Cam holder bolts breaking

So I am finally putting my bike back together, and I get to the point of reinstalling the cams. I am tightening down the cam bolts in a criss-cross pattern to 112 inch pounds (9 ft lbs) when I feel that the middle intake bolt on cylinder 3 just isn't getting tight like the rest. I continue the criss-cross until they all are at the right measurement, but that bolt keeps going, then I hear a snap....I back the bolt out and it is broken nearly in two. Crap. So I grab a spare bolt from the other cam setup, apply oil to the threads and mounting, and tighten it down (didn't release tension on other bolts). I keep spinning it, and SNAP...broken bolt number two. Double Crap. I figure reusing bolts may be a bad idea, so I grab a new one I had on advice from the Valve check previously, and I proceed to repeat the first two attempts, except this time the bolt breaks all the way off. Fiddle Sticks.

What am I doing wrong? I gave up for the night, because tomorrow I have to take all 9 of the other bolts back off to remove the broken one. I only have 4 more bolts that I can break...

Don't apply oil to the bolt and clean out the hole with contact cleaner. The same torque setting on a lubricated bolt results in more tension than dry threads.

make sure you have the right length bolt.. oe thats to short ,ay strip a few threads out of the head/ block/case/whatever.. one to long may break,

[image: View Post]gll429, on 10 March 2010 - 04:25 AM, said:

make sure you have the right length bolt.. oe thats to short ,ay strip a few threads out of the head/ block/case/whatever.. one to long may break,


That's a good one. There are two different lengths.

#14 = 6x45, #18 = 6x37

[image: Posted Image]

While I havent done the VFR


I do it by hand with a quarter inch ratchet, too many cam journal broken bolt stories with torque wrenches. Its such a light weight, many torque wrenches over torque that small setting.

[image: View Post]spud786, on 10 March 2010 - 05:21 AM, said:

While I havent done the VFR


I do it by hand with a quarter inch ratchet, too many cam journal broken bolt stories with torque wrenches. Its such a light weight, many torque wrenches over torque that small setting.


I do It by hand to, dont use torque wrench on small bolts.

Plasma.

good point on torque wrench, except knowing tightwad, he'll want to be precise. i did the same thing while using a larger torque wrench. it just wasn't accurate enough. i bought a micro torque wrench and had not further issue....

point: check your torque wrench to insure its tolerance and range aren't causeing the issue. buying a smaller wrench might be the "right" answer

Wow.
The fun just never stops for ya, does it...
Sounds like turtlecreek's got the answer.

Good luck with it.

P.S.
I've never used torque wrenches, but then again, I've never delved that deep into the engine either.

Hope you get to ride soon.

Are you using an inch pound torque wrench??

[image: View Post]rhubarb, on 10 March 2010 - 02:52 AM, said:

Don't apply oil to the bolt and clean out the hole with contact cleaner. The same torque setting on a lubricated bolt results in more tension than dry threads.


per the HSM for the vfr, apply oil to the threads of those bolts before installation.

+1 on making sure you have the correct bolts for the inner and outer holes. IIRC i think the inner bolts on my bike were black with copper washers and the outers silver like most other bolts. could be mistaken as it's been a while since i've done a valve check on a viffer.

I am using a �� drive inch pound wrench that is set to 112 inch pounds (9 ft lbs) per the manual. I wouldn�t be too concerned, except the last time a torque value wasn�t followed I got into this mess�

The oil on the threads is a thought, but the manual states to do that.

Is there any possibility that tightening just one bolt is causing the problem? The bolts are breaking in the same spot, the top 3rd thread or so near the shoulder.

[image: View Post]kwr8728, on 10 March 2010 - 09:52 AM, said:

[image: View Post]rhubarb, on 10 March 2010 - 02:52 AM, said:

Don't apply oil to the bolt and clean out the hole with contact cleaner. The same torque setting on a lubricated bolt results in more tension than dry threads.


per the HSM for the vfr, apply oil to the threads of those bolts before installation.

+1 on making sure you have the correct bolts for the inner and outer holes. IIRC i think the inner bolts on my bike were black with copper washers and the outers silver like most other bolts. could be mistaken as it's been a while since i've done a valve check on a viffer.


Yes, the bolts are the correct (longer) ones, they are black and have the copper washer. If they were too long they would torque down before they actually tightened against the cam holder.

HMM is there a warped mating surface?

As regards keeping the bolts / washers / fasteners / pins, etc... lengths and placements correct. I got this method from a ZR-7S site. When you begin your tear down, take a cardboard box, preferably newish and not pre printed. Trace or draw the work piece (valve cover, side cover, head, etc...), with any applicable notes (torque values, loctite, special greases, etc.) on the box and then as you remove the fasteners push them into the cardboard drawing at the corresponding place they were removed from. After the disassembly set the box aside. Then reverse the process for reassembly. It may sound kindergarten, but, it keeps the subtle differences from biting you in the ass and it keeps the bits organized and out of the way while you work on the project.

