HOWTO: Clutch pedal adjustment

[Test_Drive]

OK guys,
I've finally gotten around to adjusting my clutch pedal. What I wanted to fix with this adjustment was:

- I thought that the pedal was too high off the floor when the clutch engaged. Too many "accidental" 2500 rpm launches, when I wasn't intending to.
- I thought that the clutch pedal was too high, period. I would like the clutch pedal to be roughly the same height as the brake pedal.
- I wanted to shorten the pedal throw.

Apologies on the length -- this is actually a pretty simple adjustment. This writeup is long because I am trying to be clear, even to somebody who has never worked on a car before. Experts, feel free to send me any corrections.



Q: What happens when I make this adjustment?
A: I personally found that the uneasy-unnerving clutch engagement was improved, but YMMV. Clutch engages much closer to the floor, and pedal height is lowered. I also found that clutch pedal effort seems to be slightly lighter than before.

Q: v6 or i4?
My car is a v6, but it should be similar for an i4.

Q: Warranty issues?
A: Possibly. If you have or think you'll have issues with your clutch and/or tranny, you probably shouldn't do this until all of those are resolved. If you wreck your car, it's not my fault. Suck it up!

Q: Anything else come to mind?
A: You are worried about 2 things, when making a clutch pedal adjustment. That you can fully disengage the clutch in all conditions, and that you are not putting any pressure on the master cylinder when the pedal is at the top. Otherwise, your have a lot of freedom to play.

Q: +25hp?
A: Yes, but only if you PayPal me $50.

Q: This adjustment sucks, and your writeup sucks. What else can I do?
A1: Live with it, punk!

A2: Try to convince your Mazda dealer to adjust the clutch pedal for you. Complain about funny shifting, or whatever else you think will get them to do it for you. You're more likely to have success if you are less than 20,000 kms and newer than 1 year, during the adjustment period of the warranty. That is, if you didn't want to have to pay for it (you cheap bastard).

A3: Try a clutch stop -- this will lessen the amount of pedal travel you have to deal with. You can use just about anything for a clutch stop, as long as it won't move and/or come loose. Whatever you use, make sure it won't come loose! I used floor felt pad thingies, until I got sick of that and did this pedal adjustment instead.
<see photo A, floor felt thingies>
<see photo B, ghetto clutch stop>




Materials: 12mm wrench, 1/2" wrench, ruler, wheel chocks, floor felt thingies (from now on, known as "FFT" in this writeup). A trouble lamp or flashlight would probably be good. Everything is in metric, you might want to do some conversions before getting started.

Time required: 15-30 minutes to do adjustment, 45 minutes to test drive the car afterwards. Or, maybe 1+ hour to test drive if traffic is light and the local curvy road is clear.




Step 1) First, check to see if you have a manual tranny in your car. Three pedals, not two! BTW, this would also be a good time to check your brake fluid (clutch uses the brake resovoir).


Step 2) Optional step. Make some measurements, in case you poop it up and need to return to factory settings.
Step 2a) Pedal height. Make sure to measure this from the same spot and in a consistent manner. My pedal was about 145mm off the floor, from the top of the pedal.
Step 2b) Freeplay in clutch pedal. Mine was.... 0mm. (WTF? Nice work, you bums! ) Freeplay is how "loose" the pedal is. Get down there for a look, and press the clutch pedal with your hands. You'll notice that in the first few mm (less than 1/4 inch) of pedal travel, the pedal's resistance is very light. It should suddenly increase at a certain point ... that "loose" part is the freeplay.

NOTE: If you continue to push the pedal further down, you should feel a "wobble" somewhere in the pedal travel. That would be the clutch disengaging and the springs in the pressure plate that you are feeling.
<see photo C, ruler measuring pedal height>


Step 3) Measure the clutch engagement point (strictly speaking, this step is also optional...). This is the height of the clutch pedal, when the clutch begins to engage. In the Euro service manual, you are supposed to try various clutch pedal heights while shifting into reverse. If it shifts, you are good. If it grinds or resists going into gear, then you are still partially engaged. Obviously, making this measurement sucks.

