Bosch Alternator questions Options

[TRP]

Hello Gang!

While the motor is out being rebuilt I figured I would look at the starter and alternator and replace what might need replacing. The starter has a cracked cap on the solenoid, so I've ordered a new starter, will be here Monday. I'll ship the core back and recoup some of that money.

The alternator (Al75x) makes a funny noise when I spin it. It appears to be older possibly the original to the motor (82k miles), so I think I'm going to replace it while it's out. I ordered one from Pelican, they called to let me know that the one they had is sold and they didn't know when they would get more. Sierra Madre is out as well. Is this something I can just get from my FLAPS? I understand that it's doubtful that they will have on on the shelf, but is there any issue with going Oriley or Autozone? A Bosch Al75x should be universal, no?

Any benefit/risk with going with the 70amp unit?

Where is the voltage regulator on a 1975? is that hiding over on the relay board?

Thanks!
Ted

[Ishley]

I bought a 75 amp off ebay... ~$350. Works great... I have about 6K miles on it. Moved the pulley over and no core returned. I did replace the Regulator on my '72/4 after a year as my Voltage would jump around a bit. I have replaced my fog lights with driving lights and I have a small sub woofer. I also changed to a WOSP hi-torque starter from Pelican. All and all it seems to charge well. I'm guessing these are not really 75 amp. I remember someone had a post and said it tested lower.

[fiacra]

Hello Gang!

While the motor is out being rebuilt I figured I would look at the starter and alternator and replace what might need replacing. The starter has a cracked cap on the solenoid, so I've ordered a new starter, will be here Monday. I'll ship the core back and recoup some of that money.

The alternator (Al75x) makes a funny noise when I spin it. It appears to be older possibly the original to the motor (82k miles), so I think I'm going to replace it while it's out. I ordered one from Pelican, they called to let me know that the one they had is sold and they didn't know when they would get more. Sierra Madre is out as well. Is this something I can just get from my FLAPS? I understand that it's doubtful that they will have on on the shelf, but is there any issue with going Oriley or Autozone? A Bosch Al75x should be universal, no?

Any benefit/risk with going with the 70amp unit?

Where is the voltage regulator on a 1975? is that hiding over on the relay board?

Thanks!
Ted

VR is on the relay board. If you have a good quality original alternator I would have it rebuilt. I would not get an alternator from your O'Rileys or Autozone. Just my two cents. It might be a bit of a drive for you but Alternators Unlimited on San Pablo Ave. in Berkeley is the go-to place around here for rebuilding an alternator. I would expect there is probably someone more local to you. Good luck.

[TRP]

I will give the shop out in Berkeley a call and ship one of these two alternators out to them, maybe both!

Thanks for the info.

Ted

[porschetub]

Hello Gang!

While the motor is out being rebuilt I figured I would look at the starter and alternator and replace what might need replacing. The starter has a cracked cap on the solenoid, so I've ordered a new starter, will be here Monday. I'll ship the core back and recoup some of that money.

The alternator (Al75x) makes a funny noise when I spin it. It appears to be older possibly the original to the motor (82k miles), so I think I'm going to replace it while it's out. I ordered one from Pelican, they called to let me know that the one they had is sold and they didn't know when they would get more. Sierra Madre is out as well. Is this something I can just get from my FLAPS? I understand that it's doubtful that they will have on on the shelf, but is there any issue with going Oriley or Autozone? A Bosch Al75x should be universal, no?

Any benefit/risk with going with the 70amp unit?

Where is the voltage regulator on a 1975? is that hiding over on the relay board?

Thanks!
Ted

I believe X in the part number denotes and exchange unit ,would suspect the original was most likely exchanged as a core for replacement ,the early exchange units were pretty good but newer on don't appear to be that great ,I have done my share of Bosch rebuilds on altenators ,the 55amp units are are a DIY job if only doing brushes and bearing ,when you need diode work in gets put done to a suitable shop .
I believe the 75 amp unit fits with a change to vanagon unit which has and external cooling fan .
Good luck.

[brant]

I have a couple rebuilds from the Berkeley shop if your in a hurry

Can sell one

But sending cores and waiting is good advice

[JeffBowlsby]

Uh oh…

Google says Alternators Unlimited in Berkeley is permanently closed as of this month.

@TRP

[TRP]

Uh oh…

Google says Alternators Unlimited in Berkeley is permanently closed as of this month.

@TRP

Naturally...

Thank you for the heads up. There is an old alternator / generator and starter repair shop in Gilroy, under 10 miles from my house. I will swing by there next week and see what they say.

[MartyYeoman]

If you're looking for a reputable rebuilder, might I suggest, talking to machine shops around your local general aviation airports. They're in the no mistakes business. You'll probably get sound advice there.

[bdstone914]

@TRP

' date='Mar 13 2026, 05:31 PM' post='3249040']
I will give the shop out in Berkeley a call and ship one of these two alternators out to them, maybe both!

Thanks for the info.

Ted
[/quote]
.if your core us rebuildable i can get one done by a rebuildaber with 37 years experience for $200 plus shipping. I may have e one on the shelf.
I have cores and can get one in a couple days.
Beware of FLAPS rebuilds including Bosch.
Not the quality they once were.
Im in Riverside. Shipping probably about $15.
Bruce

[TRP]

Thank you all for your offer in the cores/rebuilt units, i have 2 cores here. Im in no rush. With one of them I will give the rebuild guy in Gilroy a shot.

[SKL1]

Just had the alternator from my '71 rebuilt at Lancaster Starter/Alternator in Lancaster PA.
Quick turn around and it looks better than new. Heard good things about them at rennlist. In talking with them on the phone you can tell they are gearheads- the guy that rebuilt mine has a Lotus, and he loved the Fuchs on my car...

[TRP]

Just had the alternator from my '71 rebuilt at Lancaster Starter/Alternator in Lancaster PA.
Quick turn around and it looks better than new. Heard good things about them at rennlist. In talking with them on the phone you can tell they are gearheads- the guy that rebuilt mine has a Lotus, and he loved the Fuchs on my car...

Thanks for the info, what did it run you?

Ted

[TRP]

@porschetub - my apologies, I should have been more specific, the two cores I have are no marked *AI75x. They are only marked with what appears to be the original stickers, please see below. Are these rebuilt or original units?







The one with the Audi/VW logo came out of my 80k original miles 1975 1.8. The one with only the VW logo came out of another 1.8 core.

Thanks for all the info!
Ted

[SKL1]

Ted, PM sent.

Also got an alternator refresh kit from 914rubber- really needed a new air flow boot as my original basically disintegrated when I removed it- and it came with new wiring and a new belt.

[TRP]

I was able to get one of the original Bosch alternators rebuilt by the shop out in Gilroy, CA. The owner, Steve was great. I dropped one of the cores off a little over a week ago. Steve called me on Monday and said the Alternator was in good working order. I had him go ahead and replace the brushes, bearings, and clean it up anyway. I mean... it was already out! When the motor goes back in it will have a new motor, new trans, new starter, all fresh powder coated tins, new grommets, refreshed FI harness, refreshed injectors, new ignition harness, new alternator harness... may as well get the alternator in good nick while I am at it!

I dont know much about rebuilt alternators, but it looks great and is super smooth/quiet.







The zip tie is keeping the bushing from sliding off and getting lost. Cost for the rebuild was less than 200.00. If this works as expected, I will bring the other core to Steve for the same service.