S15DET wrote:I've seen a few projects that take this approach; grafting subframes from car A into the body of car B. In fact, I have both front and rear subframes from an FD RX7 (same wheelbase as our 510) at home because this was my original idea. I've always been concerned when car A has a different wheelbase as car B. In your case, car A has a 99" wheelbase and car B has a 95.3" wheelbase. This would cause a change in the roll center axis among other things. Have you made plans to alter the geometry slightly to correct this, or do you feel it's not going to be a problem. How are you going to go about determining the exact mounting height (Z axis) for each subframe or crossmember, this was the sticking point for me? When I discussed this with a friend who's a GM suspension engineer, I was led do believe this isn't a good idea, I'm curious to hear your thoughts, since you're going through with it.
Looking forward to see how it turns out, you're off to a great start!
I haven't done the exact measurements and calculations for the roll centers yet and therefor don't have anything for the roll center axis. In saying that, if I stay as true to the S15 setup as possible and set it up correctly, I can't see reducing the wheelbase by a bit under 4" is going to make that much of a noticeable difference to the average driver. In saying that, I will be altering the geometry in the front end and that will effect the roll center, as the angle of the front struts will be laying over a bit more than on a standard S15 by approx 10-15mm further in. Camber will be corrected at the hub, and I will be setting the control arm angle to compensate for the extra strut angle to keep a good roll center height as close to a S15 that has been lowered about 40mm (I've been told this height works well for them, but I have to do my own research on this to ensure this is the correct height to aim for.)
I've pulled the engine and front suspension assembly out of the donor, I've removed the 510 radius rod mounting points and the front suspension unit is ready to be raised into position with motor mounted. So I'll get some measures and get it all worked out. I'm no suspension guru, but I should have it covered.
I'm keen to hear input from people with suspension setup experience to hear a few different opinions on the setup.