320i automatic to manual transmission conversion

[Jester323]

I had originally written this article for the bmw320i.com site, which as we all know is no longer around. I though it was a good enough resource to revive and post up here. I scrounged up what I could on this but will have to look for the original pics. I hope someone else finds this useful. Josh, you may want to fix the link in the FAQ thread and point it here, I happened to be looking around that thread today and noticed the broken link.

E21 Automatic to manual transmission swap
Written by: Jester323 (aka Jesse Nemec), November 30th, 2004

Donor vehicle: 1982 320i
Receiving vehicle: 1983 320i
Replacing the 5HP22 with the Getrag 245-5

Time to complete project: approximately 30 hrs, and 15 hrs of assistant time
Note: take your time, I completed mine in 3 days over two weekends, plan accordingly.

Introduction: This is a big task. No question about it. However, it’s not particularly difficult. It will take some good general understanding of your drive train, and good mechanical common sense. If at all possible, con one or two of your gear head buddies into helping. This is not a one person job. It could be give that you have a really nice shop with a lift and a hydraulic transmission jack.

Parts list:
Transmission w/ matching linkage and drive shaft lengths
3.91:1 ratio differential
shift plate
shift boot & base plate
shift knob
transmission support/cross member
flywheel
clutch disc
pressure plate (and bolts)
clutch release bearing
clutch release arm, pivot pin and retainer clip (these may already be mounted to the donor transmission)
clutch slave cylinder
clutch hydraulic line
clutch master cylinder
clutch master cylinder fluid supply line
pedal box
speedometer cable (should already be mounted to donor transmission)

Fluids needed:
1.5 qts Redline MTL
1.0 qts Redline 75w90 diff fluid
brake fluid
locktight
super glue
Penetrating lubricant

Tools needed:
clutch alignment tool
various metric sockets and extensions from 8mm - 22mm
various metric open end/box end wrenches from 10mm - 19mm
a couple of pry bars
crescent wrench that will span somewhere in the mid 20's mm
various length and type screw drivers
torque wrench and breaker bar
air tools/impact wrench will really help
10mm allen wrench
17mm allen wrench
hammer/mallet
Snap ring pliers
Wire cutter/stripper/crimper

It's also very good to have a pile of extra nuts, bolts and washers on hand.

Day 1:
So the car went up on stands Sunday around noon. First order of business was to unbolt the automatic transmission from the block, and the drive shaft from both ends. The 5-spd drive shaft is about 1.75" shorter than the automatic drive shaft.



In order to pull the drive shaft free from the vehicle, I needed to unbolt the muffler from the center section of the exhaust to make enough room for it to come out.

The transmission cooling lines had to come out, the tranny fluid dipstick, the wide-open-throttle gear kick down cable, the gear selector linkage, the shift lever and cover, the reverse/light/"P" or "N" ignition enabler wiring harness, the torque converter and ring gear.

The next big hurdle is to figure out if you want to try to swap the pedal assembly or modify the existing one. The automatic pedal box can be modified by simply drilling 3 holes in it to accept the clutch master cylinder and bolting up the clutch pedal. But the down side to this is that the manual transmission pedal box has the two nuts welded to the firewall portion that hold on the clutch master cylinder. This would mean that you would need to have a helper install the clutch master cylinder, or if you ever had to replace it in the future. The up side is that you wouldn't need to unbolt the pedal assembly from the firewall. The steering linkage and the steering shaft would have to come out as well in order to remove the pedal box, and that’s really the only challenging portion about swapping the pedal box.




Here is a picture of the automatic pedal box on the left, and the manual pedal box on the right. Notice that the clutch pedal is mounted to the same shaft bolt as the brake pedal. Also note the hole that is visible directly behind the clutch pedal. This is where the clutch master cylinder penetrates the fire wall portion of the pedal box. It is almost impossible to see in this picture, but what prompted my decision to swap the boxes is due to the location of the bolt holes for the clutch master cylinder. One of the two holes is barely accessible and would add to the difficulty of mounting the clutch master cylinder, even with an assistant. If you have a welder at your disposal, then you could weld new nuts in place, but in order to do that correctly, then you would still need to pull the pedal box any way, and at that point, you might as well put the OEM 5-spd pedal box back in, unless you can’t find one.

