The saga continues. After replacing the clutch and reinstalling the trans recently, I tested it out last week and the car would go into gear and go forward and reverse, fairly smoothly. This was only in a driveway for a few feet either way, but there were no issues getting it into gear or driving either direction.

But just now, after installing some other, unrelated parts, I tried to move the car, and it would just barely go into 1st and jerk forward roughly, but not into reverse, even with the clutch pedal all the way in and me waiting a few seconds so the revs matched. The gears grinded horribly, and I immediately backed off.

I had to turn the engine off and push it back, and even then it barely budged, with the trans in neutral. I haven't worked on the clutch or trans since putting them back in and test moving the car. Weird.

However, there are several clues.

First, when I opened the hood today, I saw a tiny part that looked like the round metal "valve plate" that goes on top of the spring inside the clutch slave cylinder line valve bore, that the banjo bolt screws into. If this is that part, the slave cylinder might have a hard time pushing the pin onto the fork and releasing the clutch, which would make it impossible to get the trans in gear without really bad gear grinding.

I thought I inserted this when reattaching the clutch fluid line, but perhaps it fell out and I didn't notice. I've done a ton of work on the car the past 4.5 months and fatigue does its thing.

It's part #1 on page 6-14 of the 1991 FSM.

Second, under the rear diff or a bit forward of it, I saw what looked like several recent leaks of fresh fluid. It could have been diff fluid, brake or clutch fluid. Hard to tell.

Third, it's a lot colder today than it was when I was able to get the trans in gear and move the car, around 20 degrees. It was around 62 then and 42 today. I put 90W gear oil into the trans and t-case, which is a bit heavier than the recommended 75W-85 oil, and I understand that the heavier the oil, the "notchier" shifting is until it warms up during use. If so, all the more so, I imagine, the colder the weather.

I used this because it's going to end up being "sacrificial" oil as I'm going to need to pull the trans again soon to fix an issue with getting into 1st gear and I didn't want to waste the Mopar oil I bought on it. Jack's Transmission told me that it's ok to do this if I'm not going to put many miles on the car.

Anyway, which of these sounds more plausible as the cause of this new issue, the apparently missing part on the slave cylinder, the leaks, or the combination of heavier oil and colder weather?

I should also add that the flywheel wasn't resurfaced. Long story there that I've explained elsewhere, but SBC told me that it's ok to drive it just a few miles on the old flywheel (whose surface looked pretty smooth to me and which I cleaned up as best I could with a brush) before resurfacing or replacing it. I just need to drive around 5 miles r/t to get the car inspected so I can park it on the street again. Could this have destroyed the clutch disc, or preventing it from fully gripping the flywheel? But even if so this wouldn't really explain the gear grinding issue.

The griding noise if sounds like the clutch isnt engaging, it could also be damaged synchros inside the transmission. Do you know the condition of the transmission.

Well, back before the clutch disc wore out, the trans worked fine, except 1st gear, which it started popping out of under load several months before the clutch died.

Car hadn't been driven since, so no wear & tear. With oil inside and everything sealed, not much to go wrong I would think. That was 5.5 years ago.

Then, after I put in a new clutch and reinstalled the trans and everything several weeks ago, I test drove the car in the driveway several feet forward & reverse, several times, on separate days, and it drove fine for these short distances. No noises or grinding--or popping out of 1st.

Now on a 20 degrees colder day, it grinds like crazy. I hope I didn't do serious damage but I backed off each time immediately. But it can't be the trans, at least, not primarily the trans since it did have an issue with 1st gear previously.

Sounds like the clutch not disengaging to me too, and I have physical evidence that backs this up, namely what appears to be the valve plate outside the slave cylinder, and a small leak under the car that looks like brake/clutch fluid, because it's thin and clear. It could also be a leak further up in the clutch hydraulics, since the leaking fluid is several feet back of the slave cylinder.

I'm going to raise the front tomorrow and have a look. It's too cold today and I'm tired. If it's what I think it is, at worst I'll need a new slave and maybe master cylinder and not a new trans.

Well start with the obvious, the slave cylinder, is what i would replace first its a simple fix.

