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Old 05-19-2019, 12:52 PM   #1
tomasss
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Default Pressure plate fitment issue

Clutch rookie in the process of installing the upgraded pressure plate & 850GLT clutch onto the B204FT flywheel needs help.

All the parts I have are the ones recommended >here< (clutch 861862 314 032 and pressure plate 883082 999763, original lh2.4 flywheel).

Everything basically fits together, but I have a problem that when I put the clutch & pressure plate on the flywheel, the clutch gets tight between the pressure plate and the flywheel when the gap between the PP and flywheel is still around 5mm.

Is this expected? Do I need to tighten it down? To me it looks suspicious, because the original flywheel just popped out when I was removing it...but no extra preload was present...



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Last edited by tomasss; 05-19-2019 at 01:10 PM..
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Old 05-19-2019, 02:13 PM   #2
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It looks like the alignment pins are tight in the alignment holes for the pressure plate. If the pressure plate is for the dog dish it should snug up tight when you tighten up the bolts. I've had this problem. Just start tightening up the bolts a little bit each and the pressure plate should start to get closer to the flywheel, if not then you might have a problem and need to ream your alignment holes in the pressure plate.
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Old 05-19-2019, 03:24 PM   #3
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Issue with the alignment pins was the first thing that came to my mind. But no, that is not the problem. As I said, when the gap between the PP and the flywheel is still around 5mm, the clutch already has no front-back play.

I just made some more measurements and it seems I have a systematic problem here...

The step of the flywheel from the clutch surface to the PP surface is 24.5mm.
The clutch thickness is 7.8mm.
The PP step between the flywheel surface and clutch surface is 21mm.

That means the PP with the clutch already needs at least 21+7.8=28.8mm gap...but that is not the case with my flywheel.

I double checked the clutch and PP number and these are correct.

Do I have some wrong flywheel? Could anyone measure the depth of the lh2.4 flywheel?
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Old 05-19-2019, 04:47 PM   #4
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Pretty sure the step height is spec'd at 25.0mm.


https://forums.tbforums.com/showthread.php?t=348776


Easiest fix would be to put 0.5mm washers between pressure plate and flywheel for each of the bolts.

Weird how that is also your thread and you had it resurfaced and we told you the 25mm spec yet after it being done it's now at 24.5? Did you not tell them that was the spec?

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Old 05-19-2019, 04:54 PM   #5
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Quote:
Originally Posted by sbabbs View Post
Pretty sure the step height is spec'd at 25.0mm.
Ok. That means my flywheel is the correct one.
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Easiest fix would be to put 0.5mm washers between pressure plate and flywheel for each of the bolts.
But I am not missing 0.5mm. I am missing almost 5mm (see the numbers and pics above).
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Old 05-19-2019, 04:55 PM   #6
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Must be the difference in the performance pressure plate then. Just use 5mm of spacers washers then.
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Old 05-19-2019, 05:00 PM   #7
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Yeah, I am just wondering how it’s possible many people here used the same pressure plate and nobody ever mentioned any spacers. Also then I should probably use longer and maybe stronger studs...
What should be the gap available for the clutch travel? If the clutch is 7.8mm thick, should the gap for it be I don’t know, 1cm?
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Old 05-19-2019, 05:10 PM   #8
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I've never used that pressure plate so not sure about it. But what is actually stopping you from bolting the pressure plate all the way down to the surface of the step? What stops it? I can't see that part of the stoppage?

As far as pressure plate gap the fingers of the pressure plate when it's bolted down should be about level maybe up a little from the outer ring of the pressure plate. The pressure plate should be able to go further then where it sits when it's bolted all the way down cause you still have to push the clutch in and that raises the pressure plate even more off the flywheel towards the outer part of the fingers of the plate so something else is stopping the pressure plate from moving in and out. Find out what that is.

Each pressure plate as an area of ideal pressure on the clutch disc and as the plate moves in and out the pressure it can put on the disc changes. I've have to put a few washers under the pressure plate but I used a ceramic 6 puck disc that was thicker then stock and to make up the difference I put washers between pressure plate and flywheel.

Some machine shops can measure the ideal clamping force of pressure plates and where that corresponds to the different positions of the pressure plate as it is pushed in and out.

Do you have your old pressure plate? Compare the two see if you can find what is the problem that way.

Without the clutch disc in there does the pressure plate fit on the flywheel all the way?? Try that.

Hopefully someone who has used that pressure plate before will post.


As for your measurements of the pressure plate, the pressure plate the plate moves so if your measuring it with it all the way out and then saying it's too high, your forgetting as you bolt the plate down to the flywheel it moves the plate back. Maybe it being a higher pressure plate it just takes a bunch more force to move the plate. CAn you move it at all? CAn you move the stock old pressure plate at all by hand or some force besides bolting it all the way into the flywheel and using a hydraulic system to move it?

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Old 05-20-2019, 02:57 PM   #9
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The pressure plate should measure roughly 20 (give or take 1mm) from the face to the flange that bolts to the crank. You say yours is 21mm so that sounds about right. The 3-4mm that you are squashing down is applying the clamping force that holds the disk. If the friction plate was only lightly pinched it would have no hope of clamping and would just slip
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Old 05-20-2019, 03:44 PM   #10
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As I said...clutch rookie coming from the Aisin world.

After watching several youtube videos to understand how the pressure plate actually works, I figured out that the gap that I see is caused by the preloaded metal spring tabs that create the clamping force. And indeed if there would be no gap, there would be no clamping force and the clutch would just slip.

So ...I have tightened the PP all the way down, and the metal tabs went more inside the outer ring of the PP as expected.

So now I just want to double check. The distance between the fingers and the outer ring of the PP is 5.5mm as depicted. Is that OK or should I add any spacer to make it more closer?

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Old 05-20-2019, 04:40 PM   #11
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As I saw other people mentioning adding the washers with various transmission conversions, this actually brings another question: how do I check if the throw out bearing is touching the metal pads as it is supposed to? Is that just using the air gap measurement as shown here? https://www.youtube.com/watch?v=MbALZWJCGJs
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Old 05-20-2019, 05:06 PM   #12
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That looks good the angle of the fingers with it bolted all the way down. As far as the throw out bearing touching the metal pads. It touches the metal pads all the time usually, that part that touches spins with the spinning flywheel pressure plate. It should all work correctly didn't you just replace worn out stuff with new stuff?
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Old 05-20-2019, 05:27 PM   #13
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Not really.
The oem clutch and PP has been replaced by 850GLT clutch and performance PP.
Also M46 replaced by M90.
So there are quite some changes that could cause some misalignment...
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Old 05-20-2019, 09:06 PM   #14
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Did you put the clutch disc on the right way?
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Old 05-20-2019, 10:28 PM   #15
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Okay yeah if putting in m90 with dog dish your supposed to move the pivot ball out more with a few washers behind it. That is about it.
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Old 05-21-2019, 02:31 AM   #16
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Quote:
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Did you put the clutch disc on the right way?
Yes, I triple checked that
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Okay yeah if putting in m90 with dog dish your supposed to move the pivot ball out more with a few washers behind it. That is about it.
Ok, you mean put washers behind this thing? How do I know how many shims is enough? Just watch the operation through the clutch fork opening?


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Old 05-21-2019, 07:24 AM   #17
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4-5mm thickness you want
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