Custom Trailing Arms, A Progress Thread Options

[andys]

Though it about time I start a progress thread on some custom trailing arms I am designing and fabricating.

First, a little background: My car is a planned LS1 V8 conversion that will use an Audi/Getrag 6 speed transaxle (which I already have). From this, two things result; 1. The drive flanges are placed wider then on the 914, and are assymetric to the centerline. 2. The drive flanges will require adapters, as the bolt pattern is outside of the CV. The 911 axles I intend on using are shorter than the 914, but not enough to provide room for the flange adapters. The motor/transaxle will be placed off-center in order to get symmetry of the drive flanges.

By fabricating the trailing arms, I can accomplish a couple of things. First, I can position the bearing carrier further outboard to get the additional space for the flange adapters. This will also help keep wheel spacers from being so thick. Second, I can use the larger (+5mm dia and 5mm wider) late model 911 bearings, along with the late 911 wheel drive flanges. Third, I can adapt any brake caliper I want, which will be an '89 Carrera to start with since I already have it. It is not my first choice (heavy!!), but it will do for now. I will employ the Wilwood mechanical spot caliper for the parking brake. Fourth, this custom fabrication allows me to create a structural part suitable for V8 power, and yet meet a target weight comparable to a stock trailing arm. Fifth, I can make provision for the pivot shaft bearing of choice. Though I considered the needle bearing setup, I will start off with Weltmeister Polygraphites' (I do have some other polyurethane material that I may try later as well).

So why go through all the trouble? Because I can, is my best answer. Being an engineer, I just can't resist! Also, I have the equipment to do all the machining and welding. Now having said that, I don't think I would start a project like this again, considering all the research, design, fabrication, etc.....takes waaay too much time; time I don't really have.

Ok, enough of all that! I'm sure you'd rather see the pic's, then read all the blather......

This pic is of some of the parts I've made up so far; Pivot shaft housing, pivot shaft bushings to be welded in, bearing carrier, caliper mount, and the large axle tube. I'll add more parts as we go along: