Need 2019 Rav4 Rear-only lift; modest spacers or airbags?

[Lindenwood]

Hey! As I outfit my new Rav4, I am finding the rear is starting to sag a bit--it is about an inch lower than stock right now. I have added a ~53lb hitch, another ~12lb of bike carrier (pretty much full-time), and easily 125-150lb of gear in the back that I've always carried in my daily driver like tools, recovery gear, and my air compressor. Soon I'll be looking into mounting my hi-lift jack and recovery boards on the roof (perhaps not daily), adding another ~45lbs for a total of ~250lb added to the vehicle.

I don't necessarily want a complete lift--just enough to basically return to factory rake.

So, my first thought was to ask one of the two companies making lifts if I could buy just the rear coil spacers, which should return maybe .75 to 1" to my current height and be perfect. I am assuming I could do this for maybe $200-250 installed.

Then, I had the 2nd thought of adding airbags to the rear, which would allow me to run a modest setting if I take the gear out, pump them up when loaded, and more easily remove them if necessary later on. I already have a 12v compressor, so I'd be looking at simply the $90-100 for the standard airbag kits.

I don't know if anyone makes complete aftermarket coils for these vehicles or at least knows which existing springs may be compatible.

Thoughts?

 

[Dilldog]

I would go for air bags if possible if it were me. I like the added versatility of an air bag helper, also if you ever tow the air bags will help massively with stability.

 

[smritte]

I run a set of Air Lift springs in the back of my cruiser. When I put the trailer on, I fill them with about 60psi. They go inside your coil spring. If you need more weight capacity these rock. If you just want to go an inch higher then do the spacer.
I did a quick google search to see if they made the bags for your Rav4.
Here's what I found. 1996-2000 Toyota RAV4 2WD & 4WD - Air Lift 1000 Air Helper Springs [REAR] [60789] | $84.95 | SD Truck Springs | Leaf Springs, Helper Springs and Suspension Parts

 

[Wawa Skittletits]

I don't recommend spacers to address a sag (spring) issue. They would make it look right but your suspension travel is still lessened. Toyota is releasing a 2020 Rav4 TRD and one of the changes is springs. Not sure when you'd be able to hit up the parts catalog.

 

[RecklessCreation]

my preference would be airbags ... with one definite modification to installation. don't link the airbags, ie separate fills. if the air bags are installed with a linked fill they will do the exact opposite of sway control, when one airbag compresses it will push its air into the other sides airbag exaggerating the axle movement.

the above statement is something I'm going to playing with for my grand cherokee via a custom airshock setup in the rear to try and give the versatility of daily onroad running (loaded or unloaded), pulling trailer, and moderate offroad. with pressure, and linking/unlinking the air bladders

 

[smritte]

don't link the airbags, ie separate fills

Wild guess how I learned this? I did it on my dually with a huge camper. First cross wind and I thought I was tipping.

 

[Lindenwood]

Thanks for all the responses. Will airbags reduce total flex offroad? Also, they will stiffen up the ride a good bit if I keep enough oressure in them to eliminate this ~1" of sag, right?

 

[smritte]

Heres how it works in a nut shell. The springs support weight. The shock controls how fast the suspension moves. Buy making the spring stronger or lighter you make it higher or lower as well as effect ride quality. Shock, stiffer slow's slows travel. If you increase or decrease spring tension signifantly, or change spring lengh more than an inch, the shock needs to be changed to match. Your only looking at an inch (ish).

Types of springs are Leaf, Coil, Air, Torsion. You have coil, your thinking of adding an air spring. More air increases tension, less air, less. If you add in weight, you need to increase spring tension. But if your like me, my springs match my load except when I add in the trailer. The trailer tongue weight on the back pulls the rear down. I fix this with adding air to increase my spring rate. Your application is similar. Sag under load. You "should" be changing the coils to a heavier set but, you probably daily drive this.
These air bags allow flex because of their size but, you will loose a small amount. This is why the total spring/shock combo needs to match what you need. The air bags are kind of cheating.

