BP-51 help (9 Viewers)

[TNLNDCRZR]

Rig:
2021 HE 3 Row
BP-51
2721 rear springs
Slee sliders
No extra weight front or rear over stock as of now.

Need some help! I cannot get my ride dialed in. My main issue is in the rear. I can’t seem to get enough rebound dampening to keep the rear from rebound too quickly.

If I push the rear compression up to 4 to keep the spring from compressing as much the ride starts to get a little rigid. If I soften the compression to 2, it feels like the rear is launching after the springs are compressed even when rebound is set to 8, like there is not enough rebound dampening.

OR, maybe I am oversprung with the 2721 at stock weight? Considered switching to the Bilstein rear springs which are rated at 170lb.

I’m tempted to throw in the towel on the BP51 for fox 2.5 dsc.

Please help if you can! Would love to make the BP51 work.

 

[linuxgod]

I doubt it's the shocks, per se - just the settings you're using. What I mean is... changing out your shocks to Fox or King or something else likely won't provide a significantly different ride than a well tuned BP51.

Shocks: A Mystery No More - Hyper Racing

Racing shock technology.

www.hyperracing.com

Compression is when the shock gets shorter; rebound is when the shock gets longer. For example, when the front bumper is depressed, compression occurs, when it is released, the shocks rebound.

The velocity of a shock is the speed at which it is compressing or rebounding

You probably need less rebound along with less compression, but someone very familiar with the BP51 tuning should chime in. For most of our rigs I think folks run compression of 2 or 3 and a much higher rebound, with the notion that low compression allows for a soft ride over bumps but high rebound prevents you from being too floaty. In your case your probably have a bit too much rear spring, so the spring is already forcing the shock to rebound quickly. The high rebound setting combined with the high spring rate feels like your springs are trying to push your back to neutral too quickly. Having run 240# springs on a stock vehicle I don't think 270# 2721's are necessarily too stiff, but you need to back off on the rebound and compression numbers to compensate for an imperfect spring rate. (170# Bilstein springs would be a better match but if you are planning to add weight then you may regret swapping to them)

Set your compression as low as you can without making your ride feel like your a floaty cadillac. Set your rebound low as well and then notch it up a little at a time until you feel like your springs are a bit harsh and responding too quickly, then back it off. FWIW I don't have BP51 but my Tough Dog shocks have a single adjustment knob which is basically compression and rebound in one setting, and despite my build I keep them at ~3.

 

[TeCKis300]

Rig:
2021 HE 3 Row
BP-51
2721 rear springs
Slee sliders
No extra weight front or rear over stock as of now.

Need some help! I cannot get my ride dialed in. My main issue is in the rear. I can’t seem to get enough rebound dampening to keep the rear from rebound too quickly.

If I push the rear compression up to 4 to keep the spring from compressing as much the ride starts to get a little rigid. If I soften the compression to 2, it feels like the rear is launching after the springs are compressed even when rebound is set to 8, like there is not enough rebound dampening.

OR, maybe I am oversprung with the 2721 at stock weight? Considered switching to the Bilstein rear springs which are rated at 170lb.

I’m tempted to throw in the towel on the BP51 for fox 2.5 dsc.

Please help if you can! Would love to make the BP51 work.

I've said this elsewhere but spring rate is the primary dictator of compliance and ride quality. For a stock weight rig, you have too much spring rate, and it is oversprung as you suspect. No amount of shock dialing or adjustment will lessen the spring rate.

Shocks are there to absorb and control the energy that is put into the suspension. Given a specific spring rate, there is a corresponding requisite range of compression and rebound. Any less, and there is insufficient damping and control. It's the trade between a harsh but controlled ride. Or a harsh, uncontrolled, and bouncy ride.

2.5 dsc won't change that. If the goal is a compliant ride, compliant spring rates are what's necessary.

