BMW 2002 AUTOMATIC TO 5-SPEED CONVERSION PAGE
By Peter Siposs - last updated 9-22-06
By Peter Siposs - last updated 9-22-06
BASICS OF THE PROJECT
UPDATE: The car was sold via Ebay and has a new home in Texas as of April 8, 2001.
This page is intended to outline the steps required to convert a BMW 2002 from an Automatic transmission to a 5-speed. If you are converting your car from a 4-speed you will have it a bit easier and can skip the AT portions. Converting other BMW models will be very similar and you will gain insight as to what is needed here. I bought my 76 BMW 2002 with a dead automatic transmission and only reverse gear working with the intention to convert in right away to a 4 or 5-speed. I nearly changed it to a 4-speed to keep costs down and simplicity at its peak. But I soon learned that there wasn't much more work or costs involved to do the full 5-speed conversion. Value when reselling the car was also a serious consideration.
The primary difference between a 4 vs. 5-speed conversion is the costs of having to use driveline shop graft the 320i front flange onto the original automatic shaft AND the shift linkage and shift plate also has to be shortened. Converting a 4-speed car to a 5-speed would be cheaper and simpler because it would already have a 3 pedal box (clutch/brake/gas) and clutch master cylinder - unlike the automatic cars. I also had to buy a center shift boot interior plate, which is different from the automatic models. There is a complete list of required components and costs listed at the end.
This was my car when it was towed home after purchase.
Here are a couple shots of the 5-speed trans (on the left) and the original automatic
AUTOMATIC TRANS REMOVAL:
The auto-box on this car is pretty big and is longer than the 4 or 5 speed transmissions. It has a flat oil pan, which was handy for placing a floor jack under it. I tried to drain the unit before pushing the car into the garage for the big work but the drain plug was seized solid. Perhaps lack of changing the ATF oil led to a premature death (89k)? Knowing the trans would likely be thrown out afterward I decided to butcher the beast and drill a 1/4" hole in the pan. Not graceful but effective. I also removed the trans cooler hoses. ATF is messy stuff and doesn't clean easily. It seemed to drip for days. The torque converter seems to hold quite a bit too. I didn't want any oil dripping on me while under the car so I started the engine briefly and pumped out even more ATF oil into the drain pan. Being a bit anal, I degreased the engine bay and under the car as best I could. I even sprayed right onto the trans tunnel area with cleaner and hosed off thoroughly. I left it to dry out in the heat of summer & overnight. The next day with the help of a friend I pushed the car into the garage for its slumber while I worked on it. Once inside, I removed the gear selector mechanism from inside the car. The black interior plate surrounding the selector area has to be changed for a manual trans car as well, so the old one came out. Before jacking up the car, I removed the upper bell-housing bolts. Then I jacked up the car as high as the jack stands would allow. One jack stand on each corner. Removed the switch wiring for the reverse lights and starter interrupt, shift selector pushrod and levers, drive shaft, exhaust support brackets, exhaust down pipe from manifold. Then removed remaining bell housing bolts. Finally I began to pull back the trans and discovered I had not removed the kick-down cable, which attaches to the carburetor. Also forgot the lower bell housing plate just like I did with the 5-speed on the 320. Then it seemed to get stuck by the body tunnel. Finally I read in a manual that the torque converter bolts must be removed first. I thought the converter would stay on the engine like a clutch does. I could not access the bolts for this with a socket and ratchet, or common wrench. So I ran out and bought an offset 13mm wrench and a wrench with a socket on one end. These worked and upon removing the last bolt, the trans fell to the floor - literally. Boom. Out! Since I was working from the front of the car I wasn't using the floor jack to support the trans. Duh! The photos here of the automatic has the pan removed which is why it looks a little smaller than usual. Before dumping the old trans I removed all the accessable bolts and nuts which provided a large cache of metric fasteners. I removed the bell-housing which is 8lbs of cast aluminum and donated it to a recycling center.
TEST FIT AND PREP:
I ordered a clutch kit and other parts and took the opportunity while waiting to install the new 5-speed trans onto the engine without the clutch mounted. This prevented having to align the input shaft with the clutch etc and allowed me to make the critical drive shaft measurements. Also, I was able to determine the best method to attach the trans mount to the body.