You had mentioned a spacer. Spacers give you lift without changing spring weight. If your springs are in good shape, a spacer is fine. I run them in the front to level out my vehicle. I don't like the back at a rake. This way I keep my same ride quality. What you don't want is to add a spacer because your springs have lost tension from age and it sags. The issue here is, when you add in the gear is when you have the problem. You will still have too light of a spring for the load. Hitting bumps could be an issue. A spacer only makes it "look" correct.

 

[Lindenwood]

Thank you for the info! Fortunately, I do actually have a pretty solid understanding of suspension dynamics--better, than most, I would expect (I uses to teach physics, and have been a long-time gearhead). Specifically, I do understand that spacers effectively lengthen the spring without increasing the spring rate; interestingly, this is more in line with what I want, given my desire to maintain offroad capabilities.

So, really, I guess I am just trying to confirm what I have since researched, that airbags basically increase the spring rate in order to minimize sag with dramatic increases in weight. I don't expect to tow at all with this vehicle (any towing we do will be with our 4Runner). Thus, beyond what I have in there already, the most we would carry on a typical trip would be maybe another 150lb of bikes, cooler(s), and other campinc gear. I am willing to except a little bit of sag in the rare instance I have full gear + two extra adults in the back, so I think I will be going with spacers.

In short, I don't expect large variances in weight beyond what is already riding in the vehicle, and I would rather lift this relatively small amount by increasing spring length (spacers) than by increasing spring rate (air bags). This is simply because increasing spring rate will reduce relative flex which, in a vehicle without any locking differentials, would be a not-insignificant degradation in offroad capabilities. Thus, I think I'll be going with spacers!

I did pull the coil yesterday to measure its ID and OD. Preliminarily, it seems like spacers from the previous generation Rav4s will fit, so I might try ordering one of those.



*edit*

I should say, however, a system that allows me to variable link and unlink the two airbags might actually be the best of all worlds; on flat ground, airbags certainly do the best job of minimizing sag, while on undulating terrain the ability to link the two sides (even with a simple ball valve) might do wonders to increase suspension flex.

 

[RecklessCreation]

Thank you for the info! Fortunately, I do actually have a pretty solid understanding of suspension dynamics--better, than most, I would expect (I uses to teach physics, and have been a long-time gearhead). Specifically, I do understand that spacers effectively lengthen the spring without increasing the spring rate; interestingly, this is more in line with what I want, given my desire to maintain offroad capabilities.

So, really, I guess I am just trying to confirm what I have since researched, that airbags basically increase the spring rate in order to minimize sag with dramatic increases in weight. I don't expect to tow at all with this vehicle (any towing we do will be with our 4Runner). Thus, beyond what I have in there already, the most we would carry on a typical trip would be maybe another 150lb of bikes, cooler(s), and other campinc gear. I am willing to except a little bit of sag in the rare instance I have full gear + two extra adults in the back, so I think I will be going with spacers.

In short, I don't expect large variances in weight beyond what is already riding in the vehicle, and I would rather lift this relatively small amount by increasing spring length (spacers) than by increasing spring rate (air bags). This is simply because increasing spring rate will reduce relative flex which, in a vehicle without any locking differentials, would be a not-insignificant degradation in offroad capabilities. Thus, I think I'll be going with spacers!

I did pull the coil yesterday to measure its ID and OD. Preliminarily, it seems like spacers from the previous generation Rav4s will fit, so I might try ordering one of those.

View attachment 101248

*edit*

I should say, however, a system that allows me to variable link and unlink the two airbags might actually be the best of all worlds; on flat ground, airbags certainly do the best job of minimizing sag, while on undulating terrain the ability to link the two sides (even with a simple ball valve) might do wonders to increase suspension flex.

An off the shelf airbag system for you vehicle would generally only be made to stabilize within your vehicles tow capacity .. which on yours I believe would be 150ish lbs of tongue weight ... in their normal operating psi range (ie not going full psi/firmness) would probably only be around 200lbs of additional lift ... when in normal unloaded driving kept down at their minimum 10psi the additional stiffness would be felt but minimal ...bit I believe somewhere else you had mentioned removing your rear sway too ...so the slight addition of spring rate (and the ability to link/unlink as mentioned) might just work for you

 

[Wawa Skittletits]

In short, I don't expect large variances in weight beyond what is already riding in the vehicle, and I would rather lift this relatively small amount by increasing spring length (spacers) than by increasing spring rate (air bags). This is simply because increasing spring rate will reduce relative flex which, in a vehicle without any locking differentials, would be a not-insignificant degradation in offroad capabilities. Thus, I think I'll be going with spacers.

