First it must be noted before anything that the swap requires fabrication. This is not simply a bolt-in swap. Automatic equipped cars do not come with the brackets attached to the frame for the manual mounts. Mount brackets must be fabricated from 1/8th inch or 1/4th inch steel and welded or bolted onto the frame of the car. Also, the old brackets for the automatic have to be cut off for the manual to fit properly into the bay. Lastly, five holes have to be drilled in the firewall for the clutch pedal and master cylinder assembly.
This swap was done with an HM282 with a Quad 4 bellhousing and the external clutch slave cylinder. The procedures for the HM282 w/ internal slave or the izuzu are similar, with some differences concerning how to hook up the hydraulic lines and shift cables (izuzu). Also the matching parts are somewhat different.
Items I used:
An HM282 Muncie/Getrag transmission from a 92 or previous year Quad 4
Hydraulic clutch assembly (includes master + slave cylinder and line) from a 1992 N-car
Clutch pedal from a 1992-1998 N-car
Shifter and shift cables from a 1992-1994 model N-Car
Flywheel from a vin code “A” 2.3L Quad 4 engine
New clutch, pressure plate, and throwout bearing for a vin code “A” 2.3L Quad 4 engine
Front transmission mount
Rear transmission mount
Left and right half-shafts from a manual equipped n-body. 89-94 will fit, as long as it had a getrag.
Intermediate shaft
Intermediate shaft to engine block bracket
2.5 quarts of synchromesh manual transmission fluid.
Transmission brackets cut from a donor car, or some thick steel handy.
Tools you will need:
Flat head screwdriver
Crowbar
Jackstands
4lb hammer
Rubber mallet
Hand drill
Cobalt drill bit, preferably 7/16 of an inch or larger
MIG or Arc Welder
10mm hex socket (for the break calipers)
T57 Torx socket (for the wheel hubs)
Decent metric ratchet set, with 13, 15, 18, and 19mm deep sockets
Decent metric box wrench set
21mm ½ drive socket and a 32mm axle socket
breaker bar or impact wrench
Automatic transmission removal
You will need to remove the torque converter to drive plate bolts, bellhousing bolts, remove the CV axles, the left suspension support, shift linkage, transmission mount, transmission to engine block brace, all electrical and vacuum connections from the transmission before it can be dropped from the car.
Flexplate bolts: Support the car securely on jackstands. Underneath the car, remove the plastic cover that shields the bottom of the drive plate and torque converter. You will see the plastic cover on the driver side of the block by the oil pan, next to the transmission. There are 3 bolts holding on the torque converter; hold the flex plate from moving with a large screwdriver while loosening the bolts with an open end wrench. If I remember correctly they were 19mm bolts, but these may differ with year model or transmission type. All three bolts should come of easily.
Removal of CV axles: With the car still on jackstands, remove both front tires, brake calipers and rotors. You may want to support the calipers off the ground with a few blocks of wood so they do not hang from the brake lines. Now, you want to mark the position of the CV axle right above it on the body of the car so that when you install the transmission, you can line up the differential to this spot so you have proper driveline alignment.
The following process will work for both axles: use a screwdriver to keep the hub from rotating, and remove the nut from the end of the axle using a 32mm axle nut socket and a breaker bar or impact gun. Using a 4 lb hammer, knock the end of the axle loose from the hub. Remove the hub by removing the 3 Torx bolts holding in place and prying it off carefully. The 3 bolts should take a size T57 bit. You will have to remove the steering knuckle, but BEFORE YOU DO THIS mark the positions of the nuts/bolts with paint, so they are exactly in the same place when you reinstall them. If you do not, your wheel camber and wheel toe will be off when you reinstall! Remove the 2 steering knuckle nuts with a 21mm socket. The studs are splined so they will have to be struck out with a hammer. Pry the steering knuckle down until you can get the end of the axle out. Using the prybar, work the end between the CV housing and the transmission until the other end of the axle pops out.
Removal of driver side suspension support: Remove swaybar end link. MARK THE POSITION OF ALL BOLTS CONNECTING THE SUPPORT TO THE BODY OF THE CAR WITH PAINT. Remove all bolts connecting the suspension support to the body of the car. Remove the swaybar mount. Since the steering knuckle has been detached the steering knuckle, control arm, and engine cradle should drop as a unit.
Removal of electrical and vacuum connections: The transmission has 2 vacuum lines—one for engine vacuum from the throttle body, and one that is for ambient pressure. Remove the engine vacuum line from the vacuum modulator on the front of the transmission. The vacuum modulator will be on the driver side of the transmission, near the front. There are 3 electrical connections to be concerned with. The first is a plug above the vacuum modulator for the TCC and the ECM command for the shift solenoids. Remove this. The second is the shift position switch located near the back of the transmission on the driver side. Remove the connections from the back of this, and while you’re at it remove the shift cable. The last connection is for the speed sensor, located by the passenger side differential seal.
