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CAM PULLEY COATINGS

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Old 10-07-2009, 11:51 AM
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dprantl
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Are there no steel cam gears available for the 928? When I did the belt on my wife's 968 recently, it had a steel cam gear.

Dan
'91 928GT S/C 475hp/460lb.ft
Old 10-07-2009, 11:57 AM
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Giovanni
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Originally Posted by dprantl
Are there no steel cam gears available for the 928? When I did the belt on my wife's 968 recently, it had a steel cam gear.

Dan
'91 928GT S/C 475hp/460lb.ft
Interesting, can anyone tell if they are the same size as the 928? And what is the weight difference?
Old 10-07-2009, 11:59 AM
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AO
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Dan-

The issue isn't so much with the materail choice (well maybe a bit...) but rather with the factory coating (annodize). Once the coating wears off, the magnesium/aluminum wears quickly and results in sharp edges on the gears that can wear the belt. I think steel would have similar deficits (oxidation, strength, weight, etc.)

The dry film lubricant provides a long-wearing surface and has been designed for this exact application. As long as you don't have deep grooves in your current gears, they should be able to be re-coated (at a fraction of what they cost new) and put back into service.
Old 10-07-2009, 12:00 PM
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dprantl
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Originally Posted by Giovanni
Interesting, can anyone tell if they are the same size as the 928? And what is the weight difference?
I'm not sure if they are the same size, but they looked very similar. It was a lot heavier, but I would accept that extra weight in exchange for a huge increase in durability in such a critical part.

Dan
'91 928GT S/C 475hp/460lb.ft
Old 10-07-2009, 12:03 PM
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dprantl
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Originally Posted by Andrew Olson
Dan-

The issue isn't so much with the materail choice (well maybe a bit...) but rather with the factory coating (annodize). Once the coating wears off, the magnesium/aluminum wears quickly and results in sharp edges on the gears that can wear the belt. I think steel would have similar deficits (oxidation, strength, weight, etc.)

The dry film lubricant provides a long-wearing surface and has been designed for this exact application. As long as you don't have deep grooves in your current gears, they should be able to be re-coated (at a fraction of what they cost new) and put back into service.
The gear on the 968 had over 150k miles on it and looked like it was new. I put a straight edge on the tops of the teeth and they were perfect, no runout at all.

Dan
'91 928GT S/C 475hp/460lb.ft



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