930 tub vs 911 tub

[aftermath]

I have 2 rollers that I own . a 84 930 and a 77 911. Im going to build one street and one track car.

Is there a difference in the tub between a 930 or 911? Someone I had chatted with in the past said yes and talked about a torque tube, but I have no idea myself if there is a difference.

Im still gathering parts and researching what Im going to do.

[Emission]

Bump, I am interested in this answer.

[KobaltBlau]

torque tube sounds like nonsense but perhaps there are differences between the gauge of metal used in certain places or welding.

I do know that metal thicknesses increased over the years in some areas so the 84 might be beefier because of its year even if it's the same as an 84 non-turbo.

Sorry I don't have any real data.

[Slider79SC]

Aren't the way the trailing arms mount to the torsion tube different between the turbo cars and non-turbo?

I thought they had better anti-squat geometry (turbo cars)

[smdubovsky]

I think they meant "torsion tube" area. The trailing arm mounts for a 930 are slightly different. I don't know if there are any other. If you put the adjustable camber boxes on the rear (which requires removing the factory mounts), then you can make them essentially the same (If you put 930 trailing arms on the 911). There might be slight differences due to the years of the cars (like what KobaltBlau said), but I think the chassis are identical except for the torsion tube mounts (for the same year).

There MIGHT be a slight difference in the rear seat area for tranny clearance. Nothing a hammer doesn't solve. I've also heard the 930 motor mount points are slightly moved (rearward?), but haven't had my hands on one yet to know.

SMD
Whos still looking for a 78-80 930 or a real 914/6...

[Nine9six]

The torsion bars are different from the std 911 and the 930. 930 torsion bars have a larger dia both front and rear.

[ChrisBennet]

Obviously the fenders are different.
The pickup points i.e. where the inner control arms pivots around is different.
The tunnel and torsion bar tubes may be different. Wasn't the 930 transmission physically larger?
-Chris

[Bill Verburg]

• 930 trailing arm mounts on the t-bar tube are different, you will need to use 930 arms on a 930 tub 911arms on a 811 tub
• rear quarters are of course different
• not strictly a tub component but front hubs and fenders are different
• 930 is wired for dual fuel pumps

[KobaltBlau]

Originally posted by Nine9six
The torsion bars are different from the std 911 and the 930. 930 torsion bars have a larger dia both front and rear.

yeah, but that ain't the tub. lots of stuff is different that ain't part of the tub ...

does anyone know if there are differences in unibody stamping thicknesses or welding to beef up the 930? my guess would be not, but I don't know.

[Emission]

So, nothing in particular to make the tub stronger, just different for different shape/size components?

[SC-targa]

Originally posted by Nine9six
The torsion bars are different from the std 911 and the 930. 930 torsion bars have a larger dia both front and rear.

Some one chime in here, but I thought all years of the 911 & 930 used 19mm front torsion bars.

Regards,

Jerry Kroeger

[safe]

Originally posted by SC-targa
Some one chime in here, but I thought all years of the 911 & 930 used 19mm front torsion bars.

Regards,

Jerry Kroeger

Yes, as far as I know all 911s has had 19mm front bars. Maybe some early cars had slightly smaller bars, but maybe I'm wrong.

[safe]

Originally posted by safe
Yes, as far as I know all 911s has had 19mm front bars. Maybe some early cars had slightly smaller bars, but maybe I'm wrong.

Nah, I was wrong according to Paul Frere all production models has har 19mm front bars.
I was probably confused because the rear increased from 22 to 23 from the SWB to the LWB cars.

[Bill Verburg]

n/a '74-77 used 19/23 t-bars, 16/none or optionally 20/18 roll bars
C3 '76-77 used 19/23 t-bars, 20/18 roll bars
930 '75-76 used 19/26 t-bars, 18/18 roll bars
n/a '78-79 used 19/23 t-bars, 20/18 roll bars
n/a '80-85 used 19/24 t-bars, 20/18 roll bars
n/a '86-89 used 19/25 t-bars, 22/21 roll bars
t-look+t '77-88 used 19/26 t-bars, 22/20 roll bars
t-look+t '89 used 19/27 t-bars, 22/18

All f/r t bars are interchangeable thru '86
in '87 they used the new style t-bar tube and t-bars

the '78 -86 turbos had the engine moved back 30mm to allow the trans to clear the t-bar tube

[beepbeep]

Rear engine mounts are moved further back on all 930 from 78 on.

[javadog]

The biggest difference that would affect your intended use is the rear torsion bar tube, as others have noted. Porsche designed the rear of the car with essentially the same rear axle geometry that they used on the RSRs. The pickup points for the trailing arms are different and this helps generate some anti-squat as well as a different camber curve as the car rolls in a turn. It's been a long day, but I seem to recall that the 911 has less camber change for a given suspension travel than the 930. Some people like the 911 camber curves better than that of the RSR or 930. I'd suggest that you ask some of the guys on the racing forum what they think.

The other consideration would be what brakes and tires you might use. Do you need the extra fender width in the rear that the 930 tub gives you? Do you want to use the turbo brakes? I realize the you can change the rear fenders and adapt pretty much whatever brake you want to use, given the use of adapters and a little machining, but if you start closer to where you'll end up, you'll spend less.

Lastly, which tub is in better condition?

Hope this helps,
JR

[Bill Verburg]

Do you need the extra fender width in the rear that the 930 tub gives you? Do you want to use the turbo brakes? I realize the you can change the rear fenders and adapt pretty much whatever brake you want to use, given the use of adapters and a little machining,

Not quite, the 930 tub and t-bar tube will require the 930 suspension arms which have 3.5" caliper mounts set up radially for 309mm rotors. No way anything less than the 930 caliper will go there. The 993tts and 965s can be made to fit but like you said it's not going to be cheap and there are a couple of big compromises that would need to be acctepted.

[javadog]

Bill,

That was the point I was trying to make, actually. If a person wanted to use turbo brakes, he's better off starting with a turbo chassis, than adapting turbo brakes to a 911. I didn't mean to imply that you would start with a turbo and use some other caliper. Personally, I am not in favor of machining calipers, welding on trailing arms or using adapters to mount things differently than originally intended. Just because something can be made to fit doesn't mean that the guy who made the adapter had the engineering skills to analyze all of the forces involved. I have seen things in the past that were done wrong.

JR

[ChrisBennet]

Well if you want to be really picky, the front torsion bars were 18.8mm...
-Chris

[ZLP]

I remember comparing my 1980 930 to my buddy's 1980 SC and with both of our cars stripped out the rear deck in the interior is a lot different. It is higher ni the 930. Not sure if thats anything significant but definately a difference.