73' Bavaria Engine Swap
73' Bavaria Engine Swap
I have a 73 Bavaria that has sat on and off over the years. I started using it as my daily driver and with old seals and this and that leaking it eventually got the best of me and I threw a rod. I want to replace the engine with an 88 735 engine. I have read a lot of different posts and the technical FAQ but can't be certain if the Bavaria's 4-speed manual transmission will be compatible with the 735 engine (tranny housing, etc.) Thank you for any information/advice you may be able to offer. Regards, Brian
M30s are all the same in that department. If I were you, I'd put a 5-speed in, though. A few more parts to source, but it would be better in the end.
Also, with the motor coming from an '88 735, you shouldn't have a problem mounting it since it has the early style mounting bosses present on the right side. Good luck!
Also, with the motor coming from an '88 735, you shouldn't have a problem mounting it since it has the early style mounting bosses present on the right side. Good luck!
The problem with that is twofold. First a new driveshaft would be needed, second there is no provision for a speedometer drive for the mechanical speedo.DMS wrote:I use the gearbox that comes with the '88 engine so that's possible aswell. Ratios of the first 4 gears are the same as the 4-speed but the 5th is a nice overdrive.
Mike W.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
So if I wanted to do this right I should swap the transmission as well, or just the gearbox. He mentioned if the gearbox was changed to a 5-speed that the drive-line would need to be replaced as well. Is this true? Should I or could I swap the entire transmission, driveline, etc from the 88 735 with the engine? Forgive my ignorance, but just trying to account for all parts before I even start in on the project. Thank you.wkohler wrote:M30s are all the same in that department. If I were you, I'd put a 5-speed in, though. A few more parts to source, but it would be better in the end.
Also, with the motor coming from an '88 735, you shouldn't have a problem mounting it since it has the early style mounting bosses present on the right side. Good luck!
Brian
Transmission and gearbox are the same thing.bkoch wrote:So if I wanted to do this right I should swap the transmission as well, or just the gearbox. He mentioned if the gearbox was changed to a 5-speed that the drive-line would need to be replaced as well. Is this true? Should I or could I swap the entire transmission, driveline, etc from the 88 735 with the engine? Forgive my ignorance, but just trying to account for all parts before I even start in on the project. Thank you.wkohler wrote:M30s are all the same in that department. If I were you, I'd put a 5-speed in, though. A few more parts to source, but it would be better in the end.
Also, with the motor coming from an '88 735, you shouldn't have a problem mounting it since it has the early style mounting bosses present on the right side. Good luck!
Correct, with a different tranny you need a different driveshaft. Usually. It just so happens the one from a 3HP22 auto car will work with a G265 5 speed, which is the only one with a speedometer drive. Or at least provisions for it as ones from E28s often don't have the drive but it's easily installed. If you swapped the tranny from the 88 735 you would have no speedometer.
I did a big writeup on 5 speeds but never quite finished it for a FAQ, still, search and there is much more in it.
Mike W.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
Hi Brian,
I am not sure how much time I have to type this, as I am in the middle of some stuff, but I am in the process of the same engine swap in my '73 Bavaria with an automatic. I hope I can be of some help. There is a lot of good help here and other places on the internet. Research is your friend!
1. Mounting: The early (1987-88ish) B35 engines (like yours) should have the proper mounting bosses on the block to so that you can just bolt up your existing motor mounts and drop it in. 1989 or so they changed the block casting and eliminated some of the proper holes. If this is the case with your block, you have two choices: buy adapter plates ($125 & $85 for both) or fab your own solution. FWIW, there are some people out there running mounts with no adapters using only three bolts.
I chose to make my own adapters, as I had some spare steel lying around. Not hard, but time consuming without the proper equipment. The FWIW, the 1988 735i that I saw in the yard recently did NOT have the proper mounting bosses for the old mounts.
