You can see in the picture below the strake lines of the grease being centrifugally thrown outward and by extension on to the clutch disc friction area. I wont be using it any more becasue the clutch on my 928 where I first used it barely holds and the next and last OT project I used it on failed.

It's entirely possible I used too much but the Sachs grease is clear so it's hard to tell. From the strake lines of grease it easy to see that it succumbs to heat and doesn't stay in place. This clutch is from a long stroke Jaguar Inline 6 that barely wants to rev's above 5200 RPM. I'm going back to the alu or copper anti-seize that's drier and has served me well for the previous 20 years. It's easy to tell when you've got sufficient coverage from the color change.

Grease contamination is may explain why this clutch was fine initially but soon after wont hold 1800 RPM in 5th and perhaps why my 928 clutch is tenuous and doesn't hold any better then the worn out clutch and presure plate it replaced.

I've read the procedure here but I think this grease is better suited to projects with loose and lower spline counts.
Like it said it's just my thoughts on the subject. Clearly this product isn't right for me so that dry-ish bottle of Permatex Alu Antiseize is looking kind'a good to me right now.

 

You're supposed to use Optimol HT (superseded by Optimol Olistia Longtim 3EP). It's the only stuff that is thick enough to work in 928 clutches.

That Sachs stuff just doesn't cut it as you found out.

It has a Porsche number of 000-043-305-73 and can be bought at any dealership for ~$20 per tube.

 

Interesting thanks. This stuff?
It's listed / described as a Gold color paste. That sounds better and more like the dry-ish Alu / Copper Anti-seize I'm used to using. I think the gold color is the tell for coverage while the clear Sachs grease does you no favors.

I used the Sachs product becasue it was recommend by the clutch and P-plate retailer and It seemed a bit loose out of the tube but I incorrectly though it would dry or flash off. Clearly a mistake on my part.

Clutch Jobbers Take Note.

 

I assume the Sachs EP grease is different from the Porsche spec'ed stuff? (Castrol Optimol Olista Longtime 3 EP, # 08198-406, for use on the clutch splines and fingers? (000 043 024 00, superceded to 000 043 204 35, then to 000 043 305 73 - 'Scuse all the part numbers, went down the rabbit hole of all the supercessions)

 

You got to do whatever works for you!

 

The super sticky grease pictured below works great if used properly, which means applying it and then using a toothbrush to wipe as much of it out of the splines as possible, leaving just a thin residual film. The amount thrown centrifugally in your picture is enough to do 3 clutches.

You're correct though that if this stuff migrates onto the friction surface the clutch won't hold at all. Learned that the hard way as well and why I developed the toothbrush technique.

 

So I am interested to know what the difference is between the Porsche and the Sachs grease?
They are both sold under the same part number. One would also assume Sachs would know about clutches and their needs.
Most of the clutch component parts on our cars are Sachs OEM.

 

I'm fairly certain that they are the same, because of the same logic that you used.

 

I use both and do not see any difference between them.

Except the cost of having one in a cool looking black tube with a Porsche logo.

 

based on your picture you used too much grease and didnt use a toothbrush to smear it around the splines
this will remove excess grease.
then hand fit the discs and stub shaft to verify your results.

 

The Porsche / Sachs items may be one in the same. As far as I can tell its a product called Optimol Olista Longtime EP3 and well documented.


According to the product’s tech sheet (linked below) it’s a Lithium based grease with a “drop point” of 365F. That’s the point where it liquefies. That seems a bit low for a clutch environment because it certainly would start to flow and become affected by centrifugal forces well before it liquefied. I found multiple sources which suggests clutch operating temps can approach 300F or higher for multiple engagements. And the highest specified application temp for this product is just 284F

Here is the tech sheet. It’s described as a bearing grease, no mention of high temp resistance or clutch parts.
https://msdspds.castrol.com/bpglis/F...PXE-9RYGFN.pdf

Conversely Porsche Originally specified Optimoly HT which is a gold past. Also Suitable for High Temperatures. (HT) is in the name. This is very similar to common anti seize, both are graphite based. It’s good to 2000+ F and wont fling out.
Here is the tech sheet. https://msdspds.castroladvantage.com/bpglis/FusionPDS.nsf/Files/28B0515F1A93B9188025779600301729/$File/453855_XI_en.pdf