What I did was:
- parking brake and wheel chocks (if you drive through your garage door, we want pictures!)
- start the car first (if you do what I did, you'll be interfering with the starter switch)
- use a FFT for a clutch stop (remember photo A?)
- try to shift into reverse
- if it shifts in smoothly, add another FFT and try again (and again....)
- if it resists, then you are at the approximate height of the engage point
- measure that stack of FFTs, that's the (approximate) number you want

In my case, the clutch engagement point was 9 FFTs/50mm (almost 2 inches) off the floor. Waaaay too high. Euro spec manual states that it is a minimum of 20mm (less than 1 inch). I would target 25mm myself -- this gives you some room for error. OK, some quick math here. I want a clutch engagement point of 25mm, and it is currently 50mm. That means I want to lower everything by 25mm... so my 145mm pedal height should become 120mm. Fudge factor time: this "FFT" method of measuring the engage point is not very accurate. When I finished everything up, my pedal height was about 128-130mm.... Don't let the numbers discourage you though -- it made enough of a difference in my car that I readjusted my seat position.

Clear as mud?


Step 4) Loosen locking nut on master cylinder pushrod with a 12mm wrench. Turn the pushrod to adjust, and retighten locking nut. Make sure you have removed the FFTs/clutch stop before starting this step. Remember to tighten locking nut up when you are done. If you are lowering the pedal like I was, then you should now have a HUGE amount of freeplay, much more than before -- if you have "zero" freeplay, then you are raising the engagement point. You can check with your hands, while you are down there.
<see photo D, pushrod, locking nut, clip>


Step 5) Now you want to adjust the pedal height, and take up some of that freeplay. There's a big gold bolt, which is used to adjust the clutch pedal height. Loosen locking nut with 12mm wrench, and adjust the big gold bolt with a 1/2" wrench. You want to LOWER (or raise, if you went that way) the pedal height, until you get to 1.0 - 3.0mm of freeplay (from Euro specs).

CAUTION: not enough freeplay will put stress on your pressure plate, throwout bearing, shift forks and you won't get 100% clutch engagement. Too much freeplay will make the pedal feel sloppy, and will probably annoy you. It won't however, damage anything (unless it causes you to blow a shift -- yeah, that's what caused it). So that means if you are going to run out-of-spec, try to do it on the side of too MUCH freeplay. Tighten locking nut when you are finished.

Measure the clutch pedal height, it should now be something close to your target height (calculated in step 3). Repeat from steps 4 and 5 if necessary.... and remember that all of these measurements are only approximate. Don't sweat the small stuff, unless you find a problem in your test drives.
<see photo E, clutch stop nut>


Step 6) Try driving the car a short distance.... and repeat steps 4 and 5 if necessary. Before you drive off, remove the wheel chocks. You are testing the clutch engagement point, so try starting from a dead stop, and sloooowly letting the clutch pedal up. From the Euro spec service manual, engagement point should be at least 20mm off the floor. If you aren't sure, then it's time to make another stack of FFTs to measure this (just like in step 3). CAUTION: make sure that the engagement point isn't too close to the floor. Remember that the driveline moves around, and you'll want to make sure you have some room for error during spirited driving... otherwise it's going to get a bit crunchy.

Speaking of which, drive with a little more spirit now. Make sure there isn't any excessive grinding or shifting issues.


Step 7) Final tests:
- Make sure that you haven't lowered the clutch pedal so much that the cruise control kill switch is being thrown. Test by: hitting the freeway and using cruise control. Try your CC, it should work like before. Press the clutch pedal down, and cruise should shut off. If it doesn't behave like this, then you'll have to make adjustments. Remember this moment, in case your CC starts acting funny 2 months from now...

- If you decide to have a clutch stop at the bottom end to further limit pedal travel, make sure that it isn't so high that it intereferes with the clutch/starter kill switch. Test by: starting your car. If the car starts, you pass. Try cranking the engine over, without pressing the clutch pedal down and in neutral. In NEUTRAL!! Nothing should happen. Again, if you find that your car mysteriously doesn't want to turn over 2 months from now, remember this moment.

- Last check: make sure that your adjustments haven't put constant pressure on the master cylinder. A simple way to do this, is make sure you have some freeplay in the pedal. If you are paranoid like me, you'll also crawl underneath the dash one more time and look again. Side benefit is, all this under-the-dash gets you ready for yoga classes.

