I am wanting to lower my 1955 F100 while retaining the stock axle. I have been considering either Posie Dual Flex or Down and Forward springs from Mid Fifty. One of my concerns is clearance with the oil pan on my 289.

My truck is setup with a 289 and C4 transmission that was installed by the previous owner. From what I can tell it has the original leaf springs but as you can tell from the picture they have no arch left in them and do not appear to have much travel either as it is not far to the bump stops.

Currently the back of the oil pan sump is inline with the front of the axle with about 2-1/2 inches of clearance. If I install lowering springs I am concerned in not having enough clearance between the axle and oil pan. Is my best or only option to convert to a rear sump?

I was measuring tonight to see if I might be able to go with a drop axle instead but from what I can tell I do not have enough scrub line clearance to do that.

 

Note the stock springs do not have arch when loaded. They are about normal in your pix.
Since there are two of them, the axle does not travel very far, and unless you are going offroading the axle is unlikely to contact your oil pan before the bump stops. If you are concerned, and/or want to lower the springs, swap your oil pan for a "semi" rear sump and oil pump from a bronco or Ford racing parts, or on ebay.

 

Thanks AX!

I am not having any clearance issues now but would like to lower the front of the truck about 1-1/2 to 2 inches and improve ride quality but after looking closely at it last night became concerned that even using the Posie springs that leave the axle in current location I would run into clearance issues if I install new springs without also converting to a "semi" rear sump pan at the same time.

Upgrading/improving the ride and lowering the truck some is next on my build list and I am trying to figure out what is the best approach and best value for my $$. Since this is my first project like this I am not sure how much difference in ride quality replacing the front springs would actually give me. If the only significant difference will be a slightly lower ride height then I might put off doing that and simply lower the rear of the truck to get a more level stance by using Posie Super Slide springs and Midfifty adjustable spring hangers at least for now.

 

If you don't want to move the axle forwards, then follow the instructions in the mid fifty catalog (and/or do a search on here on lowering and softening the ride by removing every other leaf out of the stock stack and adding the HMW plastic slider strips between the remaining leafs. It will bring it down as much as a set of lowering springs and soften the ride about equal as well for only the cost of a new set of longer headed centerbolts, the roll of plastic strip and a couple pairs of caster shims. I'd suggest replacing the spring eye bushings and also the shackle pins if they show wear while you have the springs out. That will also improve the ride and handling noticeably.

 

Thanks again! Just the type of feedback I was looking for.

 

Be careful when disassembling the springs, they pack a lot of energy in a safe looking package. Lay the spring on it's side on the floor, place a large C-clamp (4" +) on each side of the centerbolt, stand on the spring while removing the centerbolt and slowly releasing the clamps.
Clean the spring leafs by sanding with a block, wire wheel or a belt sander, sanding lengthwise only, NEVER ACROSS or circular! DON'T paint the leafs!

 

Its interesting that you say to sand lengthwise, why is that? And painting the leafs, why is this bad? Is sand blasting ok for leaf springs?

 

Answers:
A leaf spring flexes equally along it's entire length 100s of thousands of times. A crosswise nick or even a sandpaper scratch causes a change in thickness at that point (granted minute in the case of the sandpaper scratch, but real!) producing a weaker spot or stress riser as the engineers call it, at that point that can become the start of a broken spring leaf.

Blasting with glass beads or soft plastic media is OK. Don't use a hard sharp media like sand, black beauty, etc. and direct the nozzle in the lengthwise direction. IMHO sanding with a belt sander is quicker and leaves a smoother surface (see next answer). Sand with progressively finer grits like 80 then 120, 240, 320 will leave the leaf smooth slick and shiny.

In a multi-leaf spring stack as the leafs flex they rub against the leaf above, again 100s of thousands of times. The easier they slide the smoother the ride will be. (Why the plastic slider strips work so well) any surface roughness will increase the friction and reduce the ease of movement. Any surface roughness can hold tiny particles also causing more friction.

Painting the leafs increases the friction. As the spring flexes heat is produced, more than most imagine. That can make any paint get soft and sticky. That sticky paint can also trap dirt and grit. If they REALLY bother you you can darken them with "cold bluing" a chemical agent most often used on guns, or a light wiping with a non-film producing rust converter like sold in spray cans by Rustoleum or Eastwood. Wipe off any excess immediately upon application. You can also lightly paint just the edges of the leafs by using a small roller or brush applied nearly dry. It's OK to paint the top surface of the longest (main) leaf and/or the bottom of the shortest.