Replacing 1989 964 Alternator

[dgagne]

My alternator needs to be replaced on my 89 964 C4.
Any links to good do-it-yourself articles?
Any special tools needed. I only have basic tool kit.
Thanks,
Derek

[uwanna]

Here's a great how to thread from Pcar workshop. Pcar workshop is a 993 site, however
the removal/replace of a 964 alternator is identical. Take a look.
993 - Alternator Replacement - pcarworkshop

Also if you don't have the factory alternator belt removal tool from the toolkit (which is a piece of crap and will most likely ruin the splines, don't risk it!) get this set of triple square wrenches. You need a 10mm triple square wrench like the one shown used in the "how to". You will need to grind/cut it down to 2" in length to be able to fit in the space between the fan and the motor mount. It can be found at most FLAPS like O'reilly or Northern Tool, or Amazon, do a search to find it locally.
Performance Tool W1395 - Power Bit Set | O'Reilly Auto Parts

Good luck,
Grant

[porterdog]

Also.... the word on the street is that the typical quality of FLAPS rebuilds is frustratingly spotty. I elected to have my stocker rebuilt by a well-respected local shop instead of trading it in for some off-shore rebuild.

[uwanna]

Originally Posted by porterdog

Also.... the word on the street is that the typical quality of FLAPS rebuilds is frustratingly spotty. I elected to have my stocker rebuilt by a well-respected local shop instead of trading it in for some off-shore rebuild.

He is exactly correct! Just needed an alternator on my GM other car. Went to my local FLAPS and a rebuild was $160. Took to my local alternator/starter shop and my original came back looking like new and cost $95! Just ask around about the best shop in your area. I wouldn't even trust the rebuilds from our host!!

[umgang]

Originally Posted by uwanna

He is exactly correct! Just needed an alternator on my GM other car. Went to my local FLAPS and a rebuild was $160. Took to my local alternator/starter shop and my original came back looking like new and cost $95! Just ask around about the best shop in your area. I wouldn't even trust the rebuilds from our host!!

YES! cheap chinese junk! Even aftermarket items labeled "Bosch" are useless.
There is a reason the Porsche alternators are so expensive- but if you plan to keep the car that is what i did. Starter too.
several folks i know who own auto shops told me, due to cheap customers wanting the lowest price, they spec the aftermarket junk- only to find 1 out of 2 fails!

[Tremelune]

Can the alternator be souped up a bit during rebuild to output more amperage? Maybe have the voltage regulator set to 14.5V as well?

[uwanna]

Originally Posted by Tremelune

Can the alternator be souped up a bit during rebuild to output more amperage? Maybe have the voltage regulator set to 14.5V as well?

Not necessary and the brush/regulator unit is a single combined part, so I don't think so. The regulator is built to sense the charging needs of the battery and does just that. When battery charge is low, it raises the voltage to compensate and visa versa.

[Tremelune]

Originally Posted by uwanna

When battery charge is low, it raises the voltage to compensate and visa versa.

I don't believe that is correct. Ideally, you want a constant 14.2V at the battery and all electronic components when under load. 13.8V to 14.4V is considered healthy.

I do not know how battery charging is regulated, but the battery is just another load on the electrical system. Seems they just take the current they need from what is available at the voltage supplied.

[uwanna]

Originally Posted by Tremelune

I don't believe that is correct. Ideally, you want a constant 14.2V at the battery and all electronic components when under load. 13.8V to 14.4V is considered healthy.

I do not know how battery charging is regulated, but the battery is just another load on the electrical system. Seems they just take the current they need from what is available at the voltage supplied.

I know when I have a low/marginal battery charge, after startup my charge voltage will be at the upper end (14.2), but after a 15-20 minutes of driving, the charge volts will stabilize at about 13.7-13.9V. i.e. the battery became "charged up"

Here's a good explanation why an alternator output much above 14.2V is NOT desirable

WHY 14.2VOLTS, BUT WE CALL IT A “12 VOLT SYSTEM?

The 14.2volt level is said to be the ideal voltage level for the “12volt automotive system” because that’s the amount required to fully charge a standard “twelve-volt” battery. By itself, without a battery charger, and without cables connected, a typical, fully charged “12volt” battery produces 12.6 volts. The on board charging system must exceed the 12.6 level for electrical current to flow through the battery during charging. Electrical current must flow through the battery during charging to cause chemical reaction between the liquid acid and the lead plates within the battery. The 14.2volt level causes about the correct amount of current flow through the battery to maintain a fully charged condition. Extended periods with higher than 14.2volt level will over-charge the battery (at most temperatures).

[Tremelune]

Interesting.

Charging System Basics

"If the voltage starts to fall below the target voltage (approximately 13.8 volts depending on the alternator's design), the alternator produces more current to keep the voltage up."