1st gen 105 amp bolt in alternator.

Not sure why people say the GM upgrade is hard. You can reuse your same belt with the right alternator and there is a harness made for like $15 that makes it completely reversible. Spacer wise, I just glued 3 washers together and wrapped it in tape. You all are doing the big 3 upgrade to support the higher amp alt and that's way harder than installing a GM alt.

I did it because the big 3 all run in the same loom. If you are going to upgrade the ground to the block, you might as well upgrade the starter wire while you are there. Like you are just adding two more crimps to the list of things you are doing.

It all runs in this bitch:



Stripped down you are left with this:



And finally:

 

Well shit. That's some pretty thin wire. Clean job! Can you do mine? Lol

 

That thin wire is a signal wire for the starter not the power. Just showing what is left if you remove the wires that I did when you replace it.

 

I never said anything was hard about it, I just like this option better. I'm not running any kind of crazy electrical stuff besides a winch with a single battery so I really didn't need all the amperage that the GM alternator offers.

 

Not me, I'm not a big 3 kinda guy, but I did upgrade my alternator wire. I just like the way the Denso alternator is a tight fit and it bolts right in, to be honest if I did not upgrade the power wire and just the alternator I wouldn't lose any sleep at night, it'd work just fine.

 

Well, spent a few hours swapping out the old alternator for the new one this evening. Was pretty easy except I had to go get a nut and bolt using with a socket to compress the sleeve in order to get the new alternator in the top bracket.
Make sure you have a bolt, socket and nut handy for this.
I spent 10 minutes trying to move the sleeve, no luck before going to get the bolt and nut for that process.

I disconnect the battery to be safe.

The alternators cable bolt is now under the alternator so you have to attach everything from underneath the truck. The wires will all fit just fine but you have to wrestle them around to fit in the new position because they will be facing down instead of up.

I went to NAPA AUTO parts and they made me a copper 6 gauge cable 18” long and crimped the 1/4” end
adapter leads for the alternator and the other side lead for the battery bolt,
.
They charged me 15.00 for this and heat wrapped the two ends too.

My old alternator was a 80 amp and the volts were 13.5, now the 105 amp alternator volts are 14.2.
So for me this was a thumbs up.

Thanks OP
Happy camper

 

Looks good. Did you only upgrade the power wire for the alternator or did you also add a ground strap? Not sure if it's necessary since it grounds to the engine. What do you think?

 

What is the voltage at idle with and without accessories on?

You're also assuming your old alternator was working 100%. The improvement could just be because you replaced a broken alternator with a new one. You should test all the diodes in the rectifier to be sure they were all working. If one diode was dead it would cause a reduced voltage.

 

Just did the 6 gauge cable from the battery directly to the alternator.

The stock neg side ground straps and cables are pretty thick, I’m sure is more than capable

 

Do you have a pic of that? I might go the same route and get a cable made at Napa also.

 

The old alternator I just put new brushes in 6 months ago, so it was working just fine

 

I didn’t take a photo,
Just take the new alternator in to them so they can match up a copper cable 1/4” lead and depending on what you decide for the battery post.
I bought a battery post with the wing nut style so they matched up that size.
Was easy that way

I was totally surprised with the 15.00 charge custom

18” will be a good length, 20 will get you more for a lift maybe.

 

Was the voltage measurement taken at idle?

 

14.2 volts

14.2 volts at idle

 

Yea, just have Napa make you one, this way you get the correct copper size end connectors and length 18”.
The standard size battery eye is way to big to use on the alternator side. So this eliminates most of the
off the shelf options.
The connector that goes to the alternator you want it to have a drop in angle not straight so it fits
into the OEM alternator boot.
You install the factory cable 1st into the alternator, then the 6 gauge cable and the boot will close pretty well to cove everything up.

At idle, with AC on, fan on high, head lights on, wipers on, radio amp and subwoofer on, foot on the brakes, turn signal on, the voltage shows 14.1 , it dipped to 13.8 and jumped back up immediately when everything was on idling at 700 rpms,
As long as the idle is at 700 rpms with all my accessories on my volts are at 14.

If my idle drops below 700 rpms the volts drop which would be normal

 

Powermaster makes a boot part number 100, that fits the 6 gauge wire well.

 

So I decided that it was probably a good idea to upgrade the alternator fuse to 120 amps, then I looked at the fuse box feed wire and figured why not upgrade that as well. Then I looked at my battery terminals and thought about the mil spec ones posted earlier. So ya might was well do that while I'm at it and here we are. 20 bucks on Amazon and some repurposed cables I found in my garage.

 

i dont remember, but the alternator fuse. is it one of the ones that bolted from the bottom or no?

 

Im not sure but if a cable is running from the alternator to the battery the fuse will not make a difference unless you go through the fuse with a 6 gauge cable, correct?

 

Yes its bolted from bottom.