economical 915 swaps? Options

[Johny Blackstain]

Since I don't have my original engine & the trans I have has been converted to a side shifter, I was thinking of converting my six to a 915 transaxel & would like to know what everyone thinks is the most practical, or the most economical, or the most bullet-proof, etc... Or should I put in some sort of shifter that will notch me up a bit. The car has new shift bushings & it's still sloppy. I suspect I should check the rear mounts as well. Thanks. (IMG:style_emoticons/default/smoke.gif)

[John]

The 901/914 trans is cheap and can handle up to 300hp reliably as long as you keep the 1st gear burnouts to a minimum.....

I respectfully disagree.

In our track only 914 3.2 conversion (~220-230 HP), It took us about 6-7 years to get to the point where we could push the car hard enough (be on the throttle hard enough) to continuously break 901 transmissions. (NO BURNOUTS HERE)

We would routinely break teeth off of the 4th gearset. For the street, I would agree that a 901 would live a long long time. For a track car with two experienced drivers, I would say it is a matter of time.

We went through 4 boxes in 4 seasons (one season 2 boxes). I built three of them, and bought the 4th rebuilt by someone else. All failures were virtually identical.

We attributed the problem to shaft flexure. When the engine produced enough torque in 4th gear, the 4th gearset would seperate enough to start a gear tooth root fracture. When the fracture grew enough for the tooth to break off, the gearset would self destruct. The last time I rebuilt a 901, I used a billet intermediate plate for better bearing support. Instead of using it, we went 915. The rebuilt 901 now resides in my 3.2 street car. That car is never pushed hard, so I believe that it will last a long time. I have another 915 for it if I am wrong.

When we went 915/916, we bought the complete package fully sorted and ready to bolt in. New clutch/pressure plate, shift rods, rebuilt trans, 915 shifter, 911 axles, flipped R/P, assembled kit.

The total price for the complete assembly was above $10,000.

just my $0.02