2. Brake Booster: As you know, the brake booster in the Bav is HUGE! It sits all the way out in the middle of the engine bay and makes it a nightmare trying to install the motor with Motronic manifold (the one on your engine). There is much speculation out there about what fits and what doesn't. I took measurements, as well as pulled the booster and dropped the engine in the car. The engine will not fit with this booster in place. It will also not fit with an E21 booster. The length of the bracket won't allow it.
This leaves you with a few solutions:
a. A brake booster from a 2002tii (It is narrower in diameter, gives plenty of room, but some have said not as good braking power/pedal feel. Plus they are very pricey IF you can find them).
b. A "hydroboost" system from an E28, 32, or 24. This is a solution that I strongly considered, but decided against. I feel it is a good solution and parts can be found at the junkyard pretty cheap. In fact, I believe that your donor car runs this very same system.
c. Cut the booster arm and actuating pushrod by 3-4 inches. Personally, in my opinion, I feel that this is an even better solution than the others. If you know someone that can weld. They can do this for you. You can then run with a variety of different boosters or the hydroboost.
d. My favorite, but the most work, switch to an early style L-jet manifold and all of its associated bits. It is quite a bit more work, but fits in and is arguably aesthetically nicer in the Bav engine compartment. This is what I did.
I listed off the pros and cons between manifold choices and came up with something like this:
Motronic manifold pros:
1. latest evolution of performance for M30
2. Need to rewire nothing on engine side
3. Better performance?
Motronic cons:
1. Clearance issues
2. Need to devise a throttle cable/linkage
3. Less room for access (starter, hoses, mounts)
L-Jet manifold pros:
1. Period specific
2. Linkage for throttle bolts right up
3. No clearance issues
4. Some think aesthetically more desirable
L-jet cons:
1. Sourcing parts for complete manifold
2. Need to source injectors that work with Motronic 1.3
3. Wiring
4. Performance?
In the end, I ditched the Motronic manifold and went with a log style manifold from a 1980 528i. I am almost done with the swap, minus wiring and fuel pumps/lines. I am confident that I will have a set-up that looks and runs well even if it took a little longer to source parts.
As Mike said, you can drop the engine in with your 4-speed or upgrade to a 5-speed. I am not sure how the auto from the 735 would work. I, to save time, decided to swap motors and temporarily keep the automatic that is already in the car. Four hours of cursing, head scratching and sweating in 115 degrees, we came to the realization that there is a missing boss to mount the tranny to on the new block. So, I had to go with my 5-speed swap right away. Good news is, automatic Bavaria driveshafts are a bolt up for the 5-speeds. Remember this!
Sorry for the verbosity, I actually have much more to say, but I am thinking of doing a write-up that is more detailed, yet sectioned up. That is if anyone wants one...
Cliff notes: Research. Lots of work. Worth it. Car will be down longer than you planned. Budget out what you think you need, then double!
Good luck!
Scott C.
As an after thought, the people on this board are a wealth of info (and nice, too boot!). Another good place to search(if it is okay to mention here) is E9coupe.com.
I am not sure how much time I have to type this, as I am in the middle of some stuff, but I am in the process of the same engine swap in my '73 Bavaria with an automatic. I hope I can be of some help. There is a lot of good help here and other places on the internet. Research is your friend!
1. Mounting: The early (1987-88ish) B35 engines (like yours) should have the proper mounting bosses on the block to so that you can just bolt up your existing motor mounts and drop it in. 1989 or so they changed the block casting and eliminated some of the proper holes. If this is the case with your block, you have two choices: buy adapter plates ($125 & $85 for both) or fab your own solution. FWIW, there are some people out there running mounts with no adapters using only three bolts.
I chose to make my own adapters, as I had some spare steel lying around. Not hard, but time consuming without the proper equipment. The FWIW, the 1988 735i that I saw in the yard recently did NOT have the proper mounting bosses for the old mounts.
