how often do rear coil springs go bad?

[64stpside]

On my 64 c10 I got pretty bad bouncing in the rear when hitting bumps, especially when hitting a bump in a turn. I think my rear coil springs are shot. Things I have done so far to try to correct the issue:
new shocks, new trailing arm bushings (rubber) , new panhard bar w/rubber bushings.
I work at dealership and had the truck aligned this last saturday. I thought i found the issue as the thrust angle for the rear axle was +.37 deg (should be 0 deg). We got that right but I still got a bad bounce. Is there a common test as far as how many times the springs go up and down after pushing the rear bumper down by hand and letting it go? What do you guys think?

[mongocanfly]

usually new shocks helps with this...but you've already got that...usually when springs ,get weak/go bad, they start collapsing ...I wouldn't think thrust angle has any effect on a bouncy ride...is the truck lowered? that bouncy test is usually a way to check for worn shocks...you could have a bad set ..even when new...were they quality shocks or the el-cheapos?

[64stpside]

Originally Posted by mongocanfly

usually new shocks helps with this...but you've already got that...usually when springs ,get weak/go bad, they start collapsing ...I wouldn't think thrust angle has any effect on a bouncy ride...is the truck lowered? that bouncy test is usually a way to check for worn shocks...you could have a bad set ..even when new...were they quality shocks or the el-cheapos?

Not lowered, the whole suspension is stk. The rear shocks might have 40 miles on them. I think I bought these but not positive, put them on about a yr ago:
https://www.autozone.com/suspension-...64_793522_7413

I know I bought white ones cause I painted them black. I'll have to see if I can find the receipt or #s stamped on the shock.

[The Rocknrod]

I dont think bouncing is the springs, You may you need better (read Different) shocks.
The “bounce test” requires some effort. Go to one corner of the car and push down. When you let go, the car should bounce up, then settle back to at-rest height. If the car bounces more than twice, you most likely need new shocks.
Also a vid on the subject - https://www.youtube.com/watch?v=BiW0ISi8N-w

[64stpside]

Originally Posted by The Rocknrod

I dont think bouncing is the springs, You may you need better (read Different) shocks.
The “bounce test” requires some effort. Go to one corner of the car and push down. When you let go, the car should bounce up, then settle back to at-rest height. If the car bounces more than twice, you most likely need new shocks.
Also a vid on the subject - https://www.youtube.com/watch?v=BiW0ISi8N-w

I talked with the front end guy here at work and he asked what kind of shocks I put on it. He's said if the shocks I got were heavy duty then that would cause a bounce with no load as the heavy dutys are meant for vehicles with a load on them. I gotta find out what I bought.

[theastronaut]

Do the bounce test right after driving it. I've seen shocks go "limp" if they've sat for a bit and might need to be cycled a few times before they dampen like they should.

The thrust angle would probably be the panhard rod not being the exact length it needs to be for your exact ride height. They make and adjustable bar to help with that.

Before buying new shocks, add a few hundred pounds of weight in the bed to see if the bouncing gets worse. If the shocks are bad they'll have a harder time controling the body movement and the bounce will be worse. If it rides better then the shock valving is too stiff for the amount of weight on the truck when unloaded and the shock isn't allowing the suspension to absorb bumps like it should.

[PGSigns]

Tire pressure and sidewall construction also can make it bouncy.
Jimmy

[AcampoDave]

Fifty plus yeas is still a long time for truck springs. Even if they don't cause your bounce, they are probably worn out anyway.

[jayoldschool]

These things are bouncy with no weight in them. That's the price you pay for driving a truck. Throw 500lbs in the back, it will ride great. Mine has old springs, new shocks, good used trailing arms with good bushings. Bouncy when empty, great with a load.

Full dress iron head small block. Delivered it across town, drove great.

[Short 3/4]

Originally Posted by jayoldschool

These things are bouncy with no weight in them. That's the price you pay for driving a truck. Throw 500lbs in the back, it will ride great. Mine has old springs, new shocks, good used trailing arms with good bushings. Bouncy when empty, great with a load.

Full dress iron head small block. Delivered it across town, drove great.

I agree with what Jay said

[64stpside]

Originally Posted by PGSigns

Tire pressure and sidewall construction also can make it bouncy.
Jimmy

I got 255/75/15 cooper cobras, side walls were fairly easy to work with when I mounted them, not stiff

[64stpside]

Originally Posted by jayoldschool

These things are bouncy with no weight in them. That's the price you pay for driving a truck. Throw 500lbs in the back, it will ride great. Mine has old springs, new shocks, good used trailing arms with good bushings. Bouncy when empty, great with a load.

I'm concerned about getting it on the interstate with it like that. I still got to check to see what shocks I bought. The thing is, I don't know what "this is as good as you can get it" is with the stk suspension. What does that feel like?
Thanks for everyone's help so far...

[jayoldschool]

With brand new KYBs on mine, it feels bouncy. Until you load it. Not dangerous, it drives fine. At 5 or 55. Not uncontrolled bouncy like with worn shocks. No hopping, no skipping, nothing dangerous. Hope that makes sense.