Side note: I soon found the roundish bottom of the trans was making lifting it with the floor jack very difficult. It kept tipping over or slipping off and its tough to hold straight with much muscle while cramped under the car. So I made a cradle from angle iron and mig welded it together. I used a couple of the rear bolts on the trans to support it and it just rested on the forward section. See the photo of it. This was still a little awkward so I mounted a short piece of wood onto the floor jack and this combination did the trick. Doing the whole job by myself also meant I had to operate the jack while still being under the car at the same time. Not easy!
This is the transmission cradle I made to make lifting with the floor jack easier
This is the rear trans mount I made from a stock 320 mount, cut to clear the exhaust, added heavy angle iron and mig welded.
The automatic pedal box and pedals is of course useless with a clutch required. So the old unit had to come out. It was a little trickier to remove than I expected. This definitely should be done with the trans out of the car. This gives much more room to reach up toward the brake master cylinder to remove the linkage for both the brake and accelerator. The pedal box has braces that go all the way up to the brake master cylinder. The large bolt here has to be loosened, but not removed. Accessing the pedal box bolts from inside the car meant I had to cut the carpet where itís not otherwise visible under the AC area. This allowed me to peel back the carpet to reach the bolts. 8 bolts from inside the car hold the box in place and the box is removed from under the car. Once I received the new pedal box I cleaned and painted it. Nothing is interchangeable between the automatics pedals etc and the manual trans type so make sure itís in good shape. Even the hard foam pad which covers the inside hole is not interchangeable. I used 3/4 inch thick closed cell single sided foam tape as a seal between the box and the floor. Once I got it into position from under the car I had a friend put the bolts in while I pushed up to squeeze the foam tape. Otherwise the bolts weren't long enough to start.
Side note: Having the car still way up on jack stands allowed me to work on the floor inside the car while sitting comfortably on a short rolling garage chair. I just worked with the door open.
Pedal boxes: Old AT on the left, manual trans version on right
The pedal box goes in this hole from underneath.
I measured 6 inches from the mounting bolts of the linkage plate to the center of the body tunnel shifter hole. Rather than concerning myself with how much to cut off, I was more interested in the end result figure. I cut the linkage plate with a metal cutting blade on my electric miter box shop saw. Worked well. The plate gets narrower the closer it gets toward the lever. This prevented the plate from attaching square on the mounts. So I eased the crease out a little in a vice. This kept the strength of the unit while fitting firm. I used new trans to plate bushings. It really firmed up the flexing. So it was time to measure the linkage pushrod changes. I simulated the same position as was original, which meant the new shaft length should be 2-9/16" (it was about 6 inches originally). I cut out a section of the rod with the end result hoping to be a little more than 2-9/16". This way I could fine-tune the length by using a grinder and also smooth out the edges. There was a natural line to follow which prevented the shaft from being in a twist before welding. Once I got the size and position I pinched it in a vice on its ends. Out came the mig welder and itís a joy to weld clean metal like this. It came out great. My welding skills are getting better too - just in time. I installed new bronze bushings in the joints and this further tightened up the whole linkage. Once the cutting and welding was complete, a coat of paint was added to the plate and rod to prevent rust. The lever must not be mounted when the trans is installed. It simply gets in the way. Also I found the original 320 foam pad that sits between the plate and the body tunnel was too big. It caused a lot of vibration. I later replaced it with the stock 2002 foam donut which fits perfect and causes no vibrations.
Side note: the plate on the 320i is held to the body on the tail with a rubber mount. A 2002 doesn't have this. I thought it was best to reuse this and attached a metal bracket to the body to provide a solid mount. I wanted the shifting to be very solid with very little slop. It all paid off and the linkage is very tight yet smooth and the spacing is right on.
