Spring Hanger Bolt Recommendations
 

I'm replacing rusted rear spring hangers on my 76 3/4 4x4. any recommendations on brand, size and torque specs? i know grade 8 steel, but should I use coarse or fine thread? replacing rivets with bolts, are there recommended torque specs? where are the best places to buy these kinds of bolts? thanks for any help - mark

Re: Spring Hanger Bolt Recommendations
 

General bolt torque spec. chart. http://www.fastenal.com/content/feds...0Gr8%20Gr9.pdf When I did mine it was good and tight. Torque will depend on the diameter of the bolt. I don't remember the size off hand, measure the bolt hole and buy accordingly. I also used course thread. Brand doesn't much matter. I got most of mine at local Fastenal, or Tractor Supply.

IIRC- I also used a med. strength locktite for a little insurance.

Re: Spring Hanger Bolt Recommendations
 

When I did all the ones on my 3/4 crew cab 4x4 I used grade 8 3/8 course thread but mine were all 3/8 holes I drilled in the frame since i relocated my mounts. But never had a bolt break or loosen.

Re: Spring Hanger Bolt Recommendations
 

Donut gave a very good response. Buy grade 8 bolts of good quality and torque to the chart specs that he linked to. Use a lock washer or loctite.

I get a lions share of my hardware out of the Grade 8 bins at Tractor Supply.

Re: Spring Hanger Bolt Recommendations
 

Good advice here. One thing I would also say is that a lot of times I have found that the rivet holes are oversized for 3/8 bolts. For those holes, I would align the holes and drill out for 7/16 bolts. Also get bolts that have 1/4" of shank. That way everything has full contact.

Re: Spring Hanger Bolt Recommendations
 

A Grade 8 3/8" bolt was the factory repair for a missing or mis-hit rivet.

I tried to get them to build my truck with all bolts/no rivets, since I knew I would be lowering it, but was unsuccessful.

K

Re: Spring Hanger Bolt Recommendations
 

Now that would have been the **** right there.

On the day your truck was being built, walk in to work with spindles, springs, shackles and hangers. I'm sure there's a 1000 reasons why that wasn't possible, but in reality, building it with those parts wouldn't have added any significant hiccups in the process.

Again, its just a crazy dream.

I can just see the line supervisor standing there......

"Hey Keith, come over here. What's wrong with that little red shortbed there ? It sits lower than the other 1.6 billion trucks we've run off this line"

<Keith with dumb look on his face> "gee, I dunno boss"

Re: Spring Hanger Bolt Recommendations
 

LOL!

I love you, man....

K

Re: Spring Hanger Bolt Recommendations
 

In all seriousness it probably would have faulted out at the front end alignment rack (alignment and trim height out of bounds).

Also - we received front suspensions already put together: so the A arms, spindles, coil springs and brake corners (knuckle, rotor, caliper and dust shield) were all attached to the engine crossmember, which was set on the frame and secured via 3 horizontal bolts and 3 vertical bolts per side.

Let the "1000 reasons" begin!

K

Re: Spring Hanger Bolt Recommendations
 

That's too funny.

Had a few-12 more cups of coffee. Yes, I did use 3/8-16, grade 8. I don't remember if I got shoulder bolts, they may have been to long. I did use a flat washer on the bolt head and lock washer on the nut. I may have used lock tite also?

I did mine 4 or 5 years ago and sold the truck a couple years ago.

For me, Fastenal was closer and I also bought bolts for cab mounts and the spring bolts as I did the bushings while they were out. I did buy the 3/8ths bolts, washers by the box as most of my engine accessories used that size. Plus driving 15+ miles for 1 bolt wasn't cost effective.

Re: Spring Hanger Bolt Recommendations
 

thanks for all the replies, guys! (i wouldn't get this kind of awesome reply on the 'Vette or Olds boards i read.) i've got a Fastenal nearby: 3/8-16 grade 8, flat washer and lock washer, torqued to 44 ft/lbs (dry). that doesn't seem especially tight, but i think i'm reading the chart correctly.

While i've got a captive audience: any recommendations on anti-rust treatment for the frame, etc.? this isn't a show car restoration, just want to get the truck serviceable, and not have to do it again (i'm also on a budget...) right now i'm thinking i'll use a variety of tools to grind off as much rust as i can (there's a lot of surface rust, but nothing too deep), then brush-on POR 15 as primer (two coats, maybe dep. on $). i've used it before and it seems to work well. has anybody used Rustoleum Professional Rusty Metal Flat Rust Preventative Primer? or are there any other suggestions (similarly priced)? finally a top coat, flat black enamel (probably sprayed)? Suggestions? thanks again, guys! - mark

Re: Spring Hanger Bolt Recommendations
 

When we were building Cadillac D cars for armor jobs, the suspension was 1/2 ton Chevy pickup. Cars set 6" higher than a normal car - before they got 2000# of big block and armor.

Rolled the shift superintendants' 85 caddy in one night, it rolle dout at end of shift with fresh paint and all 87 trim. Ah, the good ol' days.