Additional hardware: There is a bracket on the passenger side, accessible from the wheel well, linking in the tranny to the block. Remove it after the CV axles have been removed. Also, do not forget the lines from the transmission to the radiator. Some cars also have a bracket linking the exhaust manifold to the oil pan. This should also be unbolted. It will fall when the transmission is removed.
Remove all bellhousing bolts from around the transmission. It is imperative that the transmission still be connected via the mount, or you risk personal injury! The last step of removal is the
transmission mount: Be sure you are NOT UNDERNEATH THE CAR while removing the mount and the bracket. Make sure the car is securely supported. The automatic transmission mount is on the driver side of the car, visible from the driver side front wheel well. It is easiest to remove the bolts connecting the mount to the frame (4), and then those connecting it to the transmission(4). They are hard to get to, but possible if you have several open-end or box wrenches. These bolts are either 17 or 19mm bolts, I don’t remember off hand… Don’t bother messing with the bolt connecting the rubber insert to the bracket, it’s a pain to remove and unnecessary.
With everything out, you should begin to pry the transmission from the block with a crowbar. Upon separation, the transmission may fail to drop out of the car. A stout kick will shake it loose and it will fall.
Clutch Installation
You will have to remove the stock driveplate. There are six bolts in the center of the drive plate that have to be removed with an impact wrench or a breaker bar. They are fixed with threadlocker.
Before you install the flywheel, have it resurfaced.
When you install the flywheel, do not reuse the bolts that attached the drive plate to the crank. Since the flywheel is thicker, you will need longer size bolts. You should be able to get the proper size bolts from a dealer. USE NEW BOLTS. Use threadlocker blue on the flywheel-to-crank bolts and torque them down to specification (22 ft lbs and then an additional 45 degrees).
Next you must install the clutch disk and the pressure plate. The clutch disk sits in between the plate and the flywheel. There are 6 bolts that attach the pressure plate to the flywheel—do not tighten these down at first! Make them just barely hand tight. You need to be able to move the clutch disk so you can center it. Use an alignment tool to center the disk—it will fit into the teeth of the clutch disk and the recess and the end of the crank, perfectly aligning the clutch disk. Once this is one, remove one pressure plate bolt, put threadlocker blue on the threads, and reinstall. Do this in sequence for all the bolts. Now torque the 6 pressure plate bolts to spec (15 ft lbs, then an additional 30 degrees). Now remove the alignment tool.
Tranny Installation
Before you install the transmission, make sure it is in good working order. Check the clutch fork for rust and wear. Install the throwout bearing over the input shaft, making sure the two teeth on the clutch fork are placed between the notches on the throwout bearing. You also should grease these areas with lithium or moly grease.
There is a bracket for the automatic tranny mount that is welded to the body of the car. This needs to be cut off completely so the transmission will fit! The endplate of the transmission will not clear this piece if it is not removed.
The transmission has to be installed from underneath the car. It cannot be lowered from the top. I do not recommend being under the car trying to benchpress the unit up onto the engine while the whole car is supported by jackstands. The car can fall on you and kill you.
The safest way to do it is to place the transmission under the car, and hoist it up from the top. You can do this with a variety of methods—a engine crane, a hydraulic jack, whatever you can rig up. Personally, I removed the hood, removed the brake master cylinder for room, and put the tranny under the car. Then I lowered the entire front of the car to the ground, so I could reach down through the engine bay and grab both ends of the tranny by hand. I lifted it up and got the spline on the input shaft to go into the clutch. Then I proceeded to replace all the bellhousing bolts and torque them down.
Mount Installation
There is a front and a rear mount for the transmission. The rear mount attaches the transmission to the body of the car, the front attaches it to the suspension support. I recommend getting new mounts and brackets from GM
There are two brackets that must be welded onto the frame of the car/engine cradle for the mounts, and you will have to get these out of a junkyard car. You will need to cut them out yourself. There is no way to get them through any other means. GM does not supply them and no aftermarket company makes them, because they are considered part of the frame. If you can’t get the ones out of a junkyard, you will have to fabricate them.
Now, this is critical. You need to make sure your driveline alignment is correct. Position the transmission so the differential is in line with the marks you made before you removed the cv axles. Now hold it there with jacks, put on your mounts and mark spots on the frame so you can weld/bolt on the mount brackets you cut off/fabricated.
Hydraulic Clutch System Installation
The easiest way to install the hydraulic clutch system is simply to buy the whole system as a unit from GM. It cost me 158 dollars, and you get the slave, master, line, and reservoir, all assembled as a system—and the system comes pre-filled and bled. Just bolt it on and go. Otherwise you will have to put pieces together, fill the system with brake fluid, and bleed it—this is a real pain.
