Saggy Rear... And way too many spring/lift/air bag threads...

[steven1955]

2007 V8 Limited, non air suspension, non XReas, and 105,000-ish miles on the OEM springs. Bilstein 5100 shocks with the front shock snap ring set for 0.85 inch lift. 5100s have only about 15,000 miles on them, so don't want to replace them.

I know my answer is somewhere in the forum, but after hours of reading, reading, and reading some more I decided to ask for advice.

When empty except two people with groceries the 4R is nicely leveled. With four people and hiking gear the rear is only slightly low. But when we really load up the rear sags too much.

At first I thought that an air lift bags would be the easiest fix, but my GF drives the 4R more than I do, and I worry that the bags might leak down below the minimum inflation pressure and get damaged because I wouldn't always be able to check them out.

Questions and thoughts:

1a. Do the OEM springs go soft or are they prone to failing at 100,000+ miles?

1b. Maybe replacing the springs makes the most sense. While we don't need to lift Dobinson, and maybe others, make progressive rear springs with a mild lift,

2. Assuming there is no reliability based reason to replace the OEM springs, can you reasonably make air lift bags leak free enough to not be an issue. Like only having to check the every couple of weeks?

3. I know there are on board compressor based air lift control systems, but I think I'd rather spend those hundreds of dollars on a Bilstein 5100 compatible 1.5 to 2.5 inch lift. I would prefer a slightly firmer ride and maybe a little more roll resistance.

4. Are there any progressive rear springs other than the Dobinsons?

Thanks for any guidance you 4rth gen experts may offer.

 

[Warwicke36]

2007 V8 Limited, non air suspension, non XReas, and 105,000-ish miles on the OEM springs. Bilstein 5100 shocks with the front shock snap ring set for 0.85 inch lift. 5100s have only about 15,000 miles on them, so don't want to replace them.

I know my answer is somewhere in the forum, but after hours of reading, reading, and reading some more I decided to ask for advice.

When empty except two people with groceries the 4R is nicely leveled. With four people and hiking gear the rear is only slightly low. But when we really load up the rear sags too much.

At first I thought that an air lift bags would be the easiest fix, but my GF drives the 4R more than I do, and I worry that the bags might leak down below the minimum inflation pressure and get damaged because I wouldn't always be able to check them out.

Questions and thoughts:

1a. Do the OEM springs go soft or are they prone to failing at 100,000+ miles?

1b. Maybe replacing the springs makes the most sense. While we don't need to lift Dobinson, and maybe others, make progressive rear springs with a mild lift,

2. Assuming there is no reliability based reason to replace the OEM springs, can you reasonably make air lift bags leak free enough to not be an issue. Like only having to check the every couple of weeks?

3. I know there are on board compressor based air lift control systems, but I think I'd rather spend those hundreds of dollars on a Bilstein 5100 compatible 1.5 to 2.5 inch lift. I would prefer a slightly firmer ride and maybe a little more roll resistance.

4. Are there any progressive rear springs other than the Dobinsons?

Thanks for any guidance you 4rth gen experts may offer.

Air lift 1000 will suffice. I have em. They dont leak down. Keep 5 to 10 psi in them at all times... More if loaded up. Problem solved.

 

[pauldub]

I have the Airlift bags on my 3rd gen and they don't leak down. They really are the best solution if you want to adapt to widely varying load.

 

[steven1955]

Air lift 1000 will suffice. I have em. They dont leak down. Keep 5 to 10 psi in them at all times... More if loaded up. Problem solved.

I have the Airlift bags on my 3rd gen and they don't leak down. They really are the best solution if you want to adapt to widely varying load.

Well, between Warkwicke36 and pauldub we have two votes for airbags. Maybe I watched a few too many YouTube videos of people unhappy with air lift bags. Air bags will certainly be cheaper than springs.

1a. Do the OEM springs go soft or are they prone to failing at 100,000+ miles?

Yeah, I quoted my own question. I haven't seen any posts about problems with the OEM springs, but that doesn't mean they aren't out there. Is there a point near 100,000 miles that I should consider replacing the factory original springs because they are getting old?

And if there is no reason to replace the springs at the time, who makes the best air lift bag? The Air Lift Company and Firestone are two that I know of.

 

[Warwicke36]

My OEMs had 200k on em with airbags for about 13k... They weren't really sagging... I also had a Daystar 1.5 spacer at the time... I now have toytec 2.0HDs in there though because I added a RIGd Ultraswing and still tow.... Those bad boys are tall AF FWIW

 

[ThirdCoastStroker]

I had firestone bags on my last F350 and loved them. held air fine for 100,000 miles

 

[BackOff]

I ran a set of the Airlift1000 extended bags with zero air pressure and the valve stems removed for over 2 years, granted was only about 10k miles total.

I had no problem with running them on zero air pressure, when i pulled them out i cut the bags open to look at wear. Did not apear to be any damage from no air... got the idea from another member on here... was thinking it was working as a sort of air jounce/bump stop.
Fast compression= less air can escape.
Slow compression= more air can escape for better articulation.
This is all theory and conjecture on my part of course.

They work great for added weight and towing too.
I have use them the proper way as suggested for years before and was happy.


Eibach makes a rear adjustable coil for the 5th gens, dont know if its a 4th gen compatible, but i dont see why not.
Load leveling kit.
Eibach 5th Gen Rear Load-Leveling Kits

 

[steven1955]

OK. A lift, meaning taller springs, might be fun. But Airlift 1000s are far cheaper and adjustable to boot. And you folks have convinced me they can be leak free. So Airlift 1000s it is.

Just in case anyone else was going to order them this Memorial Day Weekend Advance Auto has a 25% discount (code RAKAAP25) this weekend plus another 10% back if you are a member of Rakuten. $111.99 becomes $75.60.

**** Alternate Schrader fill valve location needed. ****

Most 4Runner folks seem to install the Schrader fill valves behind the tailgate so that they are hidden when the tailgate is closed. That will not work for us because we'll have a receiver mounted bike rack with two e mountain bikes preventing the tailgate from being opened.

Anyone have a good alternate location for those Schrader valves already figured out?