Stock compressor question

Dug into my leaking air system today and discovered the fitting between the pressure chamber and the pump was fubarred. Removed the compressor and cleaned up the push connect fittings. To check it out I dead-headed a pressure gauge onto the compressor to check for leaks. The thing only came up with 75 lbs. Explains why, with a diesel short block in the trunk, the compressor couldn't keep up. Drove most of the way to Toronto on springs alone (compressor would quit after 7 minutes then the air would leak out).

Had three other GM compressors and the best I could get out of any of them was 95 LBs. (this is now installed in the car). Is this normal?

According to the specs that came with the Delco shocks I bought last year, they are good for 150LBs. Before I got the load equalizing hitch for the trailer, I would usually air up the shocks to 130 LBs on the Roadmaster from shop air (auto level removed) but have left the leveling system intact on the Caddy. Would really like to be able to get some more air back there, but would prefer to do it with the stock compressor and wiring.

Bill

Not sure about the stock GM unit. You want to try an aftermarket unit, like for use with air bags. I have one in my crew cab dually for rear bag use and I can lift the truck loaded with a car on the hook. I do have an in line tank, but it fills the tank back up rather quick. I have used the comp. to fill the bags direct as well. And they are small enough to fit in the stock location.

94 LT1 Wagon wrote:

Not sure about the stock GM unit. You want to try an aftermarket unit, like for use with air bags. I have one in my crew cab dually for rear bag use and I can lift the truck loaded with a car on the hook. I do have an in line tank, but it fills the tank back up rather quick. I have used the comp. to fill the bags direct as well. And they are small enough to fit in the stock location.

Your probably right. I do have an aftermarket compressor that will do the trick but have to find a dump valve (for the exhaust side) and a 140 PSI cut-off switch. If memory serves, this particular compressor is capable of 250 PSI. I will also have to fab up a manifold to mount the above plus figure out a way to adapt the GM air lines to the new set-up.

Just can't believe the OEM pumps are only capable of less then 100 PSI. My crappy 29 dollar tire inflater can give me 200 and its 1/2 the size of the OEM ones, with really cheap valves and such. The GM ones seem well made and the design is good, its just that I can't believe they won't pressure up. They really should be capable.

Bill

Bill, look into the air ride stuff that is used for air bag lowriders. The pumps are good, and you use electric soleniod valves to fill and exhaust the air. You need a valve for fill, and a valve for dump. You can get pressure switches for whatever pressure you want.

Check out this place in Toronto:

http://www.airassisted.ca/

The comp. are one in the same. You just need to figure what duty cycle you need, I have a 100 % duty cycle. I did forget to mention I put an air coupler on my tank and I'm capable of inflating tires or run an impact gun. You can look at airbagit.com or firestone.com or even airliftcompany.com, all three have the panels with the control buttons and a pressure gauge on them. As for the pressure cut off switch and quick connect air line connectors can be purchased at your local truck parts store. I get my stuff at International, they have all kinds of fittings so you can even build a custom piece to screw directly into your air shocks if that's what your running.

Thanks for the info guys.

Jay:

Going to check out Princess in their surplus bins and compressor section first. Only really need the high pressure shut-off and dump valve. If I was super motivated, I could actually use the OEM dump valve and machine my own valve block. The question now is how to get motivated now that I have the better of the three pumps re-installed and its working, sort of.

thanks again guys

Bill

Bill, if you buy a set of Airlift 1000 bags from Summit Racing that you put inside the springs, you can reuse the compressor. Those bags only need about 30psi max and they crank the back end right up. One time I hauled around 1000 lbs of material (evenly distributed across the back seats) and the bags only needed maybe 20-25psi to get back to normal ride height. I don't recommend doing this (and I only went about 40 miles like this), but it illustrates how capable those bags are without a lot of pressure.

sherlock9c1 wrote:

Bill, if you buy a set of Airlift 1000 bags from Summit Racing that you put inside the springs, you can reuse the compressor. Those bags only need about 30psi max and they crank the back end right up. One time I hauled around 1000 lbs of material (evenly distributed across the back seats) and the bags only needed maybe 20-25psi to get back to normal ride height. I don't recommend doing this (and I only went about 40 miles like this), but it illustrates how capable those bags are without a lot of pressure.

This certainly was not my experience with the Airlift bags. Did exactly as you suggested on the Roady when I first got it on the road. My tent trailer at the time had a tongue wieght of 300 lbs. and with the trailer hooked up, I was incapable of achieving stock ride hieght, even with 45 lbs. in the bags (didn't trust the 50 lb rating on the bags). Used it such for about two months and both failed (read blow out) within 20 feet of each other. Cost me an expensive tow, 60 miles back home for the trailer (now have the RV endorsement on my CAA membership). Re-installed the air shocks and had no further troubles.

Perhaps if I had ramped it up a notch and spend the dough on the Firestone version my experience would have been different. Regardless, the airshocks are more then up to the task assuming I can get more then 80 lbs into them. It is even more important now that our trailer has tandem axles. Level ride hieght is necessary.

Bill

Now that we are talking about air ride, why not actually replace the springs for some real bags? Firestones, or better yet, Slam Specialties. I have some you can look at if you want to see how they are made. You won't pop one of these, ever.

Let's go to Princess Auto soon. I need some fittings. Speaking of compressors, I just dragged this home:




Jealouz much, bewbs?

jayoldschool wrote:

Now that we are talking about air ride, why not actually replace the springs for some real bags? Firestones, or better yet, Slam Specialties. I have some you can look at if you want to see how they are made. You won't pop one of these, ever.

Let's go to Princess Auto soon. I need some fittings. Speaking of compressors, I just dragged this home:




Jealouz much, bewbs?

Now we got to get serious about takin some stuff apart. Even if it doesn't need to be takin apart Always good for a trip to Princess. I would suggest a days outing to the new Harbour Freight in Watertown but that would be dangerous.

Would reaaly consider the Firestones as they have been used on buses and trucks for years. As for the others, I have spent the last couple of nights cruising the other air ride sites but most of the stuff is designed for cars with much more horsepower then ours....so they can drag the damn car around on its chassis.

Seriously though, I have considered replacing springs since I first built the Buick, and now it looks like I will have to address the Caddy. Guess we will have to wait to see if the Gods of financial benevolence will shine on me.

Bill

i,d be disappointed in the rear springs of any car i owned if it squatted down with 300lbs of tongue weight,.
there are some really strong vatriable rate springs in the moog catalogue that'll handle a lot of weight, and still give a great ride, and won't lift the rear of the car up high.

Nick