E12-based vs. E-28 based E24 635CSi

[RobertRO]

I am considering buying an E24 635CSi and I need some advice to decide between the e12-based (1980+ with Motronic engine) and e28-based (218 HP Euro engine) versions.
I have spent a lot of time during the past month reading through old Internet archives on the E24, and I've learned many things. However, I didn't find a detailed e12-based vs. e-28 based analysis.

It is obvious that the e28-based version is more desirable, being newer. However, due to the fierce taxation where I live, by having an e12-based E24 I could register it as historic vehicle and get rid of all those taxes.

It would be great if you could briefly point out the pros and cons for the early vs. late E24 635 CSi.
I am interested in any aspect, but mostly in:
- how they rust: is the e28-based much better than e12-based?
- how they ride: is the e28-based much superior to the e12-based suspension?
- how they brake: I know that the brakes on the e28-based can be easily upgraded, while with the e12-based you're stuck with the OEM ones. So how good does the e12-based brake?

Thanks.

[oxen]

e-12 i think handles better has better brakes , but some of the electronics have been obsoleted so they can be hard to get. also has great brakes . the chassis seems to rust out bad on the e12. also hard to tune if you dont swap engie harness. but was good car in its day.

e-24 recived a few things the e12 did not. like better rust protection . ud date locks and window mechanisims, a over drive 5 speed. interior parts are a bit easier to find. personaly i thingk the e24 is a better car. oh sus parts fr e12 are startign to get scares as well.

thats just my take on the two as i had both :)

[Bert Poliakoff]

E12 based Euro 635 is lighter and faster. Consensus is they are behind the M635 and M6 in value, so at the top of the list. Your post asked aboutE12 based cars with Motronic post '80?? '82 was the last year of the E12 based cars. There is only one year of the Euro 635 M90 engine with Motronic and that is mid 1981 to mid 1982. The M90 engine is the same block that was used in the M cars. All pre 82 euro 635s had this motor.The other desirable thing, at least to some of us, is the "dogleg" 5 speed which is a close ratio 5 speed. I am guessing that at this point many other opinions will start to come in.

[Alex E24 E30]

If you are looking to avoid taxation and reduce operating costs, I would go with the E12. There is a smaller aftermarket out there on them, but if you are looking to keep it mostly stock, then that doesn't mean anything. Suspension and brake options are out there, and if you are up for the challenge, you could swap in a later Motronic engine, if that's what you want. Due to their front suspension design, the E12 cars do not suffer from the front end shimmy that the E28 cars have. Both series have 4 wheel disc brakes, about the same diameter, with the E12 car being lighter. So the math is in favor of the E12.

You will need to watch more closely for rust on the E12, but if you stick with the later years (78-82), you will be in good shape. The 76-77 car bodies were manufactured by Karman, and were notorious for rusting out when they were new. BMW noticed the problem and quickly corrected it by producing the bodies in house. When they did that, build quality improved and rust issues went down.


Alex

[Shipper]

Note that a lot of the M90 based e12 635's also came with LSD's. So there is a good chance a late 81 or early 82 635 will have the 5 speed dogleg and an LSD.

The e12 cars drive more like the E9, are a little lighter but the e24 cars were put together better. I prefer e12 base and love the older interior.

The M90 engine can be taken to 3.7 litres easily while the B34 can only go to about 3.55 litres before things get costly. This is due to the fact that the M90 has a bigger bore and smaller stroke. Put an M30 crank in and presto!

Still, either way, as long as she is rust free and has great paint, you have removed the two most costly problems.

[oxen]

Note that a lot of the M90 based e12 635's also came with LSD's. So there is a good chance a late 81 or early 82 635 will have the 5 speed dogleg and an LSD.

The e12 cars drive more like the E9, are a little lighter but the e24 cars were put together better. I prefer e12 base and love the older interior.

The M90 engine can be taken to 3.7 litres easily while the B34 can only go to about 3.55 litres before things get costly. This is due to the fact that the M90 has a bigger bore and smaller stroke. Put an M30 crank in and presto!

Still, either way, as long as she is rust free and has great paint, you have removed the two most costly problems.

^^^^ im working on painting this e28 . and assembling a motor right now in my spare time . paint even tho i can get it thru work is still rather costly to do proper :eyecrazy .

i in my constant searches of bmw parts dont often see a e12 LSD up for sale very often. i note that if your watnign lsd i do know w agent that has 1 he would sell for a e12 . i can put you in contact with him.