Dam.... Broke a bolt

[mvalenti]

Assembled the head torqued everything down. Cam shafts in, one more bolt celt like it was made out if clay.... So one of the cam retainers is missing a bolt....

[rapidray]

Remove that cam, center punch the bolt remaining in the hole, pack the hole with grease to catch chips, use a LEFT hand drill bit to back out the reminder of the broken bolt. Ray.

[FLHGSRay]

I broke off a couple of those on my Z1 back in the day, before I realized the Chilton manual I was using was wrong on the torque specs. Shouldn't be hard to get out. When you do, make sure nothing is in the bottom of the hole.

[mvalenti]

Thanks guys. Just discouraging... Missed the whole season..

[mvalenti]

Pondering..... considering how easy the bolt broke, I'm thinking I should replace all. Tough to get an M6 x 40 Flange bolt locally, but I can get plenty of M6 studs and flange nuts.... Thoughts?

[almarconi]

I would use the bolts.

What happens if one of the nuts comes loose?

[mvalenti]

Good point. I talked with one of the machinists here, one of the old timers. He suggested since the bolt is broke deep in the hole that I take another M6 and drill it out on the lathe, thread it in the hole (dont bottom out) and use it as a drill bushing.. Genius! I thought! I'd hate to have to do helicoil work in the head with a hand drill and a weird angle.

[Nessism]

The stock bolts are hardened, similar to a SAE grade 8 bolt. These bolts are strong, but apparently quite brittle since breakage is not uncommon. Many times when these break you can just spin out the nub. Here's to hope anyway. Using an old bolt as a drill guide is a fine idea, particularly if the jagged broken bolt edge is not flat. Most likely the nub will spin out well before you get near the threaded diameter though, so making a bushing isn't mandatory I'd say.

[Steve]

Tough to get an M6 x 40 Flange bolt locally, but I can get plenty of M6 studs and flange nuts.... Thoughts?

Around here, Auto Zone has a selection of flange bolts. Not sure if they have M6 x 40, but it might be there.

The stock bolts are hardened, similar to a SAE grade 8 bolt. These bolts are strong, but apparently quite brittle since breakage is not uncommon.

Not doubting you on the "hardened" part, just wondering why they would have to be.

After all, they are going into aluminum with very low torque settings.

.

[FLHGSRay]

I've spun those out with a pneumatic scribe before.

[tkent02]

Not doubting you on the "hardened" part, just wondering why they would have to be.

After all, they are going into aluminum with very low torque settings.

.

That's a good question. Are they actually hardened bolts, or have they been hardened over the last thirty years by heat cycles and overtorqueing? Just for the record I haven't had any break yet. But I have well calibrated fingers.

Unlike the exhaust screws. And the oil filter studs.

[Nessism]

The screws have a 9 on them.

[mvalenti]

Mine have a 7

[Nessism]

Mine have a 7

Maybe that's the problem.

[mvalenti]

dam..... I cant find ones with 9's or 6's....