PIU struts/shocks

[UNBROKEN]

Do you have a link to the post where someone measured a brand new PIU with no accessories installed versus a ST?

I'm not convinced it's weight related.

But before we start, let's agree on some assumptions. Because the PIU shocks are more dampened, we can assume that the PIU springs have either the same or higher spring rate compared to the ST springs. If the spring rate is higher, than the ride height should be less affected by weight than the ST.

Now that we have that out of the way, let's take a look at some factory specs:

https://www.ford.com/suvs/explorer/models/explorer-st/
Ford specifies the "minimum" ground clearance of the ST model to be 8.3".
They don't provide any other curb weight other than 4,345lbs for a 2.3L (2WD) model. Obviously a 3.0L (4WD) model will weigh more.


Now let's take a look at the specs for a PIU:
https://www.ford.com/police-vehicles/hybrid-utility/
Ford specifies the ground clearance of the 3.0L EB model to be 7.2" which is almost 1.1" lower than the 2024 ST.

I will say that 0.5" of that is probably due to the tires because the stock sizing on a 2024 ST has a 30.7" to 31" diameter. The stock size on a PIU results in a 30" tire so the ST will sit anywhere from 0.3" to 0.5" higher due to a larger tire. It still doesn't account for the PIU being a full 1.1" lower.

https://www.autoblog.com/buy/2024-Ford-Explorer-ST__4dr_4x4/specs/
I wasn't able to quickly find the curb weight for the 2024 ST on the Ford site so I'm using numbers here.
Curb weight: 4,701lbs
GVWR: 6,160lbs

https://www.ford.com/police-vehicles/hybrid-utility/
PIU 3.0 EB GVWR: 6,500lbs. *This is significant because it indicates a higher spring rate than the ST models. This reinforces the assumption that the PIUs feature a higher spring rate than the ST models.
PIU 3.0L EB curb weight estimate = GVWR - payload capacity = 6,500lbs - 1,670 = ~4,830lbs *This number can be a bit fuzzy because it's not clear whether the payload capacity accounts for the constants such as the weight of a driver + fuel. Either way, 4,830lbs is not all that different from 4,701.

We have received a few brand new 2024 3.0L EB PIUs with no accessories installed so it's basically a bare bones interior. They still appear to sit distinctly lower than an ST with all its creature comforts, etc.

I think there's convincing evidence that the ground clearance of the PIU is not due to weight, but rather due to different (shorter but higher spring rate) coils.

Go take it apart and measure then. Or…just measure axle center to fender on both. And no…I’m not scrolling through years of a FB group to hunt something down.
There’s also no proof the PIU shocks and struts are more dampened than the ST versions. There’s talk…and rumors…but there’s no actual proof.
There’s also multiple ground clearances advertised for the PIU depending on engine choice…as high as 7.6”…there’s most of your difference in tire height.

 

[jrgoffin]

When I picked up the PIU rear bar and shocks, I cross-referenced my ST springs and their codes came up as the same for a PIU. As mentioned, the ride height difference is most likely weight and tires. I still say the dampers are stiffer per SOTP feel, but again, no hard data. Either way, the shocks go great with the thicker rear bar, and there’s most likely a reason for it.

 

[Polo08816]

When I picked up the PIU rear bar and shocks, I cross-referenced my ST springs and their codes came up as the same for a PIU. As mentioned, the ride height difference is most likely weight and tires. I still say the dampers are stiffer per SOTP feel, but again, no hard data. Either way, the shocks go great with the thicker rear bar, and there’s most likely a reason for it.

View attachment 23043

View attachment 23044

Why would the GVWR be different between the PIU and ST then?

What's the weight difference between the 3.0L EB PIU and ST?

 

[EDWYER]

Why would the GVWR be different between the PIU and ST then?

I assume something to do with its structural reinforcement vs the ST.

 

[Polo08816]

I assume something to do with its structural reinforcement vs the ST.

Unlikely. In fact, given the same/unchanged spring rate, additional structural reinforcement would increase the curb weight of the vehicle and, therefore, decrease payload. It will probably make the vehicle handle better as the chassis would deflect less under dynamic load.

Structural changes shouldn't yield minor changes in GVWR. And I say this because the chassis shouldn't be a mode of failure. Structural changes should yield significant changes in GVWR if it was chassis limited. Most cases, minor differences in the same model but different trim/package are a result of spring rate differences. For example, the F150 was sold in different configuration options such as Max Tow versus HDPP. The difference in GVWR is largely due to the difference in the rear leaf pack. Same thing with the SRW F250 vs SRW F350. The difference in GVWR is due to the additional leaf in the rear leaf pack but structurally, the trucks are basically the same.

