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Rear end sways over bumps


96firephoenix

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Hey all, I'm hoping you can help me track down the issue in my rear suspension.

I've done some searching and I've come up with an answer to the clunking issue... but nothing for the other problem, and I'm wondering if there is a connection (or rust where a connection should be).

Basically, whenever I go over a hard bump above about 20 mph, the back end kicks out the the right, and it feels like the axle is rotating clockwise as seen from above. Almost like an over-steer condition. For whatever reason, RailRoad tracks are worse than pot-holes or speed bumps.

Could worn out shocks cause this? I know the shocks are offset from the axle, with the DS going rear and the PS going front, and it seems to me that it would push the axle in this direction if they were not giving as much shock absorption as they should be. I'm not used to doing suspension work on pickups, and I know it differs a lot from RWD cars that I've worked on.

I know from following my wife home the other day that the axle tracks a little bit that way already, and I haven't found a cause for this.

I've already replaced the rear shackles and mounts, as they were rusted off. Everything else looks solid, but will be eventually replaced on General principles. Bed will eventually be off to do a fuel tank swap and some frame R&R.
 


BRUTUS_T_HOG

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Spring eye bushings solid? Any rust stains between leaf springs indicating a broken leaf?

My rear end hops and feels like a loss of control over bumps at 20MPH. Maybe you are just going over bumps too fast considering the lack of weight over the rear axle.

Having good quality shocks doesn't hurt.
 

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It's the nature of a truck....unloaded the spring rate is too stiff and the truck chatters/jumps sideways over rough roads. I've thought of using lighter rate springs and air bags to compensate when loaded, but haven't got there.

Richard
 

96firephoenix

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Spring eye bushings solid?I'll check when she gets home Any rust stains between leaf springs indicating a broken leaf?None that I could see when I checked.

My rear end hops and feels like a loss of control over bumps at 20MPH. Maybe you are just going over bumps too fast considering the lack of weight over the rear axle.

Having good quality shocks doesn't hurt.
It's the nature of a truck....unloaded the spring rate is too stiff and the truck chatters/jumps sideways over rough roads. I've thought of using lighter rate springs and air bags to compensate when loaded, but haven't got there.

Richard
Seems like the lack of weight is an issue...

This may be a stupid question, if so, I apologize. Like I said, I'm used to dealing with Car suspensions...

Are Coilovers in the rear an option? is this just a stupid Idea altogether? Looking at it, I'd have to do some fabbing to get a top mount, but it seems to me that I could make it somewhat like my car's suspension, where the shocks go straight up to the unibody. How would that effect it for loading and balance though?

Thoughts?
 

96firephoenix

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Update: So I took a load of scrap out today, and with 200-225 lbs in the bed, the effects were mildly reduced.

I crawled under there, and the bushings at the front of the springs are pretty dry-rotted, and the bushing mounts are pretty rusted... I think this may be the source of the swaying and of the clunking... off to RockAuto I go!

As for the speed, it does this on the highway with the little bridge bumps.

Thanks for the input on this, guys.
 

strvger

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my '97 does it as well. for some reason the po replaced the std springs with some heavy duty ones in the year before I bought it from him. it won't be bad this winter as I always have at least 250-300# of salt and floor dry over the rear axle. the rest of the year, it's just bumpy back there, although reducing the pressure in the back tires has helped some. I rarely carry more than 100# except in winter.
 

96firephoenix

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about $250 from RockAuto later, it feels like a new truck.

Lesson learned: when all else fails, replace everything.

Also got this for my troubles:

Despite safety goggles and a faceshield, I still got metal in my eye. scratched cornea should heal in 3-4 days.
 

BRUTUS_T_HOG

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Lucky you get to keep your eye!

Last time I got something in my eye I blacked out from the amount of force the doctor used to dig it out using a pick. Lesson learned indeed.
 

96firephoenix

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Lucky you get to keep your eye!

Last time I got something in my eye I blacked out from the amount of force the doctor used to dig it out using a pick. Lesson learned indeed.
me too! I didn't know there was novocaine eye drops until yesterday... if it weren't for the faceshield, I prolly would have lost both eyes with how much shit we stirred up!



Thats about 15 lbs worth of rust and former suspension components... ran through 15 cut-off wheels.
 

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