#1 By: dr(Bawb), April 16th, 2013 10:23
This is an infodump about diagnosing and repairing sudden clutch failure on a 1993 Ford Mustang LX. Specifically the 2.3L I4.
(The 2.3L I4's T5 handles lower torque output, has a different bellhousing, and some minor differences inside the transmission. I think a lot of this information is applicable to the 5.0 as well, but I make no guarantees.)
So you're parking your Fox Body when suddenly you hear a loud noise and your clutch pedal drops to the floor.
If your foot was on the gas, and your car in gear, the clutchless pony might decide this is an excellent time to fully engage the clutch -- lurching you forward into a median.
Hopefully you survived this experience unscathed -- but your pony is going to need some maintenance.
As you can probably guess: this happened to me.
Unfortunately for you, dear reader, I haven't fixed my precious pony yet. However, as we diagnose and repair the Mustang over the next week or two, I will update this post with plenty of juicy photos, gory details, and maybe a video or six.
The Internet is always thirsty for information, so I'm glad to oblige. -- Let's list out what we know.
The transmission can still hold the car, even with the pedal to the floor, so the clutch face is probably still in tact, and being held against the flywheel.
(This is good, it means we might not have to spring for an entire clutch kit.)
The Mustang has a self-adjusting system on the pedal, known as the "clutch quadrant." The OEM piece can break pretty easily, so this is a good place to start looking. -- It's made of plastic, replacements are often [non-ratcheting] made of aluminum.
(As an aside: if you get an aftermarket metal quadrant, consider getting a firewall adjuster so you can still futz with the tension on your cable. -- Adjustable cables are OK too, but the OEM clutch cable is actually pretty beefy.)
To look at the quadrant, you're going to need to open your pony's driver side door, lie on your back so that your head is in the pedal compartment. I would highly recommend having a friend nearby. This is an awkard position to get into, and quite painful to get out of; having an extra set of hands to help you up beats grabbing the steering wheel. If you can, get somebody with a smaller frame to look at the quadrant.
Our quadrant is fine; but we can't pull back on the pedal. This likely means that the ratchet is at the end of it's travel. -- This might have been the source of the loud noise. (A heavy duty plastic ratchet suddenly going through it's entire travel could easily make a loud snapping noise.)
The pedal has no resistance, this is not good. -- This would point to cable failure, but let's keep looking.
On the 5.0, you'll need to remove a cover on the bellhousing that's hiding the cable / clutch fork. -- The 2.3L [N/A] does not have this cover.
Get a second set of feet to push the pedal while you look at the cable and fork. -- In our case, the cable is moving [throughout the pedal's entire travel], as is the fork.
This is probably bad, this means the fork itself is providing almost no resistance.
(Spend the $20 to replace the cable if the fork is not moving the same distance as the pedal. The quadrant will pick up the slack, but the pedal and fork should still move ~1:1...)
If a new cable doesn't fix your troubles, I hate to say it, but in all likelihood you're dropping a tranny. (Come tomorrow, I may be doing this myself.) Your trouble is likely a failed pressure plate [diaphragm], or even a failed throwout bearing (although this would surprise me, since the pedal still returns).
A new clutch cable may alleviate the symptoms of a partially failed quadrant. -- In our case: the new cable let us disengage the clutch a few times! Then the ratchet popped and the pedal lost tension again. -- Old / worn cables put a bit of extra stress on the quadrant, but not much.
- Our next attempted fix is replacing the quadrant. As we can't afford to wait, we're going to bolt a metal plate to the existing plastic quadrant.
This is [in theory] all you need to fix a broken quadrant on a '93 Mustang. Again, this type of fix is best left up to MacGyver.
Slight hangup: you try fitting a drill under the dash of a fox body Mustang! -- We could go in through the console, but not w/o cutting away some frame
Gorilla glue it is! -- We glued the quadrant together; AND IT WORKS! -- Hopefully it'll hold until Tues. when we can get a new quadrant shipped.
Use the kind that (A) foams up, (B) takes 30-60min to cure, (C) is water activated. -- This seemed to work for us. I believe the epoxy may eat through plastics, but I'm not sure. -- Obviously if you can use plastic cement or something else, that'll probably work even better.
The other thing to keep in mind is that gluing in this fashion is going to make it more difficult to take the quadrant OUT. Since this is only a temporary fix, don't go too overboard!
All in all: a new cable + gorilla glue on the old quadrant has done wonders. She's driving like a new pony.
Now we wait for the new quadrant, fingers crossed.
FYI, I ordered this quadrant which comes with a firewall adjuster.
I'll update when it's installed, let you guys know how it handles.
I'm hoping to grab some videos of the old [gorilla glued] quadrant versus the new one, as well.
I don't have any videos of the old cable; but it disengaged at the floor pretty much. Started engaging about 3/4 of full pedal travel, and was incredibly stiff to work. (I could push myself back in my seat without the clutch pedal moving.)
#2 By: dr(Bawb), April 23rd, 2013 11:45
Some glorious photographs of the final macgyvering.
The quadrant, in all it's destroyed glory. -- You can see the gorilla glue residue. Also notice how worn down the teeth are. They should be, well, jagged, sharp, and able to withstand the pull of a cable clutch.
The actual ratcheting mechanism. -- The teeth aren't as worn out, but they're in pretty rough shape.
Best part? This was supposedly not the OE ratchet. -- Yes, it's an OEM piece, but it's been replaced once before. -- FORD, what were you thinking? You should've recalled this plastic turd!
The franken-quadrant in it's FULL 1080p GLORY.
The clutch disengages at the floor: but hey, it needs to last like 24 hours.
Unless the quadrant physically breaks, this should stand up to the apocalypse.
More pics to come after the install!
#3 By: dr(Bawb), April 26th, 2013 11:22
The new quadrant is installed: it is BOSS MODE.
Unfortunately: it was machined out of tolerance. (.045" off... how you manage to fsck that up so badly? I have no idea. -- That pin hasn't changed since 1974.)
Anyways -- the firewall adjuster works amazingly. I've got a good 1/4" of play on the pedal. The clutch disengages before the pedal hits metal [awesome], the pedal feel is consistent throughout the whole range of motion, and the pedal is way easier to work [thanks to the new cable, mostly].
Plus: when we build out the motor and transmission this summer we can throw in a heavier clutch w/o too much worry. I'm sure this setup can probably stand up to at least a stage 2 clutch.
There's still plenty of work to be done, but I'm glad this is taken care of. -- Now we need to track down the turn signals not working intermittently, as well as the rough/low idle. -- Both issues just started showing up as the weather got warmer (and wetter).
The rough idle might be a vacuum issue or just shoddy spark plug installation. (Though if it were the latter I'd expect some misfires under load...)
The turn signal has me baffled, but that car has already gone through three sets of wiper control modules. (It currently has two, at the same time . . .) so I may be out $120 for that part.