Backhoe Ford 555 front axle wanting to seperate from the block

[bestes1206]

Guys/Girls,
I have a vintage ford 555 that keeps wanting to come apart at the front axle to where it mates with the block

No matter how tight I get the bolts 1-1/8" Grade 8 it always comes loose I even tried red loctite last time * granted it was a hurried fix and probably didn't set up properly

The threads don't seem too bad

any ideas I am bout to just weld the front support to the block which I don't want to do but I am tired of the front flexing and potentially buggering up the threads
I am not sure how I could tap out a larger thread size due to the space constraints
Basically what will happen when those bolts work loose is the radiator support and hyd tank "nose" will move up and down with the terrain the interesting thing is there are 2 other bolts that are always tight no matter the relation of lower bolts being tight loose



http://i.imgur.com/mpDitc1.jpg


http://i.imgur.com/bV331dv.jpg



http://i.imgur.com/s0BN2Gh.jpg

Ideas

 

[hosspuller]

Thermal cycling is the likely issue. The block expands and contracts each time you use it. Two suggestions. Clean the hole and bolt threads with solvent, then primer before locktite. Place a hardened SAE washer on the bolt. (not as wide as regular washers) The washer provides a bearing surface for the bolt head and allows greater tension to be developed from the torque. The bolt will then stretch and take up the cycling.

PS ... This assumes the grade 8 bolts are the original bolts specified. A lower grade bolt will stretch differently.

 

[LD1]

Did you clean the grease/oil off the bolt before loctite? oil wont allow it to stick

What are you torquing them to? Do you know the spec?

Have you tried loc-washers?

A 1-1/8 bolt put in dry should torque to about 1200ft-lbs. With lube should be about 650. You aint gonna get near that with any 1/2 drive stuff unless you have a multiplier.

 

[bestes1206]

Thanks for the replies
The repair manual states 200 ft/lb as spec for bolts
Also in a hidden section on the repair manual it states there should be shims between the block and front support there never were any
so I am going to try :
cleaning out the threads really well
finding or making shims
and lock washers with some red loctite

if that doesn't work then perhaps tack welding the bold heads not a good fix by any means but no way I could ever cut new threads in the engine block at a price that was worth it for a high hour machine

 

[hosspuller]

and lock washers ....

Forget the split lock washers. They do nothing to prevent loosening. Under heavy load they will open leading to joint failure. They are only effective in soft or thin materials or electrical terminals where the "bite" helps make the connection. I've trashed all the split washers.

See here: Split Washer Placement - Automotive Engineering other topics - Eng-Tips

 

[oldtimer 66]

I would get some brake clean to clean out the threads it comes with a long plastic nozzle you can reach way back in the hole to clean it out do it several times with air blasts in between do the same with the bolts the hard washer is an excellent idea but also check your thread depth to make sure you are not bottoming out the bolt lastly maybe you should get some new bolts just an FYI they do make 7 pitch and 8 pitch bolts in that size make sure you have the correct bolt

 

[aginn]

The wrench size is not the bolt size. Make sure what size it is before torqueing so it doesn't shear. Just a guess on my part, but unless that is a huge vise I would guess that is more like a 7/8 bolt with a 1 1/8 head. I'd hate to hear of you using a torque chart and breaking that bolt off in a really bad place.
Maybe you could use carb cleaner in that hole, and clean the bolt thoroughly as well as using the grade 8 washer. If left to actually dry afterward, there is little chance of a good bolt backing off from correct torque specs.

 

[oldtimer 66]

Ift the torque value specified is only 200 foot pounds maybe the joint only takes a grade 2 bolt or something like that because if you don't get the stretch in the bolt the joint will not stay tight

 

[oldtimer 66]

1.125 across the flats is a .75 bolt let everybody know what size the bolt actually as

 

[LD1]

3/4 boltaked a lot more sense.