1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

Flex-O-Matic

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Old 08-11-2009, 09:02 PM
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Flex-O-Matic

Okay, guys, I'm going to ask my first question of all of you. I've replied to a lot of threads and tried to share my knowledge, so I hope you'll be as kind.

My 70 Ranger XLT 2WD LWB is equipped with the Flex-O-Matic rear springs. I'm sure the springs are weak, as my wife's grandfather (who bought the truck new, by the way) used it to haul some heavy loads on a trailer. (As an aside, he never hauled ANYTHING in the bed, so it's still as perfect and dent-free as you'll find)

A couple of years ago, I tried a set of air shocks to give it a little extra lift, and the springs hit the Flex-O-Matic brackets with just a few pounds of air. After seeing this, I know that re-arching the springs will produce the same results.

My question is this: How much trouble would it be to convert the original rear suspension to the classic leaf spring suspension? I know I'll have to change the springs because of the difference in length (4", according to the Ford parts manual). Other than that, what does the conversion require?

ANY help will be GREATLY appreciated!!!
 
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Old 08-12-2009, 06:25 AM
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Springs and rear shackle is all that you'll need.
 
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Old 08-12-2009, 10:42 AM
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From what I've found the std rear springs for the F100's run almost $300 each. This is from LMC or NPD..
Did a little searching today and found that Chevy 1/2ton,(67-72) used a spring with the same dimensions as the 67-72 ford's.
That being A/B dimensions 24/28, spring width being 2.25".
Now I'm not saying they'll work, the front eye OD may be bigger. The bolt size may be different. Not sure what the arch measures.. But they may be worth looking into at $149 each.
http://www.generalspringkc.com/index...=127&parent=13
 
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Old 08-12-2009, 11:07 AM
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Originally Posted by convincor
From what I've found the std rear springs for the F100's run almost $300 each. This is from LMC or NPD..
Did a little searching today and found that Chevy 1/2ton,(67-72) used a spring with the same dimensions as the 67-72 ford's.
That being A/B dimensions 24/28, spring width being 2.25".
Now I'm not saying they'll work, the front eye OD may be bigger. The bolt size may be different. Not sure what the arch measures.. But they may be worth looking into at $149 each.
http://www.generalspringkc.com/index...=127&parent=13
I assume your referring to 67-72 Chevy 4x4 rear springs.........most 2wd chevy/gmc's in that period used rear coils rather than leaves,especially in the 1/2 tons.....getting into the 3/4 tons and up,and possibly in the "camper Special" type models,you typically got rear leaves
 
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Old 08-12-2009, 11:15 AM
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if you go to the link I posted there listed for "1969 - 1972 GM pick up 2wd rear - C10 / C20 2WD"
 
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Old 08-13-2009, 09:57 AM
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F100 rear springs are the same dimensions 1953/72.

24" > > eyebolt < < 28" // 2 1/4" width.

What load rate do the springs have?

Look on the main leaf in the vicinity of the eye bolt, Ford stamped the spring ID number there, like this for example: C5TA-5560-MA.

Rear springs decoded here: 1964/72 Ford Truck Parts Catalog / Text Section 55 / Page 2.

Or post the code here.
 
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Old 08-13-2009, 08:08 PM
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NumberDummy, your information is MOSTLY correct.

It seems that in 68 (first year for Flex-O-Matic), they increased the length on two of the available springs by 4".

Look at the dimensions on C8TZ5560A and C8TZ5560C. Those are 24 x 32 x 2.25. The 24 x 28 x 2.25 were still used, but these were only available for F100's starting in 68. Prior to that, it looks like you are 100% correct.
 
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Old 08-13-2009, 10:11 PM
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Originally Posted by 70_RangerXLT
NumberDummy, your information is MOSTLY correct.

It seems that in 68 (first year for Flex-O-Matic), they increased the length on two of the available springs by 4".

Look at the dimensions on C8TZ5560A and C8TZ5560C. Those are 24 x 32 x 2.25. The 24 x 28 x 2.25 were still used, but these were only available for F100's starting in 68. Prior to that, it looks like you are 100% correct.
The problem is...and has been for decades...the parts catalog makes absolutely no mention at all inre to Flex-O-Matic when rear springs are looked up.

Since what you say makes perfect sense, I have to agree that the C8TZ rear springs were used with Flex-O-Matic only.
 
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Old 08-13-2009, 10:26 PM
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NumberDummy is like Dove soap. He's 99.44% right ALL OF THE TIME.

Like stated, the parts books don't always give all of the information.

I have the utmost respect for his info, and he has set me straight a NUMBER of times.

This one is tricky, and you have to apply some MAJOR logic to it. In addition to logic, it takes a LOT of "deciphering" to understand something like springs on a Ford truck. That's one of the ONLY places that GM outperforms Ford.

Thanks, Bill, for chiming in!!!!!!!!!
 
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Old 02-12-2011, 02:18 AM
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What do I need in order to convert a non flex-o-matic rear suspension over to a flex-o-matic rear suspension on a 1967-72 Ford Ranger F-100?
 
  #11  
Old 02-13-2011, 07:22 AM
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If I remember correctly that was Ivory soap... 99.44% pure.
 
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