[stsalvage]

I feel a set of Gabriel air shocks fixed my problem plus your rear bushing might need to be replaced

[PGSigns]

One thing that makes this hard is what is bouncy to you? Bouncy to me is when you have bad shocks and it goes up and down many time before it stops. So is bouncy a floating feeling or it feels like it bounces off every bump in the road? If it is bouncing off the bumps in the road its the springs and they are just a bit stiff compared to what you are used to. These old trucks ride like trucks and not the cowboy caddy's they make now.
Jimmy

[64stpside]

Originally Posted by PGSigns

One thing that makes this hard is what is bouncy to you? Bouncy to me is when you have bad shocks and it goes up and down many time before it stops. So is bouncy a floating feeling or it feels like it bounces off every bump in the road? If it is bouncing off the bumps in the road its the springs and they are just a bit stiff compared to what you are used to. These old trucks ride like trucks and not the cowboy caddy's they make now.
Jimmy

It just doesn't feel as stable in the rear as I would like. If I hit a bump in the road taking a sweeping turn at say 40 mph, the rear feels like it struggles to keep contact. It's not a violent reaction but noticeable.
As far as the "cowboy caddy's", I do pre delivery inspections, which includes a test drive, on all the new cars here at work so maybe I'm a little biased as to what I'm expecting..lol, though I'm not expecting my 64 to ride like a 2018. I just want to make sure it's safe regardless of the ride.

[vince1]

I had a well worn out 68 shortbox. The scale guy yells 1.8 ton when I had it loaded with sand. It took all of that to plant it firmly down and I was probably lucky the wheels didn't fall off going over the Granville bridge in Vancouver. They drive good with weight on them. After unloading it was right back up to its usual height.

Driving that truck empty over the railroad tracks from work and it would really bounce around. Make sure your U-bolts holding the differential in are tight as mine was flopping loose.

My 66 with 8' box has new springs/shocks and still bounces around like you describe. It's just the nature of the beast I think. Are the front end components good?

[PGSigns]

The weight split on these trucks is a good bit front and and will seem WAY different then anything you drive. I have a long bed with the tank behind the rear wheels and I can feel the difference between a full tank and an empty tank. Have you got a sway bar on the front? Many did not and that can make a sweeping turn fun at times. Your truck is safe and as long as you drive it like what it is and realize the limitations of the more than 50 year old design and what it was designed for you will be good.
Jimmy

[64stpside]

Originally Posted by vince1

Are the front end components good?

Seem to be. No movement in the ball joints, tie rods, idler arm and pitman arm are tight as well. Put new shocks on the front when I did the rears. Also has a cardone reman steering box from when I added pwr steering.

[64stpside]

Originally Posted by PGSigns

Have you got a sway bar on the front?

No. That is coming soon. I'm considering a rear sway bar as well. Obviously It would help with the handling in general but do you think that would help at all with controlling the bouncing in the turns?

[theastronaut]

Originally Posted by 64stpside

If I hit a bump in the road taking a sweeping turn at say 40 mph, the rear feels like it struggles to keep contact. It's not a violent reaction but noticeable.

That's normal for a straight axle, and its worse for trucks with very little weight on the axle. Softer springs will help the truck absorb the bump better without it "hopping" over it as badly. I've watched the rear end of stifly-sprung solid axle Pro-Touring cars bounce over mid-corner bumps on an autocross course, part of it is the high spring rates and part of it is the solid axle's inability to conform to the road source as well as independent suspension.

A huge part of the problem with a truck is that the percentage of sprung (weight that the springs support) vs unsprung weight (axle, wheel/tires) is at a really disadvantaged ratio compared to a vehicle with a more even weight balance front to rear. That's half the reason why they ride better with weight in the bed. There's not enough sprung weight to keep the unpsrung weight settled and under control.

I'm pretty sure that the factory coil springs are dual-rate. Check to see that the center part where the coils are closer together still have daylight between the coils at normal ride height with no load in the bed. If they've sagged any and the coils have closed up then you're riding on the part of the spring with a higher spring rate and it'll ride rougher.

C10's had the option of standard or HD springs, yours may have the HD springs from the factory. Another option is to replace the coil springs with Airlift D2600 bags. They won't need much air pressure to pump up to ride height since it's a larger bag so the spring rate will be lower. A sway bar won't help with the bouncing/skipping effect; if anything it'll make it worse.

[64stpside]

Originally Posted by theastronaut

C10's had the option of standard or HD springs, yours may have the HD springs from the factory.

How do I know what I got? Is there a thickness difference in the coil size? More coils? different configuration?

[PGSigns]

Just post a picture of what you have.
Jimmy

[64stpside]

Originally Posted by PGSigns

Just post a picture of what you have.
Jimmy

This is what I got

[64stpside]

I also checked my shock part #. They are 20851 which are monroe 20851,HD shocks. That might be my issue as the shock might be rebounding too quickly, acting like a spring with no load? Does that make sense?