Swap from 4.10s to 3.55 done

[Diesel JD]

Hey guys, how goes it? I just got finished having my 3.55 donor axle swapped in. Wow, what a difference. I don't even get into my tallest gear until 35-40 mph, and 70 now seems acceptable RPM wise. 60-65 feel like 50 or 55 used to. Needless to say I am pleased. I have only driven it 20 miles so I will have to wait awhile to see if the hoped for fuel economy improvements happen. Once I am sure that this axle will do the job my 4.10 rear end will be on the market, you all here get dibs. I haven't decided what I want for it, so if you're interested PM me and we'll talk. Like I say I still need to check it over and make sure teh R&P are in good condition in the 4.10 axle and that the new one will run ok... It needs a set of backing plates, brake drums, shoes to run, but everything else s there. I was blessed to have a good mechanic friend to help out with this job,a dn for economy's sake it is best if anyone contemplatinga similar swap has a friend like that who will help them out or if you want to DIY, you need to at least be competent with drum brakes and having access to some impact tools is helpful.
J.D.

 

[Agnem]

That swap is good for a 500 RPM reduction. You will see a big fuel savings.

 

[Diesel JD]

Yes, that was the idea, plus not to be as ******* the engine or our ears at highway speeds. I was averaging 11-14mpg on the 4.10s, I'll let you all know as soon as I know something what this one does,
J.D.

 

[Mr_Roboto]

I never quite got why they went with 4.11 gears and the high first gear in the 4 speed. Give me 3.55's and the granny gear and all will be good. It's not like it's a 302 gasser.

After a week I'm already tired of my wrecker screaming at 50 mph. I'd love some higher gears.

 

[stiesel]

i went from 4.11 to 3.73. made the truck much more enjoyable to drive. of coarse i rarely tow anything. unfortunately it also threw off my speedo. i think by 13%.

 

[Diesel JD]

I'm not sure how the T19 communicates with the speedo, but on the C6, there is a speedo drive gear and it is color coded for each gear ratio. The one for 3.55 is brown/orange, and the one for 4.10s is yellow. My speedo is pretty accurate with the swap I think, but maybe I should GPS verify it again just to be sure.

 

[Mr_Roboto]

The T-19 uses the same simple gears. The Ford dealer can set you up with the right plastic driven gear (goes on the trans end of the speedo cable) for your axle ratio.