cam sprocket replace?
I would bet that overtightened belts and dry tensioners are more of a factor here than overall miles. But luckily most of us will only have to change them once. Unfortunately it adds a bunch of $$$ to the TB service, but better than a shredded TB from sharp worn gears..........
Jim
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I don't think recoating is a viable option unless the gears are 100% flat and true. The cupping of the teeth will just lead to early wear. These gears are just another wear item, and these cars are getting old.........
I would bet that overtightened belts and dry tensioners are more of a factor here than overall miles. But luckily most of us will only have to change them once. Unfortunately it adds a bunch of $$$ to the TB service, but better than a shredded TB from sharp worn gears..........
Jim
I would bet that overtightened belts and dry tensioners are more of a factor here than overall miles. But luckily most of us will only have to change them once. Unfortunately it adds a bunch of $$$ to the TB service, but better than a shredded TB from sharp worn gears..........
Jim
I just finally installed mine. I'll try and keep a log on how they wear.
The original gears had very slight cupping on a few of the teeth before recoating. I didn't do the re-coating myself. MrLexse here on R
list did it for me a couple years back. He used Powerkote's DFL-1. http://www.ceramteck.com/dfl1.htm
I'm not sure on the specifics of how it is applied, except that it needs to be oven cured, so you probably need to have a dedicated oven for stuff like this.
more threads:
https://rennlist.com/forums/928-forum/237536-cam-gears-anodise-material.html
https://rennlist.com/forums/928-forum/219673-melted-cam-gears-pics-not-for-the-squeamish.html
928 Engine Re-Re-Rebuild Specialist
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Mine are wearing just fine with over 10k miles (Andrew is correct). Since the re-coating covers the whole gear, not just the teeth, I needed to scuff mine up a bit where the cambolt clamps down. The non-stick surface was allowing the gear to slip against the bolt (stopping at the gear's slot) when I was rotating the engine to set valve timing. This was after I had already logged 6k miles on the re-coated gears but had to replace a head due to a chain tensioner issue.
They're working perfectly now. They weren't cupped at all when I had them -re-coated.
They're working perfectly now. They weren't cupped at all when I had them -re-coated.
928 Engine Re-Re-Rebuild Specialist
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Here's a shot of a re-coated gear vs. a normal used gear:


Here's another example of a gear that's been eroded..this time an oil pump gear:

Once the protective coating is gone, the erosion can happy quickly. It creates edges on the gear teeth, further in from the actual edge of the gear:


Here's another example of a gear that's been eroded..this time an oil pump gear:

Once the protective coating is gone, the erosion can happy quickly. It creates edges on the gear teeth, further in from the actual edge of the gear:
928 Engine Re-Re-Rebuild Specialist
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These are the gears before I had them re-coated...all shiny, but none were eroded.
I had an extra set laying around that weren't usable, so I had them recoated too, to have a spare set.
I had an extra set laying around that weren't usable, so I had them recoated too, to have a spare set.
Hi Dave,
What was the cost saving - new v recoating?
New is $100 + or - a couple of bucks.
Thanks,
Roger
What was the cost saving - new v recoating?
New is $100 + or - a couple of bucks.
Thanks,
Roger
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."

Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."

928 Engine Re-Re-Rebuild Specialist
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IIRC, Andrew had a set done for about $10 ea. The person that re-coated my first set wanted $5 ea., although he's not doing powdercoating any longer.
It's essentially the same cost as powder-coating. It's just a non-stick material that's being applied.
It's essentially the same cost as powder-coating. It's just a non-stick material that's being applied.
Very good info! Thanks Big Dave and Andrew. I am at this point now and my gears have a shiny surface but are still flat, it looks like this is a very good option for a standard timing belt job. If Roger is interested in doing this it would save alot of searching/sourcing out.
Roger thank you again for sending out those worn cam gears at N/C. If you decide to do this I will gladly send them back to you so you will have a spare set on hand.
Roger thank you again for sending out those worn cam gears at N/C. If you decide to do this I will gladly send them back to you so you will have a spare set on hand.


