The Stovebolt Site Forums The Shop Area General Truck Talk 3/4 ton leaf spring improvement?

I have a question regarding replacement springs for an AD 3/4 ton pick up truck. And yes, I have done a search going back 10 years for springs and found no subjects.

The springs I'm referring to are the leaf springs, front and back. In my case, I'm mainly concerned about front springs.

I see all kinds of spring kits for 1/2 ton AD trucks, but never anything for 3/4 ton trucks. What I'd like is a better ride. My springs are so stiff that it rides like it's got no suspension at all, and it takes even small bumps way too seriously, resulting in the truck skipping all over the road and experiencing bump steer. Makes it kind of a challenge to drive on rough roads.

Are there any spring kits to replace these springs with either softer steel springs or perhaps fiberglass springs? There's only so much improvement I can do without going to an IFS, but I'd like to make it a little softer-riding.

I am not looking for a drop in ride height. I am of the minority that like my truck having a truck stance, and not slammed to the ground pretending to be as low as a car. In fact, I want to convert mine to Napco 4WD, so I probably have to keep mine riding high. I just want to soften the ride.

Any sources or leads that I can look into?
Thanks.

So your steel might be "worn out" and flexed too many times. You can measure your steel leaves and have new ones made. This is not likely. Although you've probably lost some of the arch over time and you might want to get them re-arched. Get an extra 1" or so of arch if you are going for a NAPCO. You can also have an extra leaf added, which is what I did.

The most likely problem is that you've got rust and road grit between your springs and they have worn grooves into one another. Now they stop acting like leaves which slide past one another to one giant chunck of steel that has little give.

Don't add grease to them to help them slide, as the grease will only catch dirt, dry out and make the problem worse.

Take all your springs apart and grind away that grit, rust, and grooves to make a nice smooth surface. Be carefull with the grinder and keep a light touch. You don't want it to get hot and loose it's "spring temper". Some people will claim that you should keep the springs aligned in the same direction as they were originally, so if you are concerned identify the fronts and backs and left side and right side.

Now that they are all nice and smooth, paing them with some good paint to keep them from rusting rapidly again. Now put some polymer liner between the leaves. I forgot where I got mine, but it is standard stuff now days. I had to trim it to fit for width as my rear leafs are 2 1/2" wide, but you might be able to find some that fit your width exactly.

The polymer liner acts like a permanent lubricant between the leaves and allows them to slide past one another. I have seen a noticable difference on mine. When I jump up and down on the bead, the springs actually spring. It didn't do this before.

Good luck.

Hot Rod,

Regarding your front springs...they are the same springs
that are on a half ton for the Advance Design series.

I need to do some work on mine as well and now I know that the springs are the same does anyone know if the U-bolts are as well?
In checking the assembly manual they carry two different part numbers.

The 3/4 ton front u bolts are slightly larger than the 1/2 ton.
9/16" vs. 1/2" I think, I don't have a parts book in front of me.

That's excellent advice.

I did see a couple of spring options in Speedway Motors catalogue for the 1/2 ton AD, one was a 2-leaf and the other something like a 5-leaf. They both were advertised to provide a 3" drop compared with stock. But you know what, my stock springs are so shot that they have no arch left in them at all in the front. They're better in the back, that one has some arch and probably just needs cleaned up as was mentioned before.

I'll bet even with a 3" drop in front compared with stock, it'll still probably ride higher than it does now, since I have no arch left.

It's just that Speedway wants kind of a lot for a set of springs. I'll try some other sources like Langdons, etc. to see if anyone else carries them.

But thank you very much for your informative reply.

If you want to stay at original ride height I would do what jhaa said previously. The "poly" liner is available from almost all the parts suppliers. If your springs aren't ridged too bad you can grind them smooth and reuse them. You can get them re-arched for any ride height you want at any quality spring shop. If you get your springs apart and find that they're deeply grooved I'd toss 'em. You can get stock replacement springs from several suppliers and even JC Whitney carries them.

I ordered my new replacement springs from Jim Carters
http://www.oldchevytrucks.biz/47_55/full.asp?page=118

At only about 100$ each I thought that was a good. Since your springs are shot I would replace them with new. I also added two short leafs from my old springs. This should raise the vehicle "two leaf widths" without stiffening the ride. I also ordered a replacement center bolt, which is excesive long, to account for more leafs, then trim off un-needed length. I purchased the poly liners but never used it. I didn't want to completely dissasemble the my brand new springs.

