Rear Suspension Options: Leaf Springs, Shocks, Shackles, and Blocks

About a year ago I installed a 2.5" RC spacer on the front of my 2018 Platinum Crewmax 4x4 to get a more aggressive look and fit some larger AT tires. The kit also came with a block spacer for the rear leaf springs, but I never installed it. The front sat a little high, but the truck was still new and I figured the coilovers would settle a little.

More recently, I added a camper shell with Yakima bars and a BajaRack cargo rack. I've now noticed that truck sits a little lower in the rear than I'd like and has a noticeably "heavy" feel when I'm loaded up with passengers and gear (coolers, camping gear, dogs, etc.). It almost feels like the rear is bottoming out when I hit bumps/dips in the road (I'm not sure that it actually is). In a few weeks, we'll be picking up a 20' camper trailer (3,500lb Gross dry weight, 350lb hitch weight) and I can only imagine that this will exacerbate the issue.

This is a daily driver (most of mileage is on the road), but is also our family's primary vehicle for camping and hunting trips. I'm not doing any serious off-roading, but want a capable truck in the backcountry. I do plan to do the front "right" and get some 2.5" coilovers and UCA's sometime in the future, but right now I need some help on the rear...

I'm hoping to understand:

• What do the rear suspension components (leaf springs, shocks, shackles, block) do for the: 1.) height of the rear, 2.) On-road driving experience, 3.) off-road performance, and 4.) towing performance?

• What component(s) upgrades would you recommend to fit my needs? Shocks? Leaf spring(s)? Shocks & leaf springs? Shackles? etc.

Sorry for the novel. I just wanted to make sure you have all of the relevant info!

-Beau

Here's my truck: https://www.tundras.com/threads/2018-platinum-crewmax-4x4.74254/

 

Lots of info out there an lots of different opinions. I've run blocks in the past without issue. This time around I went with a shackle. I have no complaints. My buddy has an add a leaf in his Tundra. None of these options will really help with amount of sag but more help mask it by starting at a higher point . I never noticed a night an day ride quality difference between them. But that's just my opinion. If you end up doing a nice adjustable coilover in the front down the road I would pair it with a comparable shock for the rear for a matching set.

Currently I run a toytec shackle at 1" with a 1" block because I wanted 2" lift. I tow a camper almost every weekend. I went with a sumo spring to help with the load of the camper I also have a weight distribution hitch. In hindsight I would opt for a airbag setup I think the Sumo spring didn't do much.

So that being said I'd recommend a add a leaf or shackle lift to get the back up where you want it an maintain decent ride. An maybe a air bag setup for towing / heavy loads but that's just IMO.

If you already have the block it may be worth just throwing it in there. It's a simple install an it will bring your height up. If you hate it then you haven't lost anything by trying it .

 

Thanks for the response. Your post above is helpful, but I guess I'm hung up on exactly what the benefits of each setup are and which components can, or should, be paired together.

For example, if I were to add the block, I understand that the ride height will be greater. But is this purely aesthetic, or do I gain anything from the "higher starting point" as you put it. Would new shocks compliment the block? Would upgraded shocks, alone have an impact on ride height and "sag"? When would beefier leaf springs be desirable? Etc.

 

I got ya, generally speaking most inexpensive options are mainly asthetic. A block is not changing anything. It's literally just a spacer between the axl an the leaf springs. So in theory it should ride the same as stock. Some folks claim it increases axle wrap. Or twisting/ movement of the axle under acceleration, I've seen lots of people say it makes the ride bad. I've never noticed any notable issues with this personally. A shackle usually will replace the rear eylet bushing on the leaf springs with a polyurethane unit. It has been said to free up some movement in the leaf springs thus ride a little nicer but again. Just lifts the connection point up a few inches to achieve the height. Some folks will claim things like it flattens the leaf spring faster over time. An add a leaf actually gets added to the stock leaf pack. In theory this is the most robust option because your adding another leaf to a sort of weak factory pack giving the pack a boost if you will, to achieve height. Some claim this can also increase the stiffness of the ride due to that additional leaf or leafs and doesn't really give you any additional load capacity. A full leaf pack can be good option however expect to pay alot. And some heavy duty packs are said to make the ride harsh. If your driving more or less empty most of the time the ride would suffer a bit, but full leaf packs can be custom built to do pretty much whatever you want just need the $$. Shocks won't help with sag. But they will help control the movement of all the components. It depends on what they are valved to do. A popular option like a 5100 Bilstein. Is valved a little stiffer then a stock 4600 for example.. I'd say it's good to match front to back so they are working in harmony.

