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Discussion Starter #1
Swapping my original clutch pack for a full Sachs assembly sourced from IAP. The thrust bearing (machined piece on the back end where the fork engages) has significant slop as compared to the 90,000 mile one I just removed. However, if I push it forward firmly against the pressure plate, simulating depressing the clutch pedal, the slop disappears and it spins smoothly with little to no play. Everything is obviously new manufacture. Need I be concerned?
 

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Throwout bearing

H There

Okay you said.

"..... The thrust bearing ..." The word you want is throwout bearing. The thrust bearing is inside the engine, and is a simple piece of metal with no moving parts.


"....has significant slop as compared to the 90,000 mile one I just removed....." Hmm, not really following you here. Do you mean that the new throwout bearing makes noise ?

" However, if I push it forward firmly against the pressure plate, simulating depressing the clutch pedal, the slop disappears and it spins smoothly with little to no play." The Milano and GTV6 clutches are pull clutches which is the reverse of the usual practice. Most clutches like the clutch in the Alfa spider are push clutches.

Clutch - Wikipedia, the free encyclopedia

Push/pull

Friction-disc clutches generally are classified as push type or pull type depending on the location of the pressure plate fulcrum points. In a pull-type clutch, the action of pressing the pedal pulls the release bearing, pulling on the diaphragm spring and disengaging the vehicle drive. The opposite is true with a push type, the release bearing is pushed into the clutch disengaging the vehicle drive. In this instance, the release bearing can be known as a thrust bearing..

When you push the throwout bearing towards the pressure plate you are not " ... simulating depressing the clutch pedal...".
To simulate depressing the clutch pedal you need to have someone hold the body of the assembly and then pull the throwout bearing away from the pressure plate.

"..... Everything is obviously new manufacture. Need I be concerned?....." Well sometimes parts are defective out of the box, but SACHS is a highly reliable vendor and it's probably fine.

A lot this depends on whether you are doing this yourself, or paying somebody else, and what your tolerance is for taking the clutch back out if it doesn't work the first time and so on.

I'd encourage you to replace the clutch slave unit while you are down there. Be sure to inspect the clutch pivot ball for damage and cracks and lather it in grease. Also apply grease to the flat sides of the throwout bearing that are held by the clutch fork.

Let us know how it goes.

P.S. Don't throw away your old unit unit. They are, at least potentially, rebuild-able.

Bye for now
 

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Discussion Starter #3 (Edited)
Hi Milanoguy,

First, thanks for the reply.
I was using the factory shop manual term per the diagram in the Clutch section- Thrust Bearing. Let's go with TB so we're both correct :)

By significant slop, I meant with the two units (old and new) side by side on my bench, the old TB has little axial or radial play. The new one had a significant amount (comparatively).

I did not intend to refer to the drawn vs. pull diaphragm systems Alfa used, I was only referring to the action of the TB against the Pressure Plate (PP).

Yes I'm doing this myself.Clutch slave and hose are recently replaced.
 

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Discussion Starter #5
Thanks for the reply Richard. There's no spring present on the inside of the PP, on either the old or the new assembly; just a spacer and a retaining ring (circlip) is present on both. There is a Belleville spring present on the new assembly, it lies outside of the PP between the PP and the TB, just as the exploded diagram in the shop manual depicts. I did a test fit on the car, and once the new assembly is slid into place onto the transmission input shaft spline, the TB steadies up nicely and spins smoothly.
 

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Throw-out bearing, axial play

Hi Jim

Right TB it is.

I'm perplexed by your clutch issue. That you can move the TB around just seems wrong.

I've never touched a brand new clutch unit but all the used one's I've dealt with had the TB firmly fixed in place.

Have you contacted the vendor about this? Could they pull a few new units off the shelf and see if they have all have loosey goosey TB.

When the clutch is installed it will be centered by the input shaft so maybe it's okay?

Bye
 

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Discussion Starter #8
Yes I think so- the play made it easy to slide the assembly into place on the trans input shaft- I wonder if they figured out this way there's no need for an alignment tool when assembling the pressure plate body to the flywheel.
 

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Discussion Starter #9
Following up...

A message from Jake at IAP after a phone call with him last week:
"I checked a couple of clutch assemblies. Both of them showed about ¼” radial play; I’m pretty sure that this is to allow some self-centering on the transmission input shaft collar. If the throwout bearing were fixed to the pressure plate, it would have to be perfectly centered, and the input shaft of the transmission would have to be perfectly aligned to allow the components to fit properly. In a less than perfect world, having a bit of play in the bearing assures that the parts will fit together."
This makes sense to me. The shop manual depicts a centering tool for use during assembly of the clutch pack and the available play negates the need for such an alignment tool. I'm going to proceed with assembly and test drive. If all goes well, this is my last post to this thread.
 
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