The clutch isnt disengaging. You either need to bleed it, or there is a major issue somewhere else. Get someone to help you and measure the slave cyl travel when you push the clutch down. Should be close to 0.625"

The metal plate isn't your issue. That is a restrictor designed to slow engagement. It is sometimes modified or removed.
As stated above it's likely a bleed or adjustment issue. Start with the basics there. I would adjust first. 5 min fix. If either master or slave are original to the car or very old they are highly suspect of not working correctly.
I could totally see them doing the job once then leaking and performing poorly a week or two later. Make sure you tightened the adjustment jam nut on the master also. If you didn't it can screw itself back in. If that's the case simply adjust back out and tighten it down.
This should be easy to diagnose and fix.

So we're all agreed that it sounds like the clutch not disengaging, the only questions being why, and how to fix it, right? Grinding gears, clear thin fluid leak on ground, soft clutch pedal. All point to this.

As for the adjustment jam nut on the master, I actually didn't do anything with the master other than add fresh fluid to the reservoir after reinstalling the slave. Was I supposed to? I just reattached the banjo to the slave and the slave to the trans, opened the bleeded, added fluid, bled till no more bubbles, then closed the bleeder and shut the master reservoir. There were more steps?

when i replaced my clutch with a new ACT, everything was fine at the first test drive. Then, the day later, clutch wasnt engaging. Found out i needed to adjust the master cylinder shaft under the dash.
Few turn and everything was perfect. You should take a look as this.

Bock said:

when i replaced my clutch with a new ACT, everything was fine at the first test drive. Then, the day later, clutch wasnt engaging. Found out i needed to adjust the master cylinder shaft under the dash.
Few turn and everything was perfect. You should take a look as this.

Click to expand...

Thanks. I'll take a look at all these things tomorrow. It's obviously not as simple as I thought. Or, it could be defective parts that need rebuilding or replacing.

Jack’s has a very helpful video about clutch adjustment. I followed it and it helped a lot. New clutch would require MC rod adjustment. Slave not necessarily so, but you’ve done both.
We’re all rooting for you, So close!

Clutch adjustment is literally just a few min. You will take a little longer since you've never done it but seriously very very easy. A little sucky laying on your back under the dash but anyway....

when the rod is adjusted properly you should have some play in the pedal up top . but also make sure all the air is out of the system .

Additional relevant information to help those that are trying to assist OP diagnose the problem:
https://www.dsmtuners.com/threads/probably-need-new-flywheel-recommendations.532247/

Mech Addict said:

Jack’s has a very helpful video about clutch adjustment. I followed it and it helped a lot. New clutch would require MC rod adjustment. Slave not necessarily so, but you’ve done both.
We’re all rooting for you, So close!

Click to expand...

Actually I haven't adjusted the clutch master cylinder yet. That was next, after doing a final confirmation that the trans gets into gear and the car moves back and forth. That was supposed to be today, but obviously it failed this test. I like to work in steps, and until one step is complete I put the next ones off, at least if they're part of the same subsystem. I think I have a leak in the system AND the master needs to be adjusted. Not sure why it's leaking but I'll look into it tomorrow.

I'm actually glad that this happened. Better in the driveway than on the road. It's like The Right Stuff, the Disney+ series I've been watching that's based on the movie and book and of course history. They were lucky that unmanned rockets exploded on the launch pad or shortly after, so they didn't get cocky and lose astronauts sent up in insufficiently tested and refined rockets, and realized that they still had a lot of work left to be done. If you're not failing, you're doing something wrong.

Just make sure to fail off the road.

2gmitsueclipse said:

Additional relevant information to help those that are trying to assist OP diagnose the problem:
https://www.dsmtuners.com/threads/probably-need-new-flywheel-recommendations.532247/

Click to expand...

Heh, you're linking to a thread that I started.

Thanks all. A relatively simple process that one nevertheless needs to do a few times to get the hang of. I'd been hoping I could avoid these steps but hope is not a plan.

I just took a look at some photos I took the other day, before today's gear shifting issues. Take a look at the slave cylinder in the upper left. It appears to be leaking from the bore, where it meets the boot. Does this indicate that it's junk, or could a rebuild kit fix this?



Here's a more detailed closeup:



Btw the leak on the underside of the t-case is just excess gear oil that dripped from the fill opening, not a leaky seal or case. No cause for alarm there (I hope!).

