I finally saw a Jag IRS setup

[cobrashoch]

Olddog - I too understand your concern with the Jag setup and in my mind it is valid, SORTA. Yes these guys are right, there are few failures reported on the Jag setup, but if that's your only problem with this setup then you can tie off the upper hub with saftety cables to keep the wheel upright if a halfshaft breaks. Another solution would be to to fabricate a upper control arm to the hub or some kind of trailing link. Of course there are other double/wishbone arm setups out there, but that's another thread. My question is this though. Why a Jag setup in the first place? I will repeat what I have said many times and I know this will draw fire. The only advantage ANY independent setup has over a live axle setup is it gives you more suspension travel for when things get really rough. PERIOD! Virturially everything else is compromised a bit with independent setups, from a hot rodders viewpoint. A fact not lost by the NHRA or the SCCA for that matter. So if the ride on your solid axle car is rough, the chances are it is in a overspring condition, or something else is wrong, because even they can be made to both ride soft and perform. Don't forget that Factory Five spec racers use a live rear end setup most times, as does several other sports cars. For further example, the majority of the pro street rods out there use a mono spring setup for heavens sake, and some of those cars are both heavy and have well over 1,000 horsepower.
So my question to the original question is still valid. Why the Jag setup in the first place, over other designs? As with all engineering designs there trades to be made. So you do's your research, pays your moneys, and takes your chances. The Jag setup is relatively inexpensive and has history, but its not perfect.
cobrashock

[strictlypersonl]

Originally Posted by cobrashoch

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So my question to the original question is still valid. Why the Jag setup in the first place, over other designs? As with all engineering designs there trades to be made. So you do's your research, pays your moneys, and takes your chances. The Jag setup is relatively inexpensive and has history, but its not perfect.
cobrashock

If your primary use is hole shots, then by all means stick to a solid axle. It's been engineered over the years to work pretty well, and it's hard to beat zero camber for traction.

On the other hand, a standard wheelbase Cobra replica with the engine in the proper place has a driveshaft that's only about 12" long between joints. If you stick to the recommended maximum joint angle, that translates into about 4.5" wheel travel, total of jounce and rebound. That's OK for a smooth track when you're using stiff springs, but not so good on real-world roads. Maybe my (in)tolerance for bottoming out is less than yours, but I think that a car whose suspension can't soak up normal bumps is not acceptable. I can only grit my teeth so much.

It's much easier to control the roll center height on an IRS, so that there's less jacking and more predictable handling, and the lower unsprung weight allows softer damping without losing wheel control.

RWD high performance production cars universally have IRS because it combines good handling with good ride, something that's much harder with a solid axle.