits 2000rpm at 7mph which is ridiculous, but just fine for me. It's a work truck, not a race car. I'd rather have the added towing capacity than acceleration capability.

The overdrive 5th gear puts me just under 2000rpm at 65mph as well, which is exactly what I was looking for. The old transmission was at about 2150, which apparently is the point at which the old 300 i6 likes to just guzzle the fuel.

I have a couple of pleasant surprises with the swap too. It has gobs more power and torque in any gear at any speed or engine rpm. I used to be able to floor the throttle and not feel any extra pull from the motor. Now, just a slight bit of throttle tip in and you get that seat-of-your-pants torque feel. I think the bearings were so bad on the R2 that the parasitic loss of power was exponentially greater than it is now. I'm sure the synthetic Dexron VI that I put in doesn't hurt either. I'm going to hold off on my vacuum gauge for a tank to see what sort of mpg the tranny swap alone yields. I'm guessing I'll get a few more mpg's even if I beat on it, considering how much peppier it feels.

There also used to be a shimmy at about 20-30mph that I thought might be tires, or even worse, the rear gears. Turns out it was the M5R2 or my old driveshaft front half, because the shimmy is gone! While testing out the driveshaft that I shortened, I took it all the way up to 70 after starting out on some slower streets, and it's smooth as glass all the way through the speed range now. Overall, I'm very happy so far with the results.
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