TR4/4A Rear leaf spring bolt torque

[Popeye]

Hi all,

I am reinstalling my rear leaf springs. The manual says the front bolts should be torqued to 30–35 pounds. The rear bolts to the same; 30–38 lbs.

The front is a 5/8 bolt, and 30 lbs seems awefully low. Is this the correct toque?

 

[TR3driver]

Just curious, which manual is that? Mine says 28-30 in the front and 26-28 in the rear. Same numbers in the TR3 workshop manual as well, so I'm inclined to think they are right. Never had any trouble with them (but I didn't bother with a torque wrench either).

 

[Popeye]

Thanks Randall. I am using the blue TR4/TR4A manual. My torque numbers are from memory and may be off by a little. But the minimum torque for both ends of the leaf spring are 30 ft-lbs.

That just, intuitively, seems like a low torque for a 5/16 bolt. I will stick with that value until proven orherwise. (As an aside, the manual references a 1/2" bolt.)

 

[TR3driver]

The pin body is pretty big, 1/2" sounds about right (don't have one handy to check). But the threaded portion is smaller and also has one side cut off (to keep the flat washer from turning). The parts catalog shows the nut as having 1/4-28 threads (even though it is 3/4" across the flats).

This is from a PDF, but matches my copy of the TR4 workshop manual 2nd edition (with TR4A supplement) in the blue binder

 

[Popeye]

Thank you Randall. I will look when I return home - I am traveling at the moment (it's my father's birthday).

 

[Geo Hahn]

Given the trouble many have removing that pin plus the fact that it is secured mechanically with a split pin - I never thought to consider a specific torque. In any case, with the split pin you have to tighten more or less to get the holes to line up.

 

[TexasKnucklehead]

...not to mention the nut isn't doing much but keeping the bushing from wandering off the pin, and keeping the center of the bushing from spinning on the pin.

 

[Popeye]

No split pin on the 4A; instead a little bigger bolt (5/8 UNF on the 4A vs 1/2 on the 4) and a nylock nut.

Again, I plan to follow the manual unless advised otherwise. Recognizing that amateurs like me tend to over-torque, 30 ft-lb just seems low!

(Note, I will check the manual again, when I return home.)

 

[TR3driver]

My apologies, I totally missed that this was a solid axle 4A. My bad. Everything I posted above is wrong, so please ignore it.

 

[Popeye]

Everything I posted above is wrong, so please ignore it.

No, you were very much right - and I was wrong - in the torque values in the tech manual. Picture below to prove your innocence!

i will torque to the equivalent clamping force for the bigger 5/8 bolt, namely 36-38 ft-lbs. This is basis the calculator at https://www.engineersedge.com/calculators/torque_calc.htm

 

[TR3driver]

Strange position, having to argue that I really was wrong

But, that's the TR4 section (same thing I wrongly copied above). On the next page is the TR4A supplement, which shows

 

[Popeye]

>scratches head<

You mean i've been torquing to the wrong values... DOH! (I would guess most are the same.)

You say you were wrong, yet I say it is "right" that I learned something in the thread! :wink-new:

Seriously, thank you for your - and all others - contributions. I really learn a lot here.