engine and drivetrain Do you need the 320i bracket for the alternator swap?(Final)

[Guest Anonymous]

Im sorry, the search doesn't like the new iBook. Im going for the 320i alternator swap tommorow, in hopes that it will clear up some of my engine idle shaking (Kfunk). My alternator was putting out quite less then what I had expected, with a reading as low as 11.7 at idle and a jumpy 12.3-12.8 while reving. I know I have to get a pre 320i alternator with a built in voltage regulator (Pre 1980 correct?) but Im not so sure as to how the mounting works. I was looking at the website with the 318 alternator swap detailed out, but I wasn't sure if that applies to the 320i swap. Do I need to get any brackets or anything like that? Any quick clear up would be greatly appreciated, and I once again apologize for not being able to use the search function.

[KFunk]

no need for a bracket if u get one from a 77-79, just bolts right on. Make sure yours comes with a pulley. I got an off-brand one for cheap, and it didn't come with a pulley. Unfortunately, the 2002 pulley doesn't quite match. I put some washers on it and left it without a woodruff key for now, and it works. When I find a 320i pulley, I'll put it on. Oh, and be ready to grind off a little bit so your fan will clear. I didn't have a grinder, so I whacked a little off my fan blades with a knife, but that probably wasn't the best solution.

For a 80-83 320i alt, I think you just need to swap the faceplates of the alternators. It'll get you 10 more amps, but you gotta take apart your new alt to do it. Maybe worth it, as it looks like a few bolts and itll slide off. But that just what i saw in an old thread, haven't done it myself.

[Chris_B]

If you are talking about the E21 320 alternator on a non-tii motor, it bolts to the original 02 brackets. The e30 318 alternator swap requires replacement of the brackets. However, I have to say that a weak alternator (unless it is not charging your battery properly) is not going to be the primary cause of your engine shaking at idle.

What kind of troubleshooting have you done? If you have a healthy, fully charged battery (+12.6V for a standard, lead acid battery... a bit higher for gel batteries and other types), the output of your alternator is irrelevant, re.- performance of the motor at idle. This is presuming that you have a healthy ignition system. Far more likely suspects for a shaking motor at idle are: bad motor mounts; poorly adjusted or performing carb; poorly adjusted ignition system, particularly timing; poorly adjusted valves, etc.

With all due respect, have you checked out all of the above, and what makes you think that alternator output would affect idle smoothness? Almost all alternators have reduced (below nominal) output at idle (say, below 1K RPMs).

[Jack]

May not be an issue on yours but, When I swapped mine out on the 72 I put on new rubber bushings. They were not strong enough to secure the alt from getting into the fan blades. As a temporary fix I tie it off to the block, messed with the mounts and washers/bushings and finally bought/ installed urethane alt. bushings. They completely fixed the "line-up" issue and I had no more fan blade worries.

[Guest Anonymous]

The car has been doing it ever since I bought. I have made quite a few changes to it, and it continues to do it. It originally had a 32/36 carb and I switched to dual webers, and the change did nothing. I have also put on a tii distributor, set it using a timing light, a crane ignition box, and hotter plug wires. I have had the valves checked, and the motor mounts are stiff.

[Chris_B]

What about the battery? Is it kept at a state of full charge by your present alternator?

[KFunk]

Chris, you should look up my thread he referred to.... it's not your typical problem.

as myself and others found, all those things you listed did not solve the engine shaking. I replaced motor mounts, motor mount bracket (by steering gear) is is in fine shape, did everything in ignition, all kinds of head work, valves right, carb tuned perfect, new urethane alt bushing, tranny mount, and still shake was there.

I replaced my alternator because it was charging poorly, and magically the shake went away once it got charged up. You make your own conclusions.

My guess is that the alt wasn't putting in enough power to make the ignition system work right. At higher rpms, engine ran smooth.

Mine still shakes a little when I start it in the morning, but I think my battery is pretty weak at this point. Once its warmed up, its far smoother than it had been. My shifter bounces a little still, but I've never changed my shift tower mounts, and they're probably toast. I've got the shift tower mount ordered, and will put it in tuesday.

[oranzok]

If you go for an aftermarket cheapie- watch out, but they do work- the shafts on the rotor come in different lengths! Most parts books incorrectly list the long shaft type as a fit, this long shaft will hit the fan on 02s- you need the short one. Its obvious when you have two them stripped of the pully and on a bench, not so obvious if the two are not side by side. Bad news- the short shaft that fits also costs more (?).