Mounting a Delco 12si into a 71 FJ40

[Tacoman99]

Hi
Need some ideas. I am trying to mount a 94 amp Delco 12si in a 71 FJ40. I am running a winch a lot and the 40amp original has a hard time keeping up. I am having a problem with the lower mount. The alt is mounted down low on the drivers side. I have included a pic with the alternator next to the mount in the position where the alternator, crank and water pump pulleys will all line up. I have seen a couple of Universal Alternator brackets on ebay and amazon and it kind of looks like they are trying to solve the right problem. They are intended for mounting alternators on old tractors. None of them have dimensions so it is hard to tell what will work (A200 is an example). They look kinda wimpy and are a little expensive.
http://www.amazon.com/Tractor-Gener...-1&keywords=a200+universal+alternator+bracket

Has anyone used anything similar? I have not ruled out of moving it to passenger side to get it out from under the exhaust manifolds. Wiring is not really an issue. Any ideas would help. I am about ready to just fab something.

John

 

[shawnfj40]

That is very similar to factory and looks like mine does. It sets pretty low and with a Saginaw conversion the steering is close. I am thinking of moving it over to the passenger side myself just to get it up higher for water crossings etc...

 

[Steamer]

I've been "slowly" working on putting a 170 amp 12si onto my 74 F.5. I'm moving it to the passenger side to make room for a PS pump and I'm using the 2F bracket. I have two grooves (small & large) on the harmonic balancer & water pump. With a little grinding on the bracket the 12si lines up with the rearward large grooves. "But" I want to use the large groove for the PS pump. So I got the 12si with the small groove pulley and modified the bracket to move it forward. That took a bit of time to do and keep it looking somewhat clean but it's doable. In hind sight I wish I'd just gone with the Mean Green or the CS series many here go with and not mess with bracket fabrication. The bracket is finished and mounted but not the 12si. I'll go snap a pic. Here's the 12si I got.

http://store.alternatorparts.com/7273m-a170-amp-12si-series-standard-regulator-alternator.aspx

 

[Steamer]

 

[Steamer]

Well you inspired me to continue this project. Just need to do some re-wiring, replace the ammeter with a volt meter and add the idiot light. The belt lines up pretty much perfect. Hope this helps or maybe sparks some ideas.

 

[Tacoman99]

That's a very interesting install.

If I understand it right the bracket was from a 2F engine and modified to take the 12si. I have some questions:
Did the both the upper and the lower brackets come from the 2F?
The lower bracket looks like:
1) The center lug had to be trimmed
2) Two plugs were put in to extend it forward to line up with the belts
3) A spacer on the shaft.

Is that correct?

Thanks for the help
John

 

[Steamer]

Your observations are corrects. The outer "C" shaped piece was cut from 1/2" x 2" flat bar. The spacers that hold it off and forward are cut from 5/8" plate. The single hole round one with a hole saw, and the two hole kidney shaped one with a jig saw. 5/8" worked out just right for spacing. The hole in the "C" shaped piece that holds the alternator bolt. was drilled last. Used both existing ears and a transfer punch to get that hole just right. Last was to cut of the forward factory ear piece. The spacer on the alternator bolt was 1" round bar drilled out. The long bolt is 7/16 and reamed the alternator a little to fit.

 

[Steamer]

Oh! I should mention not all 2F alt brackets are alike. The one with the tapped holes were needed for the mod I did. Not sure what those holes are for. AC compressor maybe?

Also it was important to me to get the hole size and spacing nice and tight so there was no play. This took me two tries. I drilled the 3 bolt on holes first in the 2"x 1/2 flat bar leaving the shaping for last. When I got a nice tight fit I then made and fit the spacers. Then I drilled for the long alt through bolt. Then cut off the one ear & did a little grinding so the 12si would rotate down into the curve of the bracket freely.

 

[Tacoman99]

That was an awful lot of work. You did give the idea of trimming the existing mount, adding a spacer and a forward lug. It will be nowhere near that stout. I will post a picture later this week.

 

[Steamer]

Yup! It was a bit of work but I'm real pleased that it looks ok (imo) and that the alignment is spot on. I was also worried that Marshall might call it a "hack job" lol. Good luck with it.

 

[78fj40mg]

Oh! I should mention not all 2F alt brackets are alike. The one with the tapped holes were needed for the mod I did. Not sure what those holes are for. AC compressor maybe?

View attachment 1120848

View attachment 1120849

Also it was important to me to get the hole size and spacing nice and tight so there was no play. This took me two tries. I drilled the 3 bolt on holes first in the 2"x 1/2 flat bar leaving the shaping for last. When I got a nice tight fit I then made and fit the spacers. Then I drilled for the long alt through bolt. Then cut off the one ear & did a little grinding so the 12si would rotate down into the curve of the bracket freely.

Really nice fab work!

 

[Tacoman99]

My final solution based on the idea from Steamer. The original casting was trimmed, added a spacer and added the forward lug. The two bolts are grade 8, 1/4", tight holes (only about .002 clearance) in the spacer and lug. The spacer was 1/2" thick and the lug is 1/4". The two bolts were threaded into the original casting. It puts the pulley in the plane of the water pump and crank pulleys. It only took a couple of hours and it shows. Lots of cutting and grinding. The original mount cuts, grinds and takes threads pretty well for a iron casting. Next, I have to wire it up. I should have it done in time cut fire wood.

Thanks for the help.

 

[Steamer]

Hey that'll work. And it was fast too. Now you can loose your external voltage regulator.

 

[Tacoman99]

If anyone is interested I wired it up using 6gauge from the battery term, though an ammeter to the starter positive stud, ran the sensor line to the same starter positive stud and used the existing ignition wire (from the old regulator). I also added an inline diode in the ignition wire to prevent run-on. After a small glitch it worked well. About 14.6v at idle and charges fine. I haven't tried a high load test yet.

The glitch was that the ignition power is taken from the old battery line which was replaced with 6guage. The wiring schematic (from the official Toyota Shop Manual) that I was working with did not show a tap. It had me going for a while. I found another schematic online that showed the tap. Quick fix and it is rolling again.

Now, a little rain to reduce the fire danger and I am cutting fire wood.