I'm in the middle of a tensioner pad / timing belt job on my 968, and I was wondering about the 20 cheesehead (triple square head) bolts that hold the 2 cams in place. I had to drill out 7 of them, and 5 others got a bit messed up on removal (stripped bolt heads). I was about to just replace them all with new bolts (or screws, to be proper), but the price is kinda steep for something that would probably need replacing every time I take them out.

The dealer wants $3.66 per bolt, and I need 20, so that's almost $80. I can't imagine reusing them, being that they're so easy to ruin. I was wondering if this is common, or if I'm smoking something. Also, would it be OK to just replace them with regular hex head bolts (say, 12 or 13mm) of the same length and thread pitch? I test-fitted an M8 bolt from my spares bucket and it seems to work OK, and the 13mm socket I used fit in the space provided...

The bolts are p/n 999 510 029 02, if you care. They are M8 x 40.

 

I recently had both cams out on my S to replace broken valve springs and I replaced all the cheesehead bolts with hex head, including the big cheesehead bolt on the timing belt gear. You can get inexpensive replacements at any hardware store.

 

I just made a trip to OSH, and I found some bolts with the exact same dimensions. They are hardened, and allen head - the hex head bolts were weaker. Actually, these allen head bolts have a deep head and seem un-ruinable. They're about 4mm too long, but a dremmel can fix that. Overall I think I'm going to like these a lot, and I highly recommend that anyone reading this buy these instead of the porsche bolts. They're only 60 cents each! $61.20 saved by getting something better.

 

Good job, as Peter says, standard M8 hardend bolts will work fine.

 

Yep, the local Ace Hardware had 12.9 allen bolts in the right size, thats what you want.

 

I hate those 12 pt fasteners. I'm getting ready to pull my head and they scare me just looking at them. Is it common that they strip?

 

When I did my tensioner, bought a 12pt wrench set (I think at Kragen's) I re-used the fastners, and they looked brand new after I was done. What tool were you using to install them? I'm thinking that if you stripped these ones, you might end up stripping the new ones too.

I'm not a materials expert, but something tells me if the aftermarket ones you buy have a radically different material than the factory ones, you might experiance some thermal expansion problems.

Good luck.

 

Geez, I feel lucky, all of mine came out beautifully (147K miles) and look brand new still. I used a good, new triple square bit. It is true that it does not take much to damage one of these bits though, and once that starts, you need a new bit or run the risk of more easily damaging the screws.

I wonder if there is any reason for the multitude of triple square fasteners on this car? They certainly don't seem like they would be any cheaper... but I would think there is a reason... Interesting.

 

I bought the 12pt bits from Snap On and have not stripped a single bolt.

I can't think of any good reason to use these bolts except to **** off those of us who do their own repairs.

Thermal expansion can't be significant if both bolts are steel, right?

 

My conspiracy theory is that Dealers lobby manufacturers to make it more difficult for the average Joe to work on his own car, so he's more likely to take it to the dealer for service, and then the dealer can charge more billing hours. Same reason you have to remove a body panel with dificult to reach screws to service the air filter on S2's.

 

I bet it has something to do with surface area and torque accuracy. You have more surface area in contact with the tool than a hex head bolt. I'm not an ME so, its just my theory.

 

I bought hardened hex socket (allen head) bolts, coated with something black to prevent corrosion. I bought washers of almost exactly the same size as the old bolts had on them. They are of course steel. They guy at the OSH I went to said that even the hardened bolts I was buying aren't really that hard, and that they could't compare with, say, the infamous cam sprocket bolt I showed him. However, I know that the cam saddle bolts are much softer than the sprocket bolt, because I drilled both of them, so I'm certain these hardened OSH bolts will be very good substitutes for the cam saddle bolts. I was about to buy a allen head bolt to replace the cam sprocket bolt too, but since I needed a super-hard bolt, I had to just use the OEM POS.

I bought a high quality (albeit american) triple square bit from a local specialty tool store. I'm sure a Snap-On bit would've been better, but I never see the Snap-On truck around here. My 6mm allen bit fit right into these OSH bolts like a glove, and I know these will never strip. At any rate, the bolts are in, and if they fail I'll let you guys know.

 

Snap On accepts orders on their website. I tried to meet up with the truck and the guy told me to just buy on the web.

Hope all goes well on your reassembly.

 

The replacement bolts supplied by Porsche are now internal hex (Allen) head.

 

Call the local Snap-ON rep, theyre listed on the site. Theyll come to your house.