Suncore Heavy Duty Rear Suspension Air to Coil Spring Conversion Kit

pbagley

Original poster
Member
Oct 19, 2012
7
Greetings all,

Cross-posting from another site after being told that the other forum is a ghost town, and all the cool kids are hanging out over here. Now back to the regular post and review.

Our Bravada's air suspension has been giving us problems recently. It has been collapsing to the spring stops in a day or two, then not pumping back up easily. Last week it would not pump up at all and I decided to look at our options. After a lot of reading here, and quite a few searches, I decided to go with one of the Suncore conversion kits. I liked the fact they came with springs, issolators, and shocks. The price on e-Bay was attractive too. I ended up calling their 800 number to ask if the standard (cheaper) kit would be OK for towing a horse trailer. While on hold I found their heavy duty conversion kit. They were quite helpful on the phone, and confirmed that for a heavy trailer the heavy duty kit was worth the investment. I ordered last Wednesday night, the kit arrived today.

After work I tore into the project. I have a few photos to share, as well as a couple of mistakes that maybe I can help someone else avoid. What follows is presented for your comments, critique, and of course amusement.

Here's what I had to start with:



And the left shock is a little damp. Once it's out I find it has a bit of free travel before engaging, but it still has a gas charge.


I checked the length of the new springs, and they are about 1/2" longer than the fully extended air-bags.



And I checked the shock absorber lengths - they look good.



So it all looks good to go. I lowered the axle until there was clearance below the old air-springs. The I twisted the left side bag counter clockwise and it popped loose just fine. I could not quite get enough slack to see how to undo the air fitting, and they had a little air in them still so it would have been interesting, so I cut the line. This was interesting too. The right air bag, still attached at the top, came apart as it decompressed. I guess there was my leak. Here they are, right bag is pieces.


I made a mistake. Decompressing before I popped the other air bag loose means that the second air bag was really floppy and difficult to get popped loose. Eventually I got it, and it was probably less than 5 minutes, but it seemed longer and tougher.

Now the old stuff is out and the new can go in. The isolators are a little smaller than the bottom centering pins for the springs, but this probably OK. They are a little larger than the top pins, still probably OK. I got things into place and raised the axel back up. Things are looking good, but I wish I'd taken a second look. These are progressive springs, so one end is looser wound than the other. I put one in with the loose wound coils at the top, the other with the loose coils at the bottom. Doh! Cosmetic mistake, but still a mistake.

The shocks went in just fine, I torqued the bolts to 80 ft-lb. Too much, too little? Seems like a good guess since the bolts are the same size as wheel lugs.

Next step was to disable the self leveling switches for the air compressor. The kit comes with a couple of resistors - you cut the wires and install the resistors in place of the leveling mechanism. I had a brilliant idea - why not just disconnect the leveling arms and zip-tie them in a position where the pump won't run.



This is WRONG! The arm is locked pointed up, the pump will always run. Another DOH! I cut the zip tie, moved the arm the down, and re-zip-tied through the frame holes.

It's all back together in about 1 hour, 45 minutes. I'm not real fast at mechanic work, and I did a lot of measuring and checking as I went.

We took the Bravada for one short test drive. It seems to ride about the same as it did before, but a little less bouncy. Based on where the headlights point I think it rides slightly lower than the air suspension unloaded. My weight on the back bumper does not move the suspension much at all. Seems very stiff.

Three nights later we hook up the horse trailer to see how this heavy duty spring kit handles a 2 horse trailer. Unloaded height:


With the trailer hooked up it sinks about 1.25"


Things look pretty level with the trailer on.


And one last thing I took care of tonight was unhooking the compressor. I found a post saying that the air pump is supposed to run after start-up, even if the ride height is good. Our pump seems to run a little long after I turn the ignition on so I decided to unplug it. No more on-board compressor for pumping up the trailer tire when it gets low.

So far I think the kit is worth the $300 I spent.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Welcome to where the active community went to. And thanks for the report and pictures. Many folks also use the Arnott Industries kit, or throw in OEM springs. Pulling the fuse on the compressor is a great idea. It really isn't up to much more than filling beach balls. A fully flat tire might cause it to overheat. And it takes a long time, I've read.

If you need adjustability for trailers, you can throw Airlift1000 bags into the middle of the coil springs. Plenty of discussion here and at trailvoy about those items.
 

pbagley

Original poster
Member
Oct 19, 2012
7
the roadie said:
Pulling the fuse on the compressor is a great idea. It really isn't up to much more than filling beach balls. A fully flat tire might cause it to overheat. And it takes a long time, I've read.

I tried the "Ride" fuse (#15) under the hood and the compressor still ran. I did not find another fuse that was obvious, but I may have just missed it in the list under the hood or under the back seat. I have used our compressor to air up tires - mostly the leaky trailer tire - enough to get the rim off the ground so we can visit the nearest gas station. Probably part of the reason the suspension has failed... but the bag that came apart seems more suspicious.

Also - We had an AirLift kit under our '90 Suburban and it seemed to work well. We had a heavier 4 horse slant back then, and it was a lot of trailer for a 1/2 ton truck. I kept 20 lb. in them unloaded, 50-60 with the trailer and 2-3 horses, 80lb. if the front stall was being used. With 4 horses in the trailer you really had to plan ahead for starts, stops, and turns.

I'll keep the AirLift kit in mind if the loaded trailer is too much for the Suncore springs - thanks for the reminder.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The ECAS system is mentioned on page 4-46 of your manual but the acronym is not used. It only appears in the fuse block diagram, which was very poorly written in all years. Blame the GM manual writers, who in another life were a Toronto-based punk band with the acronym "BOFG". (That acronym includes the words "Bunch", "Of", and "Goofs" plus another one NSWF.)
 

pbagley

Original poster
Member
Oct 19, 2012
7
The report from my daughter is that the Bravada with the Suncore HD springs did just fine towing a loaded 2 horse trailer. No problems, decent ride height. So far I'm glad I spent the extra $100 for the HD kit.
 

CReynoldsMIZ

Member
Oct 29, 2012
30
Okay. So let me get this straight, you were able to retain the factory air compressor, just by zip tying the sensors so the compressor wouldnt run? I am looking at this HD system as well, since it is cheaper than the Arnott System, and it is Heavy duty as i indeed pull trailers sometimes as well. But, i would like to keep the compressor because it is just really nice to have to pump up balls, tires, etc. So would you say you recommend this system? I am looking to buy any day now. Thanks!
 

pbagley

Original poster
Member
Oct 19, 2012
7
@ CReynoldsMIZ: I theorized that zip-tying the sensors in the full-up position would prevent the compressor from running. That was a partial success. On start-up the compressor runs every time. On top of that I have cut the lines so it never builds pressure. I think you may be able to have a working compressor if you joined the left and right air line with a compression fitting so you could build enough pressure on the filling side. That or my compressor is just worn out as well. I ended up pulling the fuse.

Good luck!
 

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