I noticed that if you are driving around normal and you shift from "D" down to "2" and you let the truck coast down to about 1100 rpm the tach will bounce up aprox 200 rpm and the truck feels like it came out of gear or went into overdrive,(it makes the truck lung forward). Now if you do the same test but drop it down into "1" then it is really noticed. OK, now to complicate things more. If you turn overdrive to "off" and gear down then the truck will coast down until it comes to a complete stop with no jump in the tach or shift out of gear feeling.
So i was wanting to know if any of the truck owners with the 4r70w trannys notice this? Any other auto i have owned, the minute you dropped it down to any of the other gears
it held the truck back until you came to a crawl.


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1999 F-150 4X4 Super cab lariat, 5.4, 3.73 gears,deepwedgewood blue,
and all the options, build date 3/1/99

 

I suspect that OD isn't letting go when you shift from "D" to "2" or "1" with OD turned on. I haven't tried it with my auto - I usually let the automatic act like an automatic. (I always wondered why a vehicle with an automatic needed more choices than 'F'orward, 'N'eutral, 'R'everse & 'P'ark )

I've got the 4R100 in mine and have noticed that, when slowing, the tach jumps a few hundred RPM when it downshifts - I just never tried to help mine downshift

My truck doesn't lunge when the downshift occurs - but it weighs over 6700# when I'm NOT towing...

I think its probably just "normal" for your tranny to act that way. The OD is electrically actuated and may not be expecting the shift lever to be moving around.

 

JC, what year and model truck are you driving?....Take Care

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DOGCAM
2000 F150 Lariat flareside 4X2
S/C
5.4, 3.55 Ls, Tow Pack, Captain
Chairs, White clearcoat/w
harvest gold & wedgewood blue accent,17"X8"
BFG T/As 275x60s on chrome wheels
Mods:K&N Filter, True duals
(Dynomax) with 3.5 chrome
tips out behind the rear
wheels
dog46cam@webtv.net
dogcam@myf150.com

 

Sorry - it's in my "signature"...

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1999 F-250 XLT Super Duty Crew Cab Long Bed
V-10, Automatic 4R100, 4.30 Limited Slip.
GVW = 6700# Towing Capacity = 13,300#
4 Wheel ABS disks + Reese 15K hitch
Dark Hunter Green. Ford Running Boards.
Grey Rhino-Liner. Captain's Chairs. CD+Tape
Polished Stainless Steel Wheel-well Molding http://members.home.net/jchartier/jnctrk.html

 

Sounds like your torque convertor locking and unlocking to me? i dont think it is nothing to worry about since they are suppose to lock or unlock at certain engine RPM"s