Day 2:



Here is a view after I started pulling out the stock automatic pedal box. I figured that since I had all the parts to do it right, I might as well do it right. I really didn't like the idea of hoping that I got the holes drilled right and making a good seal on the fire wall for the clutch master cylinder.

So, the first order of business was to remove the steering wheel, one 22mm nut, piece of cake. I then removed the lower column cover, three flathead screws. Unhooked each of the 5 wiring harness clips (they all fit back together with different connectors so you can't get 'em confused, but I labeled them anyway). I unbolted all of the 10mm screws that hold the pedal box to the fire wall. Unhooked the throttle cable from the pedal linkage arm, unhooked the gas pedal from the linkage arm (one C-clip), unhooked the spring that holds up the brake pedal, unclipped the shaft that connects the brake pedal to the brake booster/master cylinder. Then I loosened the clamp that holds the steering column in place.

Then it was time for the engine bay side of things. I unbolted all 4 of the 13mm nuts that hold the brake booster to the pedal box and unbolted the two 13mm nuts that hold the brake booster to the bracket that holds it to the strut tower. Now all that I have left to do to remove the pedal box is to unbolt the engine bay side of the steering linkage and hammer the steering column free from the bracket that holds it up to the dash. I sprayed some penetrating lube on the bracket that the steering column bolts up to. Due to the fact that Hans & Co designed the car to be very difficult at best to steel, all of the bolts that attach the steering column to the dash are shear bolts and can not simply be un-bolted. The heads of the bolts have been sheared off. Don't even try to unbolt it, it's not gonna happen. The nuts on the other side are welded to the bracket. If you want to replace these, then the best you can hope for would be to drill them out and replace with new. But never fear, there is a way to remove it without doing this, Hans gave us a back door. The back door is actually a safety feature that allows the steering wheel and column to be pushed forward and absorb some energy from the driver in the event of a significant front end impact collision. The bracket will allow the steering column to be slid down towards the steering rack to slip free from the bracket.

Keep in mind when you do this that the nut that you removed to take the steering wheel off should be put back on after the wheel is gone so as to protect the splines before you start hammering, or you will be needing a new steering column and a new set of keys and locks for the rest of the car, or another big headache that is just not needed.

As I had everything else unbolted already, all I had left to pull the old one out was to unbolt the steering rack, the tie rod ends can (and should) be left in place. Once removed from the subframe, I removed the 13mm bolt from the upper end U-joint on the steering shaft. It looks like you would be able to just loosen it, but just remove the bolt completely; it's a lot easier that way. Then slide the joint off the splined end of the steering column. Once it was free, then I went back inside and marked the position that the upper bracket was in with a sharpie and used a large mallet to tap the steering column free from the upper bracket. It actually slid out pretty easily. Then I simply removed the column from the vehicle. Make sure that all of the pedal retraction springs are disconnected, brake booster shaft is free from the pedal, accelerator pedal is free, and you are ready to pull the old box out.

Of course the new box is all nicely cleaned, painted and looking good. The new Clutch master cylinder is mounted to it (a lot easier to bolt the master cylinder to the pedal box before you install the pedal box). The biggest trick to getting the new one installed is that there is a little metal tab welded to the outside pedal box that's only function as far as I can find, is to get in the way when one is trying to mount it up to the inside of the firewall. Just bend this tab up a bit and it will slide right on in. Make sure that you line the brake booster up and get all 4 of the bolts lined up. Once this was done, I hand snugged up nuts on the outside that holds the brake booster up to the pedal box, and then reinstalled the bolts that hold the brake booster on to the bracket that attaches it to the strut tower. Once these are bolted up, then you can bolt the pedal box to the firewall. Do it in that order or you won't get the brake booster bracket to line up with the bolt holes. Then I attached the brake pedal to the booster shaft, reattached the accelerator pedal, reattached the brake retraction spring and installed the new clutch pedal retraction spring. Then I reinstalled the steering column. Luckily the upper cover over the column is metal, and proved to be a good place to be able to tap it back into the bracket. Otherwise I would have had to have a helper tap it in from the engine bay side while I held it up and aligned it on the upper bracket. Then I tightened up the lower collar clamp to keep it locked in place. Then the u-joints and the steering rack can be bolted back up.

