Part 7 Rebuilding the Transmission Main Case: Rebuilding the Front Clutch

I'll set the rear clutch aside, and start working on the front clutch. The front clutch engages when the main case is in direct (which translates to 3rd and 4th gears) and in reverse. This is what was toasted in my transmission prompting this rebuild. My symptoms were that the transmission wouldn't shift into 3rd and was slow to engage reverse. The problem was the seal on the clutch piston. It had a chunk out of it. And the clutch steels and frictions were literally toasted. This, I believe, is a failure due to upgrades. Last year I upgraded the torque converter to a Hughes XFM15 low stall unit. It gets more power to the ground. I also installed a TransGo shiftkit. These two items, coupled with the fact that a few years back my throttle valve (TV) cable fell off while towing trailer, helped this "burning issue" happen. When the TV cable came off , the ATF temperatures rose almost instantly to 350 degrees. The front clutch was "engaging" but with no holding force from line pressure which the TV cable controls.

Here's the original clutch pack in all its toasty-glory! Most of the friction material is gone from all the friction elements. And the pieces have taken on a conical warp-ed-ness! It had 4 frictions and 4 steels.



You can refer to my post on tearing down for more carnage pics.

Here's the new clutch pack. I upgraded to a pack with 6 frictions and 6 steels. That gives me 50% more clutch apply area than OEM. Hopefully this horrible mess won't happen again!



Place the frictions and steels in some fresh ATF and let them soak (at least 30 minutes) while you ready the clutch retainer/drum.



Start by drifting out the front clutch retainer bushing. Mark or take note how far the bushing is pressed into the bore of the retainer so that you can install the new bushing to the same depth. The "special tool" figures this out for you. I didn't have that tool, so I made a mark. Be ultra careful to not score the sealing surfaces just above the bushing. The bushing came out pretty easily.



Then press the new bushing into the clutch retainer. Yes, that's the old pump gear I'm using to press with. It was just the perfect size. Once the bushing is flush I used the old bushing stacked on top of the new bushing in order to press it a little further into the retainer.



Here's the bushing in its final resting place.



Now install a new outer seal into its associated groove in the clutch piston. Make sure the lip faces down, or to the front of the transmission.



Now install the inner seal into its groove on the clutch retainer hub. Again, make sure the lip faces down, or towards the front of the transmission. The bottom groove , or the groove nearest to the base of the retainer, is the seal groove. The top groove is for spring retainer snap ring.



Lube all that mess up with some assembly lube. Note: this is NOT the direction the piston is installed!



Flip the piston over and slide it down into the clutch retainer. Go easy, and make sure the lips on the seals don't get folded over. You may need to use a tool to work the lips into the bores. There's a special tool for this which I don't have. I used a .010" feeler gauge. Again, go easy and take your time.



Place the 9 piston springs over the little "spring nubs" (technical term). If you have a different transmission application you may have 11 or 13 springs which would be installed in a different pattern.



Now install the spring retainer over the springs. Mine was a bit "deformed." But I mushed it back into shape with a hammer and decided to reuse it.



There's also a special tool for compressing the springs and retainer. I used these two clamps. It worked. Although not ideally. If I were to do it again, I would figure out a better solution than this. "Gee, I wonder why the spring retainer was deformed?" Could be because of this technique!



Here's the spring retainer compressed and ready for the snap ring.



The snap ring installed and the clamps removed.



Now I'm ready to install the clutch pieces. Start with a steel. It goes right on top of the piston.



Here's the first steel in place.



Now take a friction from the ATF.



And install it on top of the steel in the clutch retainer. Alternate steel-friction-steel-friction until you've installed them all.



The upgraded clutch pack came with a thinner reaction plate to accommodate the thicker pack. The new one measured right around .132".



The old one measured .280".



Place the new reaction plate on top of the last friction.



Here's the clutch pieces all in place with the reaction plate on top.



Install the wave style snap ring in its associated groove.



The clutch pack all assembled with the snap ring in place.



Now measure the clutch pack clearance. Insert the feeler gauge(s) between the top of the reaction place and the bottom of an "upward wave" in the snap ring. In other words, where you would naturally find a gap. Mine measured in at .070" which is right about where I wanted it for this upgraded clutch pack (according to some transmission gurus I chatted with). This gives me .010" clearance per clutch element for lube to enter when the clutch is not engaged. If you're installing an OEM setup with 4 frictions and 4 steels, the manual states .082" to .151".



Next: assembling the front and rear clutch assemblies and installing them in the main case.