Manual Gearbox Install

I just installed a used manual in my 1991 240sx. The gearbox was $300 + $100 core. I brought it home in my trunk, still driving on the old tranny (only reverse went out). The swap took about 10 hours of labor, most of which was getting the engine to tilt back enough for the bell housing to clear the firewall. If you do everything right the first time around your looking at 4-6 hours to swap. I thought this might interest some of the folks out there looking to get rid of that automatic slushbox and get a 5 speed.

Im going to have this done this summer. maybe you can tell us some of the problems you ran into and what were the hardest parts?

You shold have done pictures and stuff as you went through the swap. What were the problems you ran into most??

The biggest problem was the clearance between the firewall and bell housing. I drove the front wheels up on ramp stands and removed the old manual from this position, bellhousing barely clearing the firewall. When I went to put the new gearbox on I just didn't have enough room to get the input shaft even with the hole in the clutch hub. I massaged the firewall with a hammer for awhile and still didn't have adequate room. I disconected the exhaust from the chassis and rested the muffler tip on the ground. This allowed the engine to tilt backward. There still wasn't enough room so I raised the rear of the car and set it on jack stands, allowing the muffler to rest even further from the chassis and thus the engine tilted back even further. As I lifted the transmission into place I was closer but it still seemed like there just wasn't enough room. Just as I was about to give up (or my arms give out, I was lifting it bench press style) and try another plan to improve clearance the shaft slid into the hub. Then I slid the drive shaft on to the output shaft and turned it to align the splines. Once the splines are aligned the shaft slides in further and the very end of the shaft rests in a brass bushing in the back of the crankshaft; this part of the shaft is unsplined as the crank must be able to rotate around the shaft. It is a very tight fit. While rocking the gearbox in a circular motion, holding it at the rear of the casing, I continued moving the gearbox further foward until I was able to get the block-to-bellhousing bolts in and used them to draw it foward, closing the remaining gap. I only made about 1/2 turn per bolt tightening them in a counter clockwise pattern. This prevents excesive sideloads which can damage the crank and/or input shaft. If your clutch is old you should replace it while the tranny is out; I replaced mine in December 2003 so there was no need.

When my buddy and I did the Clutch swap for my friends '86 S12 200sx we couldn't get the tranny to mate back up with the block due to the bellhousing hitting the firewall as well.

It was a beater car, so we cut a hole in the firewall to help get the bellhousing to clear.... unfortunately that didn't help at all... hahah so eventually we just pulled down on the cat-converter and used it as a leverage poing to tilt the motor back.

Then we were able to get the tranny and block to match up and get some bolts in. Took us... I think 15 hours to finally figure that one out.. spread out over 3 days. :lol:

Sucks working on a car when you've just gotten off of work... too tired to think. I didn't run that great.. but it was a good little commuter car.

It passed through a few people in our group, then it was bought for $200 by a guy I know and he tried keeping up with us 'fast' guys in the canyon and blew a radiator hose and kept driving... then he blew head gasket and eventually the motor gave out.

Idiot...:lol:

BTW: I was doing a manual to manual replacement not an auto to manual swap. The manual has four switches. One is the neutral switch, another is the reverse light switch. These two will have to be spliced into the harness for an auto to manual swap. The other to switches are for 4th and 5th gears; that is, I think this is their function. I'm not sure how they would tie into the auto harness. So not only do you need the clutch, hydraulics, and pedal; you must also figure out which switch is which on the manual and where to splice into the auto harness. It can be done at home with basic tools but I'd want a backup ride or a near-by bus stop before I tore into it...Just in case it took more than my weekend. I'm guessing the whole auto to manual conversion would cost around $500 assuming that you have your tools, ramps/stands, etc.