The next step I found out the hard way, which I took just a bit too soon. On the side of the brake fluid reseviour is a little bung that needs to be cut off. This is where the tube from the top of the brake master cylinder attaches to supply hydraulic fluid to the clutch system. Slide the end of the tube that has a cloth lined rubber hose on the end of it over the end of the now dripping bung on the reservoir. This portion of the system doesn't have any pressure in it, so clamps are likely not needed, just make sure it doesn't leak. The reason that this step was a bit too soon was because I didn't have the hydraulic line from the master cylinder to the slave cylinder installed yet, so the remaining fluid in my reservoir dripped out the port on the master cylinder. If I were to do it again, I wouldn't take this step until the tranny and hydraulic lines are installed, and I'm ready to bleed the system.

Next order of business was to install the flywheel. This is fairly simple; however it is rather heavy to hold up over your head while lying on your back. There is a small thin steel sleeve that fits into one of the bolt holes. You will need to find the larger hole on the output flange from the engine and install the sleeve into that bolt hole and tap it in place. It should stick out about half way. Then locate the large hole on the flywheel and position it on the sleeve that is on the output flange. Tap the flywheel into place with a weighted soft mallet, or block of wood and hammer, it is hub centric and the fitment should be slightly snug. Make sure that it is seated all the way on the flange. Use a little high-temp lock-tight and tighten all of the bolts down. I'm sorry, but I couldn't find a torque specification for these, so I used 80 psi on my impact wrench and then used my 1/2" drive ratchet to snug the bolts up the rest of the way. I found that the easiest way to keep the flywheel from spinning was to put a phillips screw driver through one of the holes in the flywheel that the pressure plate bolts up to.

CAUTION: Be very careful when mounting the flywheel. It is rather heavy, and has all of those teeth on it for the starter motor to engage, and if it slips off while you are taping it in place, it could really mangle your head, arm, or whatever it is that it falls on.

Then I started to bolt the clutch and the pressure plate up and realized that I don't have a clutch alignment tool, so I will have to wait until tomorrow to complete any more on this project.

Day 3:

I started the day by going and picking up a clutch alignment tool and finished mounting the clutch and pressure plate. Hopefully when you sourced all of your parts you picked up all of the bolts that bolt the pressure plate to the flywheel. The automatic transmission never had these bolts, so you will need to get some.




Then it was time to get the electrical for the reverse lights, P/N ignition enabler loop. I clipped off the factory harness by the gear selector and disconnected the short harness that connects the automatic harness connector to the reverse lights connector. the two brown wires were spliced together, these close the loop when in Park or Neutral, and the white wire with the blue stripe that supplies power to the gear selection indicator light got an insulated connector for future use (back lit gauges or for an illuminated shift knob or something).

Now time to install the actual transmission. Don’t try to do this by yourself without a transmission jack. The hardest part of that is getting the upper starter bolt back in. To be honest, the best way we could figure out how to do this was to super glue the nut to a washer, then super glue that to your finger to hold it in place while the other person lays on the floor and reaches up around the bell housing to spin the bolt to thread it in place. Don’t worry; by now you will have enough grease on your fingers that it really won’t hurt very much when you rip your finger free from the super glue.

The manual transmission also uses a slightly different cross member support bracket. Make sure that you pick up this cross member when you get the donor transmission. They appear to be the same, but upon closer inspection, the manual transmission cross member mates to the large rubber bushing slightly lower that it does on the automatic.

Then it was time to install the shifter box and linkage onto the back of the transmission, and don't forget to put the reverse light wires up through the hold for the shifter and connect it. Take note of the position of the shifter lever. There is a bend in it at the ball joint. The bend should “point” towards the front of the car. If it is mounted backwards, then the shift knob will be positioned too close to the console, and it will be uncomfortable to get it into reverse, 1st, 3rd and 5th gears, as I found out the hard way.




I would check this before you mount the drive shaft. It’s much easier to get to the C-clip in the linkage when the driveshaft is not installed.

To install the driveshaft for the manual transmission, we needed to unbolt the down-pipes from the exhaust manifold to slide it into position. Bolt up the differential end first, then the flex disc at the back of the transmission, and then push it up to mount the center bearing. Then re-install the heat shroud.

I replaced the fluid in the tranny with 1.47 QTs of Redline MTL, and filled the diff with 1 QT of Redline 75w90 gear oil. This contains an additive for the limited slip too.




