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Date:         Wed, 12 Apr 2000 16:11:25 -0700
Reply-To:     "Buettner, Peter" <PGB@DOLBY.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Buettner, Peter" <PGB@DOLBY.COM>
Subject:      air suspension tests on Syncro and 2WD
Comments: To: "syncro@onelist.com" <syncro@onelist.com>
Content-Type: multipart/alternative;

For a while now I've been sitting on the air suspension kit that I got from Air Lift (http://airliftcompany.com). For the Hollister Syncro meeting I finally made the time to pull them out of the box and install them. Since my Syncro is currently on the road (without me!!! who would have thought) I installed them in Steve Schwenks Syncro Westy first. Steve has the Bilstein shocks and stock springs installed.

The air suspension looks like two red rubber cylinders with metal hose connectors on the top. Kind of like a rubber beach ball. It was easy to install. I lifted the rear of Steve's van so that the springs expanded all the way. Then the two cylinders were pushed into the inside of the spring by deflating them and inserting them between two adjacent coils. I connected a short piece of hose and a tire valve (all part of the kit) to each cylinder. Using cable ties, I attached the valves to the brake lines that run along the top of the trailing arms. This all could be done without taking the wheels off. Now the system was easily inflated with a standard tire pump (I used a bicycle pump). Because the volume of the suspension is so small it took only 5-6 strokes to bring it up to the max. rated pressure of 25 PSI. I set the pressure to a conservative 20 PSI and Steve drove his Syncro to Hollister like that.

Now the air suspension pretty much fills out the whole space inside the spring from side to side and from the bottom of the trailing arm to the rubber stop on top. Fully inflated the rubber stop just touches the air suspension. As the suspension contracts the rubber stop is pressed into this air ball. This is similar to having a spring with a progressive spring rate. The more the rubber stop presses into the air ball the more pressure inside the ball builds up. The increase in air pressure inside the ball is proportional to the increase in force that is pushing against the rubbers stop. By changing the initial pressure with a tire pump the "air spring rate" is changed. Increasing the pressure makes the air suspension stiffer (higher spring rate), decreasing it makes the air suspension softer (lower spring rate).

Initially I was concerned that the rubber stop might puncture the air suspension. I called Air Lift and talked to one of their engineers. He insured me that this is what these things are designed for and it should be save.

In Hollister Steve was quite impressed with the air suspension. His van was about 2/3 loaded on his way to Hollister. He thought the air suspension was an improvement over his stock setup. Steve also tested the air suspension on the trails with his twins sitting in the back. The pressure was left at 20 PSI. More positive remarks.

Next the air suspension went into Mark Drillock's Syncro Westy together with the new Betts springs. Mark has also the Bilstein shocks installed. In Mark's Syncro we tested the air suspension at different pressures: 25 PSI (max. rated pressure), 15 PSI and 0 PSI. At 25 PSI the rear became very stiff. I was almost thrown out of the rear seat at big bumps. At 15 PSI the rear was perfect. It now had the right damping. The traction of the rear axle was much improved. At 0 PSI the air balls didn't seem to have any effect on the suspension as expected.

Everybody was quite impressed with the way the air suspension changed the behavior of the rear axle depending on the initial air pressure. By simply changing the air pressure the air suspension can be easily adapted for different load and road conditions. Low pressure for an empty van, high pressure for a fully loaded van. Low pressure for highway driving, high pressure for off-road driving.

We also tried the air suspension on Craig Drillock's (Mark's brother) 1982 Vanagon Westy with 1.9l turbo diesel engine. At 25 PSI the we were able to lift the rear by 1/2". Guess that's great news for all you 2WDs with sagging rear springs (the Syncro was not raised because of the higher springs). Handling and traction of the 2WD was greatly improved with the air suspension in place. We did a couple of turns on the dirt track and it was amazing to see the difference between the front (without air suspension) the rear (with air suspension). While the front felt rather unstable and was breaking out left and right the rear seemed to be on tracks. Completely stable.

Everybody that got to test the air suspension wanted to get one. So I'm trying to put a group purchase together. There are also two compressor kits available for the air suspension. Theses kits consist of a compressor, one or tow pressure gauges and control buttons, and all necessary hoses and connectors. These items can be installed in the van. With the gauge(s) and controls mounted on the dash board the air suspension can be controlled while driving. With the dual-gauge kit the two air balls can be controlled independently. I think that could be very useful for 2WD Westies. This way the weight of the water tank or other off-center weight could be easily equalized. Here are some prices for the Air Lift suspension that I got from the internet:

Air suspension for Vanagon $70 Compressor kit with single gauge $110 Compressor kit with dual gauge $159

I hope to get these prices further down if we get enough people together. Please send me a p-mail if your interested. Please indicate which item(s) your interested in. A similar kit is available from Firestone. I don't have personal experience with the Firestone kit nor have I heard from anybody who does.

Cheers, Peter


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