Cam belt / balance shaft belt

[Glenn B]

Hi Folks,

I am about to start on replacing my 1992 968 cam and balance shaft belts. Any advise or tips to offer? Do you really need all of the special tools I have read about?

[mmmbeer]

I just changed these and all rollers on my 92 968. No special tools used. This being a tiptronic I put a hex socket in one of the bolts on the flywheel (through starter hole) to lock it up when loosening the crankshaft bolt.

Be sure to check the state of the rollers before putting the new belts on. If you are unsure of how to do this; replacing all might be a good idea.

[flash968]

this is a loaded question

to do it "right" you need the flywheel lock tool, and a pair of runout gauges with mounting hardware, so as to properly set the cams - marking cam positions and such only gets you "close" - the car will run and probably run "fine", but if you want all the power available, you have to time the cams, which is a tedious process requiring a good lock down of the crank, and both gauges - a couple thousandths of an inch there can mean 20 hp

Edited January 22, 2010 by flash968

[mmmbeer]

Do you have any references stating that one need to perform a camshaft setting adjustment after a simple belt job? I find the need for this quite unlikely. 20HP, where do you get that figure?

[flash968]

the workshop manual actually specifies the procedure

the reason for doing it is that the cams are NOT in the same position relative to the crank when a stretched belt is replaced by a fresh one, thereby causing both cams to be out relative to each other when the new belt is installed

the power changes have been documented by many - some claim even more - i was actually quite surprised myself until i had my cams timed on a tight engine with only 40k on it - mine did not change quite that much, but it was noticeable

basically you can move the power curve up or down the rev range, based on where you set it - it is a variance of only a few thousandths of an inch, but it works - all the high performance tuners know this

as i said, yes, the thing will run - but if you want it all, time the cams

for more information, contact pete at rs barn - he can give you a detailed explanation of how and why it works