Solutions For Rear Suspension Sag

[Blackford Oakes]

Hey guys. Haven't posted in a while. Hope the 200 village is doing well.

The PO of my 2013 installed the Bilstein 5160/6112 (5th perch) along with SPC UCAs. The truck unloaded with the 3rd row seats still installed has about a 1/2" to 3/4" rake, which I like, but with the cargo area loaded with camping gear and bikes, I get about an 1/2" - 3/4" in sag in the rear. I would be ok with being level loaded down. Having a slight rake loaded would be fine too.

The 3rd row seats will remain installed and I pack this thing down about 6 or 8 times a year.

These are the three possible solutions I'm considering:

1. Airbag Man set-up (FYI, I don't currently tow)
2. rear spacers
3. a different rear coil (I think Bilstein has a heavy load coil out now, but may be overkill for my needs.)

Looking for your opinions.

 

[gaijin]

Hey guys. Haven't posted in a while. Hope the 200 village is doing well.

The PO of my 2013 installed the Bilstein 5160/6112 (5th perch) along with SPC UCAs. The truck unloaded with the 3rd row seats still installed has about a 1/2" to 3/4" rake, which I like, but with the cargo area loaded with camping gear and bikes, I get about an 1/2" - 3/4" in sag in the rear. I would be ok with being level loaded down. Having a slight rake loaded would be fine too.

The 3rd row seats will remain installed and I pack this thing down about 6 or 8 times a year.

These are the three possible solutions I'm considering:

1. Airbag Man set-up (FYI, I don't currently tow)
2. rear spacers
3. a different rear coil (I think Bilstein has a heavy load coil out now, but may be overkill for my needs.)

Looking for your opinions.

Spring rubbers are always an option: SumoSprings

HTH

 

[kcjaz]

Hey guys. Haven't posted in a while. Hope the 200 village is doing well.

The PO of my 2013 installed the Bilstein 5160/6112 (5th perch) along with SPC UCAs. The truck unloaded with the 3rd row seats still installed has about a 1/2" to 3/4" rake, which I like, but with the cargo area loaded with camping gear and bikes, I get about an 1/2" - 3/4" in sag in the rear. I would be ok with being level loaded down. Having a slight rake loaded would be fine too.

The 3rd row seats will remain installed and I pack this thing down about 6 or 8 times a year.

These are the three possible solutions I'm considering:

1. Airbag Man set-up (FYI, I don't currently tow)
2. rear spacers
3. a different rear coil (I think Bilstein has a heavy load coil out now, but may be overkill for my needs.)

Looking for your opinions.

My first step from stock was OME 2721 progressive rear springs. I had and still have OME BP-51 set up front and rear. I had my front set at the highest preload with TJM front bumper and stock rear. This resulted in pretty level unloaded but saggy when loaded for bear. I could have lowered the front but instead I added 30mm rear spacers. this gave me about an inch of rake unloaded but was level/slight raked when typically loaded. I liked the progressive spring and this set up worked for me until I added rear pumper and LRA. Yes, it deflects at the lower spring rate initially but after a certain point, additional lbs don't make a big difference and and the unloaded ride isn't too stiff. Now I run 2724s as I'm like 7200 lbs loaded empty. Here is a table of the OME choices:

I weighed my truck and did spring rate calcs to select my 2724s. If I had done that with my 2721s I would have realized I would be saggy in the rear and would need spacers but I still may have done that as I really liked the total amount of lift. My conclusion was that for essentially stock rear having to deal with daily driving empty but trips loaded, the progressive springs were great. If you don't like different rear ride heights loaded vs unloaded, the only option is air bags.

I also considered the helper springs @gaijin posted above but in my case this would have just turned my progressive 2721s into a constant spring and I would still have needed spacers (in my current build state). For the OP, the helpers might work and would be the cheapest and easiest thing to try.

 

[777Gage]

I've got the same set-up as you as well as the 3rd row. I swapped out the regular Bilstein rear springs for the HD ones and it's a noticeable difference. I'm happy with the stance and ride when loaded.