- Drive the car around for a bit. Drive it hard. Drive it slow, in a parking lot. Look for a hill, and see about trying to start moving the car, going uphill, from a dead stop. See how you like it, and remember that things are going to feel different than what it was before.

Whatever you end up with, you'll have to make sure that you have:
= no pressure on master cylinder when clutch pedal at the top (VERY IMPORTANT!)
= no problems with start kill switch
= no problems with cruise control cutout switch
= no problems with the clutch not fully disengaging (grinding, balky shifter, etc)
= I'd recommend sticking with the minimum 20mm engagement point as a start -- fine tune to your liking later
= remember that your clutch pedal height will now be different than factory spec. At the moment, I see no reason to be worried about this provided all the other conditions are met...

8) Specs (from Euro service manual)
- pedal free play is 1.0 - 3.0 mm, measured at the pedal
- pedal height for L.H.D. cars is 210mm - 216mm (i.e.: distance at top of stroke, not sure how they measure to get this number... mine measured 145mm from factory)
- pedal stroke is nominally 140.0mm
- pedal disengagement stroke is a minimum of 20mm (i.e.: how high off the floor before clutch begins to engage).

The locking nut on the master cylinder pushrod is supposed to be torqued down to 105-148 in-lbs. The clutch stop nut (the gold one) is 87-130 in-lbs.

NOTE: everything quoted here is using Euro specs. If somebody wants to throw in the N.A. specs, that would be faaaaaantastic.


Lastly, please let me know if you find problems or mistakes, or have a better way to do this. If you think that this adjustment can cause problems don't keep it to yourself, spit it out!

Enjoy!
Test_Drive

[Test_Drive]

Photo A.
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Photo B.
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[Test_Drive]

Photo C.
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Photo D.
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Photo E.
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[GreenNuggs]

Exceptional writeup and certainly worth a sticky!

[Indy MPS6]

I haven't read this all yet but it looks good. I am going to pin this topic and allow limited responses to the How-To. Off topic posts will be deleted.

[got_rice64]

did anyone with a i4 do it yet? im having mad troubles.. i can't get the kill switch in all the way.. so my car can't start unless i hold down the kill switch myself...

if n e one with an i4 has done this w/o problems, please tell me how u did it...

[t_mo_t]

Hey.. nice write up, but can you show the pics below of every steps you have? it makes it easier...

[JTZako]

I made this adjustment today and so far so good..

I have much less movement from all the way to the floor to the point where it starts to grip.. and at the top end very little push before it starts to release..

Now, is there any way to find out if my adjustments are putting pressure on something they shouldnt? And whether or not the gear is actually engaging all the way?? Feels fine when driving but I dont want to mess it up lol.

[Test_Drive]

Make sure your switches are working (particularily the cruise control switch). Go on the freeway, and set cruise. Press clutch down, and the CC should cut out. If not, bust out the wrenches again.

Otherwise, if you have pedal freeplay then you are OK. You can feel it with your foot, but using your hands is probably easier. Get down there and press the clutch pedal with your hands .... that first 1/4" or so of low resistance is freeplay. As you continue to push the pedal down, you'll feel higher resistance. You MUST have some freeplay, otherwise the system is always pressing down on the clutch.

I've got a couple millimeters freeplay (around 1/8"). Whatever, just make sure you've got at least some freeplay and you'll be OK. (don't drive around resting your foot on the clutch pedal -- if you do, then you'll probably want to increase the amount of freeplay you have).

If you aren't sure what freeplay is, just adjust that big gold bolt so that the pedal moves up and away from the floor. Then press with your hands -- you'll feel it. Then adjust the pedal back down, close to (but NOT beyond) that point where the higher resistance begins to show up.

....anyways, good luck!
Test_Drive

[broken08]

[attachmentid=12035]i replied to someone who asked how to do this without noticing this pin, yea, i'm dumb. i made a fancy drawing so i figured i may as well share. And i dunno about the adjustment taking so long, it took me like 15 minutes. no need to measure and such, just make sure your clutch fully engages and releases at the ends of its travel, make sure there is some freeplay top and bottom. best free mod ever!