I'm needing to put a tranny in my truck. It has the 4r70 in it now. If I hit the gas hard under like 40 to 50 mph the truck will spin tires and the tranny will start slippen bad. I was thinking maybe the 4r100 or coverting it to a 5 or 6 speed.

 

The 4R100 is a good, solid transmission, and I would think it would be the easiest to convert to since it was offered on your model and year. Not sure how much electronics would have to be changed, but obviously you'd need a new driveshaft.

Then again, you could also probably just get a built 4R70W that would do nearly as well and not require any modifications or worry about the PCM at all.

As for the manuals, while I agree they'd be more fun, it would also be a huge PITA to get done.

Good luck!

 

A 5 or 6 speed manual swap into your vehicle is a major PITA, as you would have to put a hydraulic clutch master and slave cylinder in and fabricate trans. mounts, not to mention PCM and wiring changes.

The 4R100 is almost the same type of PITA swap as the manual; you will have to do wiring changes at the transmission, as the electrical connectors are different. You would also have to do a PCM change to a 4R100 compatible PCM.

Your best bet is to PROPERLY rebuild the existing 4R70W transmission to handle the stress of the supercharged engine and the 37" tires. A good person to contact is Darrin Burch at BC Automotive, www.bcatransmissions.com. And here is a link to a good article on how to build a 4R70W to handle high horsepower and torque: http://tccoa.com/articles/tranny/index.html# Click on Ford OD Transmissions 101 (the top link on the page).

Good luck with your transmission problems.

 

Ok thank you I sent them a email and I'm waiting to see what they think.

 

We have been emailing tonight and I am afraid that I am not fully able to get across the point of how capable these 4R7X series transmissions really are once they are built properly.

A little help guys

Darrin

 

I have dealt with many 'transmission gurus' who thought they knew the 4R70W, and reccommended things, especially on other websites, then I started reading posts on this website by Darrin Burch. I also started hearing from some members (especially Klitch) who have Darrin built 4R70W transmissions, and how impressed they are with the quality. After all I have read about Darrin and his transmissions, HE WILL BE THE ONLY PERSON TO BUILD A 4R70W FOR ME. You can try the 'chain' transmission shops if you want, but I will take a Darrin built transmission anyday.

P.S. Check a thread by Klitch where he shows a destroyed pinion, but his transmission is fine. That says A LOT about a transmission that can handle that kind of power that would destroy a pinion gear. I believe Klitch has a supercharged 5.4 also.

 

I had nothing but trouble with my 4R70W transmission from the factory. It wouldn't shift out of 2nd gear just before warranty was up, so I took it to the dealer and they "fixed" it under warranty (replaced tailshaft, if I remember correctly). Then same problem 10k later. Another dealer "fixed" it again (same repair, plus they replaced the driveshaft with a 5" dia. tube driveshaft cut down from a heavy duty application). After much fighting I got them to cover this under warranty since the problem started during warranty.

Anyway, I still didn't have any confidence in the transmission and it still felt funny. Then, a couple years and 30k mi. later I decided to replace the valve body, along with many other performance upgrades I did for my truck. Well, afterward it felt like a brand new transmission. Seriously: firm shifts, proper downshifting, no gear-searching at high-speed passing maneuvers... And I have had absolutely not a single problem with the tranny since. It still works like a dream and all I've done since the VB replacement is change the fluid once (which I will do again very soon; I now use only RedLine D4 ATF).

Point of the story is: I'll be the first to say these transmissions come from the factory weak and with problems, but quality aftermarket parts can make them very reliable. And mine was just a VB replacement. I'm sure a fully and properly built 4R70W could handle what you're gonna' throw at it, unless you're talking about a full-on purpose-built drag racer.

Go for the performance rebuild of your current transmission and save yourself lots of time, headaches, and money. And if you do it or have it done right, I'm sure you'll have a tough, reliable final product.

BTW, I used a Factory Tech valve body, but I don't think they're available any more for the 4R7XW. Anything you can buy through Troyer is definitely quality stuff (e-fan controllers and price notwithstanding) and his product assistance and advice are second to none. I've never dealt with Darrin Burch personally, but I've seen much praise and no complaints on these forums about his work.

Good luck!