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how to install gm 105 amp alternator


bonvo

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alright as you guys might know i now have a 105 amp alt in the car and this is how i did it

 

 

things you will need

 

1: gm 105 amp aternator (comes out of newer astro or truck)

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2: 3 feet of wire any color about 16 gadge

 

3: solder heatshrink and electrical tape and big "eye" type end

 

4: gm alt plug as shown

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5: double v belt alt pully

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6: chunk of steel 1/4 inch thick by 1 inch wide by 7 inches long

 

7: a few nuts bolts and washers of varying sizes

 

8: dye grinder with a cut off wheel plasma cutter somthing to cut steal acuratly with, a drill with a 1/2 inch chuck and a 1/2 inch drill bit

 

alright the first thing your gonna do is your going to remove the serpentine belt pully that comes on the alternator your not going to be using it i used a big pair of channel locks and the apropriate sized socket do with this as you please

 

next install the twin v belt pully again i used channel locks and socket

 

remove original alternator and place the new one in its place you will notice that the lower mounting is totally wrong we will deal with that

 

posistion the alternator so that both mounting points are close to the block and run a bolt threw the existing belt tentioner and the upper mount on the alternator

you can see in this picture that the belt lines up with the outer grove on the pully when bolted to the stock tentioner (note it may not line up exactly if its a little off bend the tentioner bracket a little)

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next turn your attention to the lower mount you will see that the lower mount on the alternator and the mount on the block look like they will never work (new alternator compared to old one for referance:

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first thing your gonna do is take your 1/4 inch steel peice and cut it in half leaving you with 2 chunks about 3 1/2 inches long drill two 1/2 holes one on each end the holes should be about 3 inches center to center

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grind down the edges so the corners arent shap

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place brakets on the original alt mount and blot them down loosly this creates the type of mount that is needed for the new alternator but it is wider then the mount on the alternator you will need to make spacers we used some tubing we had floating around i would give you measurements but each factory alternator braket is different this is the only part you will have to measure and cut yourself

 

after you have made the spacers run a long bolt thew the lower mount of the alt and the newly created mounting brakets

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you may need to buy a new belt (i did) so you will have some adjustment but with this set up the farther out on the adjustment you go the farther away the alt gets from cutting the lower rad hose

 

now we move onto wiring this is a breeze

 

looking at the stock witing there is the T plug the white wire with the small eye on it and a black wire with a small eye on it tape the T connector and the black wire back out of the way take the white wire and put a bigger eye on it so it goes over the pole on the gm alt

 

next solder about 3 feet of wire to the wire on the gm plug and plug it into the alternator

 

run the wire along the stck wiring harness up to the voltage regulator unplug the regulator and cut the white with red stripe off the connector and connect your new wire from the gm plug to it (only reason its a butt connector here is because i ran out of soder

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stuff the rest of the voltage regulator plug out of site

 

and badda bing badda boom this is the end result

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if you have any questions dont hesitate to ask i can answer them

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you might want to rethink using the stock charge wire (white) with your new 105 amp alternator. Search online for amps vs. wire gauge and you will probably find out that the stock wire is way too small for 105 amps. If you do upgrade your charge wire, remember to install the correct size fusible link in the new wire.

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Nice Fluke meter

 

wish the photos where clearer!

 

be honest Im more confused.

I see now 1 wire, 2 wire and 3 wire GM connectors from the back of those alternators.

 

by the old volt reg I thought you just jumper the wht/red with wht blk and wht with the yellow at the connector.

 

uncle wrote about upsizing the wire.

I assume you just routed the new 10gauge wire from output of alternator to the starter lug/battery cable. also putting a bigger EYE on the stock wht/red wire to the output of the alternator

 

doesnt matter now, You got it done.

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fisch: i figured it was a good upgrade so others might want the info that and ive been wanting to do a write up on something for a while

 

hainz: i wish my pictures were clearer to but all i have is a point and click that cant seem to focus when things are close the plug i have has the single wire going to the L terminal on the alternator my dad and i sat doe for a few hours looking at the wiring diagram for the 610 charging system and the gm alt we have and found this to be the best way the reason there are different plugs is for different cars different cars actually have a hook up for alt output from that plug so the computer knows what the alt is doing at all times

 

as for the fluke i was wondering if someone would notice my dad has had that multimeter longer then Ive been alive lol

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I see old Fluke meters at work.

Wait till you see a old anolog Simpson 260 meter!!!!!!!!!!!!!!!

 

I learned on a 260 meter

 

http://www.simpson260.com/260-3/simpson_260-3.htm

 

When I saw a Digital I was scared!!!!!!!!!and avoided useing them.

 

sorry for the (jesse) Hijack(son)

 

Now the cheap Chinese made pocket meters are pretty acurate and under 20-30$ Its with in 2% accurate of the FLUKES I use also

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Hey, what engine did you do this swap in? L-series I believe?

 

yes i bolted it to an l20b it shouldnt be much different for an a series though they use the same basic alternator stock

 

and i forgot to mention the alt is out of a 1999 gmc safari with a 4.3 v6 and rear air conditioning

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Hi Bonvo nice write up! Just wondering if you could add a picture that shows the how tis works with the bottom radiator hose?

 

Is the ear bracket the same as the fonrt one you made?

 

the rear is the same thing i didnt post mesurments due to the differences in stock alt brakets but the only difference would be the spacer sizes as for the lower rad belt it clears well and with the new pivot point the tighter you make the belt the further away the pully gets from the hose and for those wondering there is no fan on it for a reason the alt has 2 internal fans

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  • 7 months later...

the twin alt pulley i found floating around the garage but you can pull it off of older gm trucks as well as any rotary as for the plug i think i pulled mine off a late 90s cutlass if i were you i would print the pic and take it with you to the yard that way you can just compare it and if you can take multiple plugs

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I really like your use of things that are just laying around or because i had one.thumbup1.gif I may be crazy but i try to teach my boys this whenever they work in garage,( even though they have cut up things i didn`t want cut up), but i think it will good in the long run when they take on a project like yours.

 

only bitch i got is you need MORE pictures of your handiwork.biggrin.gif

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