[HO455]

I replaced the rear bags today. I went with Slam SS-7's like I have on the front. The mounts were different between them and the old ones so a new plan was needed. Which was fine as the old bags were bolted to the top spacer and then the spacer was welded to the frame. Which has seemed to work ok up to now but it left no easy way to remove the bags. (Photo 1) I had to take a rotary die grinder with a carbide cutter and remove about a 1/2" of material on each side of the air fitting in order to fit a wrench in and remove the fitting. Once I had the fitting out I was able to remove the nuts from the studs holding the top of the old air bags. Then I removed the bottom bolt and tossed the bags aside. Then I removed the two tabs up inside the spacer that secured the bag with a pair of Vice Grips. They were only welded on one side so they broke right off. After some clean up with a 4" grinder I noticed that the bottoms of the spacers were not cut off square. (Photo 2). Another 15 minutes of grinding got them fairly square.
I had cut two six inch circles of 1/4" plate for the new bags to bolt to. Marked the center of the plate, scribed a line through it and then center punched two spots 1 3/8" from the center for the mounting bolts. These got drilled to 19/32". Then I scribed a second line 90 degrees to the first on the center of the plate. Then center punched a spot at 1 1/4" from the center and drilled it with a 1 1/8" hole saw for the fitting to pass through. Using one of the old front mounts as a jig I welded four tabs on each plate. Some clean up grinding then a quick shot of paint. (Photo 3). After carefully test fitting the plates I locked them in place with an air jack then center punched all the holes in the tabs.
I planned to drill and tap the upper mount to hold the plates. Over the years the best way I have found to tap things like this is with a cordless drill. As long as you have room for it. (Photo 4 Just barely room) First off you must have a sharp tap to do it this way. Then make sure you have drillled the correct size hole for you tap. The trick is to put the drill in the slowest speed and then set the setting dial to screw and not drill. Then put the clutch in a middle setting. Before starting put cutting fluid (most oils will work OK) in the hole and on the tap. Start the tap in the hole slowly making sure you keep the tap in the same plane as the hole you drilled. The nice part of using the drill with the clutch is it will stop the bit if your at a bad angle and you can then reverse and start again. By changing directions often you keep the chips from binding the tap and it becomes somewhat self aligning. After each hole clean all the metal chips off the tap and reoil for the next hole.