@linuxgod made a great table elsewhere. Unless you're adding significant installed weight, I would look at the lower range of spring rates.

vendor	part #	l/h mm	r/h mm	coils	wire mm	low lb/in	high lb/in	min load kg	max constant kg	min load lb	max const lb
King Springs	KTRR-131H	450​	470​	7.2​	18​	240​		100​	250​	220​	550​
King Springs	KTRR-131HD	430​	450​	7.2​	19​	275​		100​	300​	220​	660​
King Springs	KTRR-131HHD	430​	450​	7.2​	20​	340​		300​	500​	660​	1100​
King Springs	KTPR-131HD	435​	455​	8.4​	19​	250​	350​	100​	300​	220​	660​
OME	OME-2721 0" lift	430​	440​	8.42​	18.5​	270​	350​	0​		0​
OME	OME-2722 1" lift	430​	440​	7.2​	19​	275​		0​	200​	0​	440​
OME	OME-2723 1" lift	440​	450​	7.2​	20​	340​		200​	400​	440​	880​
OME	OME-2724 1" lift	435​	445​	7.2​	21​	400​		400​	600​	880​	1320​
OME	OME-2725 1" lift	435​	445​	7.71​	22​	440​		600​		1320​
Tough Dog	TDC931L 1" lift	445​	475​	7.2​	18​	240​		0​	300​	0​	660​
Tough Dog	TDC931HL 1" lift	425​	455​	7.2​	19​	275​		300​	500​	660​	1100​
Tough Dog	TDC931VHL 1" lift	425​	455​	7.2​	20​	340​		500​		1100​
Bilstein	B12 53-297686							180​		396​
Eibach	E30-82-072-04-02	414	414			300		90​	180​	198​	396​
Icon	Dual Rate 52750					?	?			0​	0​
Trail Tailor	Tourflex Standard	505​	515​	9.77​				100​	300​	220​	660​
Trail Tailor	Tourflex HD	545​	555​		19.5​	180​	320​	300​		660​
Ironman	TOY064A 1" lift	425​	440​		19​	269​		0​	200​	0​	440​
Ironman	TOY064B 2" lift	455​	470​		19​	269​		0​	300​	0​	660​
Ironman	TOY064EA 2" lift	465​	475​		20​	286​		100​	400​	220​	880​
Ironman	TOY064C 2" lift	455​	465​		21​	371​		400​		880​

 

[1Maverick]

I’m running 2722 rear spring, 2nd row edition and I had similar issues as you. I’m still playing with it but found that my current rear setting(5r,3c) is pretty good when hitting potholes and typical hwy patches, etc. However, it feels a little floaty, like the rear-end is swaying left to right when going over speed bumps and the alike. Need to probably increase the rebound a notch. I hate and I mean hate how you have to crawl under the truck to adjust the shocks. They are a pain to turn after awhile, where i have to use another wrench to hold one dial while turning the other at the same time. Not great when you want to go off-road and you’re already on dirt. When they need to be rebuilt, I’m going to give them away and get Dobinson MRA with Icon progressive springs or similar.

Update: Forgot to mention, I am running Slee sliders and a 12.5 LRA

Update2: I have 285/70r18 Ridge grapplers 37psi.

I will eventually switch them out with 275/70r18 SL General Grabbers APT for better road comfort or the Revo3 295/70r18

 

[TeCKis300]

Probably useful to throw tires and inflation detail in the discussion. Tires are a big part of the suspension.

 

[TNLNDCRZR]

I've said this elsewhere but spring rate is the primary dictator of compliance and ride quality. For a stock weight rig, you have too much spring rate, and it is oversprung as you suspect. No amount of shock dialing or adjustment will lessen the spring rate.

Shocks are there to absorb and control the energy that is put into the suspension. Given a specific spring rate, there is a corresponding requisite range of compression and rebound. Any less, and there is insufficient damping and control. It's the trade between a harsh but controlled ride. Or a harsh, uncontrolled, and bouncy ride.

2.5 dsc won't change that. If the goal is a compliant ride, compliant spring rates are what's necessary.

