Engine Swap help: '88 3.5 into an E12

[braino]

Things are proceeding with the swap. The original motor is out and we spent yesterday comparing things.

There are clearly two issues preventing this project from moving forward - both familiar ones. I'm hoping someone who has run into these problems can share the solution.

The first is, of course, the brake booster. The booster in my car is definitely too big to allow the new motor to fit. What do I need to do to resolve this issue? Is there a later booster that I can swap in? Any help would be appreciated.

The second issue is engine mounts. The 3.5 bosses and significantly further forward in the car. Do I need to manufacture brackets to attache to the bosses on the motor? Do I keep the mounts on the 3.5 and attach brackets to the mounts in the engine bay? (using really thick steel?). How have people resolved this issue?

Feel free to drop me an email if you can. I'm going to look back in the archives, too. The car is sitting at my mechanics and I need to solve these issues so they can drop the motor in and let me tow the car back to my place. I'm going to do whatever brake/wiring work that needs to be completed. I just didn't have room for a complete engine swap in my shop :p

cheers,
Brian OKelley
braino@gmail.com

[anthony]

I am doing the same project-again. I removed the brake booster and replaced it with I believe a 3 series. Google it here.

As the the engine bosses mounts. The key, and I believe You may be too late, is to get a early, 87-88, 735 that is the same block style of an e12 and mounts straight in.

I was posting earlier and I solved this problem by getting any e28 3.5 block and replacing the pistons from the 735 (m30b35).

I am in this process right now.

Also, make sure your intake manifold has the vacuum booster port. Many do not if the car used the power steering for braking power as well.

I just got one from a p n p with the port. I figured it would be a lot easier than trying to tap were there is no base and end up having to weld. I have no welding anything.

As to your current engine mount problem, you should try mye28.com. They have discussed this issue and my offer a solution. It may by for a e28 but it is a start.

Good luck

[Tomslide]

You need an e21 brake booster to fit the intake.

The mount bosses are further forward but most get around this by bolting your original motor mount arms on the new block more rearward, so that 2 of the 4 bolt holes are used. Others have made adapter plates to use all 4 bolts but many have found success with what I describe.

All this info can be found searching this site. I'm in the middle of the same rebuild/swap on my 78 but am being held up waiting for a couple gaskets. good luck and keep us posted!

[Odometergears]

Not sure what I did but I didn't change the booster or anything else. I used the m106 m30/b34 block out of a 1984 745 into a 1980 528i. Brake booster wasn't an issue with clearance. Maybe it was changed to something else before I got the car. I couldn't tell you other than it looks nice and old. B34 intake. Could the difference in mounting be a B34 vs B35 block?

Jeff

[braino]

I've been hearing a few different things about boosters. Some say it will fit without issue, others saying I need to get a booster from a 2002tii. I'm going to move forward and see how it goes.

On the subject of motor mounts, I was wondering if I could just go with two bolts. Good to know people have had success with this. It does strike me as the most economical option. Probably the route I need to go for now.

I'll keep searching. Please share any more info...

Thanks much

Happy New Year
Brian

[scarey]

I have been doing this same swap in my Bavaria. The Bav is a slightly different animal when it comes to boosters, but essentially the same in other regards.

My B35 is a newer model without the old bosses cast in. I initially made some flat adapter plates that turned out (or so I thought) very well. I have been having several issues with the fitment of the Tii booster that I have. No matter what I did, the engine was in the boosters way by about 0.25". I have scoured the junkyards looking for others and was resigned to shorten my booster bracket.

Today, I was sitting at my desk and pondering why I felt like I was reinventing the wheel when the swap should be so simple. I realized that most likely it is the thickness of the steel that I used for the motor mount adapters. At the time I made them I used some beefy stuff I had laying around the garage. When I measured it today, it is an easy 5/16" thick. Moral of the story, pay attention to the little things.

Here are some photos of the adapters. The design is decent, the metal thickness not so much.

http://picasaweb.google.com/senorcarey/ ... directlink

Good Luck!

Scott C.

[DMS]

The brake booster fits:



Hard to see here but it has a stock brake booster and the stock manifold of a M30B35.

I modified the engine mounts a bit but they fit the new style engine aswell.

[braino]

Thanks for posting. So, if it fits one car, it should fit them all, no? Even a tight fit would be fine with me at this point.

I don't suppose you have some photos of the engine mounts and how you modified them?

cheers,
Brian

[DMS]

I only modified the passenger side one. You can see the welding I did.



The left engine mount. It's the best I could get because it's a bit crowded there with six extra injectors, a vaporisor, filter unit and lots of extra hoses for the bi fuel system

[scarey]

Hey DMS,

What about your throttle cable set-up?

Scott C.

[braino]

There's a great FAQ article on the throttle cable setup:

http://www.firstfives.org/faq/motronic_ ... ersion.htm

I think I'm already covered on that one. Seems pretty straightforward.

cheers,
Brian

[RonDwyer]

I always like to use the hydraulic booster out of one of the mid-80's E-28's. Lots of room available when the vacuum booster is eliminated!

<a href="http://s46.photobucket.com/albums/f109/ ... MG7403.jpg" target="_blank"><img src="http://i46.photobucket.com/albums/f109/ ... MG7403.jpg" border="0" alt="Photobucket"></a>

The master cylinder looks so lonely in there now! The custom *sic brake lines are temporary.

[Eddie in TO]

Ron,
How difficult was the conversion?
I heard it's a serious swap and time consuming.
Are you concerned about having a 'spongy' brake feel with the hydraulic system over the E12 version? My understanding is that the E12 system provides a more 'solid' feel....but I could be wrong.

I've been informed that an E30 ix (AWD model) brake booster is the way to go to keep similar brake boost characteristics. The E21 may be too small.


As for the engine mount brackets, have a look at the Koala Motorsport adapter brackets.
www.koalamotorsport.com

Not sure, but is this what you need?
M30 Left Motor Mount Adapter
http://www.koalamotorsport.com/proddeta ... 30l&cat=73

S38/M30 Right Motor Mount Adapter
http://www.koalamotorsport.com/proddeta ... 30r&cat=73

[braino]

That's amazing. I'll give them a call and ask them about the application. They do look like the right brackets.

Seems like a lot of folks have gotten to the same place I'm at.

Thanks for posting.

cheers,
Brian