IRS vs Swing Axle

[Jacques Lefriant]

Question for you drum brake holdouts. Given that IRS suspension has some advantages would you give up your swing axles if you could maintain your drum brakes and normal shock placement.
j

[Martin Benade]

I could live with that. My preference is really for the early wheel cosmetics, and it would be hard to explain front drums and rear disks on the same car. I am quite happy with my car in fairly stock form but I am not a purist at all. I just think the doctor got it about right. I am not personally in need of a stronger transmission but I would love a 5th gear.

[C J Murray]

Hi Jacques, no irs thank you.

[Jacques Lefriant]

CJ
"you could keep your brakes" do you have a technical objection? unless you think Kart suspension is the answer.
j

[C J Murray]

If I wanted modern and competent I would have kept my street Corvette Z06 that I never drove. If I wanted a retro irs car...wait, I already have a '67 S that I don't like as much as the 356s. A 5 or 6 speed trans would not change the basic character of the car. I like swing axles for their simplicity and lightness. They define, along with the front suspension, how the 356 feels on the road. I would never make any modification to the body structure of a 356 because the body structure is what makes a 356 what it is. It's a package, a symbiotic collection of engineering that stands the test of time. You can't make it better, you can only make it not a 356.

Then why increase power or add gears? Because that does not detract from the quintessential 356 experience while allowing us to drive safely at modern speeds, with modern traffic, on modern roads. Stone stock cars are great to drive also.

Again, every owner gets to choose for themselves. No harm in that.

[Craig Richter]

Years ago, back when he was still sawing-up and re-welding 911 cases to make his Polo motor, I asked Dean about a swing axle 5-speed. I can't remember the whole long answer, but his short answer was a "no", at least partly because he was so busy with his new project. So I've been waiting a long time to find someone with the engineering ability and interest to tackle this project!
Since then, Speedy has gone thru lots of changes (most thanks to Jack): VW rear torsion bars, long late rear shocks, front sway bar, front disks, 16" wheels widened to 51/2" with 195/50 rubber to get it low. Rides good, handles like a Go Kart, and "swishin" at road speeds, say 30 to 90, is not possible, unless driver uses technique to promote it. Seriously, car is amazing on mountain roads, and I see no reason to loose my swing axle.
Plus, Speedy has gone up in value X4 since then, and I not be cuttin' and weldin' on a valuable piece of antique automotive art (except for fixin' the rust bug, of course).
The B/E/C/G tranny in there now is quite wide-ratio, meaning you must rev it up 4500-5000 before you shift to keep on the torque curve, but it is doable. Cruise all day at 80 on the freeway, but having another gear in between would be heaven!!

[Jacques Lefriant]

Hi Craig
you might consider replacing your 7/31with my 8/31.
CJ
Do you think that late Covairs (safer ar speed) and later VW bugs wish for the the swing axle suspension?
j

[Craig Richter]

J,
You've caught me with my knowledge down: What the heck is your 8:31? Is this used with your "Cadrobbi Diff"? Got a link?
We put a 7:34 in my B-in-law's S90, which made a HUGE difference in driving fun; but he lives in the mountains, and rarely goes down to freeways. He'd need a different 4th gear on the Autobahn.

[C J Murray]

I like early Corvairs. I like them much better than the Citroen SM.

[Jacques Lefriant]

CJ to each his own i tend to like complicated things but i try to simply when possible. You know i love you like a son but your dismal of IRS hurts. I was leaning to a simple bolt in conversion not the 901/944turbo cut+paste. Very few drive their cars energenticaly enought to perceive or in my case remember the difference.
j

[Craig Richter]

Maybe we just need further explanation about what's involved with your IRS idea...

[Jacques Lefriant]

Hi Craig
Use a modified VW IRS diff with the 356 644-741 case and custom side covers so you have the stock trans no mods necessary. This is the same thing the Caddrobbi does for the swing axle. Take the outer bearing housing off the tube and to the existing spring plate attach a trailing arm that incorporates a stub axle that protrudes from the stock rear bearinging the same amount as the normal swing axle the only modification is to add the trailing arm pivot to the tube it can even be a bolt on. Simple.

[C J Murray]

Father, do you have a visual aid? I can still learn.

[Jacques Lefriant]

Hi Craig
Assuming a 25" rolling radius tire
your box at 4000RPM(BE3CG) 21.7/49.8/64.5/89.6
stock box 4000rpm (BBBC) 21.7/38.1/59.4/78.9
8/31 stock box 4000rpm 24.8/43.5/67.9/94.22
7/34 stock gears 4000rpm 19.8/34.7/54.2/75.2
8/31 alternate ratios BEBD 24.8/56.7/67.9/90.1
8/31 alternate ratios BE3CB 24.8/56.7/73.7/86.8
7/31 only tall 4th BBBG 21.7/38.1/59.4/89.6
so with your ratios and a stock 4th and my 8/31 your 2,3,4 would be equivalent to the tall 4th 3-4 almost as good as a 5spd
j

[Jacques Lefriant]

CJ