# Anybody ever swap tandem suspensions?



## sixtyninegmc (Jul 20, 2011)

Oddball question here. My semi has neway ARDAB suspension, which I have not been happy with. Been wanting to swap it out for something else, and I just got a '98 freightliner in trade that has Airliner rear suspension, which I have ran before, and like quite a bit. Thinking on swapping the suspensions around before I sell the freightshaker, wondering what methods folks have used or seen. Cutting the frame and welding the other one on has been recommended, but I do not want to go that way. I can drill new holes for the different mounting brackets, I'm just concerned about having the original set of holes open and weakening the frame. Thinking maybe insert an inner section of frame to beef up the rear?

Ideas?


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## SCtrailrider (May 1, 2016)

I have done both, cut the rear behind the cab and had a new channel made out of 5/6" to mate to the inside, welded the cut frame then bolted the inside through that.... also just drilled new holes for the different spring mounts for the new set of rears... never had any trouble out of either setup, it would depend on the use & weight you plan on doing... you could drill new holes & plate that section also for added strength....


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## glasswrongsize (Sep 15, 2015)

sixtyninegmc said:


> , I'm just concerned about having the original set of holes open and weakening the frame.
> Ideas?


Back eons ago when I worked on 'em for a living, we put bolts in the empty holes.

Mark


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## mlappin (Jun 25, 2009)

Done both as well, a lot of trucks we have had lives as something else at least a time or two before we got em, all kinds of un used holes in our frames and never had one let loose yet.

The flanges supply a lot of the strength anyways, that's why your never supposed to weld em.

I've cut a frame to replace the rear and have borrowed a magnetic base drill press to drill new mounting holes, drilling em by hand sucks.


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## SCtrailrider (May 1, 2016)

Look for a "frame drill" they stand on a base and chain to the frame to pull against, and a taper drill bit, will be quick & easy if you can find either..


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## sixtyninegmc (Jul 20, 2011)

My biggest concern is that if the front trailing arm mounts have to go in the same location on the frame, several of the holes will be right next to the old holes, as in touching. The old mounts have a 3 1/2"x8" bolt pattern, and the new ones are 4"x8". With 5/8" bolts, that's too close for my taste. I'll have to do some closer looking, see how it would look. Really hate the ARDAB, has almost no articulation, horrible weight transfer, and is hard to get parts for.


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## SCtrailrider (May 1, 2016)

Shift the axle front or back some and just change the wheel base a little....


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## skyrydr2 (Oct 25, 2015)

Whooo doggy you dont be weldin frames here in Mass. Boy they get real ulgy on you real fast...log tricks and plowing dumps get nailed all the time for bad frames.. we just did an entire frame in GMC General. Had tripple rails and the outside rail spit on the roled edge of the flange and they flagged it..you either have to fix it or show proof it was scrapped with in 1 year or face a huge fine.. total A-holes!


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## sixtyninegmc (Jul 20, 2011)

Welding a frame is no big deal up here, so long as it is done properly. Friend of mines KW has quite a few miles on a frame that they cut 21" of frame out of, to make it Canada legal wheelbase. No problems whatsoever. I think welding the frame would be the best route, but I don't trust my own welding that much, and the only welder I trust that much (same guy who shortened the KW) retired.


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## Wethay (Jul 17, 2015)

I have seen 20 =/- new trucks have their frame cut, a one foot section added and then welded back together because the bean counter that spec'd them used the wrong size beans.


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## sixtyninegmc (Jul 20, 2011)

Hah, I can believe that, having driven for large fleets and having to deal with trucks that the bean counters sent us!


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## sixtyninegmc (Jul 20, 2011)

Well, scratch the frame welding idea, took a tape out, the frame on the 'star is deeper webbed and 1/16" thicker steel.


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## sixtyninegmc (Jul 20, 2011)

Well, thank you for all the advice. At this point I have decided not to do the swap with this donor truck. The truck is too valuable to part out, and I don't feel like remounting the neway suspension to the freightliner. I will wait until I find a cut-off or parts truck with the suspension I want.


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