So some additional considerations. Look at all the different GVWRs for each PIU powertrain variant:



I'm willing to wager there are no significant structural changes between each PIU variant and that these minor differences are a result of different springs / spring rates. They will use higher spring rate coils in heavier variants to preserve the payload capacity of 1,670lbs which is advertised for all PIU variants.

https://www.autoblog.com/buy/2024-Ford-Explorer-ST__4dr_4x4/specs/
The ST appears to have a payload capacity of ~1,459 lbs (6,160 lbs GVWR - 4,701 lbs curb weight). I would expect a PIU to be rated with a slightly higher payload capacity compared to a ST.

There sure are a heck of a bunch of spring combinations:

https://www.oemfordpart.com/v-2022-...3-0l-v6-gas/suspension--shocks-and-components

This makes me wonder... hypothetically... is it possible the PIU spring for the lightest PIU variant with the lowest GVWR and the highest ground clearance - the 3.3L DI V6 - is also used on the ST? If this was the case, then it would appear to someone, "Oh, the part number of my coil spring on my ST is the same as one of the PIU variants."

Now that I think about it, I think the PIUs that the State Police use seem to be lower than the ones the Police Departments that cover more urban areas. I wouldn't be surprised if urban Police Departments purchase the 3.3L DI V6 variant because they may not have the same performance requirements as the State Police that primarily works the highways.

 

[Funnbobby]

So moral of the story. For right now better to just swap the rear shocks and front struts along with rear sway bar. And leave everything else as is….given the lack of preponderance of evidence for new springs?

 

[Polo08816]

When I picked up the PIU rear bar and shocks, I cross-referenced my ST springs and their codes came up as the same for a PIU. As mentioned, the ride height difference is most likely weight and tires. I still say the dampers are stiffer per SOTP feel, but again, no hard data. Either way, the shocks go great with the thicker rear bar, and there’s most likely a reason for it.

View attachment 23043

View attachment 23044

I want to revisit this while referencing some of the things I suggested in Post #90.

What you are saying may be true, but I'm curious if the ST uses the same/similar springs as the 3.3L DI V6 PIU variant which, coincidentally, has the lowest GVWR and highest ground clearance of all the PIU variants.

 

[Polo08816]

So moral of the story. For right now better to just swap the rear shocks and front struts along with rear sway bar. And leave everything else as is….given the lack of preponderance of evidence for new springs?

I think the issue is that we don't know, for sure, which spring part number goes with which PIU variant at this point.

Some people may correctly claim that the ST spring part numbers match ONE of the PIU variants, but I don't think anyone can say with certainty which PIU variant.

And there are a heck of a lot of part numbers for coil springs that are labeled "PIU":
https://www.oemfordpart.com/v-2022-...3-0l-v6-gas/suspension--shocks-and-components

 

[UNBROKEN]

Unlikely. In fact, given the same/unchanged spring rate, additional structural reinforcement would increase the curb weight of the vehicle and, therefore, decrease payload. It will probably make the vehicle handle better as the chassis would deflect less under dynamic load.
.

The “structural reinforcement” is the cross brace that takes place of the 3rd row seat and all of its accompanying trim. The seat weighs more than the brace.

 

[EDWYER]

Do you have a link to the post where someone measured a brand new PIU with no accessories installed versus a ST?

I'm not convinced it's weight related.

But before we start, let's agree on some assumptions. Because the PIU shocks are more dampened, we can assume that the PIU springs have either the same or higher spring rate compared to the ST springs. If the spring rate is higher, than the ride height should be less affected by weight than the ST.

Now that we have that out of the way, let's take a look at some factory specs:

https://www.ford.com/suvs/explorer/models/explorer-st/
Ford specifies the "minimum" ground clearance of the ST model to be 8.3".
They don't provide any other curb weight other than 4,345lbs for a 2.3L (2WD) model. Obviously a 3.0L (4WD) model will weigh more.


Now let's take a look at the specs for a PIU:
https://www.ford.com/police-vehicles/hybrid-utility/
Ford specifies the ground clearance of the 3.0L EB model to be 7.2" which is almost 1.1" lower than the 2024 ST.