 

Thanks! I've also been doing some reading around the site, trying to wrap my head around it all. Lots of info to digest. Let me attempt to summarize:

Block spacer: purely aesthetic, no impact to ride quality or sag under load.
Shackle: Also aesthetic, but a potentially better option than the block spacer
Leaf springs (AAL or Leaf pack): Can provide lift and reduced sag, put can lead to stiff ride on road when there isn't much weight in the truck
Shocks: Provide no lift or reduced sag, simply provide dampening in the suspension cycle (**Is this correct? If so, what is the result in "feel" from upgrading shocks alone?)

A new one that I've started reading about is air bags. My understanding is that they provide support and prevent sag on a truck under heavy load, and their pressure can be adjusted to suite your needs. Clearly this can help with sag, but how would this impact the overall ride quality on and off road? I've seen them paired with a Daystar cradle, rater than having the bottom of the bags fixes to the leaf springs. This seems logical to me for maintaining a full range of down-travel, but is up-travel limited by having airbags?

 

Tundra leaf springs are soft and sag. Airbags definitely help carry load (obviously won’t increase payload, just sag). You can also adjust airbags depending on how much weight you carry.

I have airbags and usually have 15 psi in them and it drives and feels like a truck. I have a decked and ARE cap. I recently carried half a ton of pellets and aired them up to 50 psi. I could feel the load but there was no sag. I also have the daystar cradles and wouldn’t have airbags without them. With the cradles, only travel that is affected depends on how much air you have in them. The airlift airbags have internal jounce bumpers to help with bottoming out.

I got the compressor too and can air up or down with a Bluetooth remote which is nice but not needed. You can air up with a bicycle pump if you wanted to.

A 3500lb camper shouldn’t need it, but you could look in to getting a WDH too.

 

You seem to have a pretty good grip on it. The feel of different shocks can be quit subjective. I have toytec shocks with the additional res. I think it soaks up larger bumps better. But is it night an day difference from stock? Na. An maybe I'm not as sensitive as others to these changes . I have Toytec Aluma series up front an again. It rides smooth an handles bumps well. Maybe a little stiffer then stock feel overall. Ask 10 people they would probably describe it 10 different ways.. As far as air bags I have no personal experience but my understanding is you pump them up when you want to level a load. But otherwise they run with very little PSI and shouldn't effect travel much or ride quality.

 

The WDH might be a good approach, even though it might be overkill for a 3500+ lb (5400lb GVWR). I'm thinking maybe a shackle + shocks to compensate for the added weight of the camper shell and gear, plus a WDH for maintaining that height (and handling) when towing.

Does this approach sound reasonable? Or should I be targeting leaf spring upgrades instead of the shackle?

 

Depending on what you want to spend, I’d say get shackles and airbags. That’s what I did and it carries my load really good. I’ve read some issues with add a leafs, like sagging came back after a few years.

 

I too have the Firestone airbags on my truck, with the Daystar cradles. No fancy remote on mine, but i have a gauge and pump switch in center console so i can air up and down from the drivers seat. Rides a little stiffer in the rear unloaded, and I run about 3 psi unloaded. When loaded though, what a difference it makes. Use to be able to fell every little bump the trailer hit when towing, now the truck rides smooth, and barely moves with the trailer doing it's own thing out back.

So I would recommend getting the air bags, and cradles.

 

Thanks! Any specific reason you didn't address shocks?

 

Thanks for the suggestion and first hand experience! Perhaps the added stiffness could help in my situation (camper shell and racks). Are the bags mainly targeted at reducing sag or are can they be thought of almost as shocks with adjustable "stiffness"?

