DIY: Corolla Clutch Master and Slave Cylinder Repair
I just did a master and slave cylinder replacement for the clutch this weekend. And figure I'd write down some of the ins and outs while I still remember.
I do not outline the bench bleeding for the master cylinder.
Follow the instructions that come with your master cylinder.
You need the two parts of course:
You may want to get some fuel line (for the bleeding process) if you don't have some already.
I took the new slave cylinder to the fuel line area of the auto part store, and test fitted different diameters until I found a snug fit. I don't recall the diameter at the moment. 1 foot will do I guess, I got 2 feet.
12mm shallow socket.
12mm deep socket.
1/4" ratchet. (Maybe a 3/8th but the tightness of the space(s) yearns for a 1/4" ratchet).
Small wrench for the bleeding screw. (Size?? I don't recall, maybe 5/16th).
Pliers for the cotter pin.
The master cylinder.
On mine, there were 2 nuts holding on the master cylinder.
These were removed from under the dash. :< I hate working under the dash.
The nuts were 12mm.
I used the 12mm shallow socket for the lower-right nut and a 12mm deep well socket for the upper-left nut, a small extension, and a 1/4 inch ratchet.
I got the lower right nut off with the clutch pedal in the "up" position. I got the upper left nut off with a stick holding the clutch pedal in the "down" position. Your mileage may vary.
There was a 12mm nut and a cotter pin holding the clutch to the master cylinder. The 12mm nut here is what allows adjustment on how long/short the master cylinder rod is. This was fairly easy (compared to everything else).
So remove the 12mm nuts on the 2 bolts on the master cylinder.
Loose the 12mm nut on the rod. Remove the cotter pin.
So the new nuts should be removed, and the rod-to-clutch-pedal-adapter thing should be unattached.
Back under the hood.
The master cylinder has a flare nut attached to it...and this connects the tube(s) that (eventually) runs to the slave cylinder.
The way I get flare nuts off is like this:
Do NOT start with (the correct size) open end wrench. Most likely you WILL strip the nut. Maybe not, but my experience is that you will.
I use vice grips, and I put the flat portion of vice grips (the very tips of the vice grip usually) and I adjust the vice grips so that I can barely (and with ALL my strength) can get the vice grips closed and engaged. The vice grips cannot be kinda tight, they gotta be super tight. Usually then, I can then break loose the flare nut.
The issue with the corolla is the TIGHT space between the strut tower and the master cylinder.
But I was able to get some vice grips in there (at a slight angle) and break the nut loose. I think it was a 10mm open end wrench to finish the loosening.
Now on my year, the brake BOOSTER blocks the clutch master cylinder removal.
Fortunately, you only have to move the booster a few inches.
Remove the 4 nuts (under the dash) on the brake booster.
With those removed, you can move the booster a few inches forward and slide the master cylinder out. It's pretty tight.
PAY ATTENTION to the angle that you are able to remove the master cylinder, as you'll have to follow this path backwards.
You do NOT need to remove the nuts from the (brake) master cylinder to the brake booster.
Now put your attention on the slave cylinder.
This is alot easier than the master.
Look at your new part, and while there are 3 bolts in that area, I only had to remove 2 of them.
BUT BEFORE you remove the 2 bolts, you should break loose the flare nut on the slave cylinder. I (again) used the vice grip method.
Break loose the flare nut, use the 10mm wrench to remove the flare nut all the way. Then remove the 2 bolts holding the slave cylinder to the engine block.
Assemble the slave cylinder (the rubber boot and the rod). My slave cylinder rod had a notch in it. The notch goes farther away from the slave cylinder. Most likely, you can ascertain the notch location from the old one.
One hint, I usually start the flare nut screw-in BEFORE I reattach it to the engine block. This way, you can do it by hand and avoid an accidental cross thread. Get the flare nut screwed-in 3-4 turns.
Then reattach the slave cylinder to the block.
The master cylinder.
You need to (temporarily) remove the (new) master-cylinder-rod--to--clutch pedal adapter piece.
Pull out the brake booster a few inches and wiggle in the new master cylinder.
Again, pick a time in the process that you can hand tighten the flare nut on the new master cylinder, although this is a little harder because of the brake booster making a tight fit.
After the master cylinder is reinserted, you get back under the dash and get the nuts back on the master cylinder screws. Not too hard, but one of those tight spot frustration things.
Screw on the rod-to-clutch adapter piece (the piece that the big pin goes through). You do not want to tighten the 12mm adjusting nut at this time.
Just get it reattached and do final adjustments (of the rod length) at the end.
Re attach the brake booster nuts as well.
Check point reminders:
Make sure both flare nuts are tightened, in case you only half hand tightened them before.
So right now, you should have the new parts installed, but with no fluid in the system.
There are a couple of ways to bleed the system.
One NOTE, my instructions (that came with the slave cylinder) said to NOT bench bleed the SLAVE cylinder.
