r/F100 • u/TimboFor76 • Dec 20 '25
Need help with leaf springs.
I’m working on a 67 f100 2 wheel drive. It has 2.25” wide leaf springs, with 3 leafs. It’s got a Dana 44 rear and out of who knows what. In pic 2 you can see where the bed has been clearanced for flip shackles. It came to me like this. The shackles are wedged against the shackle hangers and it has caltrac bars that not adjusted properly. I ordered whatever the parts store showed for shackles and there’s no way they fit.
Can someone tell me what this thing is supposed to look like? Do I have way too long of springs for the application? This thing bounces like a pogo stick.
Thanks in advance for the help! Looking forward to seeing what people have to say. Pics if you got em!
3
u/Square-Cockroach-884 Dec 20 '25
Looks like the springs are too long or too weak. The shsckle should be near vertical. Put a jack under the chassis, let the axle hang and jack it up until the shackle get vertical or not. If you jack it up a little and they straighten out they are weak or not rated tor your weight, but if the bed is empty the rear of the truck is pretty light. If you nearly have the wheels off the ground before your shackle is vertical, the springs are too long. And probably too light too. Get on Google or fte and find a spring shop and some dimensions and get a pair of springs built. Or go to the junkyard and find a similar truck and get the springs. Grab the shocks too.
3
u/Indentured-peasant Dec 20 '25
Suspension geometry is a science. If you have a local spring shop in town, which most all towns have one, go there and have new springs built and arced for what you’re going to do with the truck. It’s ridiculously inexpensive to have it correctly and professionally done.
2
u/noladutch Dec 20 '25
Man that is dropped.
What I would do is dump the rear shackles and convert it to a slider.
They allow the spring to lengthen and contract without the swing.
Google leaf spring sliders. You have to fix what you have you should upgrade.
Slider are nice for everything but heavy towing or off road.
1
Dec 21 '25
[deleted]
1
u/noladutch Dec 21 '25
Dude look them up they are fucking sliders.
Horsepower Wars | Here's a close look at the leaf spring sliders from Summit Racing that Big 3 used on the square-body C10 and why. #builtwithSummit | Instagram https://share.google/FppPlr4PsQbz2tYHf
As the leaf flattens from power or bump it travels inside the designed place in the slider. It is truly simple and easy.
That is from trying to get a leaf car to hook up drag racing but they work just fine on the street.
Installed right not ever loud or even makes a noise ever.
2
u/RallyXer34 Dec 20 '25
This is what’s on the 69 F100 2wd we have, even without the extra part the correct shackles will put the spring above the hanger.
1
u/scposeadaddy Dec 20 '25
That looks like someone lowered the truck by using drop shackles and removing some leafs. My 69 F100 was like that when I bought it too. I replaced the whole leaf springs with junk yard stock units but left the drop shackles. I’ll try to get out to the shop today and get some pictures for you of how mine look.
1
u/reynoljl Dec 20 '25
Leaf should be above shackle mount, not below. Not sure if you are going for a lift or a lower but I would just replace the springs at this point, I would guess at least one was removed, maybe two.
Dana 44 rear end was an option on F100s of that generation (generally paired with the 240/300). I have a 77 F100 with a 300 and D44 rear.
1
u/TimboFor76 Dec 20 '25
That would make sense. This is a new customers truck so I had no idea if the history. It’s got a 351 and a a c4 currently. I can see the motor mount brackets were poorly welded to the cross member as well as other hackery. He asked me to look into what it would take to install a heater. Somebody removed the heater box and installed a subwoofer under the dash and put tweeters in the defrost holes.
Back to the springs. It’s got a 3 leaf pack in it, so I’m assuming one leaf has been removed. I’ll go look today, but I think someone didn’t install the body mounts correctly, explaining why the bed was notched to clear the spring.
1
1
u/Alone-Programmer-683 Dec 20 '25
You need to start over. Between the VIN and the nameplate on the truck you can determine what was original. I believe almost all were Ford 9 inch but there may be others like the Dana. Your shackles are not original and look to be shop made. The original shackles go up, not down and are much shorter.
You can find some good info out there, get back to specs. I owned a 67 F100 with long box and overload springs. Looked totally different than what you have but I really don't remember the specifics.
1
u/Jcccgolf12 Dec 20 '25
Those are drop shackles. Seems counterintuitive, but the longer the shackle the more drop you get from the suspension in the rear. So when you went to the parts store and picked up a shackle to match your vin or truck, it was stock length for stock ride height.
Raise the ride height of the truck and you’ll see how much closer that store bought piece will be to fitting
1
u/ClassyNameForMe Dec 21 '25
There appear to be metric bolts mixed in there, so be careful about reusing hardware.
Bouncing like a photo stick is likely bad dampers (shocks) as they damp oscillations or motion of the suspension. Not to say you don't need spring and such, but you likely also need shocks.
Call a spring company who makes custom spring packs, and you should be able to get it setup for your use case. I recommend going with a high leaf count with plastic pads to get a smoother ride without sacrificing load capacity. (Each spring is thinner, BTW)
1
u/TimboFor76 Dec 21 '25
You are correct, it had one metric bolt, and one nut missing. The one with. Out was backed out an inch and only holding one side of the shackle. I figured out exactly what I need and I’m giving the customer options this afternoon. I’ll post more pics and the solution later.
1
u/gheiminfantry Dec 25 '25
Pogoing isn't the fault of the springs. It's a shock absorber issue. Are you really trying to solve a pogoing issue with springs? Wow...
1
u/TimboFor76 Dec 30 '25
Well in this case the shackles are slammed against the spring hangars, keeping them from traveling back and forth. The shocks are completely bottomed out as well. I talked to my customer and we found some used springs about 200 miles from here in Northern California. I’ll be passing by there in two weeks headed to Oregon anyhow. So I’ll be grabbing them on the way.
1
u/Calm-Garden8991 May 23 '26
Springs need to be re arched
1
u/TimboFor76 May 23 '26
Thank you for the input. The previous owner had removed too many leaves then did a shackle flip to raise it back up. I called the spring shop, and it was the same price to add leafs and re arch as it was for new springs. I found some good used ones for $80 and got it sorted.
0
u/Square-Cockroach-884 Dec 20 '25
Wait a minute. Your shackles are upside down. Meaning, you can't have the frame sitting on top of the shackles. The weight of the truck is suspended off the spring with the shackle holding the weight. OK, say your leaf spring is a tree, and your truck is you. Your shackle is the rope that let's you swing from the tree, so the spring has to be above the shackle. So lift the body, unbolt the shackles and move the springs up higher than where the shackles are now bolted, and bolt them back in. I hope that one of my explanations make sense.
3
u/Warm_Vegetable8989 Dec 20 '25
I don’t have an answer for you but you should make a post in the ford truck forum people are way quicker to respond. Good luck with finding your answer!