Is there anyway to tell if the rear leaf springs on my truck are good or need replacement. I replaced the front ones because one of the leafs was broken and they needed to be re-arched and the cost was almost the same. The rear ones have ok arch but are quite rusted. They otherwise appear to be intact. My other question is about gas mileage, I get about 11mpg which at todays prices is killing me. How can I go about making any adjustments to improve that. The engine is a 312 with a 4bbl carb newly rebuilt.
Chris

 

Whew! From the title of your thread, I thought you were asking about the relationship of leaf springs to gas mileage. The explanation of that is a tough one. I don't want to get into that.

I would say if the rear of the frame (and bed) is level and nothing is broken, you could leave them alone. The rust is a cosmetic thing. But if you clean and paint them, make sure not to paint the individual leaves. Paint the stack. You don't want paint between leaves.

Your mileage sounds about normal. I don't think anybody picked a 312 for great gas mileage back when gas was .19 per gallon. A taller rear end ratio or an overdrive would be the best way to improve mileage. Going to a 2 barrel would probably help some, too. But you'll have to keep your foot out of it, which kinda defeats the fun of having a 312.

A hot rod builder buddy of mine once hung up the phone on a guy who wanted better gas mileage on his hot rod. "Idiot" is all he said.

 

Randy, Why don't you want paint between the leaves?

 

Me too, Randy...I thought somebody was starting to ask stranger questions than me and was beginning to feel threatened....

I'm in agreement as well. If it rides fine, leave them springs alone. And from now on, kindly refer to "rust" as "patina". It's worth WAY more money on eBay that way...

I've had vehicles with "patina" out the wazoo. It's all good. Chicks dig patina.

Gas mileage....bummer on that one. Higher gears, lighter foot, or invest in a bicycle.

 

dffay - It will just wear off and squeak a lot while it does that.

Brent - No, you're still the king of strange questions. And the "patina" thing is right on!

 

Roger that. I'm laying in teflon on mine and I couldn't imagine it being some barrier to the slip resistance it will give.

 

Yeah I was afraid that my title would confuse people. I am a bit of a novice but even I didn't think there was an association between the springs and the gas mileage. I will paint them with some POR-15 that I have left over. Thanks for the advice any money saved is more I can spend on the paint job!
Chris

 

[QUOTE=Randy Jack]Whew! From the title of your thread, I thought you were asking about the relationship of leaf springs to gas mileage. The explanation of that is a tough one. I don't want to get into that. =QUOTE]

LADIES AND GENTLEMEN, LETS GET READY TOOOO RUUUMMMBBBLLLEEE.

Bring it on.

 

I'd guess that the rear springs would be OK, unless the truck was always carrying a camper or had been left sitting with a load of gravel in the back for 10 years.

As for mileage, just make a carbon fiber mold of the body, chop and section it, sit that on a chrom-moly tube chassis, and install a turbo 4 cylinder or electric motor.

 

Or install a 5 cylinder Mercedes turbo diesel, I'm hoping for low to mid 20s from mine.

 

If you look at your springs from the front or back, you'll see they have a groove on one side. That is for spraying oil down in between the leaves to make them work smoothly (part of a regular "lube job" back in the day). It's tough to make yourself do that when you've spent so much time cleaning and painting, but that's how they were designed!

 

I'll give that a try. I sprayed some silicon lubricant on them cause they were squeaking and that seemed to help but I'll try the oil trick too.