Looks like a leak, potentially, yes. I believe the rebuild is simple, a new piston with a seal that comes installed on it. I chose to just replace mine, but the cylinder is iron, so not much that could go wrong there. A lot like brake calipers. Could certainly explain your shift issues. Fix that, bleed it, adjust the MC, should pass inspection.

Given your car is one owner if you get a new slave pay close attention to the bore size. Two were available and you want to match what you have. Should be awd specific but who knows what aftermarket crap is out there. You may want to install a new piston inmstead. Your choice.
See this for a little education.

https://www.dsmtuners.com/threads/clutch-basic-101-a-clutch-basics-thread-for-everybody.459908/

Here's some thoughts for if you get to adjusting the master rod (although I don't think that's your problem at the moment), which you've probably already found on page 6-5 in the FSM.
In #4 they say the clutch pedal free play should be .24 to .51 inches.

But when I did this the first time I had trouble deciding where the end of the "free play" region really was.

I decided it must be how far the pedal can move before the master rod moves at all.

So I did this: I positioned a mechanics mirror (on a stalk) to where I could see the master rod, from where I was kneeling on the garage floor pushing the pedal by hand.
That way I could see and roughly measure how far the pedal had to move to start moving the master rod.

Before I thought of doing that, I had the same thing happen, I think, that was mentioned up in post #8 - worked fine for a while, then all of a sudden the clutch would not disengage. And this was with new master and slave cyls after just putting them on.
It was because I had the master rod screwed too far out of the clevis, into the master cyl.

Here's some factoids I measured with my old master cyl out of the car and on the bench.
Pushing on the master rod, it takes about 5 pounds of push to start it moving at all. Before that it is up against a hard stop at the rear of the cylinder.
Then once it starts moving, it will go about .080" forward and at that point it closes off the port to the reservoir. (I determined that with a mityvac vacuum pump connected to the reservoir with a rubber stopper, 1-hole)

When I had my experience like in post #8, I had the master rod too far into the cylinder. I suppose it was interfering with the operation of that port to the reservoir.

It does look like your slave is leaking though . My old slave leaked for a while before I saw any fluid on the floor. Seems like it accumulated in the boot for a while first. When I squeezed the boot, fluid shot out. Face shield good idea there haha.
BTW I have my clutch pedal free play adjusted to only 1/8" (by my definition of free play) because I'm trying to get as much master travel as possible. It has been ok that way.

pauleyman said:

Given your car is one owner if you get a new slave pay close attention to the bore size. Two were available and you want to match what you have. Should be awd specific but who knows what aftermarket crap is out there. You may want to install a new piston inmstead. Your choice.
See this for a little education.

https://www.dsmtuners.com/threads/clutch-basic-101-a-clutch-basics-thread-for-everybody.459908/

Click to expand...

Looks like at the very least I'll need a slave rebuild kit, if not a whole new (OEM) slave.

Thing is, as you say, there's conflicting advice on which kit to get. RTM says MD979428:

https://www.rtmracing.com/xcart/product.php?productid=18118&cat=1886&page=1

But Mitsubishi Auto Parts Direct says I need 2969A056, which RTM says is for the FWD:

https://www.mitsubishiautopartsdirect.com/oem-parts/mitsubishi-slave-cylinder-repair-kit-2969a056

So which one is it? I'm inclined to go with RTM, but I'm no expert. To add to the confusion, the parts catalog says MD997838, which neither has.

Btw is Mitsubishi Auto Parts Direct legit? There are several sites that have similar names and designs, and I don't know if they're for real or scam outfits.

Normally I’d go with RTM advice, or one of the other dsm-specialist vendors. They know. When I looked it up in the Amayama catalog, it showed MD997786 as the original part number, with MD979428 as the “replacement” (as in updated part). Price under $10, but they’re only shipping FedEx atm, and the cost is like $80!! Also, I recall that these pistons are often referred to by color; my original 90 part was anodized red. I believe new ones come in green or gold? One of the reasons I just went ahead and got a whole new unit for awd. Easy to replace, messy to bleed.
Also, as you’re considering all this, might want to check on where your adjustment rod is now, in terms of how much thread you have left protruding into the clevis fork. I swapped in a 2g bolt, which is longer, because combination of worn clutch, flywheel, and pedal/push arm meant that the normal MC bolt ran out of threads to adjust. Your clutch is new, which will help avoid this, but your flywheel definitely not. Pedal may have some wear. Shifting was night and day when done ( though my 1/2 synchros still bad, and bearing need replaced).

