Aluminum cam sprockets - longevity?

[David Borden]

Out of left field, but would nikasil coating work on sprockets? Clearly it's hard as hell and has great wear properties, but I was not able to find anything related after a quick search.

[Jonny042]

Originally Posted by David Borden

Out of left field, but would nikasil coating work on sprockets? Clearly it's hard as hell and has great wear properties, but I was not able to find anything related after a quick search.

That's a good thought... not sure it would be feasible the make the sprockets dimensionally accurate after the application of the nikasil, however.

I'm still waiting (second attempt) to hear from the supplier as to what alloy these are being made from. If it's 7075-T6 or one of the better alloys then the strength and hardness will be as good or better than the original steel sprockets which are nothing special.

If I don't hear anything I'll buy one part and test the hardness and make a call from there.

[Jonny042]

Just closing the loop one these - I never did hear back from Rosepassion who could not get an answer from their supplier as to how their alu sprockets are made, or from what. Not really a very comforting feeling. Certainly they don't even look to be anodized.

I ended purchasing a full set of 6 sprockets and 2 drive hubs from a different source in the EU (they are made in a different part of the EU) and was able to get commitment from the manufacturer that they are 7075, with hard anodizing.

They showed up yesterday, and are darn pretty. And pretty light! From my measurements they will save a little over a kg (2.2 pounds).

Not only that, they are pretty hard. Brinell hardness of the anodized surface averaged 144, a small portion with the anodizing removed showed 138. This corelates to the hardness you should see with heat treated 7075.

The original steel sprockets (one from a 3.0, another from 2.7) measured today with the same hardness tester a value of 81 Brinell. I can't even find an example of a steel that would have such a low hardness. Even mild steel should be 120 or so.

A newer set of "OEM" sprockets that I previously tested had a hardness of 119 (going from memory on that one).





Cheers!

[LukasM]

Great data as usual Jonny, and thanks for sharing it with us!

It will be interesting to see how they wear given their hardness, one good thing is that they are not parts that are very hard or impossible to change after assembly either. You probably have engine removal down to sub 2 hours already with all your practice, so an easy weekend maintenance project.

If you really want to reach 800kgs those 2,2 lbs are not going to be your most expensive price for weight savings either!


Cheers,
Lukas

[Oregon 911]

For weight savings in the car, why not get a whole saw and start cutting out some of the internal sheet metal and maybe remove the floor mats from the car and the rear seats that will save more weight than putting aluminum gears in it wouldn’t it?

[Jonny042]

Originally Posted by Oregon 911

For weight savings in the car, why not get a whole saw and start cutting out some of the internal sheet metal and maybe remove the floor mats from the car and the rear seats that will save more weight than putting aluminum gears in it wouldn’t it?

I will say a resounding "yes" to your suggestions, but only in addition to the reduction of crucial weight from the rear of the car. I have a lot more in the works, these sprockets are really a minor item.

Any mass that rotates (even if it's at half engine speed) is a better candidate for removal than static mass, and any mass that's at the rear of the car hanging past the rear axles is going to be especially important.

That last point is especially true because the front of the car is easy to make almost too light. The big opportunity here is the oil tank and oil coolers. It will have a front mount oil tank. I am going to eliminate the engine mount oil cooler and thermostat and rely entirely on front mounted cooling.

Not entirely unlike the 906 did:

[Zuffenwerker]

Originally Posted by Jonny042

I will say a resounding "yes" to your suggestions, but only in addition to the reduction of crucial weight from the rear of the car. I have a lot more in the works, these sprockets are really a minor item.

Any mass that rotates (even if it's at half engine speed) is a better candidate for removal than static mass, and any mass that's at the rear of the car hanging past the rear axles is going to be especially important.

That last point is especially true because the front of the car is easy to make almost too light. The big opportunity here is the oil tank and oil coolers. It will have a front mount oil tank. I am going to eliminate the engine mount oil cooler and thermostat and rely entirely on front mounted cooling.

Not entirely unlike the 906 did:

Now if you could just buy the magnesium oil filter ... wouldn't help with weight but would look like a 906/910

[Jonny042]

Well I've been thinking on it...



but decided on using the more modern 993 console with its paper filter instead.

[Ooffenhausen]

I dig the idea, any weight is worth losing, and especially with them being hard ano 7075 those suckers will do the trick.