Make sure you are using the correct grade of bolt... then I'd try a 1/4 drive beam torque wrench...
sometimes when using a 3/8 ball click torque wrench the barrel is set to the next higher scale... the beam
type is fool proof...

Beam type...
[image: Posted Image]

I have done the valve service on my 02 twice and never broke a bolt.i use a beam style torque wrench for inch pounds. and yes the manual says to aaply oil but i dont put any extra on.

I am using a 1/4 drive wrench, so even if I am WAY off it wouldn't be a pound off. I am thinking the cuplrit is something in the bottom of the blind hole, and instead of the bolt seating, and then stretching to the correct torque, the bolt is bottoming out and twisting apart at the weakest point, which would be close to the shoulder where it first starts to taper. Normally I would expect the bolt to torque down

To re-iterate, I am using 100% OEM bolts, both new and reused have been tried. I have used the cardboard idea int he past on engine rebuilds, but this time I just kept the bolts in the piece in question...no worries about mixing them up that wya. The torque wrench works fine for the other bolts, so I am not concerned it is way off.

I have considered taking a spare bolt, tightening it up in the vice on the threaded portion, and using my torque wrench to break it just to see if it snaps before 9 ft pounds.

Quote

I have considered taking a spare bolt, tightening it up in the vice on the threaded portion, and using my torque wrench to break it just to see if it snaps before 9 ft pounds.


Thats an idea. Maybe a bad batch of Bolts/Metal.. If so I would use another vendor for ordering more..

perhaps the threads are crossed in the head? causing a section that is difficult to tighten snapping off the bolt?

I would get a tap tool and run the threads.... just my 2 cents

Dan

You might want to check a few things closely. 1) make sure the threads in the head are good. 2) check for debris in the hole from the broken bolts. 3) make sure the hole is dry, a puddle of oil in the bottom will lock up the bolt before it is tight. of course make triple sure the bolt is not too long.

I talked to the best wrench I know and he has seen this before...The cam holder is deflecting when you torque it all at once.. he suggested using the cross pattern to torque all the bolts to 30 inch pounds then to 65 then to the finial torque setting.... Also it critical that the torque wrench used its in the upper 33% of the scale...

good luck my friend

Dan

The definition of insanity is doing the same thing twice and expecting different results. Having tried my old bolt, one from another VFR, and then a new one I pretty much ruled out a bad batch of bolts etc...so the next step was checking the hole...it checked out fine, no moisture and the toothpick I probed down with came out clean as a whistle (why are they so clean anyway???)

I decided to start over, and I backed off all the bolts. With a new (used) bolt loaded in, I tightend in ever increasing steps using a criss-cross pattern. Either that did the trick or the 4th time is the charm....either way the cam holders are torqued down.

Thanks for all the suggestions!

Now lets not have anymore issues and the next post be a video of you riding..

[image: View Post]marid2apterbilt, on 10 March 2010 - 06:32 PM, said:

Quote

I have considered taking a spare bolt, tightening it up in the vice on the threaded portion, and using my torque wrench to break it just to see if it snaps before 9 ft pounds.


Thats an idea. Maybe a bad batch of Bolts/Metal.. If so I would use another vendor for ordering more..


That will only recreate the torsional forces. When you torque a bolt, you're creating torsional and tensile(pulling) forces.

[image: View Post]SEBSPEED, on 11 March 2010 - 06:50 AM, said:

[image: View Post]marid2apterbilt, on 10 March 2010 - 06:32 PM, said:

Quote

I have considered taking a spare bolt, tightening it up in the vice on the threaded portion, and using my torque wrench to break it just to see if it snaps before 9 ft pounds.


Thats an idea. Maybe a bad batch of Bolts/Metal.. If so I would use another vendor for ordering more..


That will only recreate the torsional forces. When you torque a bolt, you're creating torsional and tensile(pulling) forces.


My thought was that the torsional forces were occuring before the tensional forces, thus causing an early breakage. I may still try this as it seems interesting.

yet another reason to not check the valve lash. :)

[image: View Post]timmythecop, on 11 March 2010 - 07:54 AM, said:

yet another reason to not check the valve lash. :)



now that is a bad excuse not to do maintenece

I ran into a similar sort of issue, doing cam chain tensioners on v4 magnas. I was shearing off the tower hold down bolts. Turns out I was using the tq spec (from memory) for the wrong bolts. The spec for the bolts 6x20 was 7-9 ft/lbs and I was going for 14 or something like that. So I fired up the torque wrench a played. The bolts consistently sheared around 12. It took 22 for same size low grade ACE hdwe bolts to shear. So, while correct torquing is important, realize the bolts are VERY soft.