The Cal-look Lounge

I've been having trouble with my alternators going out. It seams that if I just cruise it around they are ok but when I race it or get the RPMs up over 6500 they keep going out. It's the diod inside that's burning out. I've had to rebuild 4 already and just finished off another on saterday at the Dyno. I've posted this around but looking for some further insights.
What you think?

tight belt?

No not tight.

Hi do you know what voltage you are getting to at 6500 rpm I guess it's an internal regulator  any battery issues and are they all different alternators ?

Cheers andy

Don't know voltage there. Battery is new 1200 optima dry cell. Last one I bought a new interstate and failed the same. No other electrical problems with the car.

are you maybe drawing too much current due to all efi related parts? ???

Too much current drain shouldn't be a problem - we raced 6 hours with 600W halogens on the front and didn't have any power left on a battery after one hour - a.k.a. draining all the power an alternator could give for six hours straight. Alternator was an 55A bosch original unit with internal regulator.. There also rpm range was 3000-6500 for the whole time, std sized belt pulleys.

What about too loose bearings and un-balanced fan -> mechanical problem / vibration?

No mechanical problems. Good bearings, welded and balanced fan.
What wierd is the dummy light is fine then starts getting harder to turn off then a little harder till finally it won't go off.

If the diodes are burning through, i think it has something to do with the current that goes through them (that is too high)
What else can burn diodes? just thinking here

i would check you connection to the battery is ok sounds like the diodes are overheating

cheers andy

Thanks. I did. I replaced the terminals and made a throughbolt for the ground that bolts through the chassi and the tranny ground bolts there from underneath to keep it all tied together. Both my tranny case and engine case are not painted and I have solid mounts. Grind should be good.

Just an idea I have seen brushes jump off slip rings at high rpm can you check for any signs of arcing on the slip rings ?

Cheers andy

Another idea your battery does it have a low internal resistance as after discharge it may pull a lot of amps ?

Idk but I've used 2 diffrent alternators and two diffrent brand new batteries.

Ok I'm running out of ideas what about the cable from the alternator to the the battery  is that ok any joints that may arc ?

Shag --- if you want to barrow my battery for the ghia for the weekend your welcome to it --- so you can use it during the cruise or for racing let me know -- it is all charged up a ready to go

Thanks Harold! But I got a new spare interstate. Just trying to fix the problem.
Are you going bye the way?

Nope -- --- going try to have the car running for drag day

Do you use the factory wiring harness to the alternator and battery?
I see what I would call premature failures on my customers cars over the past 6-8 years ...
What I like to do is add another, much larger charge wire from the alternator. I typically run an 8 guage wire (typical stereo power cord here) from the alternator to the battery lug on the starter, in addition to the factory wire that runs the other direction to under the rear seat. Voltage goes up to the battery and systems in the car and I've seen much better current flow on original harness cars.
If nothing else, it's an easy implementation and only takes about 33 inches to make the run.

Unfortunately I don't yet have any LONG term results as I've only been doing this for about 5 years, but looks good so far ... much less failures, even on 20+ year old alternators!
TxT

I thought the same thing Tom but 1.5' of #8 to 1.5' of #4 has less loss then 3' of #8. I may try though.

Kymco's monster cable:

(http://i67.photobucket.com/albums/h311/cmhauer/67%20Bug/100_3623.jpg)

http://www.thesamba.com/vw/classifieds/detail.php?id=506399

This is a thick jacket 8guage cable that runs from the alt to the starter not battery.

Correct; mine goes to the starter.

Don't understand the 1.5' thing, but darn near anything is better than 8 feet of 40 year old 10 gauge! LOL
TxT