engine and drivetrain Best Alternator

[2002#3]

Friends,

 

Situation:  My 1974 2002tii has an alternator of unknown age and amperage (probably 40A or 45A; not checked yet) which seems to work well.  I have a virgin reconditioned 40A (run-of-the-mill model AL 40 X). I plan to install an electric fan which draws ~14A.  No A/C.  

 

Questions:  What alternator amperage output would be appropriate for my situation?  Would either of my alternators be sufficient?  Are tii-specific higher amperage alternators available?  Do I need to look for a 55/65A alternator from a 320i or an 80A from a 318i?  I ask re: these two cars b/c that is what has been suggested in some 2002FAQ posts.

 

Regards, and thank you for your collective wisdom.

[jmr_1602]

When I installed my electric fan I went ahead and upgraded to the 318i alternator. Since you have to remove the radiator and stick fan to install the new alt bracket.

I'm very happy with it, and there's enough amps to power my stereo, lights and dogs. Also a plus is the adjusting nut to tighten the belt. One man job now!

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[2002#3]

Thank you.  Just as I thought.  Any major mounting issues, e.g., brackets, arms, etc.?  Any required changes to the wiring, voltage regulator, or other electrical components?

[jmr_1602]

You'll have to use the mounting brackets from the 318i. I had no mounting issues. Remove the fan pulley to remove the old bracket. Which shouldn't be much work since you'll have easy access to it while the radiator is off (for that electric fan.) [emoji16]

Wiring is easy. The 318i alt has an internal regulator. Just hook up the blue wire to the D+ terminal.

I followed Zenons write-up. It was very helpful.

http://www.zeebuck.com/bimmers/tech/318alternator/318ialternator.html

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Edited December 9, 2015 by jmr_1602

[JohnS]

Does the 318i alternator bracket fit the tii?  2002#2 has a '74tii.  I know that the tii alternator mounts differently than the regular 2002s .. No?

[jmr_1602]

Does the 318i alternator bracket fit the tii? 2002#2 has a '74tii. I know that the tii alternator mounts differently than the regular 2002s .. No?

Whoops. Didn't notice he had a Tii. It will still work but is a more involved install than on a carb'd 02. Also you can't use the cool adjusting bracket on a Tii. Zenon explains the steps at the bottom of the write up.

Sorry for the misleading info 2002#2!

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[JohnH]

I rate this mod alongside a 5 speed box, at the top of the modification tree, just above a recaro drivers seat!!!

 

I used an 80Amp out of an E28 528i. The one in the picture below, on the right is from a 525e and is identical to that from an E30 325i. The one on the left is the old one from my may '73 tii.

 

 

 

The big difference is in the size of the mounting lugs. The tii has a wider mounting lug and a thinner adjust lug, whereas those on the 80Amper are both the same size and slightly small than the tii mounting lug. This is good news as it allows you to move the alternator fore and aft to get the pulley lined up.

 

Heres mine fitted;

 

 

 

Actually you can only see the mounting lug and enginge side mount, but what you can clearly see are the various spacers that I used to position it. The older 80Amp actually used rubber bushes in the lug, a bit like the tii alt. I've used brass bushes here to tighten it up.

 

I tried to take a pic from underneath to show the adjuster 

 

 

Its a bit of a blur, so squint a bit, but what you can see is the adjusting lug & bolt, hidden behind the anti roll bar and to the left of the bar the adjustment brace(?). This brace heads towards its mounting on the engine, but unfortunately sits about 1/2" proud so you need a slightly longer bolt and a few washers. I also had to lengthen the brace and inch or two by cutting it in two and welding in a new section.

 

The point to bare in mid is that there is not a lot of room to allow for adjustment so getting the correct length of drive belt is critical. Sorry I cant remember which one I used.

 

Here they both are showing the lug sizes;

 

 

I hope all this makes sense! 

 

 

 

 

Edited December 9, 2015 by JohnH

[2002#3]

Thank you, John.  Lots of additional info and much to digest.  I did not know there were so many higher-amperage alternator options from

older BMWs.  Larry

[winstontj]

I forget how much exactly but the e21 is (slightly) heavier and the e30 is heavier than the e21.

 

Also, iirc, don't you get to ditch that star adjuster with the e30 alternator? (I could be wrong)

 

As JohnH mentioned brass, I ended up doing urethane bushings in my alternator when I did the swap. Was a big help both keeping it adjusted properly and with the electric fan I installed on my old '74.