This is the modified shift linkage and plate with excess cut off
The tunnel hole where the shift selector comes through
CLUTCH AND RELATED COMPONENTS:
I used a new Sachs 228mm clutch kit and a used flywheel. Even the flywheel bolts were different (longer) than on my automatic. The 76 engine crank end I have needed the small narrow type pilot needle bearing but the shop I got my parts from was expecting it to need the larger ball bearing type. Another delay but got it put in along with the clutch. I decided to use a new clutch master cylinder as I didn't want to risk getting a leaking/worn used one. I did use the slave cylinder that was already mounted on the trans when I got it from the junkyard however. The 320i 5-speed uses a different slave cylinder than a 2002. This meant I needed a method to attach the new hose. Fortunately the rigid pipe was already on the slave cylinder and I bent it gently to fit the new application. A stainless braided hose was used to connect the master cylinder to the rigid pipe. At the join, I made a bracket to mount on the trans to prevent the rigid pipe from flexing or breaking.
Once the pedal box was in I was finally able to install the new trans. Using the cradle I made really helped, but it was still rather awkward. I would hate to try doing it without some sort of implement as this. I drained and refilled the unit with Redline gear oil. I found that the shift lever would have to be removed as it got in its own way coming through the body hole. I put the trans in a gear to allow rotation of the input shaft - as well as a very light coat of grease on the input shaft and pilot bearing area. I probably should have used more grease for the pilot bearing, as it was tough to get aligned properly. This was more time consuming than I expected. It always is! The automatic body tunnel is plenty big enough for the 5-speed. I read that a 4-speed body tunnel requires pounding out with a mallet to make it big enough.
I had a professional driveline shop rebuild the joints, replace the center bearing, cut/weld, balance etc the two shafts into one good one. I used the front flange of the 320i shaft onto the remaining portion of my automatic shaft. The automatics shaft is actually too short surprisingly on its own by about 2-3 inches. Despite much effort to prevent it, the new shaft was about 3/8" too short. I gave the shop the overall length needed but it seems they didn't follow that since the rear shaft doesn't need changing. The overall length for me was 59-3/4" but this could be different on your car depending on the state of your diff. mountings etc, etc. I clamped the tape measure to the diff. flange and pulled it to the quibo for measuring. Second time at the shop was correct. The modified shaft cost nearly $300 complete. The shaft alignment on the car was done by comparing to the original positions and I found it was just about straight under the linkage tunnel hole for side to side. Up and down was done by watching the quibo flex if it wasn't straight. With the new rubber mount and custom metal bracketry I was able to get the precise angle I needed. I have no vibrations at any speed.
Sidenote: The automatics drive flange was a 3-bolt, same for the 320i flange, but not the same size and therefore not interchangeable!
320i drive flange on the left with the slightly larger automatic flange on the right - within the same photo
This is most of the major conversion components required
Here is the spacer in its new relocated position
When I bought the car the automatic trans only had reverse gear working. Therefore I really don't know for sure what an improvement I've made. I've only driven 2 other 2002's as a comparison and never above 50mph. I learned that the differential ratio on my car is 3.64:1 which is a decent compromise between off the line power and high-speed / low engine rpm. At 70mph the engine is running at about 3000rpm. The clutch action is very light and all the syncros are good as there is no gear crunching. Again, converting from 4-speed manual car would have been a fair bit easier and less costly. But coming from an automatic to a 5-speed wasn't much more work than if I had put in a 4-speed instead. Since I bought the car at a fairly low cost, the cost of doing the conversion plus cost of car did not exceed the value of the car. The engine speed is certainly low when in 5th gear (0.81:1)and this must be quite an improvement from a 4-speed. A gear ratio comparison chart is toward the bottom of this page. It took about 3 weeks total but of course I wasn't working on it full time. It surely was well worth it.
Would I do it again? Having finished it now and learned what it takes and pitfalls to watch out for, it would be a lot quicker a second time. But I would be more likely to do it on a 68-73 CS coupe. Next!