The whole point of adding higher spring rate springs is because of added weight. Your situation is an ideal one for springs and you don't simply lose 'flex' but if you did the spring rate is too high. I routinely speak to fellow Subaru owners who say the same thing and don't understand that. I run aftermarket springs front/rear that dramatically improved my vehicles off road ability. Before the springs I routinely had issues with the stock springs, and spacers, collapsing under the added weight in technical terrain. Even if I did lose a small amount of 'flex' it'd be worth it for the improved ground clearance.

To each their own but I just wanted to point out that your statement isn't necessarily true.

 

[Lindenwood]

The whole point of adding higher spring rate springs is because of added weight. Your situation is an ideal one for springs and you don't simply lose 'flex' but if you did the spring rate is too high. I routinely speak to fellow Subaru owners who say the same thing and don't understand that. I run aftermarket springs front/rear that dramatically improved my vehicles off road ability. Before the springs I routinely had issues with the stock springs, and spacers, collapsing under the added weight in technical terrain. Even if I did lose a small amount of 'flex' it'd be worth it for the improved ground clearance.

To each their own but I just wanted to point out that your statement isn't necessarily true.

Are you saying I need higher rate springs (i.e. airbags, in my case) to help manage hard hits? If I was rally driving, I'd certainly agree. But, I don't expect to be driving fast enough off road that uncontrollably hitting the bump stops will be an issue. Thus, a softer springrate that allows the weight between all four tires to remain more balanced over uneven terrain will perform better in literally every slow- to moderate-speed offroad situation. I have both the mathematical and emperical experience to emphatically support this.

Lets say the combined spring rate at the tires is 300lb/in. (The coils are mounted about halfway between the center of the wheel and the control arm's inner pivot. An assumed 300lb/in spring rate thus translates to ~150lb/in at the ground, or 300 lb/in total for the axle). If I go with a longer spring (i.e. spacers), the static height would be higher, but if I added an additional 300lbs in the cargo area, it would sag exactly 1" further; 600 pounds would drop it exactly two inches further. This isn't great for load-carrying, but remaining relatively soft means that if one tire goes over a bump offroad, the softer coil allows that tire to move more freely while transferring less of that force into lifting the rest of the vehicle. Less lifting of the rest of the vehicle means more weight stays on the two adjacent corners, which means better traction.

Conversely, lets say I use airbags to create a variable combined spring rate of 350 to 750 lb/in. (I start at 350 lb/in because, based on multiple statements, there will be some modest increase in effective spring rate even at minimum pressures). A higher rate at the same length will cause an increase in ride height, because the static load on the springs will compress them less. And, lets say I set the pressure such that the effective spring rate is 600lb/in; a 300 and 600lb load would only thus sag the suspension by an additional 0.5 and 1", respectively. Off road, however, hitting a bump on one tire will cause a greater lifting force theoughout the chassis, which will resuce available traction on the two adjacent tires, and creating more of what we call a "crossed-up" situation. Of note, using a ball valve to manually link a pair of airbags would actually have the opposite effect; as described above, one tire hitting a bump will actually force the other side of the axle downward, increasing traction. Hrmm... this is getting more intriguing.

 

[Lindenwood]

An off the shelf airbag system for you vehicle would generally only be made to stabilize within your vehicles tow capacity .. which on yours I believe would be 150ish lbs of tongue weight ... in their normal operating psi range (ie not going full psi/firmness) would probably only be around 200lbs of additional lift ... when in normal unloaded driving kept down at their minimum 10psi the additional stiffness would be felt but minimal ...bit I believe somewhere else you had mentioned removing your rear sway too ...so the slight addition of spring rate (and the ability to link/unlink as mentioned) might just work for you

The total allowed cargo capacity is 900lbs, which could easily find itself mostly centered over the rear axle. For example, with the tow package's 3500lb allowed trailer weight, tongue weight could easily be 400lbs, which translates to probably 600lbs at the axle due to the leverage relative to the axle. Include a passenger and maybe 200lbs of gear in the back and you are approaching an additional 1000lbs of load on the axle without exceeding the total allowable cargo capacity. So, while this is kindof an extreme case (well, maybe not for us overlanders ;) ), I do hope the arebags are built for more than 150lbs of extra weight, hah.

