Can a gear swap cause a transmission to start slipping?
 

I have a 2011 RWD F150 with 65k miles. I couple months ago I upgraded the rear end from 3.31 ratio to 4.10. Ever since my truck slips slightly between 3rd and 4th gear, and sometimes on the highway between 50-60 mph it will randomly slip out of gear then quickly correct itself.

I have 4 different custom tunes from two very well known and respected tuners, and have even tried stock but it happens with all of them. Not as much with my stock tune but it does still happen.

Of course the guy that did my gear swap says there's no way a gear swap would cause a transmission to slip.

Any thoughts?

Your shift points are off, switch to manual mode, if the slipping stops you then problem solved.

How do you "switch to manual mode"?

Both my tune guys made adjustments to my tunes when I informed them of my gear swap.

But even running my stock tune and giving my transmission time to "relearn" my gear ratio it still happens, just not as often.

Your transmission doesn't let you change gears manually?

Oh yeah, 1st-3rd. I didn't know thats what he meant.

I know this sounds silly, but, have you checked your Trans fluid level?

Yeah, first thing I checked.

Awww, come on guys, it's so simple. Maybe you need a refresher course. It's all ball bearings nowadays. Now you prepare that Fetzer valve with some 3-in-1 oil and some gauze pads. And I'm gonna need 'bout ten quarts of anti-freeze, preferably Prestone. No, no make that Quaker State.

Is it standard today with the new rigs to have the transmission sealed?

Both of ours are '05's & they're dipsticked, ha, just realized they're both past the 10 year mark, I like to keep the old ladies newer. :hmmm:

on a gm product there is a place where you enter in the gear ratio.

not sure on a Ford.

just curious but who does the tunes for you?

Would have bet even money that an MTG thread about a tranny wouldnt have been referencing a truck

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Chances are you got water in your transmission. Pull the dipstick and lick the fluid off the end and see if you can taste water.

MPT tunes and 5 Star