Originally Posted by BruceWard

I was thinking of a pad and chain change every 60K unless the new version of the chain eliminates or reduces this problem.

If the pads fail the cam(s) will fail causing the pistons and valves to meet. The cost to repair is the normal $3K to $5K for a timing belt failure plus $1200 of cams. So in my opinion it is worth while to change the pads and chain proactively.

I purchased all of the parts, removed the head from the car and then worked with factory trained mechanics (Perfection Plus) to rebuild and reassemble. I took them the head a week before the car. The head received replacement Porsche valves from a spare head, a valve job and thorough cleaning.

The head looked like this afterwards



The pistons, bore and cam cover were all cleaned just as well []

Since the timing belt had been broken by the balance belt my cams were no longer timed to match the bottom end there was no point in trying to preserve timing. The pads and chain were changed with the cams out of the head. The only way I can see that they could be changed while installed in the head would be with a chain with a removable link. Although I do not think much time or even timing effort would be saved this way.

It is possible to retime the cams less precisely without doing so but I chose to go to the pros and have the cams retimed using dial gauges to the factory spec. To do so you need a dial gauge for the intake cam, one for cylinder 1 and to be able to force air into the variocam where oil would normally flow. Without the variocam pressurized with air the reading on the dial gauges changed by 1/3rd. Using this setup the cams were timed perfectly and based on the witness marks probably better than they came from the factory.



When I change the timing belt again I will inspect the pads. If they show wear I will change them and the chain with the cams removed from the car. I am undecided whether I will mark the cam to sprocket alignment and retime based on that mark or go for the dial gauges again. Most likely I will opt for the dial gauges.

The 968 now runs stronger than it has since I bought it []

Originally Posted by Thom

I would be concerned to replace the chain without replacing camshafts as well.

Fitting a new chain without fitting new camshafts may lead to increased cam sprocket wear and "finish off" camshafts quicker than with the chain they have originally run with.

Originally Posted by RS Barn

I've noticed on all cars I've checked the lower pad is worn 2 to 3 times as much as the top. If you see any grooves on top consider replacing pads and chain. Cheap insurance.

Originally Posted by RS Barn

Bruce, you did the right thing getting the cams times properly. way too may back yard mechanics and even Dealers use the original timing marks. They are invalid after replacing belts. The correct method sets the #1 piston at TDC overlap with intake valve open to a spec , this cannot be duplicateded without two dial indicators. I can tell if cam timing is off when driving.
Pete