C3500 front spring reinstallation

[1ton-o-fun]

Miles, please keep your ordering info from T&E handy, as there might be one of those tools in my future!

 

[Miles B]

The tool arrived. It's made in Taiwan and in a blow molded case. Looks identical to the OTC, even has the same pictures on the label and lists a Ford part number on it. I trust Taiwanese made stuff. Saying that, the threaded rod has some seriously large flats machined down each side. I don't understand why. There is what appears to be a thrust bearing above the spring plate, so it shouldn't be tempted to rotate as you do the nut up. I reckon they've machined away more than 50% of the thread. The OD of the thread is 19mm and the width across the flats is only 12.9mm. I know a high tensile M20 thread is supposed to be good to a 15 ton proof load, and M18 is 11.7. I'd just be more comfortable with all of that thread. On the plus side, the tube nut is threaded about 25mm deep, so that should help to spread the load. Of course it would be nice if there was more. The spring plates themselves are nicely cast but I could stand to see another few mm of thickness for springs this heavy. There are no load ratings. That would've been really nice.

 

[Miles B]

OK I got one spring in. It is not a fun job. GM definitely designed the front end to be put back together their way. I just don't feel comfortable doing that, and it wouldn't have gone in anyway with my control arms. It took me an hour to get each arm in. I tried every angle, one side first.. once they were "in" it still took a long time to line the holes up with the holes in the bushings. I ended up making a 1/2" and 5/8" tapered drift to center them by hammering the drifts through after each other. No way known I could've gotten that lined up with an angry spring in there.

Anyway.

The hard bit is clearing the top of the spring past the lip on the chassis. Unlike later models, the lip hangs down low. Later models, the lip is raised. You can put them in by hand. I used 6 out of 8 coils for the tool, and squeezed the spring almost 2 inches. I don't want to know how much force is on there. Probably closing in on 2 tons. I don't see any way I'd have done it without this tool. I took the spring insulator off for a little extra room, and stuck it up in the chassis with a few dabs of seam sealer. Seamed to work. Heh.

You want to be very careful assembling the tool in the spring. Make sure the pin is properly seated in the top plate. Make sure the key is properly seated in the bottom plate on the deeper side of the plate (it sits at an angle). The tool is LONG, so it hangs out the bottom of the spring a long way. This has to be stuck through the control arm hole where the shock goes. And the tube nut on it is FAT. It makes it a lot easier if you take your die grinder and open up the shock hole in the LCA. You'll see the inboard side is way open already. I guess GM are anticipating tool clearance on that side for their method. The outboard side of the hole is a straight edge. I rounded that so that the center was about 1/4" further out. This is a HUGE help. Finally I got the spring to slip past the chassis lip and it's smooth sailing from there. Nerve wracking winding that spring up tight enough though! Apparently the force I put on it was a little high, because I bent the pin that holds the top plate on the shaft. I'll have to make another one. Might see if I can get something a little stronger. Opening up the LCA hole on the other side a little more should mean I don't have to go as tight on the tool.

You want to have a lightweight tie-down strap ready. Just the kind that you pull to cinch will do. Wrap one end around the UCA, and once you get the spring crammed up into the hole and the bottom seated at 12 o' clock, you don't want it coming out again. Stick the hook under, cinch it, and it holds the LCA up and the spring in place. Then I just went and got my trusty 8x2 and used the hoist to push the LCA up enough to put the spindle on. If I had it to do again, I would've taken the rotor off before I pulled the spindle. I need to repack the bearings anyway, and those suckers are heavy after you've been pushing that spring in for 30 minutes.

This job sucks. Get the tool. Grind open the LCA hole. Have everything ready and still be prepared for your truck to be off the road for a while. For reference, I can get a first gen Camaro on and off the hoist in one day including bushings, ball joints, tie rod ends and idler arm. This takes a lot longer. My 4WD 3500 was a walk in the park. Just get the torsion bar tool and nothing is even a sweat.

 

[KRS1]

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[Miles B]

My GM service manual specifically describes how to use the LCA to compress the spring without any compressor, but it does it with the spindle already bolted up. If you did it this way, it would compress the spring straight. It doesn't say anything about using a chain to bind the spring because of the difficulty getting it back in. It says to chain the spring to the arm so that it doesn't fly if you lose grip with the jack.

I used a tool to compress the spring before putting it in, and once I cleared the chassis pocket, the arm just folded up into place nicely.

So please, enlighten me on how I didn't get the spring in the pocket, and how I've dealt out dangerous advice. I'll be happy to listen and remove anything dangerous.

And I've not ever seen a shop that will "band" a 1400lb spring and send you on your way. I can't imagine how you would put a compressed spring in there, bolt up the spindle and then cut the bands safely. One at a time? It would go off like a bomb.

 

[someotherguy]

Lots of dangerous advice in this thread.

GM Dealership Service book says to use a chain to bind the spring before removal because of the difficulty of compressing it to get it back in.

It also warns specifically of not using the lower control arm to compress the spring.

The frame pocket has a ring of "fingers" that the top of the spring needs to sit in to prevent spring movement in the frame pocket. It is geometrically impossible to correctly seat the top of the spring while jacking up the LCA without smashing those fingers.

Long story short, take your springs to a truck shop and have them compress and band them. Sooo much easier, safer, and less time consuming.

OK..