Perch collar level / lift for Sasquatch from RPG

[Raptor911]

A true coil over is the correct way to add a lift. Don’t take a short cut to save $$

Sponsored

 

[Exomodo]

Travel on the stock shock isn't changing with a spacer lift, neither at ride height or droop, given vehicle mass remains the same.
Ride height shock piston location within the shock body is not changing more than a fraction of an inch, related to the suspension geometry affecting the new settled location.
Droop increases until the shock maxes out or another suspension component stops droop, regardless of the system employed.
All that is changing is where that travel happens in the range of motion in the a-arms, therefore a spacer lift retains stock ride quality - to whatever (small but not insignificant) point in which the motion ratios are affected by the increased arc of the suspension moving toward the centerline of the vehicle - align the vehicle after a lift. On a lifted IFS the tire begins compressing outward under suspension compression until the lower a-arm is level horizontally. The side wall compression adds to the spring rate. The spring force lifted vs. stock are roughly equal and so is the piston location of the shock since it is a coil-over. Stock up travel on the spring, stock up and down travel on the shock piston, which remains at the same static stock location in the shock because the spring also stays at stock compressed length. It is an isolated linear system with only the vehicle mass force as the input. This is the #1 advantage of a coil-over system.
A bad spring perch lift on a stock Ford coil over shock would put load on the spring to compress it against the vehicle side of the assembly to increase the installed length of the assembly, removing stroke length and degrading ride quality, as well as likely coil bind, which is not great (spring rate goes to infinity). This is vehicle weight compression + 2 inches of linear spring rate compression - for a 600# linear, that's 1,200 lbs. of preload. Your shock stroke length is effectively reduced by the same distance. Less spring compression, less shock up travel, more shock down travel.
Ford reduced the shock stroke length on the sasquatch by adding an internal bump stop on the compression side beyond the standard shock to prevent rubbing the 35s.
The other (better) way to do a spring perch lift is to move the spring travel location in relation to the shock nominal overall length, typically with a threaded sleeve housing over the shock body, the stock spring and a new threaded spring cup and a extended (equal to the change in ride height) spring cup that acts on the end of the stock shock rod, retaining stock compressed spring length and the spring compression due to vehicle mass without additional preload). This preserves the stock spring travel and shock travel.
Guess what? This is functionally identical in every way to a spacer lift described above.
All three methods above are PERFECTLY FINE for anyone not crawling over rocks or undulating terrain more than 3", like concrete parking bumpers so they can fit their 37" tires.
The best way? Longer springs with a longer shock shock matched to the travel length and push the knuckle face out with longer a-arms with the lower a-arm mount dropped to preserve stock - or improved to optimize geometry.
My appeal to expertise - I worked for a vendor to Penske Racing Shocks and things I helped make were on the 2010 Williams F1 team cars.

TL;DR:
1. In a spacer or spring perch lift using stock springs and shocks, you will never gain spring or shock travel. If you add preload to the system to add height, you lose spring travel and the static location of the shock piston changes from stock and total shock up travel is reduced.
2. When you increase vehicle height, using stock springs and shocks, you retain stock up/down travel from static ride height because the spring and shock control it. when you add preload, you reduce up travel and stay the same down travel.
3. All the above are contingent on the CV compressing against the axle housing/knuckle at droop, CV angles, angles between the axle housing and knuckle misalignment, and a-arm ball joint bind.

Spacer lift stock spring stock shock
Spring installed length 1:1 stock
Spring travel 1:1 stock until other components bind
Shock static position 1:1 stock
Shock travel 1:1 stock until other components bind
Shock up travel 1:1 stock
Shock down travel 1:1 stock until other components bind
Ride quality 1:1 stock, negligible +/-
Droop increases until other components bind

Perch lift with preload stock spring stock shock
Spring installed length less than stock equal to increase in ride height
Spring travel less than stock equal to increase in ride height, until other components bind
Shock static position higher than stock equal to increase in ride height
Shock travel less than stock equal to increase in ride height, until other components bind
Shock up travel less than stock equal to increase in ride height
Shock down travel 1:1 stock until other components bind
Ride quality 1:1 stock, negligible +/-
Until spring rate goes infinite at coil bind or progressive rate makes firmer.
Droop 1:1 stock until other components bind

Perch lift no preload stock spring stock shock
Spring installed length 1:1 stock +/- adjustability
Spring travel 1:1 stock +/- adjustability until other components bind
Shock static position 1:1 stock +/- adjustability
Shock travel 1:1 stock +/- adjustability until other components bind
Shock up travel 1:1 stock +/- adjustability
Shock down travel 1:1 stock +/- adjustability until other components bind
Ride quality 1:1 stock, negligible +/-
Droop increases until other components bind

 

[Exomodo]

All this is doing is changing where ride height sits in the travel range. Instead of say 4" of uptravel and 4" of down, now you have something like 6" of uptravel and 2" down. Not exact numbers of course. The maximum distance the shaft droops away from the body hasn't changed.

