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Sun Apr 16, 2017 12:56 pm

After some experience installing a replacement alternator over the weekend, I've decided that the gasket is necessary, and that best way to make a gasket is to get some suitable material (thicker the better?) and simply trace the shape of the back place onto it, marking the holes. You can add a little extra material to help cover the too-wide washer. You can also rotate the plate 120 deg and retrace the pattern to get a more or less circular shape with bumpouts for the threaded posts.

I also trimmed both the washer and the B+ post with a Dremel cut-off wheel, being careful to cover all holes into the alternator with tape. Don't want any small metal bits in there!

Sun Apr 16, 2017 1:09 pm

I hadn't had any feedback from the video, so I thought I'd try this thread. I still haven't put mine together yet so I could redo it or add content if I'm missing a critical piece of info.

Sun Apr 16, 2017 6:31 pm

ac78 wrote: I hadn't had any feedback from the video, so I thought I'd try this thread. I still haven't put mine together yet so I could redo it or add content if I'm missing a critical piece of info.

https://youtu.be/W8_thFzpyxw
That's pretty good. I just did this over the weekend. One more thing I did was to actually trim the edge off that too-wide washer with a Dremel cutter, in addition to the chopping off the post. I made up both a paper gasket (like yours) and a foam rubber one, to add thickness.

Sat Jun 03, 2017 2:10 pm

Can't believe its been almost 2 months but I finally got around to putting my alternator back in. I did end up using the new Bus Depot harness that came last week since it was better quality than my hack job. The pic is the back side connections(some extra electrical tape for good measure) just before I put the back plate on. I did put 2 more coats of paint on the back plate too.

Jumped my battery and didn't smoke anything this time :lol: . Took her out for a good ride to quiet the lifters and it feels great to be back on the road!

Tue Jun 27, 2017 5:27 pm

Just picked up my alternators after having them fix/rebuilt.
Not too happy with the inside being spray painted this way but as long as they work [-o<

I want to prevent my alternators from shorting..
If I'm understanding this correct

1) I remove one of the nuts and the washer, keep it as nut>terminal> directly to alt.
2) Grind off the excess as you say.
3) Use cardboard trace out the plate and place between the alt and the cover plate.

Tue Jun 27, 2017 5:37 pm

It would be worth your time to scroll up 2 posts and watch my video.

Leave the washer and for sure leave the square unless you want to do it all over again with a new harness.

Tue Jun 27, 2017 5:41 pm

ac78 wrote: It would be worth your time to scroll up 2 posts and watch my video.

Leave the washer and for sure leave the square unless you want to do it all over again with a new harness.

Wow completely didn't see that link. Nice! Thank you.

So I have 2 alts with me, one of them doesn't have the fiberglass tab. What can I replace it with? Cardboard?

Tue Jun 27, 2017 7:07 pm

The fiberglass tab moves to the new alternator you are installing.

Tue Jun 27, 2017 7:20 pm

Thanks for the tip ac78 and efforts with the video. I know about cutting down the terminal but not the transferring tab over and other considerations you mentioned. Much appreciated

Tue Jun 27, 2017 7:44 pm

ac78 wrote: The fiberglass tab moves to the new alternator you are installing.

I have 2 new alternators. One of them doesn't have the tab, wondering what else I can use in place of the tab. (I want to fab another tab that way they both carry them... just in case) also the tab I have isn't a rectangle it's a square. It broke I think, the black part is where the rest is missing. Still useable?

I found this on Amazon,(https://www.amazon.com/CS-Hyde-Temperature-Fibergl...glass+tape), think it can be useful?

500*

I can't seem to find anything solid like the tab in fiberglass, hmm maybe a thin PCB board made from fiberglass?

Thu Jul 27, 2017 8:42 pm

telford dorr wrote: Slammed77bus wrote: I recently had the same problem somewhat . But as I touch the red wire to the positive on the batter it begins to spark. I used my test light to check and when I clip the alligator clip to the positive and then touched the b+ b+ bolt and the light turned on. That means it's grounded right?
Right. It means there are shorted diodes inside the alternator.

With the alternator frame grounded and the regulator disconnected, connecting a test light from +12 volts to either B+ or D+ should NOT cause the test light to illuminate. If it does: shorted diodes.

Quote: Before anyone says anything the Previous owners have the batter wires backwards. The RED is negative and BLACK is positive

I'd fix that ASAP. Should you connect the battery backwards, even for an instant, you can kiss the alternator goodbye. All the diodes will be forward biased, and thus allow ridiculous amounts of current to flow. The diodes will instantly melt and short. Shortly after that, any interconnecting wire will overheat and melt the insulation. Sort of a catastrophic failure...

Fri Jul 28, 2017 1:53 am

I bet you do have a bad diode shorted to ground rather than a shorted wire. Your connectors and wire insulation look good and I think I trust your instincts not to have wires bare dangling in your engine compartment.

