Stretched Bronco - Leaf Springs

[Fair Oaks Mustang]

New member and new to to Broncos. Just purchased a 76 U15 Bronco. The previous owner had stretched it with a plan of making it into a rock crawler. When purchased, it had been sitting for 5+ years. In the last two weeks I've gotten it running and taken it for a spin around the block. The rear springs are too soft for my liking. When he stretched it, he also lengthened the leaf springs. According to him, the leaf springs came off of a early 2000's f150...but he couldn't be positive. He also removed a spring or two. I'm wanting to purchase new stiffer springs but not sure what to buy. I measured the spring last night and it is 56" center to center. Is this a common modification for classic Bronco's. Any thoughts on what spring I should be looking for with mainly street cruising in mind with limited off road use?

 

[BanditBronco]

Longer leaf springs aren't a common mod on Broncos since there isn't much room to push the rear shackle back before it is interfering with the bumper. That said, if they were going to do it, usually F150 springs was were they ended up. Deaver, National, and atlas suspension should all be able to get you another spring pack. Or hit the junk yard and see what you can find. Depending on your plans, I would consider going back to a stock hanger and spring set up.

 

[WILDHORSES]

Some pics of this set up would be helpful. 56" is a long spring. Longer than our 4" lift 78-79 Bronco 73-79 F150 springs. If you are close bring it by and we could look at some options.

Jim

 

[Fair Oaks Mustang]

Some pics of this set up would be helpful. 56" is a long spring. Longer than our 4" lift 78-79 Bronco 73-79 F150 springs. If you are close bring it by and we could look at some options.

Jim

Looks like you are in California...I am in San Antonio...that would be a bit of a road trip. I'll take some pics this evening and post. Thanks!

 

[cldonley]

How is it stretched? Did the PO add length to the frame? Move the rear axle back on the frame? Definitely need some pics!

 

[Fair Oaks Mustang]

How is it stretched? Did the PO add length to the frame? Move the rear axle back on the frame? Definitely need some pics!

He lengthened the frame and moved axle back. Rough measurement shows about 12" added to the wheelbase and 6" to the frame. (I could be off a little). I did find one pic from the underside. I'll try to get better ones this evening.

 

[RODRIG3911]

He lengthened the frame and moved axle back. Rough measurement shows about 12" added to the wheelbase and 6" to the frame. (I could be off a little). I did find one pic from the underside. I'll try to get better ones this evening.

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You could just cut the leaf hangers off and burn them back on in the factory location if you don't like how it looks that way. If you have a spring shop in your town, you could drive it over and see if they can make you a nice custom leaf spring set to your specs. then add flares to make it look nice

 

[BanditBronco]

That thing is sweet, I would probably not change up the hanger situation after seeing it. Those leaf's have 3 per side right now haha, I would definitely swing by a spring shop and see what they can do for you.

 

[Apogee]

Have you considered just adding a sway bar?

 

[Fair Oaks Mustang]

That thing is sweet, I would probably not change up the hanger situation after seeing it. Those leaf's have 3 per side right now haha, I would definitely swing by a spring shop and see what they can do for you.

Yeah...that is one of my thoughts...pull them and drop them off at a local spring shop. I might also run by the local pic-n-pull and see what I can find there. The local spring shop might be less trial and error since they hopefully know what they are doing and give good advice rather than pulling random spring from random f-150 and hoping for the best.

 

[Fair Oaks Mustang]

Have you considered just adding a sway bar?

That's an interesting thought...I'll need to research that idea. My initial thought is yes, it will help firm it up...but would probably make it much rougher compared to new stiffer springs.

 

[Rustytruck]

Common swap was with chevy truck spring. Less leaves to deal with

 

[Apogee]

That's an interesting thought...I'll need to research that idea. My initial thought is yes, it will help firm it up...but would probably make it much rougher compared to new stiffer springs.

The opposite would be true...sway bars increase roll stiffness, whereas the spring rate will impact ride quality. In general, the lower the spring rate the smoother the ride quality and the greater the body roll, since the springs are adding less to the roll-rate, but the higher the likelihood of bottoming out the suspension on the bump stops and the lower the GVWR. The higher the spring rate, the rougher the ride and the higher the GVWR (think dump truck). The shocks should be matched to the springs for critical damping, so while they're a part of the equation, you can't really set that variable until your spring rates have been set.

The main advantage/disadvantage to sway bars is that they can limit articulation, since that's precisely what they're designed to do, hence sway bar disconnects for when you take your rig wheeling. This gives you good road manners without the drawbacks on the trail. That said, you could pick a smaller bar that works well enough in both places and run it everywhere...a lot of buggies and crawlers run setups like this.

 

[cldonley]

Definitely recommend the spring shop. I took my stock springs to a reputable spring shop in Austin, TX. Had 'em rebuild, add a leaf, and recurve for some additional height. Wound up with a 2" lift and some nice quality work. That is definitely a good lookin ride.

 

[Fair Oaks Mustang]

Some pics of this set up would be helpful. 56" is a long spring. Longer than our 4" lift 78-79 Bronco 73-79 F150 springs. If you are close bring it by and we could look at some options.

Jim

Here are some additional pics.

 

[bigjhoov]

Curious who you bought that from. It has some good parts on it that I can see, including a custom Bailie Bilt cage to match the stretch.

 

[Fair Oaks Mustang]

Curious who you bought that from. It has some good parts on it that I can see, including a custom Bailie Bilt cage to match the stretch.

Got it from a guy down here in San Antonio...introduced by a mutual friend that knew I had been looking for one. Best I can tell, he got married 5 to 6 years ago and the Bronco got set to the side after 80% completion. I feel like I got a heck of a deal on it...just needs to be sorted out. All of the big lifting is already done. NV4500 Transmission...Atlas Transfer Case...Nice roll cage...roller 351. Just needed a fuel pump, new carb...which I had one sitting in the garage, and a day cleaning out the fuel tank to get it running. Getting new tires this weekend. I think he said Bronco Alley did a lot of the work...but I can't find an address or website for them.

 

[Fair Oaks Mustang]

Update...5 months later. Finally got around to addressing the spring situation. As we we drove it more it did present to be a dangerous situation. With only having 3 leaf springs I was getting a lot of axle wrap on acceleration and hard braking. Found a spring shop here in San Antonio that added two springs on each side to get the stiffness I wanted, then de-arched the springs to get the desired ride height. It drives so much better. Completely eliminated the axle wrap but still a comfortable ride.

 

[DirtDonk]

That's great news. Looks like they were originally trying to soften it up even more by removing leaves.
A lot of work went into that setup for sure.
Was thinking earlier that shocks and tires also contribute to either too stiff (not your problem) or too soft. The Bilstein shocks look relatively new, but if they are a soft valving they are certainly contributors.
And if the tires are running low air pressure things can get a bit squishier than desired.

So even though you got the springs dialed in it sounds like, keep an eye on those other aspects.
But in the meantime, keep having fun with it!

Paul

 

[Fair Oaks Mustang]

That's great news. Looks like they were originally trying to soften it up even more by removing leaves.
A lot of work went into that setup for sure.
Was thinking earlier that shocks and tires also contribute to either too stiff (not your problem) or too soft. The Bilstein shocks look relatively new, but if they are a soft valving they are certainly contributors.
And if the tires are running low air pressure things can get a bit squishier than desired.

So even though you got the springs dialed in it sounds like, keep an eye on those other aspects.
But in the meantime, keep having fun with it!

Paul

You do bring up something I've been thinking about...because the front is really soft as well. Is there a way to determine what "valving" the Bilstein's have?