PCA Southeast Michigan Region

From the Blog

Sharks Bite, but you can Bite Back

Have you ever wondered why 928s are so plentiful and relatively cheap?  My 1991 GT stickered for about $90,000 back in 1991, but I bought it 6 years ago for just $12,000.  Adjusted for inflation, that’s over $150,000 in today’s dollars.  So while you can pick up a 928 on the cheap, the parts still reflect a purchase price above $100,000.


My first clue to this was when I had my clutch replaced on my first 928, a Chiffon White 1982.  I believe the bill came in around $3,000!  Much of it was labor.  I now know that there were ways I could have saved myself several dollars not only through doing the labor myself, but also by using some non-Porsche parts that are just as good, if not better, than the original equipment.

A 928 can be cheap to get into, but can be expensive to maintain if you're not careful

For many, the mere thought of using non-Porsche parts is heresy.  But none of my cars are show cars.  My goal is about preserving the driving experience and my bank balance.


One of the areas that many 928 owners get bitten is when it comes time for a timing belt job.  The 928 has the distinction of having one of the longest timing belts in automotive history- something like 6 feet.  Coupled with this system is a Rube Goldberg-esq tensioning system that is supposed to compensate for expansion of the block.  When it’s working properly, there no drama.  When the tensioning system is not, it can lead to premature wear of the gear that drive the cams and the oil pump.

The 928 timing belt. 1. Cam gear  2. Cam gear  3. Oil pump gear

Eventually things wear out, and every 928 owner will go through a timing belt job.  Most think that it will cost about $2,000 – mostly in labor.  So they give the nod to the shop, and a day or two later they get a call with the bad news.  It goes something like this:


“We got the front end of your 928 apart. Both cam gears and the oil pump gear need to be replaced.  Parts will run $1,300 plus an additional 3 hours in labor.”


Now that $2,000 job has just about doubled!  Talk about getting bit! You just lost a leg!


Why does this happen?  The gears are made from an extremely light magnesium alloy and anodized.  The problem is that the hard anodizing wears off from the belt after about 90,000 miles.  Once this wear off, they go quickly. The wear can lead to poor performance and premature belt wear and failure.  Add in a tensioner that is not properly working and things can go from bad to worse very quickly.

Here is one of the recoated cam gears after 30,000 miles.  There is some darkening, but overall condition is great

The solution has been to swallow the hard pill and pay the extra $2,000 or do the minimum and sell the car ASAP with “Recent timing belt job!” in the description.


About five years ago a local 928 owner and I decided to try and salvage the gears by getting them recoated.  We tried re-anodizing the cam gears, but the magnesium didn’t react well to some degreaser.  They basically melted, so we tried something different.  We had them coated in a dry film lubricant (DFL).  On first inspection they looked great, but would the hold up?

Melted cam gears!  Ouch!Here you can see a worn cam gear on the right and freshly recoated cam gear on the left

Until about 3 months ago and 30,000 miles later, these re-coated cam gears had been on my supercharged GT with over 500 horsepower.  They held up great.  They only cost about $25 each (x3) to be recoated.  Current costs have gone up to about $35 each, but for roughly $100 you can get “renewed” cam gears and save yourself a significant sum, and bite that shark that bit you.


If you want more information on getting your cam gears recoated or any other 928-related questions, stop by one of our 928 beer nights (other makes and models are always welcome too!).  We generally hold them on the second Wednesday of each month.  You can call (734-837-7908) or email (andrewmolson@yahoo.com) me for details.  Happy motoring.