What’s interesting about the title of this post, is that it’s not related to 1967-1972 Chevy Suburbans, or Chevy/GMC Trucks at all. My daily driver is a nice old 1993 Ford F150. It’s a great running truck, with a 5.0 motor and a 5-speed transmission. As the weather’s gotten colder, the clutch has gotten weaker. Until one snowy day over a week ago, when the slave cylinder finally gave out completely. I had to drive it home sans clutch, which is interesting in dry weather, but I had to do it in the snow, in four wheel drive. So… there’s one more distraction keeping me from working on the Suburban.
Truthfully, I’m killing several birds with one stone here, which is good if you like killing birds. The transmission on this F150 is actually a Mazda-made transmission called the M5R2. Or I’ve seen them called the M5OD. Ford put these in a ton of 1/2 ton trucks in the 90s as well as some 3/4 ton trucks, vans, Explorers and even the Thunderbird SuperCoupe. Whatever you call them, they’re apparently notorious for leaking transmission fluid from three plugs at the rear of the shift rails, and at the shifter pivot. Mine was leaking at both.
After spending some time cleaning up the garage and organizing my tools, I stopped delaying the inevitable, and got to work. I spent the first hour or two just familiarizing myself with the truck and getting some of the basics out of the way — removing the driveshafts, unbolting the crossmember, removing the starter. In the cab, the shifter and the transfer case shifter both have to be removed. The transmission shifter is held on by an interesting stud configuration. You remove the nut from the stud, then thread it onto the back of the stud, which pulls it out.
Maybe three or three and a half hours in I’ve got the transmission unbolted and ready to come out. It’s slow going, but I’m taking my time as I’ve got all day. Also, this truck is a 4×4, so there’s decent clearance underneath it, and I’m doing all of this with the F150 sitting on all four wheels rather than jacked up. It makes thing a bit cramped, and definitely slower, but it wasn’t too bad.
I decided early on to leave the transfer case attached to the transmission for this job. That may or may not have been a good idea. I realized after I had the tranny unbolted from the engine, that the transfer case was heavy enough to rock my transmission jack back onto two wheels. I had to put a floor jack under the transfer case to roll the entire unit out.
There’s the whole unit. You can see not only how bad the shifter pivot and shift rail plugs were leaking, but also how bad the slave cylinder was leaking.
The first thing I decided to knock out was the shifter pivot. I had bought this repair kit on Ebay a couple of months ago, and it had been sitting on my desk at work.
The kit seemed pretty good. The new seals for the pivot ball definitely tightened up the feel of the shifter. One problem I ran into was the two studs that the shifter pivots on. I punched out the old ones to replace with the new, but the new ones were just barely too small, not large enough to press into place. So I did end up reusing the old studs. They didn’t seem extremely worn though.
Next on the list was the rubber plugs at the back of the shift rails. There is a lot of chatter on the interwebs about these guys leaking. From the factory, these ship with rubber plugs, that, over time, harden and shrink from heat and age. I was able to spin mine freely. The OEM plugs are fairly deep, and the flange for the tailshaft housing is close enough that there was no risk of the plugs flying out on their own, but that flange might have been the only thing keeping them in place.
The obvious question in replacing these parts is whether to replace them with OEM rubber plugs, or something more durable. Several guys online have pointed to steel freeze plugs from Dorman (# 555-108). I couldn’t find the Dorman part anywhere locally, but I did find an equivalent Dana part (# 219-3052). Napa had two of the freeze plugs in stock, and they were able to get a driver to bring another one out from a different store for me. That’s some excellent service for a total sale of $2.21 for all three plugs. I was able to press these plugs in using two pry-bars — one to keep the plugs lined up, and one to actually lever them into the hole. Here’s a shot of the new plugs in place:
I did end up dabbing a coat of RTV over the plugs just to be safe, but it was probably unnecessary.
Next up was the clutch slave cylinder. It’s only held on by two bolts inside the bellhousing. The whole reason for the tranny removal was the fact that this is a concentric slave cylinder, which actually fits directly over the input shaft. Many cars, including older F150s have external slave cylinders, and they use a clutch fork as a lever to actuate the pressure plate. With the concentric slave, you have to remove the tranny just to get to it.
The one that was on there didn’t appear to be an OEM unit, but I don’t really know for sure, and I didn’t spend much time looking for a Ford Motorcraft logo. I do know this one had a plastic body, no boot over the spring, and the throwout bearing was pretty worn out. I got the replacement at Advanced Auto Parts and it seemed like a nice unit. The body was all aluminum and there was a rubber boot over the spring. Installation was simple — just those two small bolts.
After installing the new clutch slave cylinder, it was time to put it all back together. While I had the transmission I went ahead and put in a new clutch kit: pressure plate, clutch disk and pilot bearing. The one that came out didn’t seem bad, but for barely $100 worth of parts, there’s no real good reason to not replace it while things are already disassembled.
Things lined up pretty well, and I had the transmission in place with the input shaft aligned with the clutch within a few minutes. It didn’t take much more wiggling to mate the input shaft splines up with the clutch disk. That’s where things got tough though — going from “pretty much lined up” to “seated in place and ready to bolt up” was way more aggravating and exhausting than I’d hoped for. I spent in the neighborhood of a full hour just to get the transmission bolted up.
Shaking, and rocking, and wiggling… I got very close several times. A trip to the parts house for a couple of 3″ bolts made the difference. I was able to get the bellhousing within 3/8″ of the motor. Then using the long 3″ bolts, I ran a couple of anchors in to hold things in position while I rocked the transmission all the way into place. From there the rest of the job was pretty much nuts and bolts — just the reverse of the first half of the job.
After buttoning things up I spent a few minutes bleeding the clutch system and we were good to go. The clutch feels really good now. Nice consistent and smooth feel in the clutch pedal. All in all, if you include a couple of trips to the parts store for odds and ends, and breaks for a couple of meals, the job took me in the neighborhood of 10 hours. If I were more familiar with these trucks, things could have gone much faster. And obviously, if I had a bit more room in my crowded two-car garage, that would have helped too.
But overall, the job wasn’t too bad… and a heck of a lot cheaper than paying a transmission shop to replace the clutch. Now I’ve got a running truck to use in dealing with my other unexpected setback: my dead air compressor. Next weekend I’ll have to pick up a new one and get that installed and ready to go. And I gotta get to that point, because I have a prospect interested in my HO72 rearend. That means I have to get it swapped out for my new 14-bolt rearend.
Plenty to do, and I can’t wait to get some of this other monkey business out of the way so I can make some real progress on the Suburban. I’ll keep you posted.