The shock travel is tied to spring travel. If you take spring travel away by 2"of preload to get 2" of lift, you don't get that back in down travel. You now have 2" up travel and 4" down travel, to your example. The installed spring height is all you get until coil bind unless you spring height in relation to the shock stroke at the end of the shock rod. You must maintain the ratio of shock travel to spring travel in the system or you lose total travel.
Think of a shipping isolator wedge. It reduces vehicle movement by reducing spring travel, while adding height to an otherwise low riding car. Vehicle mass remains the same, shock and spring travel are reduced.

 

[Tricky Dick]

The shock travel is tied to spring travel. If you take spring travel away by 2"of preload to get 2" of lift, you don't get that back in down travel. You now have 2" up travel and 4" down travel, to your example. The installed spring height is all you get until coil bind unless you spring height in relation to the shock stroke at the end of the shock rod. You must maintain the ratio of shock travel to spring travel in the system or you lose total travel.
Think of a shipping isolator wedge. It reduces vehicle movement by reducing spring travel, while adding height to an otherwise low riding car. Vehicle mass remains the same, shock and spring travel are reduced.

My mistake. I was drawing on my experience of using longer springs on a coil over and didn't take into account the lost compression by having 2" of solid material. However, you have it reversed, it will be 4" of uptravel and 2" down, because the shock was not lengthened, the spring was.

 

[Exomodo]

My mistake. I was drawing on my experience of using longer springs on a coil over and didn't take into account the lost compression by having 2" of solid material. However, you have it reversed, it will be 4" of uptravel and 2" down, because the shock was not lengthened, the spring was.

The spring isolator is a poor example (droop suspension, jam rubber isolators in between spring windings, not compress spring/perch and install limiting collar) because it produces the same height result with the opposite change in length, but the result is the same.
2" of spring perch lifts remove 2" of wheel up travel that contributed to the ride height increase, 4" of down travel remains.
Again, not knowing beyond what is described, it's an affordable method to increase clearance for tire fitment, but re-using stock shocks and springs for a large diameter tire performance application, it is not ideal.

 

[rtaylor]

I will be more likely to hit the bump stops when hitting a pot hole and less when hitting a speed bump?

Yes. Until folks try the various coilover lift options and comment on ride quality, it is hard to say what the ride is like. It is likely similar to stock, since the wheel travel is 9-10". Collars are essentially the same idea as adjustable coilovers (4wp, king, fox) since they are using a fixed length spring and are modifying the resting position of the shock with a fixed or variable collar.

An alternative is to swap out the springs (I am a fan of this option). The ride can be tweaked by changing length and spring rate. This can be better than a collar or adjustable coilover since it maximizes the compressible spring length, but the lift is less predictable since it is based on weight instead of geometry. We'll have to wait and see what spring options become available from Eibach or others.

The best way? Longer springs with a longer shock shock matched to the travel length and push the knuckle face out with longer a-arms with the lower a-arm mount dropped to preserve stock - or improved to optimize geometry.

Got it. You are not a fan of stock-width IFS lifts. Not everybody wants a wide-body Bronco (i.e. Bronco Raptor) and we are willing to make some tradeoffs for breakover angle or appearance. I won't tell you that I added a 1.7" coil lift to level my Raptor, because you won't like that either.

My mistake. I was drawing on my experience of using longer springs on a coil over and didn't take into account the lost compression by having 2" of solid material. However, you have it reversed, it will be 4" of uptravel and 2" down, because the shock was not lengthened, the spring was.

Truck springs are long enough that this usually isn't an issue for 2" lift. Shock travel is less than 2" due to the geometry. But, it does point out why spring replacement is often considered superior to collars and adjustable coilovers.

 

[Tricky Dick]

Again, not knowing beyond what is described, it's an affordable method to increase clearance for tire fitment, but re-using stock shocks and springs for a large diameter tire performance application, it is not ideal.

