Narrowing an IRS Trailing Arm at the Inside Pivot End

[dd-ardvark]

What are your thoughts on narrowing a IRS Trailing Arm at the inside pivot end? Especially over the common practice of cutting the axle end off to narrow things.

dd-ardvark / David

[Steve Arndt]

The spring plate and tab on the trailing arm still need to line up in plane.

[dd-ardvark]

The spring plate and tab on the trailing arm still need to line up in plane.

Well, what about just trimming the top edge of the Spring Plate to clear the Shock Tower?



Steve, I can't help myself..., I'm leading you on , I've already made a set, just a trial run for fitment purposes on somebody else's ride because I needed a test bed to work out the bugs before I made a set for myself.

Anyway, the time it took to actually make these was hours. The time figuring out the details and getting the materials and finding the time..., weeks. Why I'm giving this information free to you, I stand nothing to gain by keeping it. Plus a different set of eyes looking at a thing helps to refine it more.

So, the verbiage below explains how I went about making these.

- Weld a 1” long x 1.5”ID x 2”OD tube section to the outside edge of the pivot end of the IRS Trailing Arm and cut the inside edge down by 1” - “Yes, it's about that simple”
- The existing pivot hole end will be used for the alignment of the new offset so the geometry per-say won't be effected.
- An added benefit of narrowing at the pivot end is that it moves the relationship of the Trailing Arm Spring Plate (TASP) to the inside of the Torsion Spring Plate (TSP) and with the use of a single plate torsion spring plate, this gives and additional 0.5” of tire clearance at the outside of TSP over a double (more room for the tire).
- The down side; the TASP will need to be clearance for the shock tower now that it resides inboard of the TSP.
- Additionally the shock tower bump stop may need to be clearance dependent upon the inset of your tire and wheel combo.

The Trailing Arm drawing amongst the photos should convey how this narrowing is done. When your in the Photobucket album take a snoop around.

Although my welding is what I'd like to see, again this was just to convey how simple it is to narrow at the pivot end instead of cutting the axle housing end off to narrow things. Enjoy - David / dd-ardvark

[Steve Arndt]

Let us know how it works out.

I cut up some arms to make 0x1.5 longer. Haven't finished yet.