more cng conversion questions, this time suspension and lift


Original poster
Mar 7, 2012
03 Trailblazer ext v8, 3" lift

i looked around a bit on the OS but couldn't really find what i was looking for, what is the highest amount of lift that someone has put on the rear suspension? i know that most people are trying to get the front up more to level it out. but im looking to lift the back more. Say another 3-4"

Reason im asking is because im putting the cng tanks under the rear bumper where the spare tire was, trying to get a little bit more ground clearance back there.

I know there is an issue with the brake lines, are there any longer replacements or retrofits? and then i should probably order some adjustable control arms for the rear. and fab up some custom shock mount. Prolly end up going through u joints quicker. but other than that does this throw anything else off in the rear suspension when lifting higher?

one other question, with z71 springs in the rear will air lift spring air bags still fit in the rear?


Lifetime VIP Donor
Nov 19, 2011
Portland, OR
The rear shocks are the down-limiting element of the suspension. What shocks did you install when you put in your rear lift spacers? If you go any more than abut 3" longer shocks, the brake lines are the problem. Ebrake lines also. I never read of anyone successfully adapting longer stainless braided lines back there - I think it's a special fitting like the front. SS stainless brake lines fit the front, and I have them, but the vendor quit making them. There may be another vendor nowadays.

Adjustable control arms are only needed if you have 34-35" tires and want to center them better in the wheel well.

Z71 Avalanche/Tahoe springs need a different air bag, but I did that research years ago and put Airlift1000 #60769 in mine.


Original poster
Mar 7, 2012
i put in bilstein hd's, i like how they ride and with the extra added weight with the cng tanks is helpful. if i was to lift it higher then i would make something to adapt the shocks longer. how much more of a lift did the z71 springs give you? or did it just hold the load better and keep from sagging?


Nov 20, 2011
Milwaukee, Wisconsin
Wouldn't the pan hard bar also need to be changed to keep the axle centered?

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