Crank pulley bolt...Lost again!!

[jrvariel48]

Joe in the past when I have experienced the exact same issue as yours even with the blower belt helping the dampening. The problem was due to a balance issue which turned out to be the flywheel area. Even red locktite would not help. I would suggest try green locktite its a lot stronger than red if the bolt still comes loose after going to green then checking the bolt regularly to be sure its tight would at least keep the bolt in place and not on the road someplace.
Ronnieroadster

Great advice as usual Ron, thank you

 

[jrvariel48]

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

 

[jrvariel48]

Could there be a problem with the space between the pulley face and crank face? It's about a 3/16" recess.

 

[glennpm]

I think you should look at the run-out of the pulley, i.e the amount between minimum and maximum at a point on the pulley.


I'd pull the plugs and try to get a helper; or turn crank bolt manually as you watch; or make a starter switch to bump it (ignition off).


If this static view isn't conclusive, I'd run it motor running through different RPMs with a helper and watch to see if you have dynamics of the pulley and/or crank snout vibrating from bending forces.

 

[cadillac512]

I don't think the distance from front of hub to end of crank is a problem as long as it's sitting properly on the machined register of the pulley and crank.

Your washer is THICK, right? Like 3/8" or so?

Joe Abbin recommends 130-145# of torque on the crank bolt, and that sounds about right.



Terry

 

[19Fordy]

I just went and checked the bolt head size of the crank pulley bolt holding the crank pulley to my 8BA crankshaft. The head size is 7/8 in. I am using 8RT water pumps and the pressed steel 49 Merc wide belt crank pulley

The 5/8 size mentioned by others in this thread seems to small to me.
Could it be a misprint? Look at what the 49-51 Merc repair manual says below..

FYI: In the 1949-51 Mercury Manual, on page 72 of Volume 1 it shows the crank pulley to crankshaft bolt to be 5/8-18 x 1 1/8 long and that it's tightened to 130 to 135 foot pounds for the 1949 and 1950 Merc and 45 to 55 foot pounds for the 1951 Merc. only.


Clarification of this issue would be appreciated.

 

[Ronnieroadster]

Joe the washer under your bolt should sit on the inner lower surface of the hub assembly not on the face of the outer pulley which is a higher surface. The washer should be thick as mentioned above at least 3/8 inch and as large a diameter possible when sitting into that recess. As to the idea the torque needs to be extremely high heck the stock Flathead washer and bolt would never set at such high torque numbers the washer is to thin the bolt is mild steel and the thread is in a casting. Toque at 65 foot pounds is plenty thats all i ever use {on street engines and all out very fast engines} when the washer is thick enough and large enough in diameter to hold the pressure.
Ronnieroadster

 

[JSeery]

Toque at 65 foot pounds is plenty thats all i ever use {on street engines and all out very fast engines} when the washer is thick enough and large enough in diameter to hold the pressure.
Ronnieroadster

65 may work fine, but all of the Ford spec's I'm seeing are around 130-140.

 

[Mart]

Here's an idea. As you have bolts nearby, why not make a plate with a hex hole in the middle that drops over the bolt head and then has the other bolts going through it to lock it in place? Or some other sort of tab washer type device, or even some locking wire attached to an adjacent bolt.
That said, a good bolt, a decent washer (turned up in a lathe as a custom job) and a spring washer ought to be all that is required.
Just thinking out loud.

Mart.

 

[jimvette59]

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

 

[GOSFAST]

Could there be a problem with the space between the pulley face and crank face? It's about a 3/16" recess.

Hi Joe, can you measure that pulley opening across? It appears (from the photo) the factory washer will not fit that particular setup?

The OEM Flathead washer measures .312" (thick) x 1.560" (O.D.) x .660" (hole size).

The Pontiac washer measures .310" (thick) x 1.625" (O.D.) x .655" (hole size).

The OEM (8BA) Flathead bolt measures 1.625" (O/A length) x 1.150" (UHL threaded) x .875" hex nut (.470" thick).

The Pontiac bolt measures 2.000" (O/A length) x 1.600" (UHL threaded) x .937" hex nut (.400" thick).

Thanks, Gary in N.Y.

P.S. I know there's different opinions above on the torque for these size bolts but I definitely would want to at least be in the right neighborhood! For instance, if you back the torque way down your wheel lugnuts who do you blame when your wheels "fall-off"?? (More or less kidding here, maybe)

 

[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

 

[glennpm]

That will be a good bolt up. Do yourself a favor and drill the bolt for safety wire now. If you find it’s getting loose, tighten it up and wire it.

Glenn

 

[Hal Beatty]

And I would have to agree with the safety wire suggestions. .041 diameter SS wire will hold a lot if it's properly installed.

 

[jrvariel48]

Looking at the pulley, I have three button head screws that I'll have to change to hex head to drill them for the safety wire.
I'll wire from crank bolt to one of the three bolts. Should I wire the remaining two bolts together?

 

[glennpm]

It would be a good idea. If you don't want to use hex head bolts, maybe limited wrench clearance, use Allen head and drill those.


Glenn

 

[Tony NY]

I would also use regular socket screws (drilled). Some info on button head screws: "Button head screws, set screws, and studs cannot be torqued like ordinary screws. These screws have a small contact area where the tool is applied compared to other kinds of head types (e.g. hex, socket, cap, Torx, etc.) Torque on these screws must be reduced. If this is not done, either the screw, the piece being fastened, or the tool will be damaged."