Fri Jul 28, 2017 8:50 am

Abscate wrote: I bet you do have a bad diode shorted to ground rather than a shorted wire. Your connectors and wire insulation look good and I think I trust your instincts not to have wires bare dangling in your engine compartment.
I don't think a bad diode is going to melt down the Big red cable. Usually it creates a parasitic draw on the battery and that is about it.
I posted telford's post, more so to show how to test for a short to ground.
One member reported, that by tightening the B+ terminal alone with no Big red wire created a short to ground. So the Alt. was shorting internally through the post.
Tcash

Fri Jul 28, 2017 10:02 am

I forgot to add these pics from my procedure. On a dry run without a gasket or standoffs, I bolted the back plate on and used my endoscope to see what the clearance really was and what could cause the short. I hope this helps.

I found that even with the double nut on the post, there is more than enough clearance from the back plate.

I concluded that the flat part of the back plate without the fiberglass wafer as a buffer was the reason my harness fried. You see it sit right on the washer. Additionally, removing the washer does NOT fix this. All removing the washer does is ensure the full length of the flat piece contacts the entire B+ donut instead of just a little section that can be protected by the fiberglass wafer.

Fri Jul 28, 2017 10:37 am

Tcash wrote: Abscate wrote: I bet you do have a bad diode shorted to ground rather than a shorted wire. Your connectors and wire insulation look good and I think I trust your instincts not to have wires bare dangling in your engine compartment.
I don't think a bad diode is going to melt down the Big red cable. Usually it creates a parasitic draw on the battery and that is about it.
I posted telford's post, more so to show how to test for a short to ground.
One member reported, that by tightening the B+ terminal alone with no Big red wire created a short to ground. So the Alt. was shorting internally through the post.
Tcash

Disregard I am in the wrong thread.
Tcash

Fri Jul 28, 2017 10:43 am

This is the money shot.

Thank you
Tcash

Fri Oct 06, 2017 1:35 am

Terminatez wrote: ac78 wrote: The fiberglass tab moves to the new alternator you are installing.

I have 2 new alternators. One of them doesn't have the tab, wondering what else I can use in place of the tab. (I want to fab another tab that way they both carry them... just in case) also the tab I have isn't a rectangle it's a square. It broke I think, the black part is where the rest is missing. Still useable?

I found this on Amazon,(https://www.amazon.com/CS-Hyde-Temperature-Fibergl...glass+tape), think it can be useful?

500*

I can't seem to find anything solid like the tab in fiberglass, hmm maybe a thin PCB board made from fiberglass?

Ever find a good replacement for the tab?

Also, putting my alternator is missing the suppression condenser but when I look for part #021903295 I can't find anything. What's the modern day equivalent for this part?

Fri Oct 06, 2017 7:42 am

I've got a good used Alternator off a CB engine if anyone wants to purchase cheaply instead of dealing with aftermarket crap.

Fri Oct 06, 2017 8:34 am

surfbus23 wrote: Terminatez wrote: ac78 wrote: The fiberglass tab moves to the new alternator you are installing.

I have 2 new alternators. One of them doesn't have the tab, wondering what else I can use in place of the tab. (I want to fab another tab that way they both carry them... just in case) also the tab I have isn't a rectangle it's a square. It broke I think, the black part is where the rest is missing. Still useable?

I found this on Amazon,(https://www.amazon.com/CS-Hyde-Temperature-Fibergl...glass+tape), think it can be useful?

500*

I can't seem to find anything solid like the tab in fiberglass, hmm maybe a thin PCB board made from fiberglass?

Ever find a good replacement for the tab?

Also, putting my alternator is missing the suppression condenser but when I look for part #021903295 I can't find anything. What's the modern day equivalent for this part?

This tab material everyone is looking for is NOT fiberglass. Its classic "Garrolite"....which is a fairly old but basic performance level circuit board material. Its the most of a century old cousin of modern FR-4 circuit board material.

You can buy it at McMaster Carr fof cheap.

A 12" x 12" sheet that is 1/32" thick is $3.53....part #8525K411

A 12" x 12" sheet that is 1/16" thick is $4.32....part #8525K111

They make it in thickness ranging from 1/32" up to 2" and sheets up 36" x 48".

Its temp range is 265°F....its the standard brown color....is made of phenolic resin laminate and is called Garolite grade XX. Its made for electrical insulation.

DO NOT cut this with something that raises a lot of dust without a mask. Garolite/phenolic resin dust is toxic. You can cut with multiple passes with a sharp box knife or a coping saw or a hobby razor saw (everyone should have a razor saw....cheap at hibby lobby).

Ray

Fri Oct 06, 2017 10:17 am

Thanks again Ray! Where would my bus project be without your and so many other's on here willingness to help. Can't wait to share it with you all soon.

How about where to find that suppression condenser? I'm sure there's a common Bosch part number for a modern one that I'm missing.