And, fair point on the bags slightly offsetting my removed rear anti-sway bar!

 

[Wawa Skittletits]

Are you saying I need higher rate springs (i.e. airbags, in my case) to help manage hard hits? If I was rally driving, I'd certainly agree. But, I don't expect to be driving fast enough off road that uncontrollably hitting the bump stops will be an issue. Thus, a softer springrate that allows the weight between all four tires to remain more balanced over uneven terrain will perform better in literally every slow- to moderate-speed offroad situation. I have both the mathematical and emperical experience to emphatically support this.

Lets say the combined spring rate at the tires is 300lb/in. (The coils are mounted about halfway between the center of the wheel and the control arm's inner pivot. An assumed 300lb/in spring rate thus translates to ~150lb/in at the ground, or 300 lb/in total for the axle). If I go with a longer spring (i.e. spacers), the static height would be higher, but if I added an additional 300lbs in the cargo area, it would sag exactly 1" further; 600 pounds would drop it exactly two inches further. This isn't great for load-carrying, but remaining relatively soft means that if one tire goes over a bump offroad, the softer coil allows that tire to move more freely while transferring less of that force into lifting the rest of the vehicle. Less lifting of the rest of the vehicle means more weight stays on the two adjacent corners, which means better traction.

Conversely, lets say I use airbags to create a variable combined spring rate of 350 to 750 lb/in. (I start at 350 lb/in because, based on multiple statements, there will be some modest increase in effective spring rate even at minimum pressures). A higher rate at the same length will cause an increase in ride height, because the static load on the springs will compress them less. And, lets say I set the pressure such that the effective spring rate is 600lb/in; a 300 and 600lb load would only thus sag the suspension by an additional 0.5 and 1", respectively. Off road, however, hitting a bump on one tire will cause a greater lifting force theoughout the chassis, which will resuce available traction on the two adjacent tires, and creating more of what we call a "crossed-up" situation. Of note, using a ball valve to manually link a pair of airbags would actually have the opposite effect; as described above, one tire hitting a bump will actually force the other side of the axle downward, increasing traction. Hrmm... this is getting more intriguing.

You’re still basing your argument on running too high of a spring rate. Let me break this down simply because there’s a reason they make and sell so many different spring options for so many different vehicles. Also when I say springs I mean actual springs..

Your vehicle was engineered by Toyota to carry X amount of weight in a certain manner ON road. Typically passenger vehicles are undersprung for ON road comfort where the surface is even. The reduced suspension travel from sag doesn’t necessarily factor in there because you traditionally only use a small portion of the dampers stroke in that environment, but I digress..

So you added Y amount of weight to your vehicle. If you add springs designed for Y amount of weight the vehicles suspension will perform essentially the same as it did from the factory. It’s literally the reason why the vehicle wouldn’t sag anymore. Don’t you think there’s a reason the 2020 TRD RAV4 is coming with higher spring rate springs? Or do you know something Toyota engineers don’t?

Another detail you’re not factoring is is spring type, linear or progressive. Regardless, do you honestly think reputable companies like OME are in the business of selling products that reduce off road vehicle capabilities? Kind of a silly thought isn’t it?

 

[smritte]

Another detail you’re not factoring is is spring type, linear or progressive. Regardless, do you honestly think reputable companies like OME are in the business of selling products that reduce off road vehicle capabilities? Kind of a silly thought isn’t it?