 

Mainly for sag, they of course will change your spring rate, which will change how the shocks work some.

 

If you are into off-roading, I would not recommend bags. The bump in them is pretty crap and affects off-road ride quite a bit. You will also need to put cradles so you don't over extend the bag. I am experiencing this now. I'm going to ditch my bags and go with a proper bump.
If you will be rolling around with weight on the bed, I would recommend aal or new leaf packs.
New leaf packs would be the best option as you can have them custom made for your truck and your weight.
AAL is a decent, inexpensive way to add some lift and rate.
Shackles would be alright, but all you're doing is adding lift. You're not addressing the spring rate issue. You'll still have the stock rate and you can put the spring negative in some situations.
Blocks... eh. No.

as far as shocks go, that would REALLY depend on the type of driving your doing, but I would recommend something tunable so you can get the best quality ride for what you do and what spring upgrade you decide to go with.

 

Thanks for sharing your experience with the air bags and bringing "spring rate" into the discussion. I think I'm finally starting to understand the various rear suspension options, but I would really like to see the intended use for each option spelled out more clearly. Based on what folks have contributed here and what I've gathered from elsewhere, here's where I'm at:

Suspension Component: Intended use
Block spacer: Increase ride height. No change in travel or spring rate.
Shackle: Increases ride height. No change in travel or spring rate. (Preferred over block spacer)
Add-A-Leaf: Inexpensive way to increase ride height and spring rate (used for heavy loads? Off-road performance?)
Leaf pack: Relatively expensive (and proper?) way to increase ride height and spring rate. Increased travel? (suited for increased loads and/or off-road performance?)
Shocks: It's still not clear to me what the intention of upgrading the shocks is. Longer travel? "Stiffer" for increased loads?
Air Bags: Maintaining ride height (and therefore handling/stability?) under heavy loads and towing. Decreased off-road performance.

Can you all help me to round out the last few questions in red?

 

I am just trying to very deliberate about what I am attempting to fix: sagging in the rear due to weight of camper shell, gear, and soon-to-be travel trailer.

I think the issue with my current setup is that much of my uptravel(?) is being eaten up by the weight over/in my truck and results in a 1.) sagging rear end, 2.) less useable uptravel, and 3.) decreased towing performance.

It would seem (in my simple mind) that a shackle could fix #1 (and maybe even #3), but definitely not #2.
Attacking the leaf springs could solve all three issues, but potentially at the expense of the on-road, unloaded drivability (stiff and rough).
Airbags would target #1 and #3, but would do nothing for #2.
Shocks....no idea (yet)!
I could also work a Weight Distribution Hitch (WDH) into the mix to address that would help to address all three (when towing)

 

Add a leaf will not increase travel. Leaf packs can increase travel and increase load support, also increase off road capabilities. shocks just help with compression and rebound. cheaper ones are preset 5100 for example. More expensive ones like king, ads, fox can be better tuned for whatever you need.

I have the deaver u748 leaf pack with ADS bypasses and coachbuilder +1 shackle. The packs is designed to increase travel and still hold up to some constant bed weight. Do to increase travel the shocks have to be a different length and bypasses are used for tuning. The shackle is needed with the u748s. Hope this helps a little.

 

It will be extremely difficult to find best of both worlds. Towing and offroad. You will need to figure out what you can live with. And what you are really doing to use the truck for.

 

Very helpful, thank you! How does it ride on the road with this setup in the rear?

 

If this is your concern then airbags are what you need. It will also affect your ride the least when unloaded.

 

Agreed. I realize everything is a compromise. That being said, I won't be towing a 40' toy hauler or doing any crazy offroading/rock crawling. I just want to be confident towing our 20' trailer (while loaded up with gear, dogs, and humans) or doing some light off-roading (mostly backcountry forest roads).

Given that I don't plan to do any serious off-roading, I'm not sure that I actually need more travel. Air bags might also be overkill for my towing needs. Maybe something in the middle will meet my needs.

