Cam Timing Chains

[mike curnow]

A question on timing chains for the 911.
The normal continuous chain out of thr parts book and PET has been 901 105 529 00 since 1965. The chain with a master link has been 901 105 529 50 . The chain for the 1973 RSR is 901 105 529 02. Does anyone know why the RSR has a different part number? It cannot be a size difference because all the dimensions for the RSR are the same as a street engine. Someone said they remembered that the RSR chain was a different color? Does anyone actually know what the difference was? Does anyone have any of these chains.

[mike curnow]

Bumping it up

[edmayo]

No answer, just a point of difference. Didn't most RSR engines have aluminum chain sprockets, could there be a reason there for different chain material? Just groping in the dark here.

[Grady Clay]

Ed,

For some more ‘groping’ (or is it the ‘blind-leading-the-blind’).

Could a “.50” at the end of the part number reflect “length as needed’ cut from stock?
Could this chain have alu or Ti pieces for mass-reduction (I never noticed any when rebuilding).
Could it be a steel chain with ‘run-in’ or some process?

I’ve used the alu sprockets with stock chains forever.
Frau Baer confirmed when these parts were first available.

Best,
Grady

[mike curnow]

Ed & Grady
Ed, yes the RSR used aluminum chain wheels, and except for the idea of chains cut from a length, I have heard all of the above ideas. However I haven't been able to pin down the reason. And Grady says the factory said to use normal chains. This at least gives me some piece of mind when I put my engine together with aluminum wheels and stock chains. Maybe they started with coated chains, found it wasen't needed and stopped using them. Does anyone make coated 911 chains currently?

Mike

[Cliff]

I have a set of aluminum chain wheels from a german supplier,not Porsche.They look beautiful and well made. Any way to assure the quality b 4 using....Thanks,Cliff

[edmayo]

Ed,

For some more ‘groping’ (or is it the ‘blind-leading-the-blind’).

Could a “.50” at the end of the part number reflect “length as needed’ cut from stock?
Could this chain have alu or Ti pieces for mass-reduction (I never noticed any when rebuilding).
Could it be a steel chain with ‘run-in’ or some process?

I’ve used the alu sprockets with stock chains forever.
Frau Baer confirmed when these parts were first available.

Best,
Grady

Well shoot Grady, now I'm really curious. I had also done normal chains on one of those engines, but I plead ignorance about the part # difference. But now that you say Frau Baer herself said to use normal ones what the heck was the reason for the # difference????? Hey GLED, do you know?

[Grady Clay]

I sure there was some difference.
Probably some little part was lighter weight or there was some ‘friction reducing’ feature (treatment?) that lasted to a 40-hour rebuild.
This may have been one of those little 99.99% items that was very costly but ‘might’ make a difference winning the 24-hour.

Looking through my January ’74 RSR parts manual, it lists “Timing chains (2)” 901.105.529.02.
As a reminder, with alu cam sprockets always use the early 911 cam flange (901.105.583.00) with the full-circle support for the cam timing pin.


Frau Baer was very good at asking “Are you sure you need that? It is very expensive.” when I tried to order something, not knowing.

In the early ‘80s, we rebuilt a ‘hot-rod’ that had the alu sprockets (all six).
The owner had driven almost 40k mi. not knowing they were installed by the PO.
While the sprockets showed wear (too much to re-use at a rebuild), they were clearly not ‘worn out’ using stock chains.

Mike, I would not hesitate to continuing using standard chains with my aluminum sprockets (all six).
I have three race engines with them.
It is important to ‘pre-lube’ chains by soaking them in lubricant and moving each link through its range of travel many times.
Ed, others; what do you now use for chain ‘assembly lube’?

Best,
Grady