[Guest]

Derek from Sweden has submitted a VERY thorough document on inspecting the Variocam and a maintenance schedule. He is quite a photographer to boot!

Procedure for inspection of Porsche 968 Camshafts.pdf Size: 988.9 KB  Downloads: 386

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[MCL968]

Anyone have a functioning link to a PDF for replacing the pads and chain? All the ones I find on here are not working properly or at all.

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[fleetwood]

I just tried and got the above pdf attachment to download and open ok

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[MCL968]

That's a great PDF, and very helpful, but I was looking for one which outlines the replacement process, not just inspection.

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[flash]

that's probably in the workshop manual.

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[Bulti]

I got a lot of info from Clark's Garage...

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[Cloud9...68]

Changing the pads and chain requires removing the cams, which means timing them. As Flash says, the procedure for all this should be in the manual. A big job.

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[kwikt]

Just did mine again along with cam timing. I think I'm getting use to this.

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[Bulti]

Does the timing need to be reset if you lock the timing assembly with 3 M5 bolts where the ones of the ignition rotor normally go?

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[kwikt]

There is slight play in the key way if you do this. Is it that close......don't know. I did it that way the 1st time(4 years ago) I did my chain. Last week I used the dial indicators. Funny that my original scribe marks lined up.





Kevin

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[Cloud9...68]

Yeah, I've always been a little skeptical that things move enough to justify the potential error in timing the cams using the workshop dial indicator method. Theoretically, you should always re-time your cams whenever you remove them, or even when you change your timing belt. But in practice, unless you do it a lot and are really good at it, I suspect that going through the timing procedure has as much potential of introducing error as it does of improving your timing.

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[flash]

it all depends on belt and chain stretch. also, it depends on if the cams were timed with new or used pads. all of these would change the position of the cams.

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[Cloud9...68]

[quote name='flash' timestamp='1387551456' post='153725']

it all depends on belt and chain stretch. also, it depends on if the cams were timed with new or used pads. all of these would change the position of the cams.

[/quote]

I don't disagree a bit - I'm just not convinced the average DIY'er can nail the timing well enough get it closer to the optimal point, than if is left alone. In other words, will the inevitable error introduced by the person doing the timing have you end up closer to the optimal point, or farther away? And how would you know, unless you put the car on a dyno before and after?

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[flash]

could be right. it's not the simplest thing to do, even if you know how to do it, and have the right tools.

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[Bulti]

Does the factory setting take the stretching of things into account? Because if it doesn't, the closest you can get to the optimal setting is to time everything again when the new belt and chain have set over time.



If the difference of the corrections made on the cam timing isn't worth the trouble, then why not keep it locked the way it was? Assuming you use the same brand of belt, pads and chain, they would also stretch or wear in the same way?

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[flash]

the factory designed in a "tolerance". the engine is right when first set, but changes as things stretch. it is a slow process, with the differences not being noticed over time, similar to ring and valve wear. they also do not need to provide a design that maintains full power over time. they only need to make a certain percentage of that when new (again falling within industry tolerances), but it can lose power over time with no penalty to them. their primary concern is that it does not require warranty repair.



in a street car, the differences are not all that much of a consideration. in a race car, you would reset things at least every season.

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[schwarz968]

Have a "new" 95 968 and have to completely rebuild the motor. Anything special about compressing the tensioner to install the lock once new pads are installed?

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[RossB]

Thanks Derek, great PDF, and clear instructions.

 

Ross

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