Coil conversion for towing 6500 lb trailer (2 Viewers)

[quincyg]

Hi folks, My first post here.
I have a 2004 GX470 with 130k miles on it. I have been having some passenger side intermittent air height issues and am getting ready to install a passenger side rear height sensor that I bought a few weeks ago. Specifically, the passenger side will drop very low every once in a while. It seems to happen only when parked on a steep decline and goes away after a few minutes of driving. It only happens once every few weeks. The airbags look newish and intact. A couple of days ago I had a similar issue on the driver's side. This only happened once.

I'm thinking I might be going down a bit of a rabbit hole with the airbag system and figure I should find out if it makes sense to replace them with rear springs and shocks. I don't do any off roading, but I do occasionally tow a 6500 LB trailer. 500-700 LB tongue weight is typical. My tires are a little oversized 265/70/17.

Any suggestions for a conversion kit that can handle trailer towing that won't break the bank. If so, can I just do the rear and not mess with the front? My rear upper control arm bushings also have cracking bushings so I will have to do those at the same time.

Super appreciative of any advice and brand/model suggestions.
Thanks!

 

[Rednexus]

I'd suggest the Ironman kit with stock height coils. Presumably you are using a WDH towing that much weight. Either way you might also want to install a set of auxiliary bags inside the coils if you have any bouncing with that much tounge weight. The aux bags would only be inflated when towing.

Or perhaps get replacement airbags given your towing weight. Your bags are probably cracked and dryrotted.

 

[quincyg]

I'd suggest the Ironman kit with stock height coils. Presumably you are using a WDH towing that much weight. Either way you might also want to install a set of auxiliary bags inside the coils if you have any bouncing with that much tounge weight. The aux bags would only be inflated when towing.

Or perhaps get replacement airbags given your towing weight. Your bags are probably cracked and dryrotted.

I don't see a stock height coil option. I do see a heavy load kit with a 2" lift for $2k. It's rated at 660 LB additional payload. I guess that would be about right. I think this would be out of my price range. I believe I could repair the air bag sensors for less and even replace the compressor solenoid if I had to.

I usually am only doing very short range towing when trailering. 50 miles range and mostly flat. My trailer empty is 3k LBs and loaded 6500 LB's.
I dont have a weight distribution hitch, but that hasn't been an issue with the air suspension. Maybe switching to springs would make it an issue.

The bags themselves look new. I bought the car 5 years ago and the previous owner must have replaced them.

 

[Rednexus]

The Ironman coil conversion kit is around $300. Its just the threaded rear spring seats and isolators, rather than a full lift kit. You'd need to source stock height springs separately.

I think that you'd have several inches of squat in the rear with a coil conversion and no WDH at that load, and probably be hitting the bump stops often.

FWIW my bags looked fine on the rig, but had obvious micro cracks when I removed them. I had the same intermittent deflation problems.

For your particular applications I don't think you'd be happy with coils only. I'd suggest either fixing the air suspension or getting a WDH or aux airbags if you do the coil conversion.

 

[quincyg]

The Ironman coil conversion kit is around $300. Its just the threaded rear spring seats and isolators, rather than a full lift kit. You'd need to source stock height springs separately.

I think that you'd have several inches of squat in the rear with a coil conversion and no WDH at that load, and probably be hitting the bump stops often.

FWIW my bags looked fine on the rig, but had obvious micro cracks when I removed them. I had the same intermittent deflation problems.

For your particular applications I don't think you'd be unhappy with coils only. I'd suggest either fixing the air suspension or getting a WDH or aux airbags of you do the coil conversion.

Ok. Thanks. I will definitely look into the distribution hitch >I guess that's why people like the air bags for trailers. Balances the load by design.

 

[CarGuyCarl]

How many miles do you drive versus how many miles do you tow? If you put those heavy 2 inch springs in the back it will not ride very nicely when not loaded, not sure if you are using it as a daily.