I will say that 0.5" of that is probably due to the tires because the stock sizing on a 2024 ST has a 30.7" to 31" diameter. The stock size on a PIU results in a 30" tire so the ST will sit anywhere from 0.3" to 0.5" higher due to a larger tire. It still doesn't account for the PIU being a full 1.1" lower.

https://www.autoblog.com/buy/2024-Ford-Explorer-ST__4dr_4x4/specs/
I wasn't able to quickly find the curb weight for the 2024 ST on the Ford site so I'm using numbers here.
Curb weight: 4,701lbs
GVWR: 6,160lbs

https://www.ford.com/police-vehicles/hybrid-utility/
PIU 3.0 EB GVWR: 6,500lbs. *This is significant because it indicates a higher spring rate than the ST models. This reinforces the assumption that the PIUs feature a higher spring rate than the ST models.
PIU 3.0L EB curb weight estimate = GVWR - payload capacity = 6,500lbs - 1,670 = ~4,830lbs *This number can be a bit fuzzy because it's not clear whether the payload capacity accounts for the constants such as the weight of a driver + fuel. Either way, 4,830lbs is not all that different from 4,701.

We have received a few brand new 2024 3.0L EB PIUs with no accessories installed so it's basically a bare bones interior. They still appear to sit distinctly lower than an ST with all its creature comforts, etc.

I think there's convincing evidence that the ground clearance of the PIU is not due to weight, but rather due to different (shorter but higher spring rate) coils.

Interesting. I wonder how much these weigh.

"Ballistic door panels – Level III+ Power passenger seat (8-way) with no-charge option(heavy-duty)
aftermarket consoles and Level IV+"

 

[Polo08816]

The “structural reinforcement” is the cross brace that takes place of the 3rd row seat and all of its accompanying trim. The seat weighs more than the brace.

The primary purpose of this is more protection for a rear impact I would presume.

 

[Polo08816]

Interesting. I wonder how much these weigh.

"Ballistic door panels – Level III+ Power passenger seat (8-way) with no-charge option(heavy-duty)
aftermarket consoles and Level IV+"

Level III+ rated body armor should be soft panels so they won’t weigh a lot. Maybe 10-15 lbs per door at most?

I can’t see most police departments outfitting most of their PIUs with Level IV armor.

 

[UNBROKEN]

The primary purpose of this is more protection for a rear impact I would presume.

The 3rd row seat frame acts as a structural member. The PIU loses that seat so they replace it with the cross brace that bolts into the same spots as the 3rd row and a couple of other spots further forward. It does increase the rear impact protection.

 

[jrgoffin]

I want to revisit this while referencing some of the things I suggested in Post #90.

What you are saying may be true, but I'm curious if the ST uses the same/similar springs as the 3.3L DI V6 PIU variant which, coincidentally, has the lowest GVWR and highest ground clearance of all the PIU variants.

You’d have to find one and get the spring codes off the VIN label to know.

Why would the GVWR be different between the PIU and ST then?

What's the weight difference between the 3.0L EB PIU and ST?

PD gear would do it.

 

[Cdubya]

The 3.0L Ecoboost PIU is the highest performing PIU variant. If you want to duplicate the suspension, try to get a VIN# from one and ask a dealer to search for the parts. Supposedly, even the drivetrain mounts are heavy duty.

 

[EDWYER]

Level III+ rated body armor should be soft panels so they won’t weigh a lot. Maybe 10-15 lbs per door at most?

I can’t see most police departments outfitting most of their PIUs with Level IV armor.

Probably true. Maybe different crumple zones add more weight.

 

[Polo08816]

You’d have to find one and get the spring codes off the VIN label to know.



PD gear would do it.

I would imagine this would be accessories installed after the fact. Of course the PIU having a higher GVWR (and payload capacity) is Ford engineering anticipating that the PIU would need to carry additional gear than a retail Explorer.

But not all PIUs are outfitted with a lot of gear. A lot of ours were purchased due to cost and are used for investigative purposes rather than for reactive responses or working the road.

 

[Dark Knight]

Armor from factory is approx 40 lbs per door, aftermarket external mounted soft armor about 20 lbs

 

[Lexaandrudy82]

what is the part number for PIU sway bar and what’s needed to change?

 

[UNBROKEN]

what is the part number for PIU sway bar and what’s needed to change?

If you’re gonna do a RSB…and you definitely should…just do the Steeda or AFe or whatever. These cars like a lot of rear bar and any of the aftermarket options will net you better results than the still smallish PIU bar.