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-   -   reuse these cam gears (http://forums.pelicanparts.com/911-engine-rebuilding-forum/430321-reuse-these-cam-gears.html)

ajwans 09-14-2008 02:45 AM

reuse these cam gears
 
Would you reuse these cam gears?

http://img258.imageshack.us/img258/7...ear1ui4.th.jpg

http://img411.imageshack.us/img411/7...ear2ja4.th.jpg

andy

304065 09-14-2008 09:05 AM

Andy,

Hard to tell. There is no pitch measurement for the gears published by the factory, nor am I aware that anyone says "X mm is go, x+0.02mm = no-go". Among the motorcycle types the practice is to use a NEW chain to evaluate the old gears-- if there is excessive slack when the new chain is wrapped around the gears, the old gear is considered worn and thrown out. Of course this is much easier with motorcycles.

I am using NEW intermediate shaft gears because you can't get at them, and USED modern-style (blunt teeth, not pointy teeth like early cars) cam gears. This way I can keep an eye on them every few thousand miles when the cam boxes are opened to take a look. (every few years in my case).

Obviously if there are any teeth that are chipped or worn abnormally they are junk.

JFairman 09-14-2008 09:21 AM

You need to show more well lit pictures from more angles, like directly from the side and show both sides of each gear.
...and clean all the dust off of them first.

From the one picture of each gear, they don't look too bad. Just oil stained from lots of time and miles and kind of polished where the chain rollers run in the valleys between the teeth.

How does the other side of the teeth look? If they are also smooth then the shim set behind the gears and alighnment with the intermediate shaft gears is good.
If one side is worn more than the shim set is probably wrong.

If on a budget I would reuse them if the tensioners weren't expanded to their limits and the engine wasn't making loose chain noises.

2.70Racer 09-14-2008 08:55 PM

Let's get this straight. These are sprockets, not gears.
Gears mesh with other gears.
Sprockets are driven by roller chain.
These sprockets are worn some. Not too bad.
As evidenced by the flats at the tip of the teeth.
Better to get a strong light and examine the sprockets on the intermediate shaft.
Sometimes these are overlooked because careful inspection is difficult.
Replacing the intermediate sprockets means splitting the case. Often overlooked.
Look for flat tips on the teeth. Worn sprockets tend to sharpen the tips of the teeth.
What did the chains look like for stretch?
Re using these sprockets may last another 50,000 miles.
If you are doing a complete first class over haul, replace all of the sprockets and chains.

ajwans 09-15-2008 01:23 AM

More pictures.
http://img230.imageshack.us/img230/4...ear9rw4.th.jpghttp://img254.imageshack.us/img254/7...ar10zv1.th.jpghttp://img99.imageshack.us/img99/581...ar11pn2.th.jpghttp://img99.imageshack.us/img99/305...ar12kq8.th.jpg
andy

ajwans 09-16-2008 02:06 AM

Anybody have a new cam sprocket that they wouldn't mind photographing
and posting for comparison?

andy

Henry Schmidt 09-16-2008 08:14 AM

A quick inspection off the link arch will indictate heavy wear if the leading edge has more curve than the trailing edge. The best way to tell if your cam sprockets are worn beyond reason for refit is to lay a new chain on the sprocket. If the sprocket is badly worn you will be able to lift a single link easily. With a new sprocket and chain lifting a single link is tantamount to impossible. The movement you are looking for is .020" or so. No hard & fast rule except "The more lift the more wear". BTW: sprocket tips can be flat and the sprocket can still be worn out and early sprockets were pointed when new so this is a poor way to judge sprocket wear.
The middle picture shows wear.
http://forums.pelicanparts.com/uploa...1221581310.jpg
http://forums.pelicanparts.com/uploa...1221581320.jpg
http://forums.pelicanparts.com/uploa...1221581334.jpg


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