@linuxgod made a great table elsewhere. Unless you're adding significant installed weight, I would look at the lower range of spring rates.

Sounds like you are thinking the same way I am. I have some Bilstein coils in my garage I’m going to try out. If they work out well, I can always add airbags for when loading up (which is infrequent for me).

Even if they the Bilstein works, I may still switch to the fox 2.5 dsc for the ease of adjustability. I have waiting to find them in stock and finally grabbed a set today. If not, I’ll send back.

I’ll report back on how the Bilstein mesh with the BPs.

 

[TNLNDCRZR]

Probably useful to throw tires and inflation detail in the discussion. Tires are a big part of the suspension.

275 70 18 General Grabber ATP SL rating.

 

[TNLNDCRZR]

275 70 18 General Grabber ATP SL rating.

Running approx 37 psi. Any softer and I get too much flex in the sidewall.

 

[1Maverick]

Running approx 37 psi. Any softer and I get too much flex in the sidewall.

This is good info. Maybe I’ll stick with E load tires. I was really hoping these tires would be the ticket. How are they on the highway?

 

[TNLNDCRZR]

This is good info. Maybe I’ll stick with E load tires. I was really hoping these tires would be the ticket. How are they on the highway?

They actually ride really well. Quiet and smooth.

Next time round, I’ll be going with the 275-70-18 Goodyear wrangler territory MT in C load. Only tire that size in C load. It’s not a true mid terrain, more of am AT hybrid. It’s also what they are putting on the new bronco.

 

[COYS]

I have the BP51s on my 80 series. One notch turn to adjust up or down makes a noticeable difference with these shocks. I wouldn’t skip notches. I love these shocks.

Gl.

 

[jefo13]

They actually ride really well. Quiet and smooth.

Next time round, I’ll be going with the 275-70-18 Goodyear wrangler territory MT in C load. Only tire that size in C load. It’s not a true mid terrain, more of am AT hybrid. It’s also what they are putting on the new bronco.

Interesting that on this tire MT stands for Maximum Traction not Mud Terrain...

 

[1Maverick]

They actually ride really well. Quiet and smooth.

Next time round, I’ll be going with the 275-70-18 Goodyear wrangler territory MT in C load. Only tire that size in C load. It’s not a true mid terrain, more of am AT hybrid. It’s also what they are putting on the new bronco.

I was not aware of this tire. It definitely is a better looking tire then the APT. I’ll be curious to hear how it compares in ride quality to the APT.

 

[Tex68w]

Crazy how I always see more complaints about the BP-51's than I do those praising them. It's enough for me to skip over them altogether when the time comes. I'd love to see some pics of those lifted with 275/70/18's.

 

[1Maverick]

Crazy how I always see more complaints about the BP-51's than I do those praising them. It's enough for me to skip over them altogether when the time comes. I'd love to see some pics of those lifted with 275/70/18's.

I honestly believe they’ve been overhyped by off-road installers because they are an ARB product. But as an owner, the endless fiddling with the adjusters can be knuckle smashing and shoulder wrenching. When they are new it’s not so bad to adjust but as they begin to get more use, the dials start sticking and impossible to turn without using a second shock wrench to counter turn them. This is where the knuckle smashing and shoulder wrenching comes into play. Top of my list is replacing them with either Dobinson MRA or King 2.5dsc with progressive springs, whichever is going to give me the most compliant hwy ride for 99% of my driving. I will say the BP-51 are excellent upfront, better then my previous ICON 3.0. The rear is giving me the most trouble. No doubt my 2722 is part of the problem but wanted the 1” lift.

 

[Tex68w]

I honestly believe they’ve been overhyped by off-road installers because they are an ARB product. But as an owner, the endless fiddling with the adjusters can be knuckle smashing and shoulder wrenching. When they are new it’s not so bad to adjust but as they begin to get more use, the dials start sticking and impossible to turn without using a second shock wrench to counter turn them. This is where the knuckle smashing and shoulder wrenching comes into play. Top of my list is replacing them with either Dobinson MRA or King 2.5dsc with progressive springs, whichever is going to give me the most compliant hwy ride for 99% of my driving. I will say the BP-51 are excellent upfront, better then my previous ICON 3.0. The rear is giving me the most trouble. No doubt my 2722 is part of the problem but wanted the 1” lift.

