Bilal928S4

Roger,
Now that you have installed a belt over the cam gears, they are used. So are you going to sell them at a cheaper/used price?

Bilal

ROG100

AO,
I think you are right as it was wear that was the cause for the change of gear material.
Now where can we find about 100 sets of very good condition 32v gears and set about having them coated.
If you have a set currently then coating is the answer.
Roger

ROG100

Bilal for you $365 - be first for the Christmas special 8>).

M. Requin

Roger, thanks for the information. I think you misuderstood me (prolly my bad) I also think the tooth profile is important, but I'll stand by my statement that it is not well understood here. Let me describe exactly my reservation: some folks have averred that a sprocket profile that gives a perfect fit between belt tooth and sprocket is desirable, and that is simply not so. If the sprocket recess fits the tooth perfectly, it will "grab" the belt tooth on both entrance and exit, adding friction and angular velocity change in the immediate area of the belt- ie stressing the material. This stuff is exceedingly well documented in descriptions of roller chain systems, to which this is an analog.

So my feeling, and I think from what you have stated above we are mostly in agreement, is that this is a materials issue: get the profile of the sprocket as correct as possible, and make it from the hardest light alloy available, which for all practical purposes, is 7075. So I very much appreciate the clarification that Porsche has not officially identified the alloy from which these sprockets are made.

Ergo, a proposal:

1) an Optical Comparator evaluation of available designs (forget normal photos- just not accurate enough) to evaluate how closely aftermarket products match original Porsche design;

2) a hardness test of the same samples.

Let's eliminate voodoo in favor of the empirical.

Please, no popcorn.

heinrich

Roger how about a cf centre with the hard running surface. I would certainly consider that a better option if it could be done for the same price circa 400 each. In fact i'd be in for a set.

928mac

Since I have never seen the engine on a 944, I was wondering what the difference is between their cam gears and are's,
and
the reason i am asking is because there seems to be a performance gear for them, why not for us?
here is what I am talking about.
http://www.lindseyracing.com/LR/Parts/944CAMGEAR.html

SeanR

I was looking at as many different cam gear make ups last night as the Google could spit out, and kept coming back to the tooth design on the 944 series cars, which looks a lot like ours. Lindsey Racing kept coming up also. I'm glad to see I'm not the only one.

heinrich

We have 48 (not 47 thanks Mr. DuBois) teeth. They have 40. Looks a lot like the same profile though.

928mac

I wonder who made that 944 one for Lindsey

Lizard928

I have been reciting the gears that are not overly worn for a long while.

I won't say what I've been coating it with but I will say that I have them on a bunch of cars with many miles on my own car, and a bunch on others.

No additional wear seen on belt, and zero wear on gears.

SeanR

I've kept all the ones I think could be saved, we might need to talk Colin.

outbackgeorgia

Martin,
Agree completely, "optical comparator" is the term I was reaching for back on posts 176/178. I have seen them in action, but forgot the actual term. There are also nowdays probably laser based, computer controlled equivalents, but any good quality control shop should be able to make the comparison accurately.
Dave

dprantl

968's have a steel cam gear stock.

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

Cosmo Kramer

I wonder if the 944 crowd beat the dead horse about whether the tooth profile of the Lindsay Racing gear was the same as the OEM Porsche gear before bolting on their car?

tmpusfugit

I hope you are kidding....all mine have 48 teeth.....