Ride Quality?

[SOHK_Alumni]

Have a very early 2019 FX4 Lariat, rear springs are KB3C-5560-ED. My very late 2019 RWD Lariat has KB3C-5560-EF's.

The FX4 sits over 2" higher in the back.

Have a set of XLT 4WD springs in my garage, exactly the same pn and shape as my RWD Lariat ones.

What kills me, cannot find any trace of the FX4 rear springs in any on-line source I can find.

Sponsored

 

[P. A. Schilke]

Did some digging and it looks like Ford put different springs on the Lariat than they did on the LX and XLT's. The Lariat both 2WD and FX4 show the part number KB3Z-5310-B for both L and R with the description: Ranger. 4wd, crew cab, lariat. Reserve series (lariat). The XL and XLT list this part number for the spring. KB3Z-5310-A Item description : Ranger. 4wd, super cab. 4wd, crew cab, xl, xlt. I Also confirmed these part numbers with other Ford parts searches.

Source

I cannot find any information on the what the differences are between the two springs, but I'd wager that the Lariat springs are a tad softer to provide a smoother ride.

Hi PH,

Hmmmm......short of pulling the engineering drawings for each spring, it would be nice to see if we could somehow get a picture of the A and B Springs side by side. We might put a micrometer on each for wire diameter for example but coil spacing and any asymmetric would show on the side by side pix.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[Clump]

I just ordered the rear Fox 2.0 shocks. I don't want to mess with changing out the front coilovers just yet - I'll try the rear shock swap first and see if it provides enough improvement in the ride. If it doesn't, I'll likely go ahead with replacing the fronts as well.

Waiting anxiously for your results.

 

[Tracy Bowman]

I found a local seller here that has 265 60 17 nitro ridge grappler 10ply M/T that wants 800 bucks. Brand new stickers still on them. Good deal? Any thoughts? Said he had a shop that closed down.

Sounds like a good deal to me.

 

[Jackson84]

Sounds like a good deal to me.

I thought so

 

[quangdog]

Waiting anxiously for your results.

They should be arriving tomorrow. Probably have to wait until the weekend to get them Installed. I'll let you know what I think!

 

[RANGER_MARC]

They should be arriving tomorrow. Probably have to wait until the weekend to get them Installed. I'll let you know what I think!

Yes, please do let us know what you think of the Grapplers. When it comes time to replace the stock Hankook ATM tires, I want to upgrade a bit to something better: either Hankook's AT2, or the Grapplers, or Wildpeaks, or Trailrunners. So any insight would be appreciated!

 

[SOHK_Alumni]

Hi PH,

Hmmmm......short of pulling the engineering drawings for each spring, it would be nice to see if we could somehow get a picture of the A and B Springs side by side. We might put a micrometer on each for wire diameter for example but coil spacing and any asymmetric would show on the side by side pix.

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

RWD vs FX4 front springs:
.600" vs .620" wire, both have 13 1/2" free length, 7 1/4 coils. 4" od, bottom coil reduced to 3 3/4" od.

And yes, the left two RWD springs appear identical and mirror the one FX4 spring, the right most FX4 is shorter by a 6th of a coil.

Maybe to counter the extra mass on the left from the t'case and front diff??

 

[P. A. Schilke]

RWD vs FX4 front springs:
.600" vs .620" wire, both have 13 1/2" free length, 7 1/4 coils. 4" od, bottom coil reduced to 3 3/4" od.

And yes, the left two RWD springs appear identical and mirror the one FX4 spring, the right most FX4 is shorter by a 6th of a coil.

Maybe to counter the extra mass on the left from the t'case and front diff??

Hi Win,


Very helpful! The wire diameter of the FX4 is slightly stiffer than the RWD. The equasion for this sort of spring is a function of the 4th power of the wire diameter, so 0.020 is a difference of tad bit higher at 1% stiffer and explains the different free length to achieve the same ride height at curb weight. Does not answer the question of the FX4 vs. the standard 4WD. Appreciate your taking the time to measure this!

Thank you!

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[Langwilliams]

I installed the Eibach rear shocks an I think it's 100% better. The rear is controlled an doesn't bounce an rock on the bumps. Feels firm an planted.

 

[MrAnalog]

... a function of the 4th power of the wire diameter, so 0.020 is a difference of tad bit higher at 1% stiffer ...

(0.62 / 0.60) ^ 4 = 1.14

It's 14% stiffer.

 

[P. A. Schilke]

... a function of the 4th power of the wire diameter, so 0.020 is a difference of tad bit higher at 1% stiffer ...

(0.62 / 0.60) ^ 4 = 1.14

It's 14% stiffer.

Hi John,

Arrrrrg..... you are correct. I did it wrong assuming .6020...not the correct .62. Thanks for correcting me...

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[HenryMac]

... a function of the 4th power of the wire diameter, so 0.020 is a difference of tad bit higher at 1% stiffer ...

(0.62 / 0.60) ^ 4 = 1.14

It's 14% stiffer.

Assuming heat treat procedures is the same.... is it?

 

[BladeRanger]

I have a 19 lariat FX4 and agreed it felt like a boat. Also had the pulsating brake feel some complain about. Took it to the dealer yesterday for the fox 2.0 upgrade. I was given a 19 XLT FX4 as a loaner and couldn't believe how much stiffer the suspension felt. Less body roll in curves and brakes stopped smoothly as well.
I got my truck back today and the fox shocks are even stiffer, the rake is gone. I'm pretty happy with the ride now but wonder about the difference I felt between the loaner and my original ride quality.
Brakes still have the pulsing feeling but I wasn't expecting any change with the shock upgrade.

Pretty sure it's not just in my head but you never know.

How much did the Fox 2.0 upgrade?

 

[MrAnalog]

Assuming heat treat procedures is the same.... is it?

Heat treatment doesn't affect spring rate. All steels have about the same rigidity (shear modulus).

It would only affect the strength of the spring - how far it can extend or compress and still return to its original length.

Sponsored