4 leaf VS 6 leaf

[akronterr]

Hi Guys, I am looking for some info. on which leaf spring I should use. My car is a 57 Fairlane 500 2 door club sdn. I have 17" wheels and P225/60/R17 tires. Nothing has been ever replaced except for air shocks. I bought everything new to do the job except the springs. That's where my ? is. I like my ride height now. so I want to stay close to it without air shocks. When I measure from floor to center of rear wheel I have 13 1/4". Floor to wheel well is 21" Has anyone used the 6 leaf in there car? I know it was used in the Ranchero and wagons. Thanks for any info you can give me. Terry

[RICH MUISE]

First, if your springs are oem, ie almost 60 years old and worn out, when you replace them with new ones, your rear ride height IS going to change.
I installed the 6 leaf on my Custom and I love them. The ride is excellent...not to stiff, but keeps the car from leaning. I've totally eliminated my plans to install a rear sway bar, as I feel it's not needed with the 6 leaf springs.
As discussed frequently recently, the 6 leaf springs will raise the car 1 inch higher than the NEW 4 leaf. However, as mentioned, your ride height is already going to change, and can be "corrected" with lowering blocks, so if it were me, I'd go for the 6 leaf, get them installed, drive for a few hundred miles to settle them, see where your height is at and pick up some lowering blocks to get the rear end back down to where you want it.
My back height dimension probably won't be the same as yours as your Fairlane is several hundred pounds heavier in the back than my Custom, so it seems logical that yours should be lower than mine with the same springs.

[John Palmer]

Terry, I went in a different direction on my Ranch Wagon.  I use it for towing vintage travel trailers which have two to three hundred pounds of tongue weight when hitched.  The Ranch Wagon is also equipped with air shocks, but they are not very effective due to their original 45 degree mounting angle.  When towing, the car was just too soft in the rear, and squatted too much.  It would be nice to have a custom air bag system but I did not want to spend the money.

I took it into my local leaf spring shop and had them rebuild the stock rear springs.  I specifically told them what I was doing (towing trailers), and I did not want the ride height to increase, or only at the least amount possible, "just make them stiffer, not higher".  They re-bushed the eyes, installed new custom U-Bolts, Re-arched the original spring leaf's, added leaf's (it's now seven leaf's), and did all of the install work for less than the price of two new store bought springs.  Plus, there was no shipping expense because they were local.

This same shop has been in the business for three generations, and all they do is custom spring work on everything from small cars to huge dump trucks.  They do all of my trailer springs and claim that the steel used in the manufacturer of springs made during the 1940's, 50's, and 60's has a much better material than any "new" spring material they can buy today which is all made in China.  I do not believe this is just their sales pitch, because they spend more time rebuilding my old trailer springs compared to just selling me some off their shelf replacements. 

[SkylinerRon]

X2  Most local spring shops can do this easily.

Ron.

[akronterr]

Thanks for all the info. I did install the 6 leaf springs and all new parts. The car sits just perfect for me. I do have one recommendation I haven't seen here. That would be to retorque the U bolts after driving car. I found mine to have loosened up after just driving 10 miles. Ford spec. was 45lbs. Thanks again for all the help! Terry

[John Palmer]

Thanks for all the info. I did install the 6 leaf springs and all new parts. The car sits just perfect for me. I do have one recommendation I haven't seen here. That would be to retorque the U bolts after driving car. I found mine to have loosened up after just driving 10 miles. Ford spec. was 45lbs. Thanks again for all the help! Terry

Wow, 45# of torque sounds very light to me for a 7/16" to 1/2" bolt?  I would have expected something in the 75 to 85 foot pound range.  I'd be surprised if 45 pounds would be enough to stretch the bolts.

Can you imagine the stress on those U-Bolts when you crank the engine up to 6000 plus RPM, drop the clutch, have 10 pounds of air in the slicks, and VHT on the track? 

[Lucky'57]

LOL. Good one Mr. Palmer. Just a quick comment on you guy's thread. Can't seem to get the 292 in my 500 Club Vic much past 3500 rpm. and clutch... well the old Ford-O-Matic would struggle a bit to get the slicks to even squeak, but heh! I'm still blowing away lot's of the new stuff.

[hiball3985]

I was surprised to see the 45# spec in the manual also when I did mine. I wonder if that is a misprint?

[RICH MUISE]

Anything to do with the fact that the bolts are actually pulling down on a relatively thin walled tube and an excessive amount of pressure could distort it??

[lalessi1]

Probably more to do with the material grade of the U-Bolts...

http://www.engineershandbook.com/Tables/torque.htm

[hiball3985]

Probably more to do with the material grade of the U-Bolts...

http://www.engineershandbook.com/Tables/torque.htm

Lynn that spec sheet is for coarse thread, the U bolts are fine thread. My theory was so it didn't crush the rubber insulators, I never did like that design and I torqued mine to 60#.

[lalessi1]

Good point. When I posted that I didn't look at NF vs NC, but the point is valid. I probably under-torque my stuff unless the application is critical...like engine bolts.

[hiball3985]

Good point. When I posted that I didn't look at NF vs NC, but the point is valid. I probably under-torque my stuff unless the application is critical...like engine bolts.

I probably under torque too, my old arms are getting weak  I can't remember the last time I snapped a bolt..