Yes, on a budget you pick your poison. Give up travel or risk binding. I can't say I've been a part of race teams, but I have some hands on practical 4x4 suspension knowledge. I've done a radius arm SAS, a 4 link SAS, a torsion bar to coil over IFS conversion. All custom designed and fabricated because of no aftermarket support.

Truck springs are long enough that this usually isn't an issue for 2" lift. Shock travel is less than 2" due to the geometry. But, it does point out why spring replacement is often considered superior to collars and adjustable coilovers.

Like I was saying, I used arbitrary fictious numbers for simplification. It's closer to a 2:1 ratio on the Bronco.

 

[Cased]

Wonder what this will do to spring rate when you compress towards full up , as you have effectively increased the spring rate

Not a hater and hell a aluminum split collar is easy to cobble up

Really hope a spring manufacture comes up with a new spring , as a block without a strap will be hard on the CV

 

[rtaylor]

The "coilovers" will have adjustments to shock body length for travel.

I am not aware of coilovers with adjustable body length. The adjustable coilovers adjust the ride height (same as a collar) and have fixed travel.

If you are going to do mild to moderate off roading I think a 2" spacer on a non-Badlands is the way to go for a small lift.

The 2" spacer is apparently OK for the black shocks since they have limited travel, but experts have said 2" is too much for BL or sasquatch because they are already near the CV limit. However, at least 2 companies are saying that a 1" spacer is safe for sasquatch.



I sent an email to RPG asking about a hybrid solution combining spacers and collars. They have considered that already and will work on additional solutions when they have time. They are playing it safe now with the perch collars. I did learn some interesting things:
1- there is a clearance concern between the upper link and gas reservoir at full droop when using spacers on sasquatch (something to watch for if planning to use 1" spacers).
2 - Fox replacement coilovers will allow more down-travel than sasquatch.

 

[Gamecock]

An alternative is to swap out the springs (I am a fan of this option). The ride can be tweaked by changing length and spring rate. This can be better than a collar or adjustable coilover since it maximizes the compressible spring length, but the lift is less predictable since it is based on weight instead of geometry. We'll have to wait and see what spring options become available from Eibach or others.

That is what I have done in the past on several vehicles...hopefully someone offers this quickly for Sasquatch....

 

[edgeflyer]

I am not aware of coilovers with adjustable body length. The adjustable coilovers adjust the ride height (same as a collar) and have fixed travel.

Not an adjustable body, the body of the aftermarket shock will have their dimensions adjusted to accommodate the new spring length and shock travel.

The 2" spacer is apparently OK for the black shocks since they have limited travel, but experts have said 2" is too much for BL or sasquatch because they are already near the CV limit. However, at least 2 companies are saying that a 1" spacer is safe for sasquatch.

What can be done and what these experts lawyers will let be done are totally different. I don't recommend more than a 1" on a squatch because downtravel and a balanced stroke is important to me. A spacer under the spring will eat up your travel. I have added spacer lifts and modified the stock shocks to restore the lost droop and have never experienced an CV failure in any way including in the rocks. Guarantee the Bronco will be the same.



I sent an email to RPG asking about a hybrid solution combining spacers and collars. They have considered that already and will work on additional solutions when they have time. They are playing it safe now with the perch collars. I did learn some interesting things:
1- there is a clearance concern between the upper link and gas reservoir at full droop when using spacers on sasquatch (something to watch for if planning to use 1" spacers).
2 - Fox replacement coilovers will allow more down-travel than sasquatch.

This pretty much confirms that CV's will be fine with a spacer lift.

Keep us posted on what you hear from them. Thanks.

 

[balucipher]

I had a lot of RPG parts on my Raptor and spent a lot of time with Corey and the gang. RPG is good people and I'm glad to see they're in the Bronco game

 

[Brock9281]

Can these be used on the stock suspension on OBX…not Sasquatch?

 

[Brock9281]

Actually just spoke with RPG and was told that by end of Nov they will have Spring Perch Collars available for all shocks for Broncos. Say goodbye to pucks!

 

[rtaylor]

Actually just spoke with RPG and was told that by end of Nov they will have Spring Perch Collars available for all shocks for Broncos. Say goodbye to pucks!

Preload spacer is safer if worried about max CV angle, but it results in loss of usable low-speed trail articulation (sway bar disconnected). I am not positive, but it looks like the Fox (Zone) 3"/4" kits may be using the aluminum RPG preload spacers (combined with poly bump stop and strut spacers).

Sponsored