73-87 chevy truck front bounces when braking

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I have a 1978 chevy k20. It is my yard/plow truck and in town run around vehicle. For many years now it has had an issue where the front of the truck will start to hop up and down when moderately braking. I find i have to pulse push the brake pedal every time the front end comes on the up bounce to try and counteract the oscillation. The shocks that were on it were junk. They were all rusted and the metal dust boots were rotting off. I recently replaced the front shocks but its still doing the same thing. It doesnt feel any better. Now the truck isnt very pretty and it is very old with all original suspension bushings and whatnot. Im not interested in sinking money into it to replace things like the bushings unless it’s necessary. Im more interested in getting ideas of things i can check out or take note of to try and pinpoint the problem area.
 
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How does it drive going down the road? Does the plow stay on it year round? Any difference with the plow on or off?

It sounds like a lot of things are wore out, especially being a plow truck. The shock you got may not be enough to counteract it all, especially if you are running a heavy wheel/tire combo too.

I'd put the front on jack stands and start moving things around. I'd bet you have a crack in the frame somewhere (especially by the steering box) and your leaf spring bushings are probably wasted too. It isn't a complicated front end though, just start looking to see what is loose.
 

joegreen

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How does it drive going down the road? Does the plow stay on it year round? Any difference with the plow on or off?

It sounds like a lot of things are wore out, especially being a plow truck. The shock you got may not be enough to counteract it all, especially if you are running a heavy wheel/tire combo too.

I'd put the front on jack stands and start moving things around. I'd bet you have a crack in the frame somewhere (especially by the steering box) and your leaf spring bushings are probably wasted too. It isn't a complicated front end though, just start looking to see what is loose.
Yeah the leaf springs bushings are probably toast. I know the steering box area is a common crack point but this frame is not cracked there yet. I inly keep the plow on for when its going to snow otherwise it stays off. It drives fine going down the road. Its a rough ride but it doesnt bounce. The wheels and tires are stock steel wheels with stock tire.
 
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Lol. I should at least feel some difference from the old shocks. Especially since the vehicle is stock.
He might be right, a snowplow is going to have heavy duty, and likely monotube shocks. Worse case I would expect them to act/feel like light duty shocks when completely worn out.
 

joegreen

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I will say this continuing to bounce issue after changing the shocks i have only experienced without the plow on. It may do it with the plow on but i have not driven it yet with the plow.
 
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Yeah the leaf springs bushings are probably toast. I know the steering box area is a common crack point but this frame is not cracked there yet. I inly keep the plow on for when its going to snow otherwise it stays off. It drives fine going down the road. Its a rough ride but it doesnt bounce. The wheels and tires are stock steel wheels with stock tire.
You need to give that old girl some love. New springs, bushings, etc. That front end is not complicated nor are parts expensive. A little will go a long way here and you'll enjoy driving her around town more. "the patient always has the answer" as they say. Kudos for to you for keeping old iron on the road, keep us posted.
 

Astro14

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My guess is worn out front suspension bushings and parts. Leaf spring bushings, tie rods, drag link, idler arm, etc, depending on set up. It won’t be cheap to fix because you’ll have to replace just about everything. This is like the “death wobble” on worn out Jeep front ends, it’s not going to get better and it is not safe in the interim.
 
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I’m also going to guess it’s a combination of worn out parts. I would not be surprised if those autozone shocks never dampened correctly or are already bad. I would get 4 mono tube shocks for it and look into replacing the rubber bushings in the suspension. I have had good success with the KYB Monotubes they sell on Rockauto.
 

D60

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Leaves are inherently self-damping and those front ends aren't exactly "springy"

OP says he's getting the bounce without the plow. I'd expect something else is going on, even with NO shocks I wouldn't expect his symptoms
 

joegreen

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I will be away for Christmas but ill look at it more closely next week.
 
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