Then run the hydraulic line to the clutch master cylinder, bleed the line, hook up the speedometer cable, hook the exhaust back up, install the shifter boot plate and shifter knob. Then go through all of the bolts that you can think of and make sure that they are snug, and you are done!


Again, I must state, take your time and be methodical about it. I was quite thankful that I did. The only things that I had to change once I completed the test drive was to re-adjust the alignment of the steering wheel, after disconnecting the steering U-joints, you can’t expect the steering wheel to be aligned up right, even if you made careful marks. And then I also had to spin the shift lever around 180* because it was too close to the console, but after reading this, hopefully you won’t make the same mistake. Other than that, everything is working brilliantly! And I attribute that to taking my time to do this job right.

The following are some references in gear ratios that may help you determine the benefit to making this swap:

The 1977-79 E21 320i uses the Getrag 242 (4-speed).

The 1980-82 320i(s) uses the Getrag 245 (5-speed).

The 1983 E21 320i(s) uses the same Getrag 240 (5-speed) as the 1984 E30 318i(s).

Automatic – 320i - 5HP22 (3-speed)
Gear Ratios
1st – 2.478
2nd – 1.478
3rd – 1.000
R – 2.090

4-speed - 320i - Getrag 242
Gear ratios
1st - 3.764
2nd - 2.02
3rd - 1.32
4th - 1.00
R – 4.096

5-speed - 320i - Getrag 245/4 Overdrive transmission ’80 – ‘82
Gear ratios
1st - 3.764
2nd - 2.00
3rd - 1.33
4th - 1.00
5th - 0.81
R – 4.096

5-speed - 320i - Getrag 245/10 close ratio/”dogleg”
Gear ratios
1st - 3.764
2nd - 2.325
3rd - 1.612
4th - 1.229
5th - 1.000
R - 3.682

5-speed - 320i - Getrag 240
Gear ratios - almost the same as a 245/4

Transmission Weights:
Getrag 242 - 48 lbs
Getrag 245 - 63 lbs
Getrag 240 - 62 lbs
5HP22 – 68 lbs

Both input shaft diameter for the pilot bearing .471”/11.9634mm

4-spd and automatic transmissions use the 3.64:1 ratio differential (final drive)
5-spd uses the 3.91:1 ratio differential (final drive)
5-spd “iS” models use a 3.91:1 Limited Slip Differential

[jimdemonic]

Thats great you need to put in the faq section

[milotrain]

You'll also need a pilot bearing. Most clutch "kits" come with one. Depending on which engine you have you'll either need a [IDxODxLenght] 12mmx32mmx10mm pilot (double sealed ball) bearing [for any of the later M10s and M20s] or a 12mmx21mmx10mm pilot (needle roller) bearing for the earlier [2.0L 2002 M10]

If you are not sure which you have just buy both, they are around $12 each but can be found cheaper at any of the major industrial parts suppliers like McMaster, Grainger, Fastenal, MSC, etc.

[danielhill2008]

It has been my experience that the Getrag 240 5-speed in the 83 E21 is not the same as the one in a 84 E30. It bolts up the same to the block, but mounts differently (the 83 tranny has only one mounting point) and more importantly, the 84 is about 1.5 inches shorter, due to the absence of the speedometer drive gear, the E30 having an electronic sending unit. So your driveshaft will be too short. While this may not be of the same critical importance if you're switching out an auto for a 5-speed, be aware that the 83 Getrag 240 must come out of an 83 if you're just replacing a 5-speed. Ask me how I know. They do have different part numbers. An expensive lesson for me.

[Twelvizm]

This is relevant to my interests.

[Thecatmilton]

I found another way to bypass the park neutral safety switch. Follow its harness and you will find a relay (arrow points to it in picture). You will see two black wires with stripes coming from the back of the relay to some spade connectors. Unplug the two wires that came from the relay (each wire is circled in picture) and connect the remaining two black wires the relay wires were plugged into together (one comes from the ignition harness). There will be another spade connector coming from the relay to a plug just above it that needs to be unplugged too (somewhat inside the left circle in the picture). After this, you can remove the whole harness if you want to.
steeringcolumn.jpg

[bruno504]

Hi,
I'm from Portugal & I want to thank you very much for this help, I'm doing exactly the same, and is going fine.
Question: Does the automatic gearbox worth any money, or is good for putting in the garbage?!

regards,
Bruno Luis

[bruno504]

thank you