The 700R4 Transmission, Chapter 2
This is the first thing that I found WRONG when disassembling the transmission. It appears that the C-clip on the 2-4 servo pin was slightly distorted. When I reinstalled it on the first rebuild I did not confirm for sure that it was totally engaged into the groove and it came off under pressure. I take responsibility. What effect would this have? One thing that I know is that I had intermittent loss of 4th gear, and maybe some partial pressure which may have caused the clutches and band to apply at the same time??, causing the band and the clutches to heat up ?? By the way, I finally found out that this 2/4 servo assembly has TranStar part numbers on it, but have found out from some blogs that I participate in that it really is a Corvette servo, which is a good thing.
There are some scratches on the inside of the pump surfaces. Don't know if they were there when new or not. Mystery. But there was no evidence of any metal chunks inside while probing with magnet on a stick....By the way, I probed all areas I could get to in the process of taking it apart in all areas and found only a couple of chunks of the busted gears. Even though my pressures were good, I'll be polishing/fine sanding these surfaces to get proper clearances on the vanes.
The band is quite dark, and there are some cracks in the surface of the band material, yet the printing is clearly undisturbed. Looks like it got hot right in the area of where the clutches are on the drum, which equals hot clutches inside the drum being transmitted to the drum, then to the band. You can see that the right hand edge and a little of the left edge are not discolored as much as the center.
When the failure happened, I was convinced that the TCI 2400 rpm stall converter had come apart internally. but after first using a turkey baster to dip out some fluid from the bottom and squirting into a clear glass bowl, I did not see a single piece of metal in it, so I got out my little magnet on a stick and swirled the converter around on the bench with the magnet at the bottom, and it came out without a single piece of junk stuck to it. Guess it didn't break after all.
The outside gear of the rear planetary shows some embedded tiny chunks of the broken gears, but does not appear to be damaged. I believe this can be cleaned up. This gallery will be updated from time to time with the reassembly other issues.....I bought a new one anyway and tossed this one.
At the suggestion of Dana at ProBuilt Transmissions, I installed a fluid filter in series with radiator cooler/heater and auxiliary cooler in front of the radiator with a temperature operated bypass valve that opens at about 160 degrees so the transmission fluid warms up faster and doesn't "overcool" in cold weather, so the lubricating fluid always stays about 160 no matter what the conditions are.
The sun gear takes a hell of a beating when teeth start coming off, and the original design bearing is a thin 3/8" bushing. The new design is a 1/2" wide bushing. LOTS better. The plumbing fitting in the background set on top of a large washer that was ground down to the diameter of the new bushing worked out perfectly to press the new bushing into the sun gear.
Southern engineering device to compress one of the numerous spring assemblies into it's position to get the snap ring in place. Actually this is the old reverse input drum with the scratches in it from the old band. That set of "modified/ground down snap ring pliers aren't worth a crap, but I got them to work anyway.
You can get this tool at NAPA, #776-9250, Transmission Seal tool for selector shaft seal. I watched a YouTube video where the guy using it had no idea what he was doing. He hammered the crap out of the black part then pulled the seal out. That's not how you do it, note the coarse threads on the outside of the tool. You just tap it a little bit to get it started, then screw the tool in (without the bolt) until it gets a little harder to turn with the flats on the black part, then put the bolt in and it pops right out. Then you use the silver cylindrical tool to tap the new seal in. Nearly MAGIC !
These are a MUST for getting that snap ring out of the pump Boost valve. The are KD #2395 and if you tighten the screws holding the silver part to the black part, they will hold position so once you grasp the ring and get it out of the groove, you can lift it out of the hole without it popping off.
This is the "hold down" tool that I made to take the pressure off the boost valve to make it easier to get the snap ring out. It's 2-1/2" long and the bolt hole is for bolting it down into the nearest pan bolt hole. The shape is important to allow room to get the snap ring pliers down in the hole to grab the snap ring.
A few weeks ago, as I was headed to Round Rock to see a new buddy of mine who has a '62 Cadillac (HUGE), I got stuck in traffic in 100 degree heat. At about the same time, I noticed that I had lost 4th gear on the transmission. I pulled into Advance Auto and checked the trans fluid level. It was low. (Later found out I had a leak at the trans cooler behind the grill, and the leak only occured while driving). Anyway, since the fluid was low, I threw a quart in, but still no 4th gear.. Turned around and drove home. After the modifications I made to the cooling system (See the Gallery named "Under the Hood Modifications", scroll all the way down). In any case, I posted some questions on The H.A.M.B and Hotrodders.com, and got some concenses on the fact that the 2/4 Servo is subject to o-ring leakage, and since I noticed/thought that the Corvette servo in the trans seemed a bit loose when I rebuilt it, I decided that I would go "full blast" and upgrade the servo system to a Sonnax 2 and 4 Servo Upgrade Kit. So here it is. BEAUTIFUL ! It has double o-rings and D-rings to seal it, and the piston diameters are even larger than the Corvette Servo. You can't get a more powerful (pushing force) on the pin to clamp the band on the drum than this servo.