We have to be very careful setting up progressive springs. If you weigh the corners on a vehicle, subtract unsprung weight, you need to factor in leverage from items hung off the back and front. Ive found progressives turn into more standard linear with the lesser part of the spring being squished all the time leaving you on higher rate coils. Unless you have the capability to run two springs stacked in a coil over, its almost impossible to get an off the shelf progressive that will work on a modified or heavier vehicle.
Its also not that manufactures like Icon, OME...ect, reduce off road capabilities, its the customer. The manufactures are going to guess what customers are going to do in the way of mod's and put out 3-4 springs to cover the whole spectrum. What you get is "this spring works from this build to this build". Too much rate on one end and not enough on the other.
Jeeps have the largest possible "off the shelf" springs, Toyota is most likely second. For the most part, people just buy a "2" lift spring or a 4" lift spring. Never realizing that all they did was raise it. They basically made it more ineffective on their own. We haven't even talked about shock tuning.
Most people just compromise. They buy what looks good or best price and never know what they actually did.
The best we can start with is talking to people who have the same vehicle and seeing what they do. With the OP posting the question, he hopefully gets options easier than trial and error.

 

[Wawa Skittletits]

We have to be very careful setting up progressive springs. If you weigh the corners on a vehicle, subtract unsprung weight, you need to factor in leverage from items hung off the back and front. Ive found progressives turn into more standard linear with the lesser part of the spring being squished all the time leaving you on higher rate coils. Unless you have the capability to run two springs stacked in a coil over, its almost impossible to get an off the shelf progressive that will work on a modified or heavier vehicle.
Its also not that manufactures like Icon, OME...ect, reduce off road capabilities, its the customer. The manufactures are going to guess what customers are going to do in the way of mod's and put out 3-4 springs to cover the whole spectrum. What you get is "this spring works from this build to this build". Too much rate on one end and not enough on the other.
Jeeps have the largest possible "off the shelf" springs, Toyota is most likely second. For the most part, people just buy a "2" lift spring or a 4" lift spring. Never realizing that all they did was raise it. They basically made it more ineffective on their own. We haven't even talked about shock tuning.
Most people just compromise. They buy what looks good or best price and never know what they actually did.
The best we can start with is talking to people who have the same vehicle and seeing what they do. With the OP posting the question, he hopefully gets options easier than trial and error.

I agree with you on progressive springs and the options vs trial/error. One I didn’t get to because I’m trying to cover the basics of spring rates and the other is the reason I looked at this post in the first place. The OP and I may not drive the same vehicle but they’re more similar than not. Weight, AWD, unibody, and IDS for example. My experience is that spacers are basically a patch and don’t address the actual issue. I’m just here to help haha.

The rest of what you said I fully understand and have been trying to explain using less words. I never said they reduce off road capability, essentially the OP did when they painted with a broad brush..

This is simply because increasing spring rate will reduce relative flex which, in a vehicle without any locking differentials, would be a not-insignificant degradation in offroad capabilities.

As I said I’m just trying to help with a commonly misunderstood topic.

 

[Lindenwood]

You’re still basing your argument on running too high of a spring rate.

Absolutely I am. As you said, most street vehicles are undersprung for best performance purely flat ground. Conversely, however, they are almost universally oversprung for best comfort and traction on rough terrain at slow and moderate speeds. In those cases, lower spring rates allow the 4 wheels to move more independently over rough terrain, which balances the weight between the tires and gives better traction. Further, it increases passenger comfort. I can recount several instances where my 3rd gen 4Runner (with the softest coils I could find, and removed anti-sway bars) cleared obstacles on the first try that stumped wranglers, all while my 6-month-old kid slept in his carseat behind me because the ride was so plush.

So you added Y amount of weight to your vehicle. If you add springs designed for Y amount of weight the vehicles suspension will perform essentially the same as it did from the factory.

That is exactly what I want, and what I have said. I do not want a stiffer suspension, which airbags seem to inherently do. Instead, I'd rather maintain the relative spring rates, but with longer sptings, which for my purposes would be accomplished by spacers.

Honestly, the only thing really keeping me interested in airbags is the prospect of being able to link the rear suspension to increase rear articulation on uneven terrain. But, I'd still have to deal with a slightly stiffer rear end on normal terrain, and the added complexity of the airbag system.

Or do you know something Toyota engineers don’t?

With well over 2 decades of motorsports experience and a physics background, I am very confident in my ability to lightly modify my vehicle to perform better for me than engineers who have to design a vehicle to suit the widely varying desires of hundreds of thousands of customers.

Another detail you’re not factoring is is spring type, linear or progressive.

