1972 torque specification

[Ron S.]

I would like to know the torque specs for the three bolts on the brake dust shield? the large one is a grade 5 and the other two are grade 3. I also need the torque specs for the calipers. Thanks Ron

[Edward J.]

Re: 1972 torque specification

Ron,

The caliper mounting bolts are 70ft lbs
The lower shield bolts and nuts are 70 ft lbs.
The large upper shield retainer is 90 ft. lbs

[Ron S.]

Re: 1972 torque specification

Edward, Thanks for the torque specs. Ron

[Joe L.]

Re: 1972 torque specification

I would like to know the torque specs for the three bolts on the brake dust shield? the large one is a grade 5 and the other two are grade 3. I also need the torque specs for the calipers. Thanks Ron

Ron------


First of all, the two bolts which fasten the spindle to the steering arm and also secure the disc brake shield are NOT grade 3. In fact, there is no such thing as a grade 3 fastener that I am aware of. Those bolts should be SAE grade 8 (6 radial lines). If what you've found on the car are anything else, they are improper replacements.

The large upper bolt is 11/16-16 thread size. The torque specs on this bolt is 120 lb/ft.

The 2 lower bolts (mentioned above) have a torque spec that I have never found published in any GM reference. I have looked high-and-low for this and, so far, I have not been able to find it. However, for 1968-82 Corvettes those bolts are size 1/2-20. The "standard" torque for a bolt that size and grade 8 material grade is about 95-100 lb/ft. So, that's what I use.

[Ron S.]

Re: 1972 torque specification

Joe, Thanks for the info and the grade three was a type-o it should have been 8. Anyone else have a thought? Thanks Ron

[Alan S.]

Re: 1972 torque specification

Hi Ron and Joe,
I found this info in the 71 CSM, Steering 9-30.
"1. Place steering arm in position on vehicle and install retaining bolts.
2. Install nuts. Use only the special locknut listed for this use in the Parts Catalog or an equivalent Chevrolet approved part."
Then in the rear Specifications Section, page 2, STEERING ARM NUTS... 70 ft/lbs..
Are these the fasteners we're talking about?
Regards,
Alan

[Joe L.]

Re: 1972 torque specification

Hi Ron and Joe,
I found this info in the 71 CSM, Steering 9-30.
"1. Place steering arm in position on vehicle and install retaining bolts.
2. Install nuts. Use only the special locknut listed for this use in the Parts Catalog or an equivalent Chevrolet approved part."
Then in the rear Specifications Section, page 2, STEERING ARM NUTS... 70 ft/lbs..
Are these the fasteners we're talking about?
Regards,
Alan

Alan------

Yes, I'm sure they are. Those specifications are not in the 1968 Chevrolet Service Mnaual, the 1969 Service Manual, the 1970 Service Manual, the 1978 Service Manual or the 1979 Service Manual. I'm a bit surprised to see that they're in the 1971 manual.

In any event, I'm still suspicious that those specs are an "anachronism" that somehow carried over from the C2 period. Here's why I'm suspicious: 1963-67 Corvettes used 7/16-20 bolts of SAE grade 8. The "standard" spec for such size and grade bolts is about 70 lb/ft. So, the 70 lb/ft spec seems very consistent with what I would expect for 63-67 bolts. However, the 68-82 bolts were 1/2-20 size. I would not expect a torque value of 70 lb/ft for a 1/2-20 grade 8 bolt, especially one that threads into a self-locking nut.

[Ron S.]

Re: 1972 torque specification

Thanks Guys, I'am still not quite sure what to torque the two with locking nuts? 50 60 70?

[Edward J.]

Re: 1972 torque specification

Ron, my 72 shop manuel calls for 70 ft lbs as does Allens 71 manuel, since the nuts are self locking once torqued they should stay the same. adding another 10lbs to these bolts should not be a worry, Since as Joe stated harden bolts and 1/2x20 dia., These bolts may very well have a higher torque in other situations.

[Ron S.]

Re: 1972 torque specification

Edward, Thanks for the additional info. I'am going torque them in the morning at 70lb. Thanks Again to all who responded. Ron