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Discussion Starter · #1 ·
Hi All, over winter I've refitted my rebuilt C64 and put a new competition clutch in with matched lightweight flywheel.

It's the first clutch I've ever done, so not experienced by a long shot. I was given advice to not use the bearing supplied as it may end up chattering after a few miles and instead to buy a new OEM toyota one, which I did. This is my lead theory for why the clutch now won't disengage.

I've done a full suspension refurb too, so it's taken a while since refitting the box before I can test fire the car. It starts up fine, but as soon as I try putting it in gear even with the clutch fully depressed it will try to spin the rear axle. If I lock them (handbrake + foot brake) the car will stall with the clutch fully down.

I've bled the clutch and brake circuits, and I can see that the pushrod from the slave cylinder is actuating nicely. This is the 'full reach' as far as I can tell.



I'm coming to the realisation that my box is going to have to come off again, no major hardship because the rear clam is off and the car still on the ramp etc - but I could really do without it as I'm sure you can imagine! Even if I do take the box off, it would be nice to have a list of things to check, and make sure that I don't make the same mistake again.

My theory on the release bearing is that the OEM one is maybe marginally shallower than the one supplied by CC - and as such is not applying correct pressure on the pressure plate fingers. I've seen that aftermarket extended pushrods are available for the slave cylinder which may overcome this mistake... is this something anyone can recommend or warn against?

I'm fairly sure the friction plate is on the right way around, despite not being labelled. I've got this side facing the engine/flywheel:


...and this side facing the gearbox/pressure plate:


Appreciate advice.
 

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First, do you feel any resistance as you push in on the clutch pedal? If so, does it start near the top of the pedal or not?

Second, does the clutch pedal resistance change as you push the pedal to the floor? At some point, since it is a diaphragm clutch, it should get easier because this is the "Clutch Point".

Third, I have used the longer rod to help move the Clutch Point closer to the top of the pedal.

Later,
Eldon
 

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Discussion Starter · #3 ·
Thanks eldonz, clutch pedal feels very "normal"

I've just this minute managed to get some footage via my endoscope and from what I can tell the fork/bearing are both doing their part but it's hard/impossible to tell if there's any clutch movement at all.

I'll go check to see if there are any better vantage points elsewhere on the box.

.

If the pressure plate is being "activated" but the friction plate isn't moving... What are the potential causes? Splines were all cleaned and lightly greased.
 

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You say the clutch feel is "Normal" but do you feel a point where the pedal pressure gets less?

Later,
Eldon
 

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Do you have stans clutch mod bolt? My car needed more petal travel to fully disengage after replacing the clutch. My guess is that the increased clutch thickness moves the bite point lower in the petal travel that I was unable to reach because of the clutch mod.

BTW the clutch orientation looks correct to me from your images.
 

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@Fonzey ,
The fact that you put the new clutch in and then left it for a while , points towards the new disc being stuck to the fly wheel or clutch cover .... this is not un heard of .. Most new fly wheels and pressure covers have a protective film on them to prevent corrosion prior to fitting .. This is not visible but will need removing with a solvent before fitting .. This is normally mentioned on a piece of paper with in the box but not always ..If not removed it acts as a glue . You have probably done everything correct and it has just stuck .. They can be snapped free with a jolt but it will depend how well its stuck ... Try putting in gear and pressing the clutch down then rocking the car back an forward quite aggressively .. This may just break it free.. There are other less orthodox methods but try the rocking first . If you can get an access to the plate through a timing hole , you can try an gently free it . Failing that disassemble clean and refit .. once it is released it will be fine ..
 

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Discussion Starter · #7 ·
You say the clutch feel is "Normal" but do you feel a point where the pedal pressure gets less?

Later,
Eldon
Yep, there's the tiny bit of slop/play, then there's the major piece of resistance then it gently "loosens" off towards the end of travel.


Do you have stans clutch mod bolt? My car needed more petal travel to fully disengage after replacing the clutch. My guess is that the increased clutch thickness moves the bite point lower in the petal travel that I was unable to reach because of the clutch mod.

BTW the clutch orientation looks correct to me from your images.
No I haven't done the mod, but I have read up on it. Thanks for confirming the orientation!

@Fonzey ,
The fact that you put the new clutch in and then left it for a while , points towards the new disc being stuck to the fly wheel or clutch cover .... this is not un heard of .. Most new fly wheels and pressure covers have a protective film on them to prevent corrosion prior to fitting .. This is not visible but will need removing with a solvent before fitting .. This is normally mentioned on a piece of paper with in the box but not always ..If not removed it acts as a glue . You have probably done everything correct and it has just stuck .. They can be snapped free with a jolt but it will depend how well its stuck ... Try putting in gear and pressing the clutch down then rocking the car back an forward quite aggressively .. This may just break it free.. There are other less orthodox methods but try the rocking first . If you can get an access to the plate through a timing hole , you can try an gently free it . Failing that disassemble clean and refit .. once it is released it will be fine ..
Thanks for this, I did clean off the flywheel/pressure plate with brake cleaner but perhaps I wasn't thorough enough so I can't rule it out. I've tried to "force" it a few times now by applying the handbrake and foot brake, then putting it into gear. The car stalls, perhaps some persistence with this might break it free. Tomorrow I may leave the car idling for a while to fully bring up to temperature and then try again. I'm only a pair of track rod ends away from being able to drop the car to its wheels, so later in the week I'll do that, pull it outside and try some manoeuvres!
 

