Cam Drive Component Wear

[Scott Clarke]

2.5SS build is underway. Well, I had the displeasure of noticing that my intermediate gear had visible wear of the teeth, with the surfaces of one side of each tooth roughed up and little pieces of aluminum flakes gathered at the bottom of most of the teeth. I'm assuming this is toast. My intermediate shaft sprockets show visible wear on the outside surface of every other tooth. How worn is too worn for these? I cannot see any obvious wear of the profile in the area between teeth. I will, of course, be using new chains. I have not inspected the cam sprockets yet. If they are acceptable but the intermediate sprockets need to be replaced, can I use the combination of new chain, old cam sprockets, and new intermediate shaft sprockets? One last thing: the intermediate gear is retained by bolts secured with locking tabs that don't show up in PET. They look a lot like oil pump lock tabs. Should I order those?
Thanks,
-Scott

[jbell959]

You can find good used complete intermediate shafts relatively cheap. I would replace it along with new chains. The same shaft was used from 68-89 just make sure you get one with the correct sprocket (There is a 0 or 1 stamped on the aluminum sprocket). If the cam sprockets look good - resuse them.

[MBruns]

Or you can use the steel straight cut gear sets that we have in stock, and not have to worry about the aluminum gear doing what you are seeing.
Thanks, Mike Bruns JBRacing.com

[Scott Clarke]

Thanks for the replies. I scored a complete assembly on ebay the day of your responses ($58). We'll see how good it is, but a happy resolution seems possible.

Mike-
How do your gears sound? You have an intriguing product.
-Scott

[MBruns]

I have never heard them over the normal mechanical noise of a 911, most of what we build are open exhaust engines although I have done a few with mufflers and didnt notice.
Mike Bruns JBRacing.com

[Scott Clarke]

Postscript: I was able to find a complete used assembly on ebay for $58. This was considerably less worn than the one I had. I did a backlash check on both, and found that the original assembly exceeded the spec in some areas by a factor of nearly two, while the replacement fell within spec. The replacement also showed some wear of the teeth as did the original, but to a lesser extent. I also examined a third assembly that had a similar tooth surface condition. With this behind me, I noticed that the assembly photographed in Wayne's book looked the same way. So, you can see this wear pattern and still have an assembly in spec, and the pattern seems to be quite common. I'm glad that for $58 I found something that is in spec. Thanks, again, for all of your comments.
-Scott

[jbell959]

Great - Good luck with the rest of the rebuild.