There are no aftermarket coils yet advertised for the 2019+ Rav4, so there is no point in discussing hypothetical options. The only options right now are spacers or air bags. The factory coils are linear.

Regardless, do you honestly think reputable companies like OME are in the business of selling products that reduce off road vehicle capabilities? Kind of a silly thought isn’t it?

Actually, the shittiest ride I've ever had in any vehicle--including my beat up old Samurai--was in my old 3rd gen 4Runner with the full OME setup that was based on the website's recommended spring rate for my modifications. Even with 250lbs extra up front and about 350lb extra in the rear, it rode harsher my bare-bones F250 (which itself I've described as "like a covered wagon"). The first time my wife rode in it after the install, she literally asked "so...does this thing still have like shocks and stuff?" It wasn't until I really dug into it and pieced together my own suspension (as described above) that my rig really performed how I wanted.

Let me break this down simply

I mean no offense, but thus far your arguments have been generally unspecific and underquantified--not overly complex.


Bottom Line:
Airbags do bring the intriguing option to manually link the rears to actually increase relative articulation on rough terrain. However, they have subjective (stiffness) and objective (operational complexity) downsides for me.

Conversely, if I use rear spacers to add about 1" of ground clearance over stock (2" over its current stance), I do lose the ability to potentially fine-tune the suspension, or make gross adjustments for larger increases in weight. Realistically, though, with such modifications, the worst case for me is I add 500-600lb of gear in the back, and it sits exactly as it does now (with the rear about 1" lower than the front). So, spacers would easily solve my current problem without increasing ride stiffness, and still handle planned future loads better than the stock setup.

 

[Wawa Skittletits]

Haha ok @Lindenwood. Still not simple enough apparently. Ok so my 20+ years of motorsports experience disagree with you. More importantly my personal experience with a similar platform disagree with you but good luck with whatever you go with.

BTW I’d be willing to bet the TRD springs are available to order now at the dealership or will be very soon since 2020 models will be arriving before long. It’s literally why I mentioned them but I’ll get back to helping other people.

 

[Lindenwood]

Haha ok @Lindenwood. Still not simple enough apparently.

Ok so my 20+ years of motorsports experience disagree with you. More importantly my personal experience with a similar platform disagree with you

You haven't actually specified why my assessments are incorrect. If you could provide some specifics to refute them, I
truly would appreciate it. For example, specifically, how could stiffer springs allow for more traction or a comfortable ride in slower-speed offroad situations, when stiffer springs inherently resist vertical wheel displacement by applying more upward force on the chassis? Could you re-read the last paragraphs of my previous post, under "bottom line," and clearly explain why any of those statements are incorrect?

Otherwise, I mostly agreed your with interim statements, like that longer springs will increase ride height without changing the suspension's resistance to wheel movement (which is exactly what I want).

BTW I’d be willing to bet the TRD springs are available to order now at the dealership or will be very soon since 2020 models will be arriving before long. It’s literally why I mentioned them but I’ll get back to helping other people.

You said they are stiffer. I said I don't want stiffer springs. How is that so hard to understand?

And, not to be ruder than I need to be, but you haven't been nearly as helpful as you think you have ;) . I appreciate you taking the time to provide information and experience, but you don't need to get sassy just someone doesn't immediate do exactly when you recommend.

To everyone else, this thread has clearly taken a silly turn into a pissing contest, but I appreciate the inputs. I decided to go with coil spacers (not strut spacers, btw) for the above reasons; physical simplicity and no increase in effective spring rate (i.e. no decrease in plushness). I just found some .75" spacers that will fit and should provide roughly 1.25" of lift, and I'll report back for anyone else who might be curious.

 

[smritte]

Sorry if I offended anyone here.
Normally when people ask suspension questions they are either to see what others run or have no real idea how things work.
I'm not a physics instructor but I am a mechanical engineer. Most of my practical knowledge came later from off road and track racing. I'm now semi retired and teach Chassis and Brake class's. Everything from stock to heavily modified. I try to post things the same as I do my lectures which is why it's common for me to start with basic "this is how it works" .
What I wrote here was based on what I thought the OP was asking.
And again, did not mean to offend.