Installed Bilstein 4600 on rear suspension of 2021 F-150 XLT

[IconicXLTsport]

Thank you for this review. On my test drive I felt the roll and excessive movement you mentioned and I had made a mental note to address it aftermarket.

I couldn’t test drive a FX4 before ordering and since my order is a FX4 I hope it will be a bit stiffer.

have you considered adding a rear sway bar or do you think that is unnecessary after the four shock upgrades?

The FX4 has different shocks so I think it will be different than my truck. If you still find it’s not good, can’t recommend bilsteins enough.

right now, the new shocks are so much of an upgrade that I’m very happy with the handling of the truck and I’m holding off on a rear sway bar. Definitely do the shocks first

When you install a spacer that adds 2" inches of height on one setup (Gen13), and then the same piece adds 2.5" of height on the other (Gen 14), That is indicative of a different motion ratio, because you have only changed the spring displacement; you didn't touch the spring rates or suspension components.

I’ve never messed with leveling kits but it was my impression that the lift amount was kinda variable anyway. Did they drive the truck and while and remeasure?

I’m gonna look for a deep dive on the 2015-2020 F150

Sponsored

 

[Gutshot]

I have a set of 4600's ready to install - part #33253183. The rear end has stepped out on me a few times off pavement so looking to settle that down, reduce body roll, & add some towing stability.

Before I break out the wrenches, do they go on boots up or boots down? I didn't see anything to specify orientation in the paperwork that Bilstein provided with the shocks. I'm assuming down as there are small drain holes in the boot by the bushing and you can read "BILSTEIN" on the shock right side up.

I had the 5100 leveling kit installed on my 22, the shop had the boots up in the rears, I couldn’t find anything online for correct orientation, so I contacted Bilstein and attached is the reply. Took me a few minutes to jack up the rear and flip em, but the damage from a winters worth of Michigan roads and salt kinda marred the finish to the top of the shock.

 

[cool rod]

I had the 5100 leveling kit installed on my 22, the shop had the boots up in the rears, I couldn’t find anything online for correct orientation, so I contacted Bilstein and attached is the reply. Took me a few minutes to jack up the rear and flip em, but the damage from a winters worth of Michigan roads and salt kinda marred the finish to the top of the shock.

Thanks for posting this, I would have put mine on upside down.

 

[IconicXLTsport]

Well now I feel I need to go flip mine too… I installed mine like the factory twin tube shocks and now I see the letters are upside down!

Just slightly annoying but I believe a monotube shock will work just fine in either orientation

 

[Gutshot]

Just slightly annoying but I believe a monotube shock will work just fine in either orientation

I agree, but with the boot on top, dirt/debris can get inside and then rest inside, never draining out, grinding away for eternity…..a bit dramatic but true.

 

[IconicXLTsport]

I agree, but with the boot on top, dirt/debris can get inside and then rest inside, never draining out, grinding away for eternity…..a bit dramatic but true.

True. It will also attach the heavier part of the shock to the truck and the lighter part of the shock to the moving axle, making a slight improvement in unsprung weight and ride quality.

all tiny improvements but still improvement.

 

[hotrodmex]

I’ve never messed with leveling kits but it was my impression that the lift amount was kinda variable anyway. Did they drive the truck and while and remeasure?

I’m gonna look for a deep dive on the 2015-2020 F150

https://www.roushperformance.com/2015-2016-f150-fox-suspension.html

Fox now has specific 21+ part numbers. The snap-ring versions have the exact same measurements externally, but are different models.

Not sure if I mentioned, but Eibach determined their dampers were good enough and just extended the application range.

I think getting measurements would be a good thing. I'm putting pieces together based on working in the suspension aftermarket previously (but not as an engineer) and being a suspension nerd for a couple decades, which also tells me I'm 100% (educated) guessing and not checking.

 

[IconicXLTsport]

I did see you mention eibach extended their applications of their shocks. It’s comforting to know they are comfortable putting their 13th Gen shocks on the 14th.

I went out in the garage and flipped my rear shocks. Might feel just a tiny bit lighter over small bumps and cracks but not much difference really.

climbed under the front and I’m still happy with how the springs are sitting on the collars and snap rings.I can see just a hairline gap between the lower part of the collar and the spring perch which leads me to believe the spring perch is resting on the top edge of the collar where it should be.

best case scenario bilstein just extends the year ranges for the 2wd trucks but if they don’t, I’m not sure I would do all that work again based on how well these fit currently.

still haven’t made an alignment appointment lol.

 

[Snakebitten]

Since there are so many damping/valving differences between manufacturers, it's highly likely the 2020 damping rate of company A got adjusted for their 2021 shock in the direction of company B's 2020 shock.

Does that make sense?

In other words, there's a range between them all and I don't think it's an exaggeration that ALL of them are heavier damped than OEM. In fact for many years almost every swap from OEM to Bilstein, Fox, Icon, King........ Heck, probably even Monroe has been described as better <> awesome.

And I would LOVE to know the REAL difference between the damping curve for a 2021 Bilstein 5100 VS 2020 Bilstein 5100.
I truly believe that they are different if the target outcome was to be identical on the truck. But I also believe in a blind test the vast majority of drivers couldn't tell you which set was on their truck in ordinary daily driving. Just my guess.

 

[GIjoe]

I agree with them all being heavier dampened than oem. Put the 21 fox’s on the rear and it took every once of muscle to compress them into the bracket. Just as heavy as the Bilstein i had on my f250. I only went fox this time around due to corrosion resistance as I’m in the snow belt in northeast Ohio.

 

[IconicXLTsport]

They are all definitely heavier damped in the sense that the aftermarket shocks produce any damping forces at all compared to the stock shocks just giving up haha.

If truck A and truck B have similar spring rates and the end goal is a similar ride, the damping curves will be nearly identical.


when compressing the shock to fit it into the brackets, you’re fighting the internal gas pressure there, which acts like an internal spring. True damping action provides no affect until the shock shaft is moving at a speed it is designed to damp out.

 

[cool rod]

OK, I finally got all my hardware and shocks, now where should I get them installed? Will dealers do it?

 

[IconicXLTsport]

I asked the dealer to quote me and they said $500, “truck shop” wanted $450, another local shop was $330 but that was fronts only. Probably another hour of labor for the rears too, add at least $100 for that additional hour. They will probably suggest an alignment too, which most shops charge at least $100

 

[cool rod]

Ooooh, that's expensive. But if my dealer will do it I'll go there because I have something else that's going to be serviced this week. Thanks

 

[Tobstertx3]

For reference for others, I had a local shop install the rear shocks as well as lowering shackles for $275. I’d say $175-$200 for rears only would be an acceptable price.

Sponsored