What would the highest MPH be to have downshifted into 1st gear? Mine is downshifting @ 30 MPH which translate to 4000 RPM's. There is a slight gear lag if I am racing someone for instance at 31 MPH and it goes into 2nd. The problem is the RPM's increase quickly after 30MPH and am wondering if downshifting over that MPH would be practical. Shift point is 5500. ?????.....Ken

 

Ken,

I'll assume you have a chip if your truck will downshift into 1st gear at 30mph. Most stock programs from the factory don't allow it to downshift back down into 1st at anything over 20-25mph. Makes for no fun, IMO.

In a vehicle that is so heavy and with rather broad gear spacing (ratio-wise) in the 4-spd tranny, I believe its beneficial to get it to downshift at about as high a MPH as it can. The reason is that while you will not be in 1st gear very long (say, if it downshifts at 38-39mph), you will certainly be accelerating faster for the brief time you're in 1st...which will really help get it going before it shifts into 2nd. Also, you keep the revs up and the motor in its powerband/"happy spot" by doing this.

Lugging the motor in 2nd gear makes for a poorly accelerating truck from my experience.

Now, how all this high rpm downshifting affects the trans is another story entirely. I guess I'll find out eventually, but I'm already saving pennies for when the trans goes so I can rebuild it with heavy-duty internals.

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Wes Tarbox
90 LX 5.0 (10.69 @ 134.7)--597rwhp/590rwtq
96 Cobra (12.34 @ 115.8)--392rwhp/433rwtq
99 Lightning (13.20 @ 103.8)--364rwhp/444rwtq
00 Expedition XLT 5.4
http://members.aol.com/Wa2fst/index.html

 

Thanks for the imput Wes, I'll be sending the chip in soon for reprogramming and will have him bump up the shiftpoint. With the 410's/pulley/mass air/chip it spools up quickly and I wasn't sure if I increase shiftpoint if there woiuld be an improvement or would there be downshift, tires slipping, a$$ end sliding and upshift in one or two seconds. Later....Ken

 

Ahh...well with 4.10s I might change my opinion. Yeah, I get some tirespin when it downshifts into 1st at almost 40mph (3.55 gears), but its in the powerband so when it shifts into 2nd I'm accelerating very well.

Obviously with 4.10s you don't need as much TQ multiplication via the engine/converter.

I'd be interested to hear what you end up with and how it works out!

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Wes Tarbox
90 LX 5.0 (10.69 @ 134.7)--597rwhp/590rwtq
96 Cobra (12.34 @ 115.8)--392rwhp/433rwtq
99 Lightning (13.20 @ 103.8)--364rwhp/444rwtq
00 Expedition XLT 5.4
http://members.aol.com/Wa2fst/index.html

 

If you stick to Ford parts, there's not much more ni hte heavy internals departmant that you can do, The 4R100 in general is pretty heavy to begin with and most of the components in a L tranny are the heavy parts out of the list of possibles, for instance, an L gets 6 gear cast iron planetary assemblies, where all the other gas engine models get either 3 or 4 gears, the one upgrade I would consider is to put in a deisel one way stack which is 7 plates instead of five, with a thinner pressure plate, gives a higher torque spike. You allready get the 7 plate stack in the coast clutch-O/D cylinder. You also get the "large" driveshaft and extension housing, a four gear coast clutch and the purpose built accumulator. If you ever get real nuts and decide to make it AWD, make sure to use the cast iron extension housing. (I'm seriously considering this myself, but it's definetly not for first time moddders)