I think Porsche got it right early. And for high performance applications the OOL EP3 is not ideal in my view. Working with dealerships on the administrative side for years has shown me OEM's change products for many reasons. Politics, inventory simplification, administrative deals or work shop issues. Performance or suitability often isn’t the primary factor. I think that’s the case here. The two products aren’t even compatible. For the 928's life cycle The Optimoly HT was fine for the first 9 years until 1987 and OOL EP3 for 8 years 87 to 95 where manual transmissions were far and few between. In my view that advantages the Optimoly HT solution.

One possibility for the change was that Porsche wanted to eliminate all graphite based items from their shops and inventory. Why? Because graphite or moly lubes often would find their way inside the engine during services such as cam/lifter services, timing gears. Then the graphite would clog oil filters leading to low oil pressure, open bypasses, unfiltered oil and engine failures. The OOL EP3 is engine oil compatible and was also specified for camshafts. The Optimoly HT would quickly clog a filter if it found it's way inside an engine.

In my case I know I didn’t overload the splines. I most likely put a small blob in the pilot bush. That Blob may have liquified from temp and wicked back on the splines and then whipped off at some point after that. That’s indicative by the strakes, I’ve seen that pattern before on HD truck bearing where they heat up, then the grease liquefies and migrates past the cap and presents with the same pattern on those nice polished alu wheels.

Both the 928 clutch and the OT clutch will need a redo. I'm certainly going back to a HT paste on the splines and little or none on the bearing. Both the 928 and the OT project use roller pilot bearings so that should be fine.

 

I have always used copperlube anti-seize on input shaft splines

 

Same here. Thin layer. Worked fine

 

I'm making the case for the earlier Porsche specified product.

Supersessions are not always ideal or done with performance considerations in mind. Case in point is the Space Shuttle Columbia disaster. At some point NASA changed the propellant used for the foam, this created a different texture and required a higher level of precision when applying the foam. It's well understood that the propellant change was made for environmental considerations, performance and suitability was NOT the primary factor and it lead to dire consequences. NASA was not able to understand that the propellant change lead to small gaps in the foam where hydrogen collected and got trapped when it expanded from heat. When heated the hydrogen expanded, popping off the foam along with some heat shield tiles. That exposed the underside of the vehicle to reentry heat and certain disaster.

This kind of thinking often permeates organizations. I also recently had a client that switched their business software platform. Not becasue the new software is better, it's not buy a long way, it was cheaper and the support is worse. In this case performance also was not considered, cost alone was the primary factor. The consequences of that are yet to be known.

So, just becasue Porsche made a change doesn't mean its the right product for every scenario. They likely had other considerations factored, like reducing very expensive warranty claims from MOLY clogged oil filters. That's a good trade for a bit of clutch chatter which would likely cost them nothing. I wish I had looked closely at the tech sheet for this product before using it. I would have saw the upper limit of 284F and threw it in the bin. It's just expensive wheel bearing grease and has no business being anywhere near a high performance clutch. I was being lazy, following the herd. Big mistake.

 

You are desperately looking for something to blame.
When all you need to do is look in the mirror.

I've been working on 928's since the very first months of their existence.
And I've been the "first one there" on dozens (if not hundreds) of clutches, in these cars.
And I can absolutely 100% guarantee that not a single one had "gold" or "silver" colored lubricant on it.

There's been a bunch of people "hinting" at your issue.
Here's the blunt reality:
The issue is not the lubricant but the application of the lubricant!
Simplified even further:
The problem is you, not the grease!

Regardless of whatever lubricant you use, when it is greatly over-applied, centrifugal force is going to sling it out onto the clutch surfaces.

Put away the caulking gun full of grease and pay attention to what a dozen other people have told you.
Super thin layer of Sachs or the factory Optimoly (now Tribol) will stay there and do its job, until the car needs another clutch.

Done.
End of story.
Move onto the next rookie mistake.