Air springs and/or rear spacer

[tony_4r]

Ok, last week I installed the FJ springs and Bilstein 5100. The fronts at 1.75". I feel that I need a bit more lift on the rear so I was thinking of going with a 1" rear spacer. However, after coming back from a 700 mile trip towing the boat I was not too happy with so much sagging (see picture). Without the boat the rear is about 0.5" higher. With the boat the rear sags about 1" so is then 0.5" lower. The boat/trailer combo is at about 4,500 lbs.
My dilemma now is should I use spacers in the rear or air springs? or both? I have read several posts and still undecided. Any thoughts?

 

[morphious]

Ok, last week I installed the FJ springs and Bilstein 5100. The fronts at 1.75". I feel that I need a bit more lift on the rear so I was thinking of going with a 1" rear spacer. However, after coming back from a 700 mile trip towing the boat I was not too happy with so much sagging (see picture). Without the boat the rear is about 0.5" higher. With the boat the rear sags about 1" so is then 0.5" lower. The boat/trailer combo is at about 4,500 lbs.
My dilemma now is should I use spacers in the rear or air springs? or both? I have read several posts and still undecided. Any thoughts?

I use to tow a boat and didn't really care about it when I was towing. If you want it to be level (or as level as possible) you will want bags. If you put a spacer in the rear and not change the front you will have forward rake, which will probably make you bump up the front to make it level out. But you will end up in the same situation when you tow again. I will say that my boat did not seem to have as much weight in the front as yours seems to as mine never dropped the back of my 4runner that much.

 

[dougiefreshmx]

Ok, last week I installed the FJ springs and Bilstein 5100. The fronts at 1.75". I feel that I need a bit more lift on the rear so I was thinking of going with a 1" rear spacer. However, after coming back from a 700 mile trip towing the boat I was not too happy with so much sagging (see picture). Without the boat the rear is about 0.5" higher. With the boat the rear sags about 1" so is then 0.5" lower. The boat/trailer combo is at about 4,500 lbs.
My dilemma now is should I use spacers in the rear or air springs? or both? I have read several posts and still undecided. Any thoughts?

I had the same dilemma a while back. I ended up getting a 1.5 spacer for the rear (to even out the stance) while also adding airbags for when I tow my boat and/or heavy loads in my utility trailer. I guess the way I think about it is even if you install a spacer, the spring will still sag with the added weight. It will just look higher in the rear but bottom out quickly. The air bags won't increase the how much you can tow, but just make the ride more comfortable. It has for mine.

By the way, love the FJ wheels. I had a set on my 3rd gen, wish I still had them.

 

[zopperman]

What about running a variable rate spring?
Anyone done that? I know MOOG makes variable rate FJ rears

 

[ARK_SWAMP_RIDER]

To handle that much additional weight, you either need stiffer coils (sag less) or air bags. The issue with stiffer coils is that they can be harsh when you're not towing. Air bags however can be easily adjusted so you get the best of both worlds.

Progressive weight coils would fall between the above two. I've had them (Metal Tech) and even though the lower half was very stiff, they didn't handle weight well at all. I prefer a constant rate coil for the rear.

Air bags are inexpensive and IMO are the correct way to address the issue. This is the exact reason I went back to my OEM air bags after switching to coils. I just couldn't find the perfect combination of weight handling and ride quality when unloaded. Instead of putting aftermarket bags in with coils, I just swapped back to the OEM system I still had laying around.

 

[tony_4r]

ARK, when you say OEM you mean that Toyota has air bags for the 4Runner?

 

[ARK_SWAMP_RIDER]

ARK, when you say OEM you mean that Toyota has air bags for the 4Runner?

Yes, it was an option on the Limited models. There are air bags (no coils at all) on the rear and also a compressor. It automatically inflates/deflates the air bags as needed to keep the same ride height all the time, regardless of load. I had converted it to coils, but now am back to the factory setup.

 

[Red]

ARK, when you say OEM you mean that Toyota has air bags for the 4Runner?

Some 4Runners came with a tow package from the factory with rear air suspension instead of coil springs, it is a self leveling automatic air system specifically for towing.

I think it was an option on Limiteds only

 

[Red]

lol I'll just let Ark reply, he keeps beating me to all the questions.

much easier to just write "What he said"

 

[tony_4r]

Didnt know that. What about a set such as the Firestone that goes inside the coils.

 

[ARK_SWAMP_RIDER]

Didnt know that. What about a set such as the Firestone that goes inside the coils.

That's the type you'd need. Firestone and Airlift both make good kits, either would do what you're looking for.

 

[tony_4r]

Where is the factory air compressor located? I would love to install the factory compressor or similar in the same spot. I guess I need to search if someone has made this mod before connected to after market air springs.

 

[ARK_SWAMP_RIDER]

There are way too many pieces to try to retrofit the OEM system. Airlift and Firestone I believe make compressors to go with their bags, or you could always go with a true on board air setup like VIAIR. To answer your question, the OEM compressor is located right behind the driver side rear tire, tucked in under the side of the bumper.