915 trans into '71 chassis

[trak ratt]

Helping a friend transplant a stock ’79 SC 3.0L/915 into his ’71 chassis. We did the engine/trans swap last weekend. Car had a ’77 2.7 CIS/911 when he bought it. So electric, oil and gas should be relatively easy. Long term plan is to mod the rear aluminum control arms for use in the ’71 chassis. But donor SC has a lot of damage on one side and that control arm maybe bent. So for now we would like to know if the CVs from the SC axles will fit on the ’71’s axles? Or; will the SC stub axles fit the early outer hubs? ’71 has the 4 bolt, 2 pin flanges, while the SC uses the 6 bolt flanges. We have all the parts so can check everything in the next few weeks. But thought I’d check here to see if anyone has done something like this before? Anyone know of any other options?

[Grady Clay]

Use the entire axle assembly including stub axles from the '79 911SC on the '71 chassis.
This will fit the 100 mm transmission axle flanges on the '79 915 transmission and the stub axles will fit the '71 hubs.

When installed, confirm the axle shaft is free to move axially 1-2 cm with the car on the ground.

Best,
Grady

[trak ratt]

Thanks!! Will make the whole project much easier! He might even be able to make the Mid Ohio event after all!

[Grady Clay]

The downside of this for a track car is you are going from the ‘overkill’ very robust 108 mm CV joints to the ‘barely adequate’ 100 mm CV joints original for the type 923 912E in ’76.

The best conversion is to use the ’86 and later axle assemblies that are 108 mm CV joints and use six M10 bolts.
These require the ‘fine-spline’ transmission axle flanges that are 108 mm.
These are expensive but available.

Best,
Grady

[trak ratt]

Good idea and I was planing on doing that on my SC track car. Seen a number of those updates on local short hoods. But as you stated; they can be expensive and hard to find!

[rs911t]

I went thru this when installing the 3.2 + SC 915 in the '72 T. Fortunately I was able to source the complete axle assemblies from a someone locally that had transplanted a 3.6 into their 3.2. The axles fit quite nicely as Grady mentions.

[trak ratt]

Originally Posted by rs911t

I went thru this when installing the 3.2 + SC 915 in the '72 T. Fortunately I was able to source the complete axle assemblies from a someone locally that had transplanted a 3.6 into their 3.2. The axles fit quite nicely as Grady mentions.

Greg, have you upgraded to the aluminum control arms? Also, R U coming out to any events this year?

[rs911t]

Nope, still the original steel control arms. Not looking like I'll see any track time this year.

[rothaus]

You also need to bang a dent in the tunnel to make space for the larger 915, One around 12h and on at 10h looking forward. Also need to extend the cable for the reverse light switch. The shift rod is also different, you can use the rod and shifter from the SC.

Hope this helps

[trak ratt]

Originally Posted by rothaus

You also need to bang a dent in the tunnel to make space for the larger 915, One around 12h and on at 10h looking forward. Also need to extend the cable for the reverse light switch. The shift rod is also different, you can use the rod and shifter from the SC.

Hope this helps

Done and done. He's going to try and use the SC wiring for the speed-o and tack. If he can't get them out he'll just use the connectors and run new wire. Nice having a complete parts car!

Project got moved up when the shift rod tip on the 911 shifter broke at our last event. I broke the one on our '71 Targa some years ago during an auto-x but was able to repair it with a hose clamp. This one had a large tear in the tub itself

[Mat 71]

Don't want to hijack this...what is to become of the 2.7L that came out of car?

Thanks,
Mat

[rs911t]

Originally Posted by rothaus

You also need to bang a dent in the tunnel to make space for the larger 915, One around 12h and on at 10h looking forward. Also need to extend the cable for the reverse light switch. The shift rod is also different, you can use the rod and shifter from the SC.

Does this apply to the '72? We had no (apparent) trouble installing the tranny or shift coupler.

[Flieger]

no, 72 was the first year for 915 standard

[trak ratt]

Originally Posted by Mat 71

Don't want to hijack this...what is to become of the 2.7L that came out of car?

Thanks,
Mat

2.7 and 911 trans will be up for sale soon. If interested I can pass the info along? 2.7 ran well, and trans worked perfectly with no indication of any problems. Problem with trans was at the shifter not the trans itself. He just got a good deal on the wrecked SC and decided why not up-gun?