classics

My 66 corv.B.B. with power steering - three times the bolt that goes through the bracket (alternator) into the head keeps snapping. The belts are all properly aligned and I've been using a grade 8 bolt (maybe too brittle) - should I be using grade 5 ??? Any suggestions? Is it suppose to be a special bolt?

John 65

Vogie

Can you look at the bolt and tell if it is failing due to shearing or torsion? Is there a possibility that the bolt is bottoming out before tightening fully on the bracket? I just thought I would throw a couple of ideas into the discussion to get things started. Good luck.

magicv8

BB with PS:
bolt that mounts 3 brackets below the alt to the head is GM 12245
bolt that mounts the alt base to the bracket is GM 9418633
bolt that mounts the other end of the alt base support bracket to the head is GM 180134

Usually a bolt with a GM part number is not standard hardware for some reason (like the 4 bolts that mount the center of the rear spring).

JohnZ

I think member "67-427c.i" (Roy) went through the same drill several months back; he can tell you what he did to stop the breakage.

67-427ci

Don: I installed power steering on my Coupe last year and immediately experienced the same problem. I used reproduction bolts from Paragon & LIC, grade 8 & grade 5 bolts all with the same results. After a few hundred miles they all snapped off at the head. My pulley alignment is good (as far as I can see).

This spring I made a bracket that goes from the bracket mounting bolt to the threaded tab on the intake manifold hoping it will give it a little more stability. So far so good; a little over 1,000 miles and the bolt has not failed.

Don't laugh at my bracket, I know it is not correct (like the rest of my car). If it continues to hold I'll make it look better.
Roy

classics

Roy - I'll give it a try - thank you for your reply and pic. Don

classics

Thank you

67-427ci

Don: I forgot to mention; I used a piece of 1/2" pipe for the spacer.
Roy

427435

I wonder if the reproduction bolts were improperly heat treated resulting in hydrogen embrittlement? This is especially common with grade 8 bolts from China.

You might go to a good hardware supplier like Fastenal and just try their grade 8 bolts and skip the repo ones.

dazvet

I had a similar problem some years ago and finally discovered a bend shaft on the alternator, the vibration was killing the bolts. Another alternator cured the problem, something to consider.

Avispa

Not sure how clearly you can see it in these pics, but in addition to the three point bracket, there is a strap that goes to another hole in the block/head, and supports the end of the three point bracket that on the alternator. The other end of the strap bolts over the top of the PS pump bracket. Without the strap, you'll kill grade 5 bolts for sure, and possibly grade 8s.

Yes, my #7 spark plug heat shield is missing. Just haven't ordered it yet.

Ironcross

A few BB alternators and brackets. The Corvette bracket is the same as the Camaros bolted to the head and made from cast iron. All OEM stuff.

JohnZ

The Corvette setup with power steering is completely different than any of the passenger car mountings; on the BB Corvette, the crank/water pump belt drives the power steering pump, and a separate belt from the power steering pump drives the alternator, which has a 4-piece mounting bracket unique to that application.

newcastlegreg

The forum needs to solve this problem!!! This is an awful problem that I have been fighting for years. someone is really going to cry when they can't dig the broken bolt out of their expensive cyl head!! I have tried to find an aftermarket setup- that would be best. Let's keep this thread going and fix this. I think Roy is on to something...Everyone keep talking-pretend it is a sidepipe thread!!

classics

Ttt

John 65

Heres the bolt that keeps snapping. Was this a problem when new also ? Must be some solution.

wmf62

i can possibly see why it breaks, the outer end is unsupported.

i suggest you make a bracket that goes between the 2 bolts i circled in yellow. just a simple piece of flat bar bent to fit under the bolt heads, do not use a spacer on the bottom bolt in order to get a straight shot at the under bolt; bend the bar to fit.



Bill

Tonytz06

If the brackets are after market, their is a good chance they are made of thinner material leading to insufficient support. I had a problem like this on a small block, the supporting bracket was thinner, thus weaker and allowed some vibration. I located some original brackets and solved the problem.

magicv8

Here's a pic of my GM brackets with a piece of sheet aluminum inserted as a mock up
of a bracket to the pump bolt. I think the PSpump bolt indicated above is too far back
on the block.


The only bolt that looks like it would give more support if a bracket went to it is the
corresponding hole in the opposite head.