HELP!! ps/box mounting threads stripped AGAIN!

[rusmannx]

so this is the second time i'm installing a saginaw box.
my first one came apart when my scab plate (1/4") ripped in half; destroying the ps/box.

when i installed my first ps/box the bolt threads (in the box) stripped out and
i drilled and retapped at 29/64".

now, the bastardly second box did the same freaking thing!!!
it must have to do with being a 35 year old box pulled from a rusted car
in a wrecking yard.

anyway, should i just go ahead and retap with the 29/64"?
i still have the bit and the tap.

i think the reason i went to this size (recieves a 1/2 fine thread bolt)
was because some of you suggested that 7/16 wouldn't move enough material
to get a good tap. fine tread obviously for the denser thread count.

wussup crew???!!! what should the freshman do???

 

[65swb45]

It's not all about threads per inch, but thread contact depth as well. As a very unscientific explanation, if you have twice as many threads per inch, but they only make 1/3rd of the contact depth, then you've only got 2/3s of the contact you would have had if you had stayed with the course thread.

I have noticed this phenomenon in comparing the 67 and older 10 spline rear axleshafts to the 68 and newer 31 spline. The 10 spline are much deeper splined, and seldom show much if any wear on the shaft or the side gear.

My .02

Mark

 

[rusmannx]

thanks.
any other thoughts?

 

[IDave]

Helicoil?

 

[TonkaC]

I've had the same thing happen to mine. I just openned up the backside of the hole so I could put a grade 8 nut on the bolt. Doesn't look the best, but is holding up great. I've done it to two of the three bolts on mine.

Chris

 

[hammerhead]

Tonk - Three bolts? Get the right box. Shouldn't there be four in a sag?

Russmannx - Are you ripping them out while wheeling or stripping them on install?

If there is enough material left a heli-coil should work. If you can get a full steel insert they are considerably stronger. Use coarse thread. Fine thread is questionable in cast unless greatly oversized.

 

[fj40charles]

Tonk - Three bolts? Get the right box. Shouldn't there be four in a sag?

Russmannx - Are you ripping them out while wheeling or stripping them on install?

If there is enough material left a heli-coil should work. If you can get a full steel insert they are considerably stronger. Use coarse thread. Fine thread is questionable in cast unless greatly oversized.

Depend on which one you use. Many of the late model trucks use a large bore saginaw box with only 3 bolts. I had a 3 bolt sag. box on my FJ40 for many years without any issues. I wonder if the bolts stripping could be due to the way it is mounted?

 

[dd113]

Coarse or fine should not really matter but coarse is better. I have used both. Sounds like you are getting flex that is allowing the bolts to strip. I would look at your mounting system. Get a new box. $150 from NAPA. Dont mess around with steering.

Eventually you will regret it but at least you wont regret it for long

 

[rusmannx]

no no this is taking place on install.
i'm just trying to bolt the stupid box on and the threads EASILY come right out.

EASILY (definition): when the threads strip out on an unbound, properly threaded
box, before the lock washer has even compressed.

i like the bolt idea that TonkaC offered. if this works, i'll take some pictures to show you why.

 

[Mace]

Take pictures and show us what is happening and your mount..

It sounde like you have issues with mounting allingment.

 

[fsusteve]

Just a thought, yer not using metric bolts on a standard tap are you?

 

[rusmannx]

nope. standard bolts.