You will have to drill 1 large hole and 4 small holes in the firewall to install the clutch pedal and master cylinder. I used a 1 ½ inch holesaw and a 5/8ths inch cobalt drill bit. You will have to remove the rubber firewall insulation on the driver side. The location of the holes are already marked on the firewall on auto cars, but the holes are not drilled. Just drill the holes where they are marked.
Now, once the drilling is done, you will have to remove the windshield wiper motor to access the portion of the firewall where the clutch master cylinder will be located. Once this is done, you can install the clutch pedal from inside the car, running the 4 studs on the back of the unit through the holes in the firewall. You might want to have somebody hold in position while you work from the engine compartment. Screw nuts on the two bottom studs. Now take your hydraulic clutch assembly, route master cylinder and the reservoir through the mess of cabling and lines around the driver side of the engine compartment. The reservoir should sit on the upper far left side of the engine bay, in the little cove right in the corner where you see the wiring harness pass through. Place the master cylinder piston rod through the large hole and the plastic flange of the master cylinder over the top 2 studs. Screw the nuts onto these top studs. Now, from inside the car, place the piston rod over the stud on the pedal arm. It should be held on by a rubber grommet, depending on what year model pedal you are using. If you are using a 96+ year model pedal, remove the spring from the pedal before installation.
Back in the engine bay, install the slave cylinder on the transmission. Make sure the fork is pulled all the way back. The piston rod is held back by 2 little plastic straps. Leave it that way! Do not remove them, install them how they are. These will snap when you depress the clutch for the first time to set the freeplay in the clutch system.
Oh, lastly, you’ll need to make the brake pedal smaller to allow enough room for the clutch pedal. I cut 1 ½ inches of the end with a hacksaw.
Shifter and Shift Cables
You will have to use the shifter and shift cables from a 92’ year model or above n-body. Depending on what year model transmission you have you may have to change the studs on the shift linkage brackets on the transmission to properly fit the cables. You can get new studs at the dealer.
The 92+ shifter assembly will bolt right into the interior of the 96-98 cars. You will have to adapt a new cover and shift boot for use with the newer consoles. 96+ shifters will not work with the cables. Also, the 96+ shift cover and boot are too small to use with the 92-94 shifter.
Electronics
The speed sensor on the getrag will work with newer ECM’s, but unless you have a 3.94 gear ratio the speedometer will be off because of the ECM calibration. You will need to splice the old-style plug into the harness. The speed sensor is located on the differential. The other connection on the getrag is the reverse gear sensor. The reverse light is controlled by the shift selector. Cut the appropriate wire and splice into the connector, and run a black wire to ground.
You will have to hook the shift selector back up to the harness, and cut the purple and yellow wires (they are the thickest of the bunch) and connect them too each other. This is your park neutral setup, and you have just bypassed it so you can start your car! If you really want to get fancy you can hook these into the clutch safety switch, if you choose to install it.
Now, you can keep the auto ecm, but you will just have to remember that you will throw codes for the transmission. If you are ok with this, you will have to remember that the shift selector must always be in DRIVE. This will allow you to rev past the 4000 RPM rev limit the 96+ up cars have while the car is in park.
Intermediate axle and transmission to engine block support
The intermediate axle is set up with a bearing and a bracket on the end to brace it up against the engine to prevent harmonic vibration of the intermediate axle. The bearing allows the axle to spin freely inside the bracket support. These you should have gotten from a donor car in the yard or from a dealer. You want to use a bracket from a 96-98 2.4 5-speed, as the older brackets will not bolt onto the block.
The rest of the car.
That was all the major stuff. You have to simply reinstall everything else. Installation is the inverse of removal for the CV axles and suspension systems. I’m sure you know how to put the brakes and wheels back on.
Remember to line up the bolts for the steering support and steering knuckle with the marks you made.
Make sure to follow these torque specs:
Suspension support – tighten center, then front, then rear. All 89 ft lbs.
Steering knuckle bolts -- 133 ft lbs.
Hub bolts -- 70 ft lbs.
Axle nut – 185 ft lbs.
And you should be done… time to test her out.
Start the car, with it still on jackstands, very carefully let off on the clutch in 1st gear. One of the wheels should be spinning. (it's an open differential) Go through all your gears carefully. Listen for grinds or any strange noises.
If all is well, put the car on pavement and test the clutch. Start the car, put it into 5th, and without touching the gas pedal dump the clutch. If the car does not immediately die, the clutch was installed improperly. This will also test your mounts. Check to see if anything broke after your car gets done jerking across your driveway.
If this checks out ok, you’re good to go. Enjoy your new 5-speed.
Linear Mode
