Bolt torque question

[perryjosh64]

Folks I posted this in general forum already but thought I try here to. Replacing water pump on 64 Ford 2000 tractor. My I&T Ford shop manual FO-20 says torque the "retaining cap screws" to 25-35 ft-lb. Bolts are 5/16-18 1-1/4in long. Already broke a 5/16 bolt replacing the thermostat but used old bolt putting it end so just assumed bolt was old/damaged so just got new grade 5 bolts for both thermostat and water pump. However when I looked up torque specs for both grade 5 multiple sources showed 157-209 in-lb (13-17 ft-lb) and 221-295 in-lb (18-24 ft-lb) for grade 8. I have another manual (Ford Tractor shop manual 1955-1960) that says 10-15 ft-lb for water pump. Any idea why the big difference in the two manuals? Should I be using grade 8 or higher bolts for a water pump? Any advise appreciated.

 

[Bern]

Manuals have mistakes in them, it's a fact of life. A water pump does not need grade 8 bolts. Stick some new
grade 5 bolts in and go with the average of the charts you were looking up. Be sure to put sealant on the
threads if the holes in the block are not blind.

 

[Tim PloughNman Daley]

Torque is overrated and many fellas do not know the proper method to apply torque. You broke a bolt when wrenching??? Must have been too long and bottomed out or you have
Popeye arms and feats of strength. Understand the scale specified - IN/OZ, IN/LB, FT/LBs... big diff and know how to convert each.

Tim Daley (MI)

 

[Bern]

Feats of strength for a 5/16 bolt? A kid could easily twist off a bolt like that. Now if he had done that with a 5/8 bolt I'd be a little more impressed.

 

[paul]

Dad and not quite as much I work on this stuff all the farming careers and he never had a torque wrench.

Just kinda do it by feel. Pretty much how the older stuff was designed.

The modern equipment that might get a person in trouble I wouldnt recommend it.

Tho the last few years it seems most come and go mechanics tighten stuff to whatever battery impact wrench they happen to be using........

Paul

 

[Tim PloughNman Daley]

Still, a 5/16 bolt snapping off by hand seems like a lot of force would be needed. Maybe he used a 4 foot fence post breaker bar? Or bolt was bottomed out.

TPD