I have a 77 F150 and my rear springs are shot. Every time I take off under hard acceleration it starts hopping. I have replaced the carrier bearing and everything else seems tight so it has to be the springs. I would like to swap in a set of F250 springs for some extra strength. My question is what years are inerchangeable with ours?

 

Axle hop usually comes from a lack of traction, so if you are having a problem with this, you have a problem keeping the tires on the ground.
This leads me to believe that you have a damper problem, or a mount issue.
How is the trans mount?
Is this a 4 speed truck? Clutch condition? IS this a chatter problem form the clutch?

I just cant see the springs causing this on the street, unless you are roasting the tires every time.

 

Well, if it IS the springs.....I don't think F-250 springs are gonna help any. I drove my 79 F-250 4x4 around for a few weeks without the bed. I knew it had axle wrap issues.....but had no idea how bad it was till I saw it in action. Just easing off the clutch while driving it around the yard was scary. Now, I know the bushings were completely gone in the upper shock mounts.....and the axle would move several inches before the shocks even started moving. But, still, there's no way it should move that much.

For comparison, I have 5.5 inch blocks on my 2005 F-150. I have no issues with wheel hop / axle wrap. Sometimes I think I'm gonna bust the u-bolts.......But I'm EXTREMELY impressed with the springs. So.....I'm considering using the 04-08 F-150 style springs on my 79 F-350 project. They are longer.....so the hangers will have to be moved.

I have some 80-96 style springs, that I MAY try. They are close enough that you can make them work without moving the front hanger. However, you may have to move the rear hanger or use a shackle flip kit to get the shackle angle right. However, I can't say for sure if they would be enough of an improvement to justify the swap.

What I'll most likely do, is use the 80-96 style. They may not help, but they can't possibly be any worse. Anyways, I'll just run them for a little while until I can afford a set of Deavers.

So, in summary.....F-250 springs wont help. There are no other springs that will directly interchange. 80 - 96 springs will work.....with a little "adjusting". 04-08 springs are awesome.....but require moving the hangers. There were no 3" springs for the 97-03 body style. So....maybe this will give you an idea what your options are.

 

Well I the tranny mount is old but seems to be together. I know I should replace it anyways. The rear shocks are good, less than a year old. It is a 4spd, honestly I couldn't tell you if it was a clutch issue. I opened the door and gave it gas and I could see the tires shift when it hopped. I need to have a friend drive it so I can watch it. The truck used to pull a 5th wheel hay trailer and now I am running 35's on it. I figured the springs were just worn out. I can get on the bumper and bounce and it just seems very bouncy.

 

1 year old shocks huh? Ever remove them and see how much resistance they offer?
Since you mentioned that you can make the truck bounce by standing or jumpin on the bumper, indicates that you have some worn out shocks.
Shocks only dampen or control the energy that is stored in the spring after they deflect. They prevent the spring from bouncing around uncontrollably.
Too much valving in the shock, or too much dampening, and you have a stiff ride.
Too little and you lack axle control. This leads to a tire that can bounce on the road, or lose traction as it no longer makes contact with the ground.
Your suggested remedy is to stiffen the rate, by adding a big ol honkin spring in there, and while this will work, you will limit axle articulation and overall flex, as well as decrease the ride comfort.
I know, I know, its a truck right? They are trucks but dont have to ride like lumber wagons.
You can have a nice riding truck that performs well in all areas without a sacrifice.

This wont take very long. Remove the lower bolt from the rear shock, and see what happens to the shock once you remove it from the bracket.
I would be willing to bet that it does not offer too much resistance at all.

I am also very confident that you have a damper problem, and your issues can be solved by replacing the shocks with quality dampers.
Many rides are improved greatly by higher quality shocks.
There is a reason why some shocks cost as much as some of these old trucks.
Im not suggesting that you run out and spend 4 thousand or more on Kings, but you will get what you pay for if you are buying cheap dampers.

If you lived closer, Id loan you a set of decent shocks, so you could see that we could solve this problem without getting as drastic as changing out the leafs.

Im sure the engine in the Mater is a real fire breather, but I dont see it making enough power to create your problems.
There is something else wrong.

 

I would have to say it sounds like a shock/steering damper problem as well. My buddy and i just did some swaping of leaf springs and shocks both front and rear on his truck and after replacing the shocks and mounting them correctly is what stopped the bouncing.

 

I will try swapping out the shocks first then. I did buy cheap shock just for the simple reason of budget and the truck didn't run that much at the time. Now the tranny has been rebuilt (still tight to shift) and I drive it more I am guessing they took a dump. I will see about getting a video so you can see what it is doing.