Cam Gear Bolts to Oil Pump Clearance

Matt Harris · Post by **Matt Harris** » Fri Jun 28, 2002 12:58 pm

How much material can you safely remove from the cam gear bolts before they are no longer strong enough to use. I am using So Cal's straight cuts with the straight up washer, and star washer. I have already removed .025" off the heads of the bolts and it still hits the pump on the front (meaning front) of the pump where the second gear slides onto the shaft. I don't know if I should remove material from the pump or more from the bolts or ? Thanks.

[This message has been edited by Matt Harris (edited 06-28-2002).]

Pablo · Post by **Pablo** » Fri Jun 28, 2002 1:41 pm

Matt

If you like, I'll mail you three buttonhead 8mm bolts (tighten with 6mm allen wrench). The rounded heads clear any pump. You'll need to cut the threded end with a hacksaw to the proper length --

Paul
(Northern Cal)

melbatoast · Post by **melbatoast** » Sat Jun 29, 2002 6:43 pm

button head cap screws are designed to be used in LIGHT fastening applications, i.e. guards, etc. i design gages, fixtures, and special machines. 12+ years design experience. i have seen a lot of button head screws get put into something and never come back out until a drill was brought into the equation.

0.025-.030 off of the top of a standard socket head cap screw is not going to alter it's holding ability.

grind on the pump itself is probably a better idea.

------------------
arlan
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you see these?
they are my carkeys.
you will never get these.

Pablo · Post by **Pablo** » Sun Jun 30, 2002 5:29 am

Gee, Melba -- I didn't think my offer or idea sharing would lead to a debate about screw types, but --

Buttonhead cap screws are for any application where clearance is an issue and/or a clean appearance is desired. We use both buttonhead and lowhead/sockethead cap screws on a wide range of torque-biasing and limited-slip differentials that we have manufactured, and these cannot be termed "light duty" applications.

The 8mm cap screw is rated at far more than the 15-18 pound torque called for on cam gears. Proper removal (virtually never on cam gears) is performed with a T-driver hex key, not a standard allen wrench (which is fine for installation).

Paul

Using buttonhead cap screws on cams for oh, about 30 years.

melbatoast · Post by **melbatoast** » Sun Jun 30, 2002 6:13 am

30 years?
cool!

can't argue with that kind of experience. it works for you and that's great. i don't want to debate screws, either. personally, in my lesser years of experience, i have seen button heads do some wild things. my experiences were probably because of improper installation.

------------------
arlan
--------
you see these?
they are my carkeys.
you will never get these.

[This message has been edited by melbatoast (edited 06-30-2002).]

Matt Harris · Post by **Matt Harris** » Mon Jul 01, 2002 10:29 pm

Hi Pablo, I'm sorry for not getting back to you sooner, I've been in the garage thrashing. I'm so grateful for your offer, you are why this hobby is great. I actually went and found some button head 5/16" allen bolts at a hardware shop and asked the owner and he said they would take way more than the 25 ft/lb that I was going to torque them too. So I get them home and notice that they are much thinner than the .025" machined hex head bolts. So I stick them in and they still hit ALLOT. So I grind them down and the pump and finally get everything to clear fine. So then I green loctite them into the cam and get two of them torqued to 25 ft/lb and on the third guess what, it stripped out, oh man am I screwed I thought. So then my dad tries to get it out with vise grips cause he can see how pissed I am, but to no avail. Tried drilling it to get an easy out in there...of course not. So I finally came up with the idea to take my cutoff wheel and grind a slot in the stripped out head so that I can get a flat head screw driver in there to unscrew them. So after cutting them as deep as the star washer under them I got them out, man what a stressful hour of work to get it out. So then I got to pull the other two out cause I ain't trusting these things and one comes out fine and the other starts to pucker and strip to, so I got that one out luckily too. So now I'm really pissed and just say eff it I'm using the .025" machined down hex bolts. So I throw those in the cam gear and they hit the pump, so I grind the pump like mad and everything clears fine finally. So I green loctite two of the three and the third one's not getting tight, and I'm like huh that's weird so I pull it out and the bolt stripped out!!! At this point I just think I'm cursed, so I get another bolt and grind it .025", clean up the cam threads with a 5/16" x 25 tap and reinstall with green loctite and voila it worked. Man oh man, talk about fighting something that should take like 10 minutes to do, whew.