Yours may vary, but I figured I'd mention it.
But this makes sense. With the braking system, you only bench bleed the master cylinder, not the brake calipers.
And the clutch-slave-cylinder is kinda the equivalent of the brake calipers when comparing the two systems.
My bleeding system is listed below.
It is one of a few ways to bleed a system.
Pick another method if you know of one, but here is my method below.
My bleeding system...I call it the wife system, or the i-got-a-friend-for-a-little-bit-of-time system.
Basically, there is someone sitting in the car who pushes the pedal on voice instruction, and you do everything else.
Fill the master cylinder with new fluid.
First, I remove the bleeding screw completely.
While you have it out, look for the super small hole in the bleeding screw.
It'll be important later.
Now with the bleeding screw removed:
I get the person in the car... to pump the pedal.
You should see fluid coming through the lines at this time.
I like to get the old fluid out of the system.
It'll make a mess. Make sure you're prepared for the mess.
Make SUPER SURE you keep the master cylinder topped off. It can get down to 1/3 full, you don't have to be anal about it, but do not let it get too low.
This is why the person in the car should be pedal pushing at a smooth, consistent rate, and not too fast, or the reservoir could get too low.
If the master cylinder gets too empty, you'll put air back into the system.
NOW, THIS IS IMPORTANT.
Put the bleeding screw back into the slave cylinder.
The bleeding screw on the slave cylinder has to be at a certain position (rotation wise) for the fluid to run. That super small hole has to be lined up correctly.
Only by getting the person-in-the-car to push the pedal can you find the "sweet spot" on the bleeding screw. Tighten the screw completely (not too tight right now), then back it OUT to find the sweet-spot for the bleeding.
Get an aluminum can or other old container, and fill it up 1/3 of the way with clean new fluid.
Put one end of the fuel line on the bleeding screw and one end (submerged) in the aluminum can.
The motivation here is that....when the person in the car pushes the pedal, it pushes fluid through. When the pedal is returning to the "up" position, it will draw something back into the system.
Without that fuel line submerged in the aluminum can (and in some fluid), it would draw air back in.
With the fuel line, submerged in fluid (in the can)..it will draw back fluid.
That of course is the key to getting all the air out.
Now you gotta do a couple of things at the same time.
Have new fluid ready to pour into the master cylinder.
Be ready with a small wrench to close the slave cylinder bleeding screw.
Have the person in the car pump the pedal. Not crazy fast. Just smooth and consistent. You should start to see the fluid in the master cylinder go down with each pump. If you don't, your bleeding screw probably has moved a little and you've lost the "sweet spot" for bleeding.
I usually over-do the new fluid....but I like to make sure all the old fluid is out ... since its only about $1 worth of fluid. Don't call the green-police on me!
But usually by the time the aluminum can is (almost) full, the system is bled well.
I try to "time" the final tightening of the bleeder screw with a down stroke by the person in the car pushing the pedal.
So close the bleeding screw (warn the person in the car that the clutch will get difficult to push right before you tighten the bleeding screw). Re-top-off the master cylinder again with fluid.
Test the operation of the clutch.
You can watch the slave cylinder rod move back and forth (of course).
Once you have it working, adjust (by screwing or unscrewing) that rod-to-clutch-pedal-adapter thing back under the dash.
It's too hard to describe the "feel". You just adjust it so that it feels right and works right. << Sorry that all I got on the adjustment process.
I think that is it.
Working under the dash is frustrating (as always).
The "upper left" nut of the master cylinder bolts is the most difficult.
When this "upper left" nut is almost off, be careful not to drop it (so that it might accidentally fall (into a difficult place to retrieve it).
Having to loosen the brake booster (my year at least) was another frustrating point. An inch here or there would have made this unnecessary, but hey, I'm not an engineer, just a dude trying to get his car back on the road.
Be careful on the flare nuts to avoid cross threading. TAKE YOUR TIME here, cross threading will RUIN your day.
Try to hand tighten each flare nut before you get the cylinder(s) tightened down all the way.
I had some big frustration getting the master cylinder flare nut started.
I tried using a screwdriver and wrench, but ended up getting it started by hand. It's just super tight in there.
There is a soft line that runs from the car body to the engine.
(Much like there is a soft line that goes from the body of the car to the brake calipers of the brake system).
I did not replace this myself. But it eventually could be a maintenance item.
It's kinda behind the block and does not look fun to replace.
I found some clues here and there at this forum, so I wanted to consolidate my experience to help anyone else.
A buddy did help me and made it alot easier.
You can do it by yourself (minus the bleeding).
It took me 4.5-5 hours (like most things, the first time takes the longest).
This included an extra trip to the auto part store, because I couldn't find my existing fuel line pieces that I've used for brake bleeding in the past. :<
(And this was with some friend help).
I think I could do it in 2.5 hours (solo) if I had to do it again.
Hope it helps!!
Last edited by granadaCoder; 01-03-2011 at 07:34 AM.