So against my better judgement I rebuilt my C6 myself. It's all back together and in my 79 F150 2wd 400cu. It seems to not want to shift into 2nd on it's own. I can manually shift it into all the gears but 2nd feels like it slips. So here is a list of parts with questions:

I used Mercon V instead of Type F. The transmission is a 1987 and the bottle says it covers vehicles requiring Dextron/Mercon.

I installed a FF servo lever with a P servo. My kit didn't come with a new spring. What effect would a worn spring have?

When adjusting the band, I set it to 120in/lbs and backed it off 1.5 turns. This seemed very loose to me. It leaves the set screw finger tight/loose, so I tried turning it in 1/2 turn but that made no difference and I won't drive it until I readjust it. Also it's a RedEagle wide band, but that shouldn't make a difference.

One place I think I could have a problem is with the modulator. I didn't have a scale to do the 12.5 lbs method, but I had a big syringe, vacuum guage, tubing and t fitting. I could hold the -15" of mercury but the rod didn't go in to the notch like it said it should. I was going to stick the old one in but it's bent and the rod is missing. Will a bad or misadjusted modulator cause the tranny to slip in 2nd? I don't think it's inbetween gears because it does accelerate in 2nd.

I used the BadShoeProductions video along with a Ford Shop manual to assist me.

Complete list of replaced items:
New Modulator
F servo lever with P piston
All Friction and steels
Pressure plates for additional friction plates per video.
All Seals and gaskets
New wide band
New pump
Hughes torque converter
TransGo shift kit
New Sun Shell (Took my end play from .070 to .012)

Everything was cleaned and tested ok per video.
Then only problem with the video is it doesn't tell you what to do when you have a problem, only shows you how to tear down and reassemble.

I used a torque wrench for everything, but if it turns out it's a valve body problem then I will go back through it but only using a nut driver.

The kick down rod is working properly.

My gear selector is set properly.

Any help would be greatly appreciated.

 

Did the piston fit the servo?
Back the band off 1 turn only.
Make sure the inner modulator valve is in the right way around.

You can use a piece of metal coat hanger for a modulator pin.
Did you install a separator plate gasket?
Did you tighten the banana plate last?

 

I had already turned the adjustment screw in 1/2 turn so that would put me at 1 turn out.
As far as the piston fitting the servo, guess I dropped the ball there. According to my invoice I purchased a P servo, but I just checked and the case says S. I'm really hoping that makes a big difference. When I was researching I thought I read to get the F lever with the P piston. I thought that worked for all C6's but either way I'm ordering an S piston. Do I have to drain the pan to change this? I am pretty confident that I assembled the valve body correctly per shift kit and video instructions. I greatly appreciate the help. I will keep this thread updated.

 

So, my first auto transmission is over and I survived. The truck is back on the road, running strong and shifting firm. It was a struggle, but I learned so much that I have confidence to rebuild other transmissions.

So, I did purchase and install the wrong intermediate servo piston. Luckily I didn't do any damage to the band. Unfortunetly my header collector was in the way of removing the servo piston so I pretty much had to lift the engine and trans up, take out the headers and set them back down and changed the piston. It killed me having to disconnect everything I just hooked up, especially the headers and the Stage 8 bolts with fasteners. Stock exhaust and this would have been an easy fix. The real twist of the knife was that instead of ordering the S piston online, I went to a local tranny shop and the guy gave me the wrong one, so my truck had to sit an additional week since I had to order it and only have had weekends to work on it. So I put it all back together, but it was still a lazy, slipping shift. I was using the modulator that came in shift kit, and figured I had it set wrong or that my engine wouldn't rev high enough for it. Wrong. After purchasing a black stripe modulator like what was in the trans before I rebuilt it from Napa, I found that I had a vacuum leak. Fixed that and the truck runs awsome and shifts awsome.

I didn't get any pictures taken of the trans while I had it apart. I didn't want to touch the camera because it seemed like I was oozing transfluid from my pores. I did get a few snapped off when it was all done.



https://www.ford-trucks.com/forums/p...ctureid=112109

https://www.ford-trucks.com/forums/p...ctureid=112110