stripped cam cap bolts

mark1122 wrote:

How about using longer studs threaded into the cam bolt holes,and drawing the cam caps down with nuts on the studs.Then removing the studs 1 at a time and installing the proper bolts,and then torque.

Then again, how about replacing all of the bolts with studs, and never have to take them out of the head again.

Jay

APE Jay wrote:

mark1122 wrote:

How about using longer studs threaded into the cam bolt holes,and drawing the cam caps down with nuts on the studs.Then removing the studs 1 at a time and installing the proper bolts,and then torque.

Then again, how about replacing all of the bolts with studs, and never have to take them out of the head again.

Jay

sounds like a good idea.

When retapping cam bolt holes with anyting oversized, it's possible for the tap to distort the lifter bore when used in certain holes....just something to watch out for..

I agree with Jay on the assy. lube. Steel and aluminum need a barriar between them....

I dont pay much attention to torque specs, i can tell when a cam cap bolt is tight enough, and yes use a torque wrench to keep track of where your at, but with loctite on the bolts they arent going anywhere. Beats the heck out of reethreading bolt holes. Got better things to do like the next step. yeah, lube the bolts and all that, put a tiny drop of loctite on the end of the bolt threads closest to the head of the bolt. And I challenge anyone to dispute this cause after all isnt that what were all about? If you ride like i do them suckers will come out. Ive had the valve cover blow off the head and was lucky to catch the camshaft in my hand. whew! The dealer told me air bags not on the z.

Post edited by: nads.com, at: 2006/10/31 00:55

Post edited by: nads.com, at: 2006/10/31 02:08

Torque wrench isn’t just to keep the bolts tight but to keep each piece the SAME tightness (torque).This keeps the parts true to each other and stress free.this is not posible by feel.

I may not use the amount of torque the manufacturer states, but I always use equal torque on all bolts and nuts. Good point, well taken.

I know this is an older thread, but I am about to deal with all of this too, and had a couple of questions and observations...
One thread talked about redrilling/tapping to 7mm. Will this still leave the dowel pin/guide in good shape?

If I went the route of going to 8mm on all the holes, it seems that all of the dowel/locators would be gone. How is this done by all those drag race guys? Is the bolt enough to locate the cam cap?

While putting in studs seems like a good idea, I would think that if by chance one of the nuts worked loose, it would creat havoc on the top end, where if the bolt works loose, it can not come out due to it's length. has anyone done the stud thing?

Thanks all!
K

Thanks for reviving this thread, augie. I'm just about to reinstall my cams, shortly, and reading about what to look out for and possible solutions is right on time
RonJ

Hi guys. When removing the camshafts of my ST on last WE, one bolt broke. I didn't want to use an helicoil. I use an extractor (I don't know what's the name in English, sorry) made by Facom (a French tool maker).

What broke :



Yeah, I know, it's written in French. Don't mind.

I drilled a small hole with a 1mm drill, PERFECTLY in the middle of the bold. If you don't drill exactly at that point, it's far more difficult to extract the broken bolt. I use a vertical driller, and I used a spirit level to be sure to drill vertically.



I used those tools:

More information about those tools

I drilled a larger hole with a small drill bit. That drill bit is not the common kind. It's made to drill a hole especially for extraction.

Then, I used the extractor. The stud came out:

The extractor is on the left, and the drill bit on the left. The drill bit costs a fortune. The full set (5 drill bits and 5 extractors) costs around USD 160. However, it's the best quality tools you can ever find.

I read my service bulletin direct from Kawasaki for the KZ650 and it says 8 ft/lb on camshaft cap bolts. Like I said earlier 12 is way to much and they will strip. Even 8 is pushing it. Just for info, I don't see where the KZ1000 with similar 6mm bolts threading into the same soft aluminum head would benefit by overtorqing to the point of stripping. These bolts never come loose.

I use mostly the SQUARE shaped extractors now. They are far harder to break than the EZ-Out shown. I am not familiar with the drill on the right. I use an automatic center punch and a cobalt drill bit.

wiredgeorge wrote:

I use mostly the SQUARE shaped extractors now. They are far harder to break than the EZ-Out shown. I am not familiar with the drill on the right. I use an automatic center punch and a cobalt drill bit.

The special drill on the right costs 4 times more than the extractor in itself. As you can see, it has a V shape. The extractor also has the same V shape. Thanks to that shape, the extractor grips in the bolt all along the drilled hole. Using a normal drill wouldn't be that efficient, since the extractor would pull the bold only on its upper part, and the extractor would probably break itself.
I often used those drills and extractors, they work as a charm.