I've ordered the steel for my Haynes build. Very exciting. I want to use an E36 for most of the donor parts. I've seen on here people using the BMW diff, but never the whole subframe (see here).

Given the increasing rarity of Sierra bits and the desire to use as much of my donor car as possible, I'm wondering why the E36 subframe is not used. I am sure that there are some very good reasons and that they will become abundantly clear to me as soon as I put the E36 subframe under a Haynes frame.

Looking at the E36 subframe, the trailing arm links are in the wrong place as they will be outside the Haynes frame. Are they modifiable? What am I missing?

Thanks, Geedle

They are also incredibly heavy, and like you said, the trailing arms are in entirely the wrong place, and bolt up into the sill area, so you'd need a suitable mounting point, which would again be, you guessed it, very heavy

Best just use the diff and make some suitable wishbones

[Edited on 6/7/16 by blakep82]

They do look sturdy...

So the idea would buy Sierra hubs/calipers/driveshafts and make a drive shaft that would take the BMW diff to the Sierra hubs?

Thanks, Geedle.

I'd imagine the weight and mounting complexity would make them unsuitable for a 7 type build. Double wishbones should be lighter and more adjustable for your build.

Some 7 Kit-cars have used the sierra rear end complete, but it's heavy. I guess the E36 sub-frame would be a similar mass so it could be done. If your going to build your own chassis you may as well go for IRS, live axle or de deion as it's lighter and a better solution, you can also choose the geometry.

I'm torn between the 6 pot and 4 pot motors. The 4 pot is plenty powerful enough. But the 6 pot is just a cool motor. I guess more weight at the back would help get the 50/50 balance if I did go down the 6 pot route, at the expense of overall weight.

There looks to be no sensible way of converting the BMW upright to be double wishbone - the angles are weird and nothing is flat on it.