short bell in a 80 SC

[gorskined]

still weighing my options.
The long bell 4speed transmission and the g50 are off the table way to many modifications to stuff in an SC.
what exactly needs to be done when putting a 75-77 short bell 4 speed in an 80sc wide body.
thanks in advance regards Ned
i would also be interested to see a gear ratio chart comparing the short bell stock gears with a 915 1980 row 5 speed.

[Matt Monson]

If you can find a short 930 for sale, it will be big money. It’s much cheaper to shorten a long 930.

[gorskined]

Originally Posted by Matt Monson

If you can find a short 930 for sale, it will be big money. It’s much cheaper to shorten a long 930.

didnt know that was an option ....if you shorten what mods need to be done to fit it to a non turbo chasse ?

[Matt Monson]

Originally Posted by gorskined

didnt know that was an option ....if you shorten what mods need to be done to fit it to a non turbo chasse ?

There are a ton of threads about this if you search. The short answer is a machinist needs to remove 1.1”.

[porschyard]

Originally Posted by gorskined

didnt know that was an option ....if you shorten what mods need to be done to fit it to a non turbo chasse ?

Dan Barnes out of Vegas can shorten the Mainshaft and Bell housing for you.
As far as what’s needed for the conversion you will need a 245 mm flywheel for 80 or later 3.3, a pressure plate, disc and TOB for a 75-77 3.0 turbo. You will need 85-89 915 108 mm one piece axles and a modified trans crossmember. You can either find a used 930 shifter assy or use your stock shifter housing and install 930 shift lever and hardware. The 915 shifter can be modified to work but the throw is different and it is a pain to get right. Shift rod, shift coupler are the same on SC as they are 930. It’s been a few since I have done any but IIRC the clutch cable should also work with no issues.

Richard

[gorskined]

Originally Posted by porschyard

Dan Barnes out of Vegas can shorten the Mainshaft and Bell housing for you.
As far as what’s needed for the conversion you will need a 245 mm flywheel for 80 or later 3.3, a pressure plate, disc and TOB for a 75-77 3.0 turbo. You will need 85-89 915 108 mm one piece axles and a modified trans crossmember. You can either find a used 930 shifter assy or use your stock shifter housing and install 930 shift lever and hardware. The 915 shifter can be modified to work but the throw is different and it is a pain to get right. Shift rod, shift coupler are the same on SC as they are 930. It’s been a few since I have done any but IIRC the clutch cable should also work with no issues.

Richard

Thanks Dan

[Ryan_Cunningham]

Originally Posted by gorskined

still weighing my options.

i would also be interested to see a gear ratio chart comparing the short bell stock gears with a 915 1980 row 5 speed.

Would be interested in this as well. I have a SBH 930 in my 1972 that is going to be receiving a G96.50 and 3.6 Turbo engine from a 2001 Turbo, at some point in the futute.

But I'm looking at putting a stronger engine in my 1981SC which has its stock 3.0 and 915. I'd consider throwing the four-speed in the SC if the gear ratios were right.

[quattrorunner]

Spec books show what you want to see. There are threads on this as well.
Short answer is 915 1st is not useable as a sporty gear everything just happens too quickly, 930 1st gear is great as well as 2nd and third. 915 ratios other than 1st is awesome. but it finishes with redline in 5th with plenty of performance left on the table.
The 930 is great till it's not in 4th. You really do need 400hp minimum to ring out the 930. 500+ if you want redline if not more than 500hp. 7200 rpm gives you 200mph if I remember correctly.

[quattrorunner]

930 4th gear is a great highway cruiser.

[flat6pilot]

Porsche Gear calculator here:

https://retro-sport.com/calculator/porsche

You can compare how the 915 and 930 4-speed looks. At the track with 300-350hp, 4th gear with a 930 box is absolutely useless.

I'm re-gearing 3rd and 4th in my 930 box to get it a bit more useable at the track but with some compromise on the street, too.

Here's what I went with on 3rd and 4th:

3rd gear 27 to 26 0.962962963 112mph (@ 6k)
4th gear 30 to 23 0.766666667 141mph (@ 6k)

4th is much closer to 5th in the 915. I'll keep my redline at or below 7k.

[quattrorunner]

That's cool.

[decisive1]

I believe Patrick Motorsports also carries the flywheel and clutch package for this combination.

[Matt Monson]

Patrick is a manufacturer with a full machine shop and can shorten the bell housing and sell you all the right parts for fitment. Not so much the guy in Vegas. I’ve seen a couple really bad bore repairs out of that place recently.

[mikedsilva]

Originally Posted by Matt Monson

Patrick is a manufacturer with a full machine shop and can shorten the bell housing and sell you all the right parts for fitment. Not so much the guy in Vegas. I’ve seen a couple really bad bore repairs out of that place recently.

that's interesting... he is quite vocal about his quality/ability on his Instagram and Facebook accounts.