 

[dcs111]

Airbags work well for occasional extra loading. I had same setup with 2721s and thought the truck was over sprung in rear when unloaded….

 

[FerrisBueller]

Another vote for airbags. They're great for the occasional loaded up vehicle, while avoiding the harsher ride that heavier duty springs would give when unloaded.

 

[Sandroad]

If you’re happy with the rake and ride unloaded, I’d also vote for airbags. Very versatile and will give you the adjustability for occasional various loads.

 

[Gr8Daneger]

I have Timbren bump stops. My ride is factory at the moment and I have the ones they designed for our trucks. The problem is with the ones they provided for my truck actually rest on the axle with no weight in the back, except 3rd row. This was good and bad. When I have the truck loaded and a Pakmule on the back the stance is perfect and rides like a dream. Unloaded it is super bouncy, but I can now swap them out without even taking the tires off with just jacking up the truck. I called Timbren and told them about the issue and the sent me shorter rubber bumps, but I never installed them because I like the way the others perform. It’s not ideal swapping them out all the time but honestly I wouldn’t do it any other way.

 

[TeCKis300]

I have Timbren bump stops. My ride is factory at the moment and I have the ones they designed for our trucks. The problem is with the ones they provided for my truck actually rest on the axle with no weight in the back, except 3rd row. This was good and bad. When I have the truck loaded and a Pakmule on the back the stance is perfect and rides like a dream. Unloaded it is super bouncy, but I can now swap them out without even taking the tires off with just jacking up the truck. I called Timbren and told them about the issue and the sent me shorter rubber bumps, but I never installed them because I like the way the others perform. It’s not ideal swapping them out all the time but honestly I wouldn’t do it any other way.

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I struggle to understand what Timbren is trying to achieve here. If they really tried to make a tailor made bump for the 200-series or just cobbled parts together to shoehorn into a 200-series application? More than likely, they're trying to create a market for their core tech but it's not a great application.

I don't mean to be a debbie downer but in general, it's bad form for suspension tuning to ride on bump stops as you experienced. Rubber doesn't have the tuning and heat dissipation of coil springs and shocks, and make a poor substitution for such. The transition from unengaged to engaged is abrupt. They're trying to market this as an "active" bump stop whatever that means, but it's a terrible way to do suspensions. It also limits suspension uptravel dramatically. More appropriate for rudimentary trailer suspensions.

Here's what competing Durobumps looks like for the 200-series rear axle. Even here, I find they're probably still 1/2" taller than necessary and I wish they engaged only at the very last bit of travel as a safety, and let the suspension do its job for overall better control.

 

[cboyd]

I’m running the progressive dobinsons and they are nice when unloaded and do quite well when loaded or trailering.

 

[Gr8Daneger]

I struggle to understand what Timbren is trying to achieve here. If they really tried to make a tailor made bump for the 200-series or just cobbled parts together to shoehorn into a 200-series application? More than likely, they're trying to create a market for their core tech but it's not a great application.

I don't mean to be a debbie downer but in general, it's bad form for suspension tuning to ride on bump stops as you experienced. Rubber doesn't have the tuning and heat dissipation of coil springs and shocks, and make a poor substitution for such. The transition from unengaged to engaged is abrupt. They're trying to market this as an "active" bump stop whatever that means, but it's a terrible way to do suspensions. It also limits suspension uptravel dramatically. More appropriate for rudimentary trailer suspensions.

Here's what competing Durobumps looks like for the 200-series rear axle. Even here, I find they're probably still 1/2" taller than necessary and I wish they engaged only at the very last bit of travel as a safety, and let the suspension do its job for overall better control.

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I hear what you are saying, but I have to disagree in a loaded application. There is nothing else that is going to give you a stock ride unloaded ( bumps removed) and a great supported ride loaded. There is no transition from unsupported to supported because they are alway engaged in my case. I’m not loaded down for anything other than highway miles, where I encounter little to no bumps that require much articulation. Bags limit travel as well and having one blow on a trip was my concern. Springs ride rough when not loaded as well. So in the end your going to have to pick your trade off.

