Crank pulley bolt...Lost again!!

[jrvariel48]

So this is the second time my crank pulley bolt came loose and disappeared onto the road. The first time it happened, I just figured I didn't tighten it enough. I installed a new bolt, torqued it to 50lbs. with red lock-tite and it came off this morning. This is a blower motor so the crank bolt and pulley are not stock, but I'm not sure if that has anything to do with it.
Looking for an explanation.
Thanks Joe

[Lawson Cox]

Gremlins,

[39portlander]

Joe could you drill the shank and use a castle nut, You got me curious.

Get one of those remote cameras and possibly video that area by the pulley and see what is going on while driving, good luck and let us know how you make out.

[jrvariel48]

Originally Posted by 39portlander

Joe could you drill the shank and use a castle nut, You got me curious.

Get one of those remote cameras and possibly video that area by the pulley and see what is going on while driving, good luck and let us know how you make out.

Not sure if I could drill the shank, but the camera's a great idea. I use three of them on board to record A/F reading, fuel pressure, vacuum and rpm when tuning.
Thanks!
Joe

[jrvariel48]

Originally Posted by Lawson Cox

Gremlins,

I hate Gremlins!!! Lol

[earlyride]

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Just a thought, how tight is the hub and pulley onto the crank? with the added load of the blower and if it's not a tight enough fit it might cause some wobbling and loosening of the bolt that holds it in place.

[jrvariel48]

Originally Posted by earlyride

Just a thought, how tight is the hub and pulley onto the crank? with the added load of the blower and if it's not a tight enough fit it might cause some wobbling and loosening of the bolt that holds it in place.

It's a pretty snug fit as I remember it. I can pull the belts and check to see if my memory serves me right!

[19Fordy]

Are you torquing bolt to specs? Are the threads worn? Is there any type of lock washer or "spring washer" you could use with the bolt.

Here's a very good link to washers that might solve your problem. Lots of great information.
https://www.google.com/search?q=spec...hrome&ie=UTF-8

Read this:
https://vention.io/blogs/best-anti-v...-fasteners-178

Read about "Smart Bolts".
http://www.smartbolts.com/insights/l...nt%20loosening.

First thing I would do is try a brand new Grade 8 bolt.
What engine is in your car?

[jrvariel48]

Originally Posted by 19Fordy

Are you torquing bolt to specs? Are the threads worn? Is there any type of lock washer or "spring washer" you could use with the bolt.

Here's a very good link to washers that might solve your problem. Lots of great information.
https://www.google.com/search?q=spec...hrome&ie=UTF-8

Read this:
https://vention.io/blogs/best-anti-v...-fasteners-178

Read about "Smart Bolts".
http://www.smartbolts.com/insights/l...nt%20loosening.

First thing I would do is try a brand new Grade 8 bolt.
What engine is in your car?

Lotsa great reading Fordy! The crank is new as was the bolt. I'm looking into the Nord-lock washer system. They seem to hold up to just about any situation.
I was using grade 8 bolts, but no lock washer, just some red lock-tite.
Engine is a blown 1950 8BA.
Thanks Joe

[Ronnie]

I would speak with Loctite on their 800 number and get it from the people that know. The red is basically bomb proof.



R

[jrvariel48]

Originally Posted by Ronnie

I would speak with Loctite on their 800 number and get it from the people that know. The red is basically bomb proof.



R

Great suggestion Ronnie, thank you

[jimvette59]

Lets see some pictures of the crank pulley with out the bolt and spring washer.

[Zeke3]

It sounds like the torque you are using is too low. If the bolt is a 5/8"-18 and a grade 8 capscrew, the torque should be in the 235 lb-ft range, reference Craftsman generic torque table.

There is a lot of torsional vibration going through that joint to the crank pulleys. Increasing the grip length of the bolt will get more stretch in the bolt and resistance to loosening. You can increase the length by adding a thick wall spacer.

I do not recommend using a lock washer, it is just another spring in the system.

[jimvette59]

Zeke3 the pulley is longer then the end of the crankshaft.

[Zeke3]

The picture shows the crank nose, and inner hub and the accessory pulley. I assume the slot in the inner hub is for the keyway and the inner hub is installed such that it is pressing on the oil slinger and crankshaft gear.

I would fill most of the gap between the nose of the crankshaft and the inner hub with a spacer, leaving the inner hub slightly higher than the spacer. Then use a thick washer, no larger than the outside diameter of the inner hub so it does not press on the accessory pulley, as Ronnie suggested. Also, a grade 5 capscrew will be perfectly adequate at 65 ft-lb torque.

If that thing still falls out, I would safety wire it to one of the other bolts on the accessory pulley.

[jrvariel48]

So I'm having my machinist make me a 3/8" thick washer at the proper diameter (1.750 OD) with a grade 8 bolt and the Nord-Lock system. I'll torque to 65-70 lbs and check it everytime I go for a ride. I also like the thought of tie wire and will do that if I find it loose again.

I appreciate all the input and will post the results!
Thanks again to everyone!
Joe

[jrvariel48]

Originally Posted by jimvette59

Lets see some pictures of the crank pulley with out the bolt and spring washer.

OK I'll get some pics in a bit. Thanks

[deuce_roadster]

I was thinking the same as earlyride, and perhaps the 2 surfaces (crank side and bolt side) of the pulley are not exactly 90 degrees from the centerline which would permit a wobble.
Also, did you clean the internal threads of the crank with Brakecleen or lacquer thinner and blow it out before using the locktite?

[GOSFAST]

Hi Joe, appears to be not enough torque on the bolt, this will cause your problem. If it doesn't get enough torque it will eventually work its way out!

What happens is having the correct "tension" on the bolt keeps it in place!

To add to the problem, the OEM dampers are NOT a press fit to begin with, this makes the torque number even more important.

Thanks, Gary in N.Y.

P.S. It's a bit ironic but Pontiac builds share the same characteristics, the OEM damper has always been a "slip-fit", getting the damper bolt up to torque does take a bit of doing! I don't have the OEM torque handy for the Flathead but the Pontiacs must get a minimum of 150# (160# preferred) to do the job! Same size bolt/washer as the Flatheads, being 5/8-18 x 1.750" I believe?

[jrvariel48]

Originally Posted by GOSFAST

Hi Joe, appears to be not enough torque on the bolt, this will cause your problem. If it doesn't get enough torque it will eventually work its way out!

What happens is having the correct "tension" on the bolt keeps it in place!

To add to the problem, the OEM dampers are NOT a press fit to begin with, this makes the torque number even more important.

Thanks, Gary in N.Y.

P.S. It's a bit ironic but Pontiac builds share the same characteristics, the OEM damper has always been a "slip-fit", getting the damper bolt up to torque does take a bit of doing! I don't have the OEM torque handy for the Flathead but the Pontiacs must get a minimum of 150# (160# preferred) to do the job! Same size bolt/washer as the Flatheads, being 5/8-18 x 1.750" I believe?

To Gary and others about the torque.
I was just going by the torque values I found here on the barn.
I'm using grade 8 bolts so I can definitely crank it down. I think I'd like to try the Nord-Lock style washers, I don't think it could hurt for the $2.50 the set costs.

It would be great if we could all agree on a torque value!!
Anyone??!!
Thanks, Joe