I can't say for sure, but I'd guess that the average temperature for the last 10 days that I've spent in the barn is about 12 degrees F. We had a nice February but ol man winter has come back with a vengeance here! I'm ready for warmer weather!!! (Be sure to remind me of this when I'm complaining it's too hot in the barn this summer!)
ANYWAYS, below are my calcs for the three and four links. These have evolved over many revisions since I began, but here it is as mocked up in metal. The ONLY thing that is final welded at this point is the rear lower link frame crossmember mounts, everything else it tacked but I do plan to final weld all of it this weekend. That is assuming that I can flex test with the PVC and everything checks out, but at this point I don't expect any issues.
Uptravel on the rear is a hard stop at 6" right now unless I get crazy with the interior. The current limitation will/would be the upper mounts smashing the tub. The front uptravel could be as much as seven inches, but I'll probably limit it to six just to be safe.
For anti squat in the front (anti dive) I targeted 45, out back I targeted 75. On both ends I have adjustable mounts, so up front I the option of 32, 51 and 67% AS. Out back I'll have the option of 74, 58 and 41% AS. I based my targets on days of research, trying to find advice from guys over here on the East coast primarily. The difficulty is that SO MANY posts are either "search there are millions of threads talking about the best setup already" or someone saying "I have X setup and it works great, although I've never tried anything else..." or even worse, "just put the links wherever they fit and call it a day, that's what I did and my rig works great!" *inserts picture of rig flexing on a stump*, as if that proves something!!! Unfortunately I believe in math WAY TOO MUCH to just "stick them where they fit". ON TOP OF THAT, the "target" for AS has changed quite a bit over the last 10 years. If you go back and read some old threads things have really changed. Likely partly due to an increase in sharing of knowledge (internet/forums), but also from bigger and better rigs, harder trails, etc. So, I don't know if I have the ideal setup, but I know I worked hard to obtain the numbers I set out to. Now that said, I originally wanted to have options of 75, 100 an 125% AS out back but after realistic mock up and some more research decided to go for previously mentioned setup. Fortunately if I ever want to go for higher AS it'll be as simple as adding new upper link mounts on the frame side a little lower - which will actually be pretty easy as I can move them inside the framerails. Not a big deal.
Of course AS isn't the only thing at work on a linked suspension, I paid a lot of attention to the roll center and roll axis. Roll center basically targeting as high as possible, roll axis I tried to keep it negative but not too high (over 5). On the rear I had it a degree lower but during mock up it moved from roughly -4 to -5. On the front -1 was about the best I could do. I had a couple setups that were positive (roll oversteer) and really wanted to avoid that based on the research I did since I do plan to drive this on the road from time to time. I hope -1 will be enough understeer to keep the front compliant at highway speeds. The lower link V has a large impact on this number and realistically I can't really inboard the frame end lowers anymore, nor can I outboard the axle lowers without hurting steering angle. The other parameter which has a large effect is the panhard height so I am going to try to get it as high as possible - it's really my only option. You may notice that in the calc sheet I have the panhard frame end "Z" dimension is highlighted yellow because it is still up in the air as I haven't finished mocking that system up yet. Every inch I raise the panhard is worth roughly -0.25 degrees of roll axis.
Happy Pi day
Whatever!
