19/29 torsion bar setup is killer.

[3literpwr]

TLDR, I have both a ‘87 and ‘81 911.

The G50 car started off stock and was upgraded to 23/31 bars, adjustable dampers, poly bushings, sticky tires and a race / track alignment. I drove the car like this for years always thinking the front was too stiff, but I lived with it. You really felt this when it was low on gas and there was less weight up front. Despite the % of change up in the rear, the car was always understeer prone. Like, on paper, you’d think it would not be, but push it hard and you couldn’t get the rear loose...it would push.

In 2022 I finished my rally car (triple adjustable shocks, no sway bars and 19/28 bars) Awesome on gravel and very balanced. Super fun. After driving this, I was was wondering why I was living with an overly stiff setup and fell back in love with a softer, more dynamic car.

Decided to finally get the 23/31 out of the G50 and opted for a 29mm rear coupled to the 19mm front given the g50s weight. Fresh alignment, new 205 /225 Sportcontacts and stockish euro ride height. Just did a 40 mile ride up the “best driving road in America” (HWY 33 out of Ojai) and it’s magic. Love the balance, turn in and compliance.

Setup bucks the 19/26 or 27 tradition and feels way more balanced too, especially for my style of driving. I also tried the 19/31 for the heck of it and that was a tinge too far. Felt tail happy, darty and unbalanced.

https://newsroom.hagerty.com/press/hagerty-drivers-club-announces-road-of-the-year-california-state-route-33-shines-and-winds-above-the-rest/#:~:text=The%20stretch%20of%20Route%2033,and%20ran ching%20valley%20of%20Cuyama.

[nickelplated5s]

What's the weight? Front and rear would be nice to know.

[3literpwr]

It's all stock. Aftermarket / lighter muffler in rear with a heating backdate, so maybe 20-40lbs lighter max.

[Rodsrsr]

On paper 19 and 29mm bars seems significantly unbalanced. That's a 10mm difference between the front and rear. The factory keep this around 7mm. A 10 mm difference should cause the rear to be much stiffer than the front which can result in oversteer and the front end feeling less responsive. Maybe others will chime in.

[3literpwr]

That is what you would think, hence why I put the post up. I even tried 19/31 and while it felt unbalanced, it didn't feel as strange as one might think. I should also mentioned I have rally raced for years (circa 2003) and worked for a motorsport shock company doing damper development. So damper tuning and vehicle dynamics work was a big part of my life for a while.

Also, I remember when Driven97 went all the way up to a 35mm rear with a 19 or 20mm front to get the car to rotate better as an autox car.

Assumed this 19/29 (hollow) combo would be a hot take, hence why I posted the thread.

[stownsen914]

Interesting result, thank you for sharing.

It's worth noting that car balance is an individual taste thing, and it depends too on intended use (street, autox, track, rally, etc.) It's also worth noting that the OP is a rally driver, so might prefer a more tail happy car

[silverlock]

What swaybars are you running and how are they set up? Surprised you find such a difference works so well!

I run 21/26 t-bars at 2550 lbs w/ no A/C, no heater blower and w/ a 915 — with 24/25 sway bars set up firmer front / softer rear. That gives me the slightest bias towards understeer but with a light rear + narrower (205/55 vs 225/50) front tires I find I have plenty of turn in and still get the rear out without too much surprise.

[3literpwr]

I've always tended to keep my sways stock and tune with spring rates. For whatever reason, likely doing a bunch of spring swaps on my 944S2 track car 20 years ago.

[IROC]

Back in the '90s and '00s I tracked my car a lot, but being of limited funds, I took baby steps to make the car handle better so I went through a lot of different setups. I am no expert, so keep that in mind.

What I initially started trying to eliminate (or mitigate) was low-speed understeer. The car was generally well-behaved but the understeer was frustrating and holding me back from good lap times. I tried three different torsion bar setups and three different sway bar setups and finally learned two things:

1. The best thing to mitigate low-speed understeer was front tire size. I had run 185s (yes, really), 195s, 225s, and finally ended up with 245s. The 245s really helped. Nothing else made as much of an impact as tire width...
2. In a 911, you can't really ever eliminate low-speed understeer (especially, the 'power-on' type). Or more importantly - you don't want to. Eliminating low-speed understeer for me led to high-speed oversteer. Not what you want in a 911 coming through turn 12 at Road Atlanta.

So...in the end, I ended up with 22/29 torsion bars, 22 mm F/R adjustable swaybars (although I will say the factory, non-adjustable late-model Carrera bars worked amazingly well) and 245/275 tires. The car still had some low-speed understeer but would drift in a very neutral, controllable way through high-speed turns. Very fun and easy to drive. Also...2350 lbs, non-sunroof coupe with a 3.2.

A big, giant YMMV, but that is what I learned. I don't think there is one magic setup. Driving style, application (track is completely different than street), etc., make a huge difference.

I apologize for mostly rambling...

[3literpwr]

I think my main point is being open to experimentation...which I support. I have actually been thinking about some aftermarket bars as they are a little easier to connect / disconnect as needed...this would be on my rally car that is.

[Grotch]

Those aftermarket bars won’t be bad afterall

[winders]

I always liked 21mm/31mm with Charlie bars front and rear on 911SC with a 3.2L engine. Oh, that was with 225mm front and 245mm rear tires.

[3literpwr]

I think that would have been a nice option. 23 was too harsh for me up front.