Maybe your Mini clutch is working fine. Maybe you’re starting to notice that the master cylinder fluid is going down slowly. Maybe the action just doesn’t seem the same. Maybe you are hearing some noises you don’t remember hearing before. The following are some quick checks even a beginner can do to make sure a clutch keeps operating correctly or to point one towards areas that may need some attention.
This article is intended for pre-verto clutches although much here will apply to the later, verto clutches as well. (You have a pre-verto clutch if the clutch slave cylinder sitting on top of the flywheel housing is mounted horizontally. If it tips down towards a stubby clutch arm, you have a verto clutch.)
By the way, at the end of this article you’ll find part numbers for many of the items mentioned.
From Pedal to Clutch –Inside the Car
The beginners’ guide to the clutch parts that you can examine and fix follows a path from the pedal on through the clutch housing to the throw out bearing. If you have a workshop manual like Haynes covering your car (you do have a workshop manual don’t you?) you can follow along in the pictures, or, even better, print this out and go out to the car.
Start at the pedal. That’s the one on the left, unless you have an automatic! Mini pedal assemblies are pretty long wearing. Unless you’ve been storing your Mini in a swimming pool or it has run over the 100,000-mile mark, the pedal usually will be OK. Occasionally a drop of oil or other lubricating fluid wouldn’t do any harm. If you can grab the pedal and rattle it around, it is probably time to get down there and take a closer look. (Hint: take the seat out. It makes it SO much easier.) There is a bushing and a shaft that might be wearing where the pivot point is on the pedal.
While you are there, take a look at the pedal pad. Time to replace it? Not a good idea to step on the pedal and have the pad, and your foot, slip off at an inopportune time – which would be any time you need to step on the clutch pedal! Here’s a money saving hint. Rotate the pad 180 degrees and put it back on. They only wear on one corner so, unless you’ve let it wear out completely, you’ll get twice the life. Even better, once both opposite corners are worn out, swap it with the brake pedal pad. The other corners are worn out on the brake pad. Four times the life!
Since you’ve been grubbing around with the pedal and the pad, did you notice if the pedal arm was a little moist? You might need to shine some light in there. Is there a black mark on the carpet where the pedal arm hits? This is a sign that the clutch master cylinder, which sits above the clutch arm in the engine compartment, is leaking. Not a good sign. It will need rebuilding or replacing. If you’ve been checking your clutch fluid and it has been going down, this is one possible reason. Also, if you’ve noticed that the clutch seems to engage much closer to the floor, but that if you pump on the pedal it engages where it used to, this is a possible reason.
Don’t get up yet. More things to check. Way up underneath where the end of the clutch pedal fits back into a recess in the firewall/bulkhead (aren’t you glad you took the seat out?), you’ll see that the end of the pedal is attached to the bottom, forked end of the rod hanging down from the clutch master cylinder. There is a pin, called a clevis pin, which goes through one fork, then through a hole in the pedal and then through the other fork. If you press the pedal down a little bit with your hand you can see the pedal move the fork via the attachment clevis pin. This pin is a notorious wear point in clutches. Even the clutch master cylinder fork wears, but the pin is the worst. If you press the pedal a little ways and you see that the forked arm doesn’t move you have more wear to take care of. Make it a routine to replace the pin anytime the clutch master cylinder is removed.
It’s still not time to get up. One last check. Is the carpet bunched up between the pedal and the bulkhead? Don’t laugh. This is common; especially, when a well-meaning person has done a halfway job of adding more soundproofing material.
Oh. You might as well do the same checks on the brake pedal while you’re down there.
Now you can get up.
From Pedal to Clutch –Inside the Engine Compartment
As you are looking into the engine compartment, the clutch master cylinder is the “bean can” looking thing sitting to the right of the other “bean can” looking thing (the brake master cylinder). Remember, if you get confused, it sits just above the clutch pedal. New cars got fancy with the brakes and the only bean can is for the clutch, and some of the latest master cylinders are plastic, but you get the idea.
Check the fluid level. It should be just up near the top of the can, not all the way to the top of the cap fitting extension. If the fluid is low, you probably have something leaking or you’ve not checked it in years. If you didn’t find a leak inside the car, it might be very slight or you might find it later in our journey.
The forked clutch master cylinder rod you examined earlier while standing on your head inside the car, pushes fluid out of the line on the top of the master cylinder to a junction on the bulkhead on the clutch end of the car – the offside in English. Check the line at the master cylinder and at the junction for leaking. This in unlikely but can happen if the clutch master or slave has been changed recently.
Where the clutch line meets the junction it feeds into the flexible clutch hose. This hose leads to the slave cylinder mounted on top of the flywheel housing. Do you know how old the hose is? Usually they hold up pretty well, but they can break down internally. The fluid hole gets restricted or a flap of the inside of the hose starts acting like a one-way valve.
When the clutch pedal is pressed, the fluid in the slave cylinder pushes a piston against the end of the rod you can see sticking out of the end of the cylinder. The rod is attached to the clutch arm by a clevis pin (the word “clevis pin” should translate to “wear point”). The arm moves outward off of the adjustment stop (the bolt coming out of the clutch cover), pivoting on another clevis pin/wear point in the clutch cover. The bottom of the arm is fitted into a hole in a plunger that slides into the clutch cover. On the inside of the clutch cover where you can’t see it (or get to it easily) on the end of the plunger is the clutch release bearing, a.k.a., clutch throw out bearing. The release bearing presses on the clutch mechanism to release the clutch disk disconnecting the transmission from the engine. On the other end of the plunger are two large nuts that only allow the plunger to move a limited distance. There are nuts there aren’t there? If you see threads and no nuts you are the victim of the “we don’t need these” school of repair. Unfortunately, it is more common than you would think. Replace the nuts and reset the throw out based on a workshop manual’s information.