Only reason I'm considering going with another vendor instead of RTM is that I need a bunch of other parts too that RTM doesn't sell, and shipping costs are starting to add up. Plus they sell the rebuild kit and OEM slave for a bit less than RTM. Money is now officially an issue.

As for the rest, I need to raise the car and look at the entire clutch hydraulic assembly, from pedal to rod to MC to line to SC, and see what's up and needs to be done to fix this.

You may be able to see the piston if you remove the boot or remove the rod also and measure the bore real quick. 1/16" difference is far enough you can just use a tape measure instead of something like a caliper. But by all means if you have a caliper handy....

XC92 said:

Looks like at the very least I'll need a slave rebuild kit, if not a whole new (OEM) slave.

Thing is, as you say, there's conflicting advice on which kit to get. RTM says MD979428:

https://www.rtmracing.com/xcart/product.php?productid=18118&cat=1886&page=1

But Mitsubishi Auto Parts Direct says I need 2969A056, which RTM says is for the FWD:

https://www.mitsubishiautopartsdirect.com/oem-parts/mitsubishi-slave-cylinder-repair-kit-2969a056

So which one is it? I'm inclined to go with RTM, but I'm no expert. To add to the confusion, the parts catalog says MD997838, which neither has.

Btw is Mitsubishi Auto Parts Direct legit? There are several sites that have similar names and designs, and I don't know if they're for real or scam outfits.

Click to expand...

RTM is correct. It should be the smaller 3/4 red or gold piston MD979428.

So I raised the car and bled the slave cylinder again, and there definitely appears to be a leak in it. At the very least I need a rebuild kit, if not a new one entirely, plus new crush washers for the banjo and a speed bleeder. I'll order these today.

I also checked under the dash. Here's a photo of the clutch pedal:


And here's one of the MC rod:



With a new clutch, old and unresurfaced flywheel that may or may not have the proper step, and the original master and slave, just re-bled but apparently leaking on the slave end, do these appear to be the correct settings under the dash, or does it look like one or the other or both need adjustment?

You can't see the important part. Its at the end of the master rod. The threaded part. Its behind the big spring in the pic. Since you picked a stock replacement clutch I wouldn't worry much about the step height of the original flywheel. Its likely in range and is good enough for the moment. Looks like master has been seeping over time but hey 28 years it should have

Ok, bled the slave again, just to be safe. At first, the pedal was firm with good return. Then I went under again and pushed against the pin, with the bleeder still closed. Went back inside and the pedal offered almost no resistance. There's obviously an air leak somewhere, almost certainly at the piston seal. I can take the slave off and pull back the boot to confirm, but given what I did just before the pedal went back to offering no resistance, and that there doesn't appear to be a fluid leak anywhere, I can't see what else it could be, unless there's another air leak somewhere.

So at the very least, a slave rebuild kit. None appear to be available local and mail order is either wait a week or longer or pay a crazy fee for fast shipping. Meanwhile, time's running out on moving the car and putting it on the street with an inspection sticker. I'll figure something out.

I assume that once I fix the leak, the other stuff with the rod can wait till after inspection, right? I mean, things might not be optimal, but I should be able to disengage and engage for a few miles, right?

So, I was going to order a slave rebuild kit but I need it ASAP and the only way to get it within a few days was to pay a lot for shipping. The total would have been just over $50. Jacks Trans sells a new slave for $65. With priority shipping it was around $35 more than the rebuild kit. So I went for a new slave instead. I'm running short on time and this seemed like something to spend a bit more on. For all I know the existing slave bore is shot, so a kit might not have done fixed the leak.

Jack's is pretty much the gold standard here for anything trans, right? When I get to fixing the trans itself, he'll be where I order most of the parts I need, I assume. Doesn't he have a "monopoly" on certain parts at this point, having bought out the entire stock?

There is a whole host of vendors on the main page you could look at. Extremepsi, jacks, tmz, rtm, STM. Likely all of them carry this stuff. Some of the stuff is so cheap (relatively) I order two. I don't care if it sits in storage for awhile. I always order two when I'm doing seals, washers etc.
I broke down and bought copper washers in a kit on amazon, Lots of sizes.