So then it gets better, I get the short block glued together and check the deck after getting the case decked and it's now positive on the deck when it should have had .015" on the deck. So now I'm really really fuming, but there's more. This time I spin the crank more and notice that something is hitting, what the heck? So I pull the cylinder off, and the 94mm piston is hitting the step bore in the case!!!!!!!! Man at this point I'm about to have a nervous breakdown and a coronary all at once. So I pull it all back apart getting fresh curil T all over me and pull the cam and crank out, pull out the bearings, dowels etc and try to grind off the step bore. So I get it ground off where the longest part of the skirt goes in, but the rest of the piston is hitting too. So at this point I'm like screw it. Pulled it apart and it's off to the machine shop to have the step removed. What a fight this has been, man.

[This message has been edited by Matt Harris (edited 07-01-2002).]

Pablo · Post by **Pablo** » Mon Jul 01, 2002 11:24 pm

Hi Matt

Welcome to the joys of performance engine building. Sheesh, you've had more than your share of headaches on this one. Sorry my suggestion caused one of them. I swear I never had an issue with the button heads ---

Better luck tomorrow ---

Paul

Bruce2 · Post by **Bruce2** » Mon Jul 01, 2002 11:53 pm

Arlan, I can't believe your knowledge of how crappy buttonheads are. I've spent 14 years in the manufacturing industry arguing with engineers on how evil BH screws are. But the engineers I worked with like the way they look. Unfortunately they don't work with them, so they don't have to suffer the consequences of a stuck screw like Matt did.

Pablo · Post by **Pablo** » Tue Jul 02, 2002 8:43 am

No kidding, Bruce? You spent this much time campaining against buttonheads??

I suspect the quality of the buttonheads handed to Matt. While there's no question that a buttonhead is easier to strip than a standard bolt, it seems that these BHs were of the cheap & soft Taiwan variety, seeing as how not only the socket stripped, but the threads stripped, too (something I've never experienced in cam installation).

The removal of a torqued buttonhead really has to be done with a T-driver, not a regular right angle allen wrench --- nor an allen socket on a ratchet (which is almost the same).

If Matt had e-mailed me for the US-made buttonheads I was offering, I would have suggested that Matt lightly install the gear with the buttonheads and first check for clearance before torquing and loctiting them. Without a T-driver, BH removal is near impossible.

Paul

Post by **Tom Notch** » Tue Jul 02, 2002 12:08 pm

Next time don't over-torque them.

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Tom Notch
Tom's Old VW Home

Matt Harris · Post by **Matt Harris** » Tue Jul 02, 2002 2:42 pm

Hi Guys,

The only reason that they stripped out was because I had to grind them down to clear the pump. If they didn't need grinding they would have easily torqued to 25 ft/lb. Plus I bought the black button heads not the cheaper stainless or whatever they are. Tom I hope that wasn't directed at me because 25 ft/lb is what I torqued the cam gear to on my old cam and is what Berg recommends in the BBB.

And Pablo, the threads didn't strip out on one of the button head screws, the threads stripped out on one of the hex head screws. The allen head on the button screws is what stripped out and only because I had to grind them. Anyways, I ended up using the machined down hex head bolts and everything worked out ok, but man I was fighting it for a long time. Having a VW and working on it has taught me something that I didn't have much of before owning one.....patience, and I'm thankful for it.

Pablo · Post by **Pablo** » Tue Jul 02, 2002 2:44 pm

There is presently a lawsuit pending against an American supplier of supposed "high quality" low head socket head cap screws that tended to pop their heads when moderately stressed. A motorsports car crash was the result. Turns out they were made in Taiwan and repackaged.

Paul

Post by **Tom Notch** » Tue Jul 02, 2002 3:46 pm

IMHO 25 ft#s is too much, I follow the VW recommendation. You wouldn't believe what aerospace calls out for that same fastener...... Would you believe around 120 INCH pounds or 10 ft#s. I have had only one cam gear come loose in over 35 yrs in VWs, I swear by thread locking compounds since then. I have seen cam threads get pulled out, too.

I have gone thru "recalls" on fasteners in airplanes at work. Not fun ripping apart a jet almost ready for ticketing for some bad heat treating or bad threads just a bit out of spec run-on torque value (which raised the red flag). Been there.

Don't over torque, just my nickle. Please no offence intended.

------------------
Tom Notch
Tom's Old VW Home

andreas5bmw · Post by **andreas5bmw** » Tue Jul 02, 2002 6:29 pm

I think you guys have too much time on your hands.The Question was about the cam bolts clearing the oil pump.And everyones worryed about some dam button head bolt.Nobody answered his question.Yes you can take .020 off the head of the cam bolt.You could also grind alittle off the back of the oil pump where its hitting.

Pablo · Post by **Pablo** » Tue Jul 02, 2002 6:42 pm

That's the nature of discussion boards, Andreas --- discussions evolve. I think Matt is way beyond the point of his original query, so are we now required to start a new thread?

Paul