 

[ttrmike]

I’ve been through multiple different rear suspension setups trying to solve this same issue. I started with oem springs plus Firestone airbags, then 2721, then 2723, then Ironman rear coils, then Timbrens, softer timbrens, then softer and shorter timbrens, then the softest sumo spring (blue) on custom shorter mounts l, then bilsteins 170lb/in springs plus sumo springs (2nd best), then bilsteins plus oem bumps. I’ve finally come full circle back to oem springs and bumpstops plus Firestone airbags.

Frankly every other permutation of rear suspension might have towed or hauled well, but unloaded ride was terrible for poorly maintained roads. I think those progressive springs and extended bumpstops only work well on well maintained roads where you don’t notice the engagement.

For highly dynamic loads I think your only options are AHC or airbags.

 

[2021 LC200]

If you’re happy with the rake and ride unloaded, I’d also vote for airbags. Very versatile and will give you the adjustability for occasional various loads.

I have the Airbag Man setup with Kevlar sleeves for longevity and ability to go to higher pressure (in my case 30psi) when we tow something heavy. Good setup with schrader valves routed to a metal clip at the hinge area of the split tailgate. Been holding up with no issues since 2021. Fingers crossed it remains trouble free.

Schrader or Valve Stem location - Courtesy of TECKIS300

I can not comment on frequent use of this setup deflated at 5 psi (recommended deflated pressure) when significant off-roading and articulation is your thing. I can see less ability to articulate. For me this is very very unusual so for the rest of my use this is the perfect setup. I am thinking A-TRAC and single wheel breaking will save the day I believe when significant articulating conditions are encountered. However I do believe it will affect this capability/party trick of the 200 series.

Trade offs…

 

[2021 LC200]

There is nothing else that is going to give you a stock ride unloaded ( bumps removed) and a great supported ride loaded.

Well, while I have not much against timbren's perse, other than point loading the axle (maybe not an issue in a 200, I do not know), I also have to disagree with this statement.

Air bags installed inside the coil springs, either firestone type or airbag man (= firestone + kevlar sleeve) provide no change of ride when deflated at 5psi and can be varied from 5 to 40psi or so to level all type of loads even keeping a 200 + heavy trailer level without WDH. They also maintain a comfortable ride like airbags do throughout their application leveling the vehicle. Since they are secondary to the coil springs they are fail safe. In addition, air bags allow for a lot of articulation off road, although not as much as stock I would expect.

A further side benefit of airbags when plumbed separate (i would recommend), is being able to level the car for inside or rooftop sleeping.

Now timbren's are a simple concept, so it is a choice for sure. I would recommend however air bags in most cases. I believe cost wise there is not much between. Installation of airbags is more involved but doable for most DIY'ers. Securely jacking up the vehicle and making absolutely sure it does not role forward when dropping the axle is paramount. I cannot stress this enough as once life depends on it.

 

[TeCKis300]

I hear what you are saying, but I have to disagree in a loaded application. There is nothing else that is going to give you a stock ride unloaded ( bumps removed) and a great supported ride loaded. There is no transition from unsupported to supported because they are alway engaged in my case. I’m not loaded down for anything other than highway miles, where I encounter little to no bumps that require much articulation. Bags limit travel as well and having one blow on a trip was my concern. Springs ride rough when not loaded as well. So in the end your going to have to pick your trade off.

Sorry if my tone came across negative. Really trying to look-out. In theory, putting a giant rubber bump stop might seem to be a good solution, but it couldn't be further from the truth.

It's always a compromised but airbags are a great solution. They are inherently adjustable for varying loads and more importantly, will give you the performance you're looking for.

 

[bloc]

At least the airbags are tunable for different loaded states.

As it is the stock axle already has a super-gradual rubber spring installed inside the stock coil that is intended to do the same thing. But when we increase height we usually don’t consider adjusting this clearance to maintain the effect. Plus these and the airbags aren’t as outboard as the timbrens so they don’t reduce articulation potential nearly as much, while still maintaining load carrying capability.

If you do lose an airbag on a trip you at least have the bump stops to prevent real problems until you get to a shop.. and any shop could do an airbag if you had one.