Re: Spring Hanger Bolt Recommendations
 

I drill mine out to 7/16 use fine thread with flat washers and lock nuts

Re: Spring Hanger Bolt Recommendations
 

my buddy and i did 7/16 on his truck. i think grade 8 3/8 would be good

Re: Spring Hanger Bolt Recommendations
 

took all yalls advice and finally got the hangers mounted. now its time to mount the springs, but i've got a few questions:

first, what are the proper torque specs for rear spring bolts (again, '76 K20) i queried around but found different specs (seems like 92 for the spring eye and shackle bolts and 80 for the u bolts keeping an eye out not to squish the bushings - is this correct?)

second, the shoulder on the bolts i took off the old hangers/shackles seem to be to short, part of the sleeves/shackle is resting on the threads (see pic). is this correct? The bolts are grade 8, 9/16" diam x 4.5" and i believe are OE. Also, does the fit of these springs in the shackles seem correct, should there be that much play (new shackle, new spring)?

http://forums.corvetteforum.com/memb...olt-158699.jpg

Finally, I need to buy new U bolts, it's a 14-bolt rear - what diam U bolts should I get? I've seen 3 3/8" and 3 1/2" in web queries, and when I measured the old bolts it looked to be 3 5/8"...

thanks for any info - mark

Re: Spring Hanger Bolt Recommendations
 

Just measured the circumference of the axle tube: 10 31/32" = 3.49" diameter. So, I get 3.5" U bolts, sound right or do i go larger, like 3 5/8"?

Re: Spring Hanger Bolt Recommendations
 

do you have a u-bolt flip kit on your 14b? stock 14b u-bolts don't go around the axle, there square & go over the leaf springs
Attachment 1176201

Re: Spring Hanger Bolt Recommendations
 

Mark, easiest way for the u-bolts is walk into a spring shop. Measure what you have, tell them. If your off a little, they should pick up on it. They have dies for bending the radius, and proper diameter blanks. All you have to do is cut to length, as they usually leave them long. (if you have a lift, or need longer, let them know.)

Going off memory. I believe there is a steel sleeve around the spring mounting bolts. This should prevent the shackle ears from crushing the bushing. Fit-up on yours looks good to me, as you tighten it, ears should pull in. Check the link above for the torque.
Believe I just hit mine with an impact.

Re: Spring Hanger Bolt Recommendations
 

3/4 ton 14 bolts go around the axle.
-Sam

Re: Spring Hanger Bolt Recommendations
 

semi-float? my bad, didn't catch that, thought he was dealing with a 10.5

Re: Spring Hanger Bolt Recommendations
 

The U-bolts on my 76 3/4 ton go around the axle tube and it's a 14 bolt 10.5" full floater all stock from the factory. Not sure why you would want them mounted upside down, whats to stop the threads from getting damaged? My friend had that setup on his blazer after doing an axle swap and he tore them up so bad dragging them over rocks that we had to cut them off.

Re: Spring Hanger Bolt Recommendations
 

Thanks for the replies, guys! So:

1. The spring eye/shackle bolts are OK (no big deal about the threads);
2. Torque according to the Fastenal spec sheet;
3. Don't worry overmuch about squishing bushings;
4. Best course is to take old U bolts to shop for bending.

Below is a diagram from the 1976 Service and Overhaul Manual Supplement which shows (a little bit) about the factory rear suspension set up. Mine is exactly like this diagram. I believe my rear has the FF 10.5"

http://forums.corvetteforum.com/memb...ram-158762.jpg

Thanks again, ill post pics once i get it all reassembled. - mark:tim:

Re: Spring Hanger Bolt Recommendations
 

Your 3/4 should be a FF 14 bolt 10.5

Like I said, when I did mine, I believe it was goodntite. (broke my torque wrench) I just hit them with an impact.

You can take the old u-bolts with you, or the top plate. The spacing on the holes will tell the diameter of the tube, just make sure you get the correct holes, lol. (u-bolts have to be pretty close to fitting those holes)

Mine were bad enough that a torch was used to remove them

Re: Spring Hanger Bolt Recommendations
 

Got new U bolts today, and the rear springs are in. now the problem is that neither the shocks nor the center brake hose reach their respective attaching points. both appear to be about 1.5" short (or the frame is sitting 1.5" higher over the rear...) AFAIK everything is stock, and i ordered stock replacements. the bed is off the truck, but shouldn't the shocks fit without requiring the bed to weigh everything down to where it will fit? i read on another forum that i could take a ratcheting cargo strap around the frame and spring to make it fit - is this a valid solution? what can i do to make things fit? thanks for any suggestions - mark

Re: Spring Hanger Bolt Recommendations
 

If you have to, you can. sometimes you can pull on the shock and physically extend it enough. Usually I do mine with the bed on and truck on the wheels.

Center brake hose is what concerns me. It should have enough play to reach in all scenarios. Did something get moved or repositioned?