2nd Gear Poster
Join Date: Jun 2010
Location: NC State University
4R70W Build Questions
Wassup guys. Haven't been around in a while. A few local folks know that I dropped a motor a couple of months ago at a track outing. While having it out rebuilding it, I thought it'd be foolish to not do a rebuild on the transmission as well.
I think this is a good point for a disclaimer: I know there are lots of people on here that could physically do this for me. I've heard SilverFox is a great option, Alan at DirtyDog has been recommended, and RobertP quoted me a ridiculously cheap price to build it for me. Several others, too. However, being the hard-headed engineer that I am, I want to do it myself, if for no other reason than to learn a few things in the process. So I thank you guys in advance for any advice I get, as well as lots of good info I've read on these forums in the past.
So here's what I'm looking for: it needs to hold up to a cammed PI head car with a ported SVO blower running a 3.1 pulley (roughly 10 pounds of boost). Based on what it trapped at the track on a 3.3 pulley (119+ mph), I'm guessing it'd be in the 425 rwhp area. Now, depending on just how fast it goes with this setup, I might also hit it with a 75ish horsepower shot of the giggle gas. So I guess I'd say the transmission needs to be reliable to a regular 425/425, and an occasional 500/550. However, it is very important to me that it not be overly harsh during normal driving conditions; I've ridden in a couple of built 4R70W cars before, and was definitely not pleased with how violently they shifted at part throttle.
I've read through Jerry's thesis on this sight, and here's what I'm currently planning from reading that:
-7 clutch direct with OEM Ford clutches and steels
-6 clutch forward with OEM Ford clutches and steels (no wave plate)
-4 clutch intermediate with OEM Ford clutches and steels
-OEM Ford O/D band
-OEM Ford pressure control solenoid
-Trans Tec overhaul kit from Transmission Center (F53900G)
As for the valvebody, I've already done the J-mod. Well, sort-of. I drilled out the holes to the middle setting, and left the springs stock. Honestly, I very much like the way it shifts now, and would be very happy if it didn't change. I think I'm going to drill the holes out to the higher level, but leave the springs alone.
So, here are a few questions I have:
1. Have I left off anything from what I listed above for my build?
2. Would you use the OEM parts / clutch number combinations I listed? Or opt for aftermarket clutches?
3. I've read things before about something related to a Sonnax product. But in searching, I couldn't narrow it down exactly. Is there some Sonnax product that I need to add to my parts list?
4. Would you change or add anything to my general parts list considering my power level goals?
Thanks in advance for the help!
1998 Mustang GT, Silver, 4R70W
Built Short Block - SVO Supercharger w/ 2.9" Pulley (12 psi) - AIS Methanol Kit - Home Ported PI Heads - MHS Stage II NPI Blower Cams - 75 mm T/B - Offroad Prochamber - 2 Chamber Flowmasters
Built Transmission by RobertP - 3600 RPM Circle D Triple Disk Converter - 31 Spline Axles - 3.73 Rear Gears
Self Tuned with SCT Pro Racer Software
Unknown Power and Torque Numbers (yet)
Full weight, full street trim, 17 x 9s on all 4 corners, MT ET Street Radials
11.51 @ 118.89 mph, 1.63 60'