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By the way, how easily did the transmission mate back up with the motor? Did it slide all the way back together or did you have to draw it up with the bolts?

Later,
Eldon
 

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Discussion Starter · #9 ·
Good question, the clutch alignment is something I was nervous about at time of fitting because my "eyeball test" disagreed with the alignment tool and I adjusted it slightly... but the box went straight on like silk, my neighbour was helping it lift it in place and we both looked at each other in shock when it just popped on, and we were able to slide it onto the dowels and flush with the flanges without putting a bolt in.

That said, at one point whilst adjusting our grip we did let the clutch take the weight (or at least some of the weight) if the gearbox as it rotated around on us a bit... but this didn't seem to hurt the alignment.
 

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It is not uncommon to have the input shaft ride on the clutch diaphragm for a brief period while trying to mate the two. Since it went together without any force then at least we know that the input shaft is not forcing the clutch disk into the flywheel.

You could try rocking the car while it is in gear and clutch depressed to see if the surfaces are stuck together but I don't give you much hope. You can order the long rod from MWR and see if a little more throw will help. It really sounds like an assembly problem with the diaphragm. I've had diaphragm fail around the mounting tabs which allowed the diaphragm to not fully disengage.

If it was me, I would first try rocking the car then installing the longer push rod. If that didn't fix it, I would disassemble and inspect the diaphragm very closely.

Good luck,
Eldon
 

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Discussion Starter · #11 ·
It is not uncommon to have the input shaft ride on the clutch diaphragm for a brief period while trying to mate the two. Since it went together without any force then at least we know that the input shaft is not forcing the clutch disk into the flywheel.

You could try rocking the car while it is in gear and clutch depressed to see if the surfaces are stuck together but I don't give you much hope. You can order the long rod from MWR and see if a little more throw will help. It really sounds like an assembly problem with the diaphragm. I've had diaphragm fail around the mounting tabs which allowed the diaphragm to not fully disengage.

If it was me, I would first try rocking the car then installing the longer push rod. If that didn't fix it, I would disassemble and inspect the diaphragm very closely.

Good luck,
Eldon
Thanks for all your help, that's pretty much my plan now. My front suspension misses just track rod ends and they'll be fitted tomorrow so I plan to get the car off the ramp, onto the street and just try a few things to try and shock any sort of chemical bond I might have between the friction plate and the flywheel.

I'm trying to track down a slave pushrod in the UK, it seems all vendors are US based and in the time it would take to get one I could just take the box out a few times! But if I can source one locally, I'll try it before committing to the teardown.

I guess I should order some pressure plate bolts and gearbox oil, again!

Oh and if anyone reading this happens to have a toyota OEM release bearing lying around, please feel free to measure the depth of it so I can compare with my competition clutch one :)
 

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I have a Lotus OEM bearing with fork. What measurements do you want?

Sorry, I also did not see that you were in the UK.

Later,
Eldon
 

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Discussion Starter · #13 ·
I have a Lotus OEM bearing with fork. What measurements do you want?

Sorry, I also did not see that you were in the UK.

Later,
Eldon
Ah that could help, would you mind measuring the depth of it? I can compare with the depth of my competition Clutch one to see if that's where I went wrong.
 

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I just measured mine, here you go.
1280479
1280480
 

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The first measurement is 22.18 and the second is 19.2

So, I would say that they are the same.

Later,
Eldon
 

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The first measurement is 22.18 and the second is 19.2

So, I would say that they are the same.

Later,
Eldon

He's holding the calipers crooked, that's why :)
 

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Discussion Starter · #18 ·
Excellent thank you. That at least suggests that using the OE bearing is not the root cause.
 

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I would not be surprised if the clutch is locked on the splines from new. Seems like most clutch manufacturers are in a race to the bottom of quality control. I've had them lock on the shaft before. I have also had the hub wall out on brand new dual clutch "sorry we had some that didnt get heat treated, send it to us if you want us to look at it"
 

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Discussion Starter · #20 ·
I would not be surprised if the clutch is locked on the splines from new. Seems like most clutch manufacturers are in a race to the bottom of quality control. I've had them lock on the shaft before. I have also had the hub wall out on brand new dual clutch "sorry we had some that didnt get heat treated, send it to us if you want us to look at it"
Thanks for the reply. What could cause the plate to get stuck? Poor machining on the female splines?

One of my fears with this is that I drop the box and the input shaft comes free under the weight of the box and I'm left with zero evidence of what was causing the problem! Then it's just a case of what next? Put it back together and hope for the best?!
 
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