Have a 2003 4.6 Manual. A couple years ago the trans chipped a tooth and so I had the trans rebuilt and clutch replaced along with a new slave and master and shifter bushings. It has been working about as well as an M5OD can work. But, recently it has become difficult to shift, especially into 2nd. It feels as if the clutch isn't fully disengaging. It does not feel like a leaky slave, you can't pump it up, it has good resistance.

I inspected the slave and I don't see any signs of leaks. While inspecting the pedal side of the master, the pushrod fell out of the master. At first I thought the end of the pushrod was damaged, but when I got it into the light I see that someone welded a bead to the end making it maybe .050" longer. When I try to reinstall the pushrod it has about 1/8-3/16" of play forward and backward. This made me think it was still too short so I put it a spacer and drove it. It shifts like new. But, the pushrod will not lock in now, I believe the clip on the master is damaged. Just leaving it seems pretty dangerous.

It is difficult to come up with a good plan to fix this right. My question is does anyone have any idea what could be going on here? Is there a similar but wrong master they could have used? It looks correct, but must not have had a long enough stroke when they installed it. So if I just replace the master, it probably won't work. Does the master actually have 3/16" extra stroke in it or would extending the pushrod just make it fail quick? If the current setup needs extra stroke to disengage, why? Wrong clutch? Slave? Shims? What? This is a bit of a mystery to me I'm hoping there's someone out there that has an idea or seen something similar.

 

The slave cylinders can be swapped between the different year transmissions. Both size slaves can be put on to any of the M5OD transmissions, so you just have to match the same slave to the clutch master cylinder.

Sounds like the shop didn't know this, OR had an extra sitting for a different clutch master cylinder. They tried correcting it's throw by doing that modification.

At this point, assuming nothing has changed with the stock clutch master cylinder (meaning it didn't get replaced), I would go to your local Ford parts counter, give them your VIN, and get the right size for your truck.

Unfortunately, to change that out, requires the transmission to be partially slid back or slightly removed.

 

This sounds reasonable. How could I confirm which was in there? Or could I just match the proper master to the current slave? I hesitant to remove a non-leaking slave, not just because of the work but because the next one might not even last this long.

 

Eh, to be honest. I'm not sure. Sorry.