See in picture how last two leafs are doubled and centerbolt needs triming
http://good-times.webshots.com/photo/2448427800100505384SmDfIS

Unfortunately I can not tell you about the ride quality since truck isnt drivable yet.

But for the cost I would start by replacing those old springs and then go from there.

Ron,
"If you want a soft riding 4x4, get a new one"?

That's kind of a cop out isn't it? I've been able to get leaf sprung cars to ride smoother. One way is with fiberglass springs. Another is with new springs and shocks.
When I look under the truck and see something like 7 or 9 rusty leaf springs with no arch left in them, it's pretty obvious to me why my truck rides so rough. It's also apparent that by buying new springs, rather than a whole new truck, I can get a better ride. How many people do you know will sell their AD truck and buy a new truck rather than just buying new springs?
Sorry, but your response kind of lit me up a little.

Real men to real things? Heh heh heh...
Okay.
The reason I want a softer ride is because I live in New Mexico, the land of undeveloped roads. Even the paved roads, which is probably only about half, are often potholed and very rough. I am south of the border here, you could say.

My '52 GMC will definitely not be a pavement queen. I want to be able to drive the hell out of it on and off road. It's just that real men don't need the kidney damage, if you know what I mean.

I know I will never get the ride of a new truck, and that's okay. That isn't what bothers me. What bothers me is how badly my truck handles when it has some speed built up and it goes over some of these bumps. It is a real handful and has threatened to skip itself right off the road. When I looked at my springs, I could see why it rides like a rock.

I checked Speedway Motors, which does sell the 1/2 ton springs, and found out in this thread that they will fit a 3/4 ton too. But Speedway seems to want an awful lot of money for their springs. They're about $340 bucks. I mean, if that's the typical price, I'll pay it. But I was able to get new springs for my '68 Firebird for almost half that much, and couldn't believe they wanted that much for them.

Having the old springs re-arched is a possibility too. And the stuff you put between the leaves is an excellent idea. I'll keep the rear springs and restore them. But the front could use about half the leaves, I think, without seriously compromising anything. And if I can get a 50% improvement in the ride quality, I'd be very happy.

In my opinion, folks can keep their new trucks. I love the looks and simplicity of my old truck, and the supergranny gear so that I can go do some serious off-road 4-wheeling. That's also why my GMC won't get a perfect spit-shined paint job. I'd just scratch it all up anyway. No, my truck's always been a worker. Not a pavement queen nor a trailer queen. And it HAS gotten trophies when trailer queens didn't, just because I think people have seen it was no trailer queen and they liked it.

Stay cool, and Happy Thanksgiving.

rdavid makes one very good point, and I'll repeat it here in my own words: It is almost always about the tires. What I've learned from riding early rigid-framed Harleys and driving lotsa different stuff - logging trucks, Jeeps, Harleys etc. - on bush roads hereabouts is that tire construction and pressures are absolutely crucial to handling characteristics. Forget what it says on the sidewall: That is for full-load smooth highway high-speed driving in very hot weather. Anything else requires lower pressure, and depending on conditions, what will work best is probably a lower pressure than you'd think.
Radials in 33/12x15 sounds okay. I have 235/85R16's on mine, and when I'm empty on a rough road I'll run between 30 and 40 psi in 'em. With a full load they'll get twice that. I don't have tire failures because, as hard as I make them work, I watch them carefully under weigh. If they get too hot I'll bump the pressure. If they ride too rough I drop it. If it's both, I'm driving too fast for conditions. Once I started sinking into soft sand and I dropped the pressures to 9 psi. No, I did not leave them there after I drove out. On a logging truck I ran I could change pressures in the drive tires as I drove, from the cab.

I believe my tires are Uniroyal 275/65R-16 all season truck tires. Yep, I got rid of the old school bus tires long ago. My wheels are 8 lug year 2000 GMC chrome wheels, and if I can keep stray dogs from peeing on them, they look pretty good.

The ride IS better, but I believe new springs and bushings, as Ron says, will make a difference.

Thanks.

I had a really rough ride in my 59 1/2 ton. I took out the springs, wire brushed and painted them, then used the Poly liner that has been mentioned. I got mine from the Truck shop out of Ca. I also replaced the shackle bushings.
Wow, what a difference in the ride. It still rides rough, but much better than before.
I eventually had a leaf break after a really long and rough ride in the desert. I replaced the front springs with "rod ride' springs from Eaton. They were the OEM supplier,and I ordered the springs for stock ride height. they ride about the same as the old ones with the poly liner.

Curly