You can toss some Arnott bags at it if you wanna keep the OEM air ride adjustability and comfy ride or do what Rednexus suggested and get a rear stock height conversion of your choice, Ironman, Dobinsons, etc... and get some helper bags to fill up for when you tow. Best of both worlds. Long term simplicity and reliability and a nice ride, but also ability to handle your occasional tow.

 

[quincyg]

How many miles do you drive versus how many miles do you tow? If you put those heavy 2 inch springs in the back it will not ride very nicely when not loaded, not sure if you are using it as a daily.

You can toss some Arnott bags at it if you wanna keep the OEM air ride adjustability and comfy ride or do what Rednexus suggested and get a rear stock height conversion of your choice, Ironman, Dobinsons, etc... and get some helper bags to fill up for when you tow. Best of both worlds. Long term simplicity and reliability and a nice ride, but also ability to handle your occasional tow.

I probably drive 1000 miles a month of regular driving and maybe 100 miles of that towing a hydraulic dump trailer. Usually loads of dirt and gravel and stuff like that. I like the helper bags as an option, if needed. I'm thinking the first thing I should do is install this height sensor for my passenger side and replace my upper control arms while I'm at it since the bushings are torn.
If I still have problems after that I can go with stock height conversions and add air bags if needed. Hopefully just doing the rear would be ok.

What about adjustable coils? Would that maybe be a good option? I could set them at 2 inches and if it felt wonky could lower them.

 

[Rednexus]

The Ironman coil conversion kit has around 1" of adjustability in it, but it's more for fine-tuning the ride height. They require removing a wheel, jacking up the GX, disconnecting a shock, etc, to get things adjusted. So while you could do it before towing it would be kind of a pain.

 

[Krazykevin]

I bet you just need new bags. It is easy to change and arnott bags are cheaper than most proper coil conversions. It will still ride great unloaded and handle the weight well. This is the ideal use case for bags, don't throw them away for springs...

A WDH also makes towing heavy significantly nicer, even with bags. I regularly tow my car on a open trailer and even though it is only 4k lbs combined, the WDH makes it so much nicer.

 

[quincyg]

Well, my alternator died and somewhere in the process of towing or maybe at the shop the airbags were ripped out of place! So now I have to address this issue. I ordered new air lines and arnott a2949 bags. Trying to figure out how to insert the existing air line into the Arnott push connector. Do you just cut the barbed end off of the factory line? Anyone know the size of the factory tubing?

 

[Krazykevin]

The factory line should slide into the arnott quick connect with zero modification.

 

[quincyg]

The factory line should slide into the arnott quick connect with zero modification.

I haven't removed it yet, but the videos show a lip on the existing line that snaps in place with the stock connector. It also has a rounded end. Arnott connector looks like it needs a clean cut tube and I'm thinking that ridge will prevent it from pushing in all the way.

 

[Krazykevin]

The fitting should be clean but only about 3/4" goes into the sharkbite fitting on the arrnott bag.

 

[quincyg]

Ahhh! Thanks for clarifying. I would have cut it shorter. Mine will be a new line. The mechanic chopped the old one and inserted a smaller piece of tube to splice it so I could drive home.

 

[quincyg]

View attachment 3479684
The fitting should be clean but only about 3/4" goes into the sharkbite fitting on the arrnott bag.

Thanks for your help! It took me a few hours to get the drivers side installed. Going to do the passenger side this weekend. A couple things that might help others. 1)The bags can be deflated to a really compact size by sucking the air out once the tube is attached. Putting a cover over the tube end keeps them deflated. Also I was able to blow the bag bag up to get it to seat the same way.
2)I used a flexible line camera to see where the clip of death lines up and slide the clip in from under the car with my hand while watching the monitor. I couldn't get to it from the outside on the drivers side and there was a brake line in the way as well.

The height was way off for the first few hours, but now seems to have balanced out somehow. Maybe this is due to mismatched bags. The rear does seem to sit pretty low when i'm parked on a slope left to right. Wondering if that could be worn out shocks.