When you release the clutch pedal, the fluid pressure is released. The clutch spring hidden behind the clutch cover pushes the arm back via the throw out bearing and plunger, and the spring stretched between the tab on the slave cylinder and the one on the arm helps pull the arm back and takes up the slack. That’s how the bits fit together. Now, what can go wrong? Well,…
Check out the slave cylinder. Peel back the rubber dust cover on the end. If there is moisture there you have a slave cylinder that is leaking and should be rebuilt or replaced. If you are ordering a new slave cylinder, order the hose, too, unless you know it has been changed recently.
Take a look at the spring stretched between a tab on the clutch slave cylinder and a tab on the clutch arm. (There is one, isn’t there?) These wear out, but loosing tension usually isn’t the problem. What happens is they wear through at the two attachment points and break. Check the attachment tabs at the same time. They also wear through. You can turn them over and get some more wear out of them, by the way, but if one or more of the three parts look suspicious, replace them.
As you can tell by looking at the external clutch mechanism there are a lot of wear points. The end of the rod, the hole in the rod, the two clevis pins, the holes in the arm, the ball on the bottom of the arm and the hole in the plunger are all susceptible to wear. Usually if you are having clutch problems that have shown up relatively fast, it isn’t because of wear in these points – unless you just had a clutch job done. This wear can be serious, though. I suggest you check out the “Clutch FAQ” article mentioned below in “Recommended Reading” for more information.
For more quickly appearing problems check to make sure that the adjustment bolt or the two big nuts on the end of the plunger haven’t worked loose and make sure there is a little grease (and not a pebble or two) stuck down in the hole on the plunger where the arm fits.
Adjusting the clutch isn’t difficult. Check with a workshop manual. Just remember that adjusting the clutch to change where the pedal is positioned when the clutch catches has nothing to do with the two big nuts on the end of the plunger. LEAVE THOSE ALONE unless clutch work under the clutch cover has just been done (like a disk being replaced).
Here’s a simple test that may point you toward solutions to clutch problems. Either get some help (someone to press the clutch pedal) or rig up a stiff wire sticking up from the top of the clutch arm so that you can see it from inside the car.
Press the clutch pedal down and hold it. The arm should move out quickly and stay in position. If it moves out slowly, you may have a problem in the clutch slave cylinder hose. The fluid hole may be restricted. Time to replace it. If once out, the arm slowly creeps back, you most likely have a problem in the master or slave cylinders. You can bleed the clutch and see if the problem goes away, but it is likely one or both will need rebuilding or replacing.
If the arm stays in place OK with the pedal down, release the pedal. The arm should move quickly back against the stop. If it doesn’t, you may have a problem with the clutch slave cylinder hose. It is probably breaking down inside and is acting like a one-way valve. Time to replace it.
A couple more clutch related items you can check. On the bottom of the round section of the flywheel housing (the round portion is the part the clutch slave cylinder is mounted on) there is a small hole with a cotter pin in it. Take a good look. Is there any oil on the end of the cotter pin? If so, wipe it off and check it again after your next drive. More oil? A drop or so and you’re OK for now, but you have a symptom of the primary gear seal going bad. The next symptom will show up when the clutch gets a bit grabby or judders when you let the pedal out. Oil is mixing with the clutch dust and is forming a nice sticky paste. The final stage is when so much oil is getting past the seal that the clutch starts slipping. By or before the juddering stage it is time to have some clutch work done.
One last check. With the engine running, push the clutch pedal down. If you hear a whining noise that goes away when you let the pedal up, you have a clutch release/throw out bearing going bad.
- Any workshop manual.
- Calver’s Corner. See on this web site under Articles. Keith has written several clutch-related articles
- Clutch FAQ. See on this web site under Articles/How-to Articles/Clutch. Written by Marcel Chichak, this in-depth look at how clutches work and why they don’t work even though things look perfect is a must read.
- Clutch Works. See on this web site under Articles/How-to Articles/Clutch. This deals with wear and adjustment.
Useful Part Numbers:
Haynes Workshop Manual, 1959 – 1969 Minis 527
Haynes Workshop Manual, 1969 – 1996 Minis 646
Pedal bushing 2A3034
Pedal shaft 2A5880
Pedal pad, square GPR104
Pedal pad, 6-sided to 1990 GPR107
Clutch Master cylinder GMC1008
Clutch pedal to master cylinder clevis pin CLZ512
Slave cylinder hose 13H300
Slave cylinder hose, braided C-AJJ4025
Clutch slave cylinder, pre-verto 22A233
Slave cylinder return spring 1G5999
Slave cylinder return spring tab, cylinder end 2A3600
Slave cylinder return spring tab, arm end 2A3601
Clutch plunger stop nut 22A427
Clutch plunger lock nut NT610041
Clutch arm to slave cylinder rod 13H3655
Clutch arm 22A2204
Clutch plunger 22A180
Clutch release bearing GRB201
Clutch arm to slave cylinder rod clevis pin CLZ518
Clutch arm to clutch cover clevis pin CLZ628
Written by Chuck Heleker