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Further to batteries. 5 years takes a lot of life out of a battery up here in Canada with our winters. 14 years might be be pushing it. Other thing is that once a battery has been run dead once it's never quite the same. Might take a charge but just wont have the power.


Looks like it was the 14 ...

Dave,

I went on realoem.com and couldn't find any 1981 635's. However, I found 633i for the 1981 year; Is it possible your bimmer is mislabeled?

Anyways, the part number on the 1981 633i ECU is "12141466072". Google "bmw 12141466072" and it will narrow down any possible sellers. Please be aware ...

Sorry, Dan I should have read your post more carefully. I think you've properly narrowed in on the spark as the culprit.

I did have a strong-crank no-start situation that was due to a partially discharged battery. Once charged, it started right up. So I think Karl might be on the right track ...

Fair question on the battery - I checked my files and looks like it's ~14 years old so due for replacement anyway. But it turns the starter over really strongly, and that doesn't explain why it's intermittent.

Hi. I have an '81 635 (e12-based) with early Motronic. Car has run well for years, mostly driving schools believe it or not. But the last couple of months I've experienced an intermittent no-start situation. Car is garaged in Chicago but just sits over the winter months, on a battery tender. Starter ...

Call Jeremy @ Ireland Engineering - he will set you up. Much less than $2k for coilovers but your challenge will be matching damping rates with the stiffer springs. I'm using modified Bilstein Sports on my e12-based 635.

I have an '81 635 that uses the ignition rotor that presses on to the front of the camshaft (p/n 12 11 1 286 072). Last week mine sheared off its indexing key (while on the track...that was exciting), backfired pretty explosively for a bit, and then the motor quit. Put the old rotor that I had saved ...

So did you plug off the two extra ports on the m/c, or loop them together?

What did you end up using for master cyl & vacuum boost?

Stock cast iron manifolds (11 62 1 274 886, no thermal reactor), stock euro 50mm downpipes (18 11 1 175 377 & 18 11 1 175 379), euro front resonator (18 12 1 175 387, in place of cat), then 2" straightpipes (no center resonator) back to stock muffler (18 12 1 175 391).

Nice snarl under ...

e39 wheels have a larger hub bore and don't center properly on an e12 without hub-centering rings. Put the stock wheels back on and see if that, plus the guibo, doesn't fix it.

No worries - have a great trip. I've convinced myself to take the easier route for now and build a set of M535i brakes for the front. Got a set of calipers from a '84 733 from a junkyard for the thicker spacers, and ordered a set of 280x25mm rotors slotted & cryo-frozen. Will also "castellate" the ...

According to the shop manual for my US 630/633, those cars all had 23.81mm master (auto or manual).

I was all set to go down the path of building some M535 brakes and keeping the stock hydraulics. Those use the thicker 25mm rotor in front, which I would get cross-drilled and cryo-frozen. I had ...

Any luck confirming that the brake booster bolts up ok, and connects to the brake pedal?

It's not even close :). It's too wide to fit between the fender and the inlet mani of the M30B35 engine. I'm going to try some other things as I would really like that easy braking 'new' car feeling.

It's ...

DMS wrote:It's gonna be something like this:

Looks great!

Any luck confirming that the brake booster bolts up ok, and connects to the brake pedal?