PARTS PURCHASED FOR CONVERSION: (US dollars)
5-speed trans from Junk yard 1982 320i - used $100
Drive shaft & shifter linkage from same above - used $17
Clutch kit w/pressure plate & disc, throw out & pilot bearing, pivot - new $200
Flywheel (used) & longer bolts (new) $90
Custom drive shaft - from used parts $300
Pedal box - used $20
Linkage plate bushings (2) & linkage bushings (4) - new $45
Guibo -3-bolt type - new $40
Clutch master cylinder - new $54
Clutch upper hose - new $6
Clutch lower hose - stainless - new $12
Clutch/brake reservoir - used $5
Exhaust bolts for lower section - new $4
Exhaust gasket & nuts for manifold to down pipe - new $6
Tachometer - used, came with complete cluster $10
Interior shifter plate - used $7
Shift boot and shift knob - new $35
Foam donut for linkage plate to tunnel air seal - new $9
Redline MTL gear oil $15
Selector shaft seal - new - (installed after leak found) $4
I was hoping it would be closer to $6-700 but the clutch, flywheel and custom drive shaft cost a lot more than I expected. I was fortunate to be able to get some used parts from local enthusiasts rather cheaply.
Short stubby wrenches:
17mm and 13mm is all you need. The top bell-housing bolts are pretty buried and there is little room for tools. Itís also very close to the firewall, which prevents being able to use a ratchet and socket on some of them.
13mm offset wrench:
Mostly to reach the flywheel to torque converter bolts but it can be used in numerous places and sort of stair shaped. I also have a set of U-shaped wrenches, which were very helpful too.
This is a ratchet, which has a T-handle on the end to allow rotating the socket without moving the ratchet handle. Ideal for the top bell housing bolts again.
2 foot long 3/8" socket extension:
This was especially useful when undoing and tightening the exhaust manifold to down-pipe nuts.
2 floor jacks:
One with a wide & low base to lift the trans. Another to apply upward pressure on the front of the engine which will tilt the engine downward at the rear for access/alignment of the trans.
4 jack stands:
Almost all of the work was done with the car as high as possible in the garage. Just having the front up won't help, as there is constant need to get yourself completely under the car. It also allows room to reach the rear bolts of the drive shaft.
Home-made transmission cradle:
See the text and photo about this very helpful tool you can make with some angle iron.
An occasional assistant:
I did 99% of the work myself and it would have been a lot easier if I had someone to assist with jacking while I'm positioning. When I installed the pedal box I had to have someone help put the bolts in while I held the box in position from underneath the car.
Before you take on this sort of project I recommend the following:
1: Expect the work to take longer and cost more than anticipated. Therefore be sure you can dedicate the space in your garage for the time required.
2: Obtain all the necessary components before beginning the work. Otherwise you might be waiting while valuable space is taken in the garage and you won't have procedures as fresh in your mind. Also the car itself is unusable.
3: Take notes how things come apart. If there is a delay in finishing you might forget how it all goes together or what some mystery part is.
4: Work in a logical order.
5: Use new fasteners and use anti-seize compound on heat related nuts/bolts such as exhaust studs.
6: Replace wear items as practical. If the quibo for example is already oil soaked then replace it!
7: If the transmission condition is unknown then at a minimum replace the seals. I learned this the hard way when soon after it was basically complete I found the selector shaft seal was leaking oil. A lot of work would have been saved had I just replaced the $4 part while the trans was on the floor. Would have been a lot easier too!
8: Sell off the removed items to other enthusiasts. This helps them and helps recoupe your expenses. Don't expect big dollars but think of it as helping a fellow enthusiast. If you don't sell the trans you can save quite a lot of fastners from it before tossing it out, .
9: Replace the oil in the differential while the car is up in the air. It probably hasn't been done in a long time.
10: Prior to starting your work I strongly suggest you take the time to thoroughly degrease the engine bay, old and new transmissions and the underside of car at least near the trans area. You'll see what you're doing better, tools won't slip and you won't go to sleep with grease everywhere on your body too.
Here is my car once it was fully cleaned up and running well.
The classic fleet at the time of the project.
Gear ratio comparison:
Useful related links and drawings:
BMW Transmission FAQ
bimmers.com 5-speed site conversion site
Aardvarc's 5-speed kit. Everything you need in one package.
Roadfly 2002 Forum on the Web. Oustanding source of info from enthusiasts.
Mesa Performance Parts - BMW/Porsche Parts
BMW Car Club 02 Registry (UK) - Great info here!
2002 Air Conditioning Wiring diagram
Weber Carb. conversion smog control drawing
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