Good to know. The King's and MRA's are the only two I am considering at this point. Based off of multiple ownership experiences in the past I can honestly say that Icon shocks are absolute trash.

 

[bloc]

As a counter point I have 2720s that are the same rate as 21s, and they are definitely not too stiff, even when empty with 2nd and 3rd row out.

When I worked with Ben at Filthy for my shocks he was adamant that springs “only determine ride height by holding up the vehicle”, meaning rate wasn’t important for ride quality, damper characteristics were.

I took this to mean there are limits.. but for the vast majority of spring options we have it’s the damper that needs tuning, not the spring, when it comes to ride.

So I wouldn’t chuck those 2721s just yet.

I’m running 2722 rear spring, 2nd row edition and I had similar issues as you. I’m still playing with it but found that my current rear setting(5r,3c) is pretty good when hitting potholes and typical hwy patches, etc. However, it feels a little floaty, like the rear-end is swaying left to right when going over speed bumps and the alike.

Your side to side sway is most likely caused by excessive panhard rod angle, considering you have 2722s in the rear. I’d keep an eye out for the panhard relocation brackets being developed at the moment.

 

[linuxgod]

As a counter point I have 2720s that are the same rate as 21s, and they are definitely not too stiff, even when empty with 2nd and 3rd row out.

When I worked with Ben at Filthy for my shocks he was adamant that springs “only determine ride height by holding up the vehicle”, meaning rate wasn’t important for ride quality, damper characteristics were.

I took this to mean there are limits.. but for the vast majority of spring options we have it’s the damper that needs tuning, not the spring, when it comes to ride.

So I wouldn’t chuck those 2721s just yet.





Your side to side sway is most likely caused by excessive panhard rod angle, considering you have 2722s in the rear. I’d keep an eye out for the panhard relocation brackets being developed at the moment.

There are a few things which can impact side to side sway. One of them I’ve found is differences in spring height. My Tough Dog rear springs were 1” (25mm) different left to right and I had a lot of that shake going over speed bumps. When I went to the Ironman rear coils recently they were only 10mm different and that shake was almost gone. I added a 10mm trim packer to the taller side to get the vehicle height level and so I’m now 20mm longer on one side and the shake is back though not quite as bad as it originally was.

 

[1Maverick]

There are a few things which can impact side to side sway. One of them I’ve found is differences in spring height. My Tough Dog rear springs were 1” (25mm) different left to right and I had a lot of that shake going over speed bumps. When I went to the Ironman rear coils recently they were only 10mm different and that shake was almost gone. I added a 10mm trim packer to the taller side to get the vehicle height level and so I’m now 20mm longer on one side and the shake is back though not quite as bad as it originally was.

My previous 200 had icon progressive springs and they never had the sway effect. It seems like the Ironmans are a great option based on comments on this forum. The Dobinsons have a couple spring options. Curious how those stack up.

 

[TeCKis300]

It may help to have a common understanding of what the shocks role is in a suspension. And how various types work. For a vender to say that springs "only determine ride height by holding up the vehicle" is a huge disservice. Yes, suspensions are complicated, and there's a need to simplify some concepts for sales, but that is straight up wrong. The litmus test is easy, keep adding spring rate and what is the logical intuition of how a car will ride? Rate also should not be used to tune free height, i.e. lift.

High end shocks don't necessarily provide a better ride, on the contrary has potential impacts of more stiction and NVH due to pressure and use of race components like spherical bearings. Things that's don't last as long on street car. The real benefit of high end shocks is the ability to provide higher damping forces for longer durations. With some having the ability for tuning, which can honestly be a double edged sword, with more ways to get it wrong than right.

Here's a great series