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Discussion Starter #1
Doing some investegation here -

Dual Alternator Trucks use a 135A alternator mounted in the TOP position
Single Alternator Trucks use a 120A alternator mounted in the TOP Postion

Anyone ever look at installing the 135A on a Single Alternator truck ?

I have compared the two units and the 135A is a larger case, same pulley
size, the cast mounting bracket is slightly shorter on the 135a vs the 120a
which im HOPEFUL will compensate for the larger case.

Electrical connections are all the same.

Has anyone tried to swap the larger 135a in place of the 120a ?
 

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Discussion Starter #2 (Edited)
FYI -

The alternators are the same DEPTH so clearance shouldnt be an issue.
 

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Discussion Starter #4
ok so its a bit confusing - i always was told the OE single was a 110a, but autozone
shows a replacement 120a - either way the dual alternator trucks are 135/large
case (up top) & a 110a/small case down the bottom.

Im happy to report that i just finished removing my OE 110a (single/top) alternator
and i installed the larger case 135a (dual/top) alternator - fits fine, no modification necessary.

nice to know, if youre 1) looking for an upgrade 2) need some more amps or 3) your in
a pinch and can only get the top 135a unit.

20 bucks for 25 amps more - cheap (when replacing a failing alternator).
 

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Then I guess the same logic would apply to put a 135 amp alternator in the bottom position on a truck with dual alternators. so you could have 2 135 amp units. Keith
 

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Discussion Starter #7 (Edited)
i should have said you walk away w/ 25 amps more over stock for 225 after core/return.

im NOW showing higher charge voltages than i ever have (in the 13.4-13.7 range, even
at idle) and ive never done that even since NEW, last night on the interstate i was only
showing 12v <charging> at night w/ only my factory headlights on - so i knew there was
something wrong & that i would likely end up stranded if i didnt replace the alternator soon.

The OE alternator lasted 105k miles and nearly 7 years (2004), a year ago i replaced
the OE batteries for the 1st (and only time) & about 4 or 6 months ago i added a
third battery (on the frame) - so as much as i know i tax the electrical system on MY
truck - it has also served me well w/ not even a HINT of a problem.

I would have liked the chance to upgrade to a 200a alternator but really that takes
more planning and at the end of the day, you cant beat autozone for their lifetime
warranty and their proliferation of stores (one or more in EVERY town).
 

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Good info Don!! Keep us posted on how it works. That may be a good option for those who are seeking a slightly bigger alternator...

Speaking of which................. A while back, I bought a 160a from Alternator parts and the voltage regulator went bad in it. I talked to them and sent it back. They replaced the regulator and returned it. It lasted a couple of weeks and the regulator went bad again.... :mad: I have tried calling them several times but they won't return my calls, so now I am having to look at other options..

I have checked my grounds and everything looks good. I have checked the batteries and they are testing good. Running the stock alternator, I have not experienced the same problems, so that leaves me wondering what the deal is.... Since I have not seen anyone else post about having problems with their stuff and most of those are even higher amp alts than mine, I am wondering if there is a heavier duty regulator out there that perhaps they don't put into an alt of my size.......

Any suggestions??
 

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Discussion Starter #9
2nd day running it and its proving out well.....idling w/ a FULL LOAD (thats ALL of my
lights, an 1100w inverter and AMPS galore) and i was NOT able to bring it under 13 volts !
 

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Very Interesting. How much larger of a case does it have? I know that the limiting factor for the stock alternator is its case size as it limits the amount of windings and cooling issues. If this is larger physically it may also allow for further bumps if necessary. Chris
 

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Good info Don!! Keep us posted on how it works. That may be a good option for those who are seeking a slightly bigger alternator...

Speaking of which................. A while back, I bought a 160a from Alternator parts and the voltage regulator went bad in it. I talked to them and sent it back. They replaced the regulator and returned it. It lasted a couple of weeks and the regulator went bad again.... :mad: I have tried calling them several times but they won't return my calls, so now I am having to look at other options..

I have checked my grounds and everything looks good. I have checked the batteries and they are testing good. Running the stock alternator, I have not experienced the same problems, so that leaves me wondering what the deal is.... Since I have not seen anyone else post about having problems with their stuff and most of those are even higher amp alts than mine, I am wondering if there is a heavier duty regulator out there that perhaps they don't put into an alt of my size.......

Any suggestions??
Chuck,

That sucks that your having problems with the alternatorparts.com one. Which one did you get again? Mine has been good so far but I did take my old Ford alternator to a local shop and had them fix the regulator on it. I will keep it for back up if this one ever takes a dump on me. all though I do have some noise coming from the alternatorparts one that is on the truck now. I have even thought about taking it off and sending it back for them to test since i have the old one fixed.

Lonnie
 

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Discussion Starter #12
Very Interesting. How much larger of a case does it have? I know that the limiting factor for the stock alternator is its case size as it limits the amount of windings and cooling issues. If this is larger physically it may also allow for further bumps if necessary. Chris
how much larger is relative i guess...its noticeably larger & i compared the
110/120a to the 135a unit side by side in autozone on their counter...its
how i determined the pulley size and DEPTH were the same as the OE 110.

bottom line, the 135a is a larger case...but dont take my word for it...
go down to your local autozone and compare 'em for yourself.

autozone parts are LIFETIME warranty...if it fails, its replaced FREE <any
time, any town> - its not as high amperage as i wanted (ultimately i
need about 250a) - but you cant beat the warranty, i dont have to keep
a spare and i dont have to mail this one back to ANYONE if
it fails (sorry lonnie, sorry chuck).
 

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Sounds Good! Thanks for the info. Chris
 

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Thanks for the thread/post. I'm currently having to change my single alt system 110 amp alternator and considering the upgrade to the 135 amp (top/dual alt system)over the stock 110 amp (single alt system) replacement. The local independent alternator repair shop says it will work but I noticed the pulley size on the 135 amp is 71 mm dia. while the 110 amp is 69 mm. Did you not have to change the pulley in your conversion?
 

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I would look into DC Power INC for a replacement it will be the last one you will ever need. They use over sized diodes to combat the heat issues which is why the stock sized alternators fail.
 
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