2. Brake Booster: As you know, the brake booster in the Bav is HUGE! It sits all the way out in the middle of the engine bay and makes it a nightmare trying to install the motor with Motronic manifold (the one on your engine). There is much speculation out there about what fits and what doesn't. I took measurements, as well as pulled the booster and dropped the engine in the car. The engine will not fit with this booster in place. It will also not fit with an E21 booster. The length of the bracket won't allow it.
This leaves you with a few solutions:
a. A brake booster from a 2002tii (It is narrower in diameter, gives plenty of room, but some have said not as good braking power/pedal feel. Plus they are very pricey IF you can find them).
b. A "hydroboost" system from an E28, 32, or 24. This is a solution that I strongly considered, but decided against. I feel it is a good solution and parts can be found at the junkyard pretty cheap. In fact, I believe that your donor car runs this very same system.
c. Cut the booster arm and actuating pushrod by 3-4 inches. Personally, in my opinion, I feel that this is an even better solution than the others. If you know someone that can weld. They can do this for you. You can then run with a variety of different boosters or the hydroboost.
d. My favorite, but the most work, switch to an early style L-jet manifold and all of its associated bits. It is quite a bit more work, but fits in and is arguably aesthetically nicer in the Bav engine compartment. This is what I did.
I listed off the pros and cons between manifold choices and came up with something like this:
Motronic manifold pros:
1. latest evolution of performance for M30
2. Need to rewire nothing on engine side
3. Better performance?
Motronic cons:
1. Clearance issues
2. Need to devise a throttle cable/linkage
3. Less room for access (starter, hoses, mounts)
L-Jet manifold pros:
1. Period specific
2. Linkage for throttle bolts right up
3. No clearance issues
4. Some think aesthetically more desirable
L-jet cons:
1. Sourcing parts for complete manifold
2. Need to source injectors that work with Motronic 1.3
3. Wiring
4. Performance?
In the end, I ditched the Motronic manifold and went with a log style manifold from a 1980 528i. I am almost done with the swap, minus wiring and fuel pumps/lines. I am confident that I will have a set-up that looks and runs well even if it took a little longer to source parts.
As Mike said, you can drop the engine in with your 4-speed or upgrade to a 5-speed. I am not sure how the auto from the 735 would work. I, to save time, decided to swap motors and temporarily keep the automatic that is already in the car. Four hours of cursing, head scratching and sweating in 115 degrees, we came to the realization that there is a missing boss to mount the tranny to on the new block. So, I had to go with my 5-speed swap right away. Good news is, automatic Bavaria driveshafts are a bolt up for the 5-speeds. Remember this!
Sorry for the verbosity, I actually have much more to say, but I am thinking of doing a write-up that is more detailed, yet sectioned up. That is if anyone wants one...
Cliff notes: Research. Lots of work. Worth it. Car will be down longer than you planned. Budget out what you think you need, then double!
Good luck!
Scott C.
As an after thought, the people on this board are a wealth of info (and nice, too boot!). Another good place to search(if it is okay to mention here) is E9coupe.com.
1973 Bavaria
So if your bavaria's automatic drive-shaft will bolt up to the 5-speed will my manual drive-shaft from the bavaria bolt up with the 88 5-speed tranny from the 735?
Also, my brake booster(master cylinder?) on the bavaria is shot anyway, so I guess when I replace it I'll just replace it with the hydroboost system from an e28 or e32.
Also, my brake booster(master cylinder?) on the bavaria is shot anyway, so I guess when I replace it I'll just replace it with the hydroboost system from an e28 or e32.
Brian
Third you need different shifting linkage.Mike W. wrote:The problem with that is twofold. First a new driveshaft would be needed, second there is no provision for a speedometer drive for the mechanical speedo.DMS wrote:I use the gearbox that comes with the '88 engine so that's possible aswell. Ratios of the first 4 gears are the same as the 4-speed but the 5th is a nice overdrive.
E12 M30B35, VEMS, HX52 never getting finished.