alt problems>>>

C

cfcjr

Registered
ok.....i read just about everything i could find under the search....
i'm still not entirely clear..........
my little batt lite has been going on and off intermittently, and from what i've read this means the voltage reg is crapping out. so.. i need a new alt.
what exactly are my options.......if i wanna get one locally..(dont really want to wait a week for shipping)....meaning we have an advance, napa, autozone( not even worth mentioning) and a good local mom and pop parts that usually carries higher end parts.( anyone have a part namebrand & part # ?) i remember reading somewhere that some guys were running alts out of cobras. if so, is there one i could use for a 94 mark???
anyone have the part numbers for the napa ones??? or should i just try the stealership??? thanx for the help!!!

and yes i've tested it a few times....fluctuates... from 10.9 - 13.0
 
I got mine from NAPA about 6 months ago...worked great....and still does!

Sorry, don't have the P/N available. I just went in a got it...it was in stock too....
 
cfcjr said:
.......and a good local mom and pop parts that usually carries higher end parts.( anyone have a part namebrand & part # ?) i remember reading somewhere that some guys were running alts out of cobras. if so, is there one i could use for a 94 mark???
Click to expand...

Tell them you want one for a '96 to '98 Cobra. Usually a good local rebuilder will know exactly the alternator you need and can rebuild yours with quality components or supply a good unit.
 
I got mine from NAPA, it went in a few months and they repalced it for free. If i was to do it over again i would have tried a local rebuilder first.
 
Out of the stores you mentioned....I'd stick with Napa all the way! Make sure you charge the battery when you put the new one on and before you start the car.

Based on your tests of 10.9 -13.0 volts...the regulator is failed when you're at 10.9 so you've tested correctly.
 
is the 96 / 98 cobra a direct replacement? I have blowed up Napa, Advance and rebuilds. Probabally 6 so far. I believe it is when I get on it, when the revs are high, last one went against a Porsche, smoked him, poor white collar suburb boy didn't know what hit him.

Shortly thereafter, same drive, I started getting air bag warnings, wierd temp control stuff, and the message center got funky. Then time to call AAA.


2001 porsche, $87,000 dollars.

Flatbed Tow back home, $33 dollars.

Handing a rich boy his ass with my Mark VIII, priceless....

Halfshaft.

P.S. I have decided to let my grammar slip for 2009.
 
Halfshaft said:
is the 96 / 98 cobra a direct replacement? I have blowed up Napa, Advance and rebuilds. Probabally 6 so far. I believe it is when I get on it, when the revs are high, last one went against a Porsche, smoked him, poor white collar suburb boy didn't know what hit him.

Shortly thereafter, same drive, I started getting air bag warnings, wierd temp control stuff, and the message center got funky. Then time to call AAA.


2001 porsche, $87,000 dollars.

Flatbed Tow back home, $33 dollars.

Handing a rich boy his ass with my Mark VIII, priceless....

Halfshaft.

P.S. I have decided to let my grammar slip for 2009.
Click to expand...

That's incredibly stupendous! :lolgrin003:

I've had the very same thing happen (well minus the Porsche of course, LOL). But I attributed my failure to the overdrive alternator pulley I had. I have the Steeda underdrive crank pulley and use the smaller alternator pulley to bring up the idle voltage back to stock specs.

It's funny that it has never happened at a track. I've had it happen twice now, once after a dyno pull at a car show and the second time on the street while ummm... showing off? :lol3:

Lucky for me I keep a spare alternator on hand. I've also learned now to keep it in the trunk. :)

To answer your question, yes a '96-'98 Cobra alternator will work. At worst, you may need to open the harness up and relieve a bit of slack in the harness wiring for the regulator plug.
 
Thanks for the info. I appreciate it. Yea, always seem to go when I am working the skinny pedal. It seems to be at the 2-3 shift point. For 170,000 miles it hits as hard as a pissed ex-wife.

I believe that also contributed to the blown oif filter adapter gasket.

Don't get me wrong, I love that car, affectionately known as the disco sled. It is all stock and other than the occasional white collar smackdown, I really drive like an old lady. Regular maintainance is the key to longevity.

I will pick up a Cobra alt as soon as the holidays die down.

Speaking of grammar. I gots a fast car, bucko.

Later,

halfshaft
 
While a Cobra alternator will fit, you still may run into the spool up issues! I was in the same boat as you when I was running my smaller alt pulley and over revving the alt and killing the regulators. I went through abou 10 alternators in 3 months, and it happened everytime I made WOT runs.
 
Thanks for the warning. I guess the next question, I am not meaning to Hi-jack, if I am please let me know. Can the output of the alternator be kept high enough at idle and driving speeds with the addition of a larger pulley?

This may help the overspeed and regulator pulse that occurs during the shift points.

Halfshaft
 
Halfshaft said:
Thanks for the warning. I guess the next question, I am not meaning to Hi-jack, if I am please let me know. Can the output of the alternator be kept high enough at idle and driving speeds with the addition of a larger pulley?

This may help the overspeed and regulator pulse that occurs during the shift points.

Halfshaft
Click to expand...

The bigger the pulley, the less of a charge at idle, smaller means better charging. I think some of the failures might have to do with belt slipping/alternator overrevving at WOT shifting. My trans shifts hard from 1/2 and thats when it would fail everytime (had an aftermarket batt gauge).
 
According to PA Performance...

An alternator needs 1800-2000 at idle to make power and will make maximum output at 6000 rpm, and will start to fail at 16,000 RPM.
Click to expand...

Pay attention class...

The stock crank pulley is 6.75" diameter.

The stock alternator pulley is 2.625" diameter.

That makes the ratio (D/d) 2.6:1.

At an idle speed of 700 rpm, that makes the alternator barely meet the 1,800 RPM minimum.

At a rev limit of 6,000 rpm, the alternator speed is just under the the max limit running at 15,428.6 RPM.

There is no room for error. What you gain on one end, you loose on the other.

I installed a 5.25" diameter Steeda underdrive crank pulley and it changed the ratio to 2.0:1 making the idle speed of the alternator 1,400 RPM, well below the recommended minimum.

I then install an overdrive pulley with a 1.875" diameter and raised the idle speed of the alternator to 1,960 RPM. OK, but now at the rev limit of 6,000 RPM the alternator is spinning at 16,800 RPM which is over the maximum recommended speed. A RPM spike of 6,500 - the alternator is now over 18,000 RPM. Too much of a good thing and after a while the alternator is toast. :eek:

An excellent resource for calculating these speeds can be found at http://paperformance.com/Downloads/RPMCALCULATOR.xls if you can't find a calculator handy. :)
 
So the trick is to NOT let it idle too long with stock pullies!!! Or put the overdrive pulley in and don't race!
 
Actually, I'm thinking of installing a 2.25" pulley and having the idle speed raised in the chip.
 
Wow JP, that is awesome info! Stupid me, lol, I must have over revved it up to 20K!!! ;(
 
You must log in or register to reply here.
Back
Top