One quick clarification from your post above: Can you elaborate on what you mean by, "shocks just help with compression and rebound". Can upgraded shocks alone help to manage the added bed weight while I'm going over bumps/dips (ie. keep it from bottoming out)?

 

Shocks won’t help carry or hold a load on a truck that’s not moving. They’ll just compress. Most of the other stuff mentioned will, like airbags.

But since obviously the truck will be moving, good shocks can help dampen the load. Better ones have more oil and will stay cooler longer. But with what you are carrying, stock shocks will be good enough.

The leafs and coils are what holds up the truck and any load. You can drive without shocks if you want, but you can’t drive without leaf springs. I had a friend who had a caprice classic 4 door. It was a huge car. He took the shocks off and that thing would roll in curves but it still got places.

 

No shocks won't help alone they can assist with the compression of the leafs.

 

Shocks will help to prevent the pogo stick effect of a free spring. The shocks will slow and control the movement of the springs.

If you're planning on something average that will do well at everything and not really be purpose built, I would steer you to start with aal and move towards full spring packs once you start doing things with your truck. Once you get an idea of what you'll be doing regularly with the truck, you can give a custom pack builder more details and be confident with those details. You would hate to have a set of custom packs made for carrying the weight you PLAN on hauling around off-road, but end up not doing much of that.

Hell, just rock it as is and see what you need. Go out and do things. Give it a shot with how it is now. There's plenty of people out there doing what you want to do with stock trucks. I off road mainly daytrips and prefer to do moderate trails with off camber sections and rocks and stumps maximum of 12" high. I'm on stock suspension as I'm a buy once cry once kinda person. I'm saving for the higher end stuff that, honestly, I don't need. Would it be nice? Of course! Would it give me more confidence to tackle more advanced trails? Absolutely! Am I having a good time doing what I do with what I got? HELL YES!

 

Great advice comin in. Thanks for all of the help!

I wanted to clarify that the only real new addition is the 20' travel trailer. We are inheriting it from my in-laws and will be pulling it from CO back to CA next month, after an elk hunting trip. We've been camping and hunting with the camper shell this entire summer/fall. When the truck is loaded with a family of four, two dogs, two large coolers full of ice (and ideally deer and/or elk meat), camping gear, clothing, food, water, jerry cans, etc., the weight is noticeable. When the truck hits a dip, even on paved roads, the rear feels super heavy and hits pretty hard. I'm concerned that adding 350+lbs of tongue weight to all of this will really make it ride (and tow) poorly.

 

Cheapest and easiest fix is wdh. That way when your not towing it still a stock ride.

 

For example here is a rear shock that you can adjust on the fly.

https://www.tundras.com/threads/falcon-shocks-are-coming.34355/

 

Just read that entire thread. It sounds like the best of both world: soft enough for everyday driving but can be adjusted stiffer for towing. Pair them with a shackle and I'd be set.

Thanks for the recommendation!

 

No problem sir. Enjoy.

 

My experience with tundra rear suspension.

My trucks are constantly loaded with about 500-700 lbs of tools and parts so take that into account with my notes. And I tow trailers ranging from 1500-8000lbs pretty regularly.

stock-very soft ride, comfortable on road, so so off-road, way to soft for heavy loads

stock with helwig sway bar- basically same as stock except major improvement in heavy load feel, the reduced body roll really fights the soft rear suspension when loaded making the truck feel much more solid when loaded

Stock with 5100 shocks- better in every department, mildly stiffer on road but I preferred it over stock

stock with 5100s and helwig sway bar- this was my ultimate setup for 150,000 miles on my last truck loved everything about it until my leaf springs started to sag which leads to

above setup with air bags and cradles- the air bags ruined the ride of my truck, I don’t know if this was due to the sagging rear springs, but I was always chasing the right psi. And it would hit the internal air bag bumps all the time, which are harder and are a real jolt when hit. Only real positive was when towing heavy it definitely help the rear of the truck and kept the truck level.

my next setup which is sitting on my garage floor waiting to be installed is 5100s for all corners, wheelers aal and the helwig rear sway bar which is already installed on my truck. I’m hopping this will be another step up from my favorite setup on my last truck.