I finally finished installing a P11 transmission into my B13 and thought I would do my best to make a how-to guide for others interested in doing the same. I had read many times over that this was a simple bolt on affair with a simple swaping of a few parts, but found out myself that it is slightly more involved. There really isn't anything difficult about it, but there are some modifications that need to be made. In my post title I'm assuming that the P11 and B15 transmissions are identical. I'm also hoping that Slow96R and SR20Turbofreak will chime in with the specifics for the B14 and P10 respectively.
Clutch Cable Bracket
-The first thing you'll notice on the P11 trans is how the clutch is actuated differently. The P11 uses a hydraulic slave cylinder to engage the clutch instead of a cable.
-Simply unbolt the slave cylinder.
-You can see the holes are there to mount the clutch cable bracket from your B13. The rear set of holes is set back further than on the B13 and may allow those using small spacers to completely eliminate the spacer.
*On my specific car, my spacer and the rear holes made for too tight of a clutch cable. I used the front holes, which have a slightly different pattern, and required drilling the holes on the bracket larger. I also needed to notch the bracket to keep it from hitting the clutch arm.
Clutch Arm
-Remove the clutch arm in the P11 trans by removing the roll pins(arrows).
*There is an inner and outer roll pin, remove the inner first then the outer.
-Do the same to your B13 trans.
-Here you can see the differences between the two clutch arms.
-The most important difference is the difference in thickness at the bottom of the shaft. This prevents the B13 arm from seating fully in the P11 trans and doesn't allow the throwout bearing to line up properly.
-To fix this I used a bench grinder and carefully removed material from the B13 shaft.
-Since the B13 arm sits in a completely different location than the P11 arm, the vent tube had an interference problem with the weight on the B13 arm. Nothing an angle grinder can't fix.
-Install the B13 arm into the P11 trans. Don't forget the return spring from the B13 trans.
*Install the outer roll pins first then the inner pins.
-It's now ready to go in, almost...
Motor Mount
-The P11 uses a different trans mount than the B13. It uses a top mount that uses 4 bolt holes on the top of the trans(black arrows).
-Lucky for us the trans is still drilled and tapped for the B13 trans mount(white arrows).
*The holes were pretty dirty so I used some antiseeze on a bolt and ran it through the holes. You could also use a M10X1.25 tap to clean them up.
Speed Sensor
-Simply undo the electrical sensor on the P11 and replace it with the B13 sensor.
*This is for 91-93 cars with mechanical speedometers. I do not know if the P11 sensor is compatible with the electronic speedometers in the B13.
Drain/Fill Plug
-The P11 uses a 10mm allen to remove the fill plug and a 14mm allen for the drain plug vs. the B13's 3/8" and 1/2" tools.
Sensors
-The reverse and neutral position sensor from the B13 are sized differently than the P11 sensors and can't be swapped. The harnesses are also different.
*I've yet to tackle this, but I plan on rewiring my B13 with the correct harnesses to fit the P11 sensors. Stay tuned for wiring details and part numbers.
Shifter rod/stabalizer
-This is where it becomes not quite a bolt on affair. On the P11 the shifter stabalizer mounts to the trans, where as on the B13 it mounts to the rear motor mount.
-Remove the bracket from the trans.
-Because of this difference the shifter rod sits further to the passenger side and interferes with the B13 stabalizer rod mount.
-This requires some major grinding and is alot easier to do with the trans out of the car. I grinded enough off until I could get the trans to bolt up.
-I thought I had grinded enough off, until I bolted up the rear mount. With the motor in its final position, the stabalizer mount was still hitting on the shifter rod.
-I trimmed a little off the shifter rod until it fit.
*This was the hardest part of the whole install, but overall not that difficult. Pictures coming soon.
Hope this helps people contemplating the swap. This will be my 4th trans since March, so I was willing to try something a little different. Slow96R, SR20Turbofreak, and javierb14 have had good luck with this trans and big power, so I hope it works out for me.
EDIT:
B14 - From what Slow96R told me, you need to do the same modifications for a B14.
P10 - From what SR20Turbofreak told me, on a P10 you won't have a clearance problem with the stabilizer mount. This is because the P10 uses a different crossmember that sits more to the passenger side giving you the clearance you need.
