Cam Nut and Impact Gun?

930LDR · 02-13-2011, 04:17 PM

I've been poking through some older posts related to removing the cam nut and saw a few people suggest simply putting the correct socket on an impact gun and using that to remove the nut without worrying about the special porsche tools.

I'm specifically working with the later version that has a 19MM nut.

Wayne's book is pretty specific in its direction that the specialized tool(s) are necessary.

Does the impact gun approach work? Sounds like it could put a fair amoutn of stress on the cam chains and what not.

Thanks

Ronnie's.930 · 02-13-2011, 04:31 PM

I used the impact gun method to remove mine - they broke free with the first pull of the trigger . . . didn't seem to put stress on anything as the sprockets, chains and cams did not move at all (other than a slight twitch).

tom1394racing · 02-14-2011, 01:31 AM

The impact gun works great for removal, however you need the special tool to reinstall the nut.

shrtshck · 02-14-2011, 04:15 PM

Used an impact gun to remove the cam nut on my 87 - 3.2, came off without issue. As Tom notes, putting it back on is another matter, will need the special tool.

Mr9146 · 04:45 PM

I know you're working with the later cams - bolt type - but I find it important to add this to the mix.

I had a particularly stubborn cam nut on a 2.7 core motor I was stripping for parts ... used an impact gun and with the first BANG! I broke the nose off the cam.

I kept the nose and nut on my toolbox as a conversation piece.

NEVER NEVER NEVER use an impact gun! The cams are too brittle.

Walt Fricke · 02-15-2011, 06:08 PM

Well, you can take Marco's advice or not.

I don't. I've used the impact gun quite a few times on my early style, large nut cams when pulling the top end apart. Never broke anything.

Yes, these cast iron cams are brittle. A shop owner friend said he once had a Type 4 VW cam on his bench, standing up on its gear as a base. He heard a ping, and looked over to see part of the cam fall over.

I've had two break in race service.

But never when removing the nut, and I don't attribute the breakages to using an impact. The first to break had been stressed when, on startup after a rebuild, for some reason I could never establish it siezed. Had to pull the end cap to push it out. Cleaned things up, put it back in. After some events it broke.

The second break was due to a rod letting go - a lot more than just one cam broke.

Maybe, if one suspected that the nut was rusted in place, a high torque impact wrench would not be such a hot idea.

SorenDK · SorenDK's Garage

Used an impact gun recently on the 46mm cam nuts... came off really nice. Can certainly recommend. If the nut is not seized - which cam nuts rarely are - i believe that using an impact gun is the only way to do this job without putting applying unnecessary stress. Tightening the nut back again is a totally different story :-)

tom1394racing · 02-16-2011, 01:46 AM

I have disassembled dozens of 911 engines using the impact gun on the cam nuts/bolts with no problems

Henry Schmidt · Henry Schmidt's Garage

If you choose to remove the nut with an impact (done it that way for 25 years, never a broken cam) simply set the gun on low.

If you have a brain fart and hit the nut in the wrong direction, fear not young Padawan.
It is a simple lathe job to repair the broken cam.
Face the stub, drill, counter bore and tap.
Now the cam is better than new because you're now using the late model bolt and washer.
Just for symmetry upgrade both cams. $90 labor and $60 parts for both.

930LDR · 02-16-2011, 09:19 AM

Thanks all for the input. I have the tool on order form Pelican already seeing as I will need it for re-assembly. By the time I get back from being on the road it should likely be sitting in my garage so I may just go that route on removal as well but I am tending to lean towards just using my impact gun set on low to make quick work of it.

eastbay · 02-16-2011, 11:58 AM

I used the impact, buzzed right off.

Walt Fricke · 02-16-2011, 02:00 PM

In fairness for the large nut cam crowd, you need the big (46mm?) crowfoot to tighten things. But it can't be used with an impact wrench (at least I've never considered trying that) for removal.

I just happened to have a 46mm socket from something (VW bus rear axle nut?) already. But initially I doubt I would have purchased such an item just to be able to use an impact gun to loosen cam nuts. I'm not a shop, and could not foresee how often I would end up futzing with my motors.

Different story with the later, 19mm bolt head, style. Everyone with an impact gun has the socket. On the other hand, the torque is a whole lot lower for this, so there is much less value in using the impact.