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Old 04-07-2019, 09:27 PM
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Default Alt & PS brackets.... this can't be that hard

Hello all, I have an 81 TA with a transplanted 77 400 under the hood. It has the 80 amp alternator. Before I go dropping cash on brackets I don't need anyone know for sure which ones I do need? Any pics of the set up in your cars or pics of the brackets? The rear alternator bracket that was on there was for the old 301, this caused some jury rigging by the old owner and crooked alt/ps belts. Thank you!

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Old 04-07-2019, 11:04 PM
Grand73Am Grand73Am is offline
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If it were me, I would not use the large 80 amp alternator. With the size and the way it mounts, it may not even fit under a TA hood.

I'd switch to the standard size 63 amp alternator. Then you can use the more commonly found alternator brackets used on most of the 70's Firebirds/TA's and even 73-77 A, B, and G bodies with 350 and 400 Pontiac engines, and 78-79 B-body.

Below are eBay links I found to 2 of the 3 brackets. I couldn't find the third bracket at this time. The photo shows the 3 brackets. There are 2 spacers and some bolts required too of course. Maybe you can find a parts car, or someone parting a car, someone selling on a Facebook page, or Frank's Pontiac parts.

https://www.ebay.com/itm/1975-Pontia...UAAOSwUiVZ1kWg
https://www.ebay.com/itm/1971-79-TRA...AAAOSws0JaZSIQ

DSCN9744 by grand73am, on Flickr
ALT BRACKETRY by grand73am, on Flickr

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Old 04-08-2019, 07:34 PM
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I'm missing something then. I have all those brackets. I wonder what the rear aluminum bracket would be? I've read that you need the 80 amp alternator for the power windows and all the accessories? I looked on franks. Thank you!

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Old 04-08-2019, 07:48 PM
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No, you don't need the big 80 amp alternator. I have power windows, door locks, ac, heated back glass, and the standard size 63 amp alternator. But, you can buy a standard size alternator built with 100 amps if you like, and it'll fit the same as a stock 63 amp.

There's no aluminum bracket for this setup. Those are all steel.

The alternator setup with the power steering pump, uses those 3 brackets, and 3 spacers. Below is another diagram showing how the pump is installed. I could measure the spacers and give you the dimensions, so they wouldn't be hard to make. The rest is just nuts and bolts.

POWER STEERING BRACKETS ILLUSTRATION by grand73am, on Flickr

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Old 04-08-2019, 08:08 PM
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The 80 amp alternator was installed on cars with the rear window defroster...

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Old 04-08-2019, 08:19 PM
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I'm sure some did, but my 79 TA with 403 and heated back glass/rear window defrost came with the 63 amp alternator. Both items are on the build sheet.

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Old 04-08-2019, 09:12 PM
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Ok awesome so I need nothing. The ac will still be on the car, I probably will never use the rear defogger, pdl's are gone, cruise control will be gone, so 63 amp it is.

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Old 04-08-2019, 10:38 PM
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Quote:
Originally Posted by 4dblnkldude View Post
Ok awesome so I need nothing. The ac will still be on the car, I probably will never use the rear defogger, pdl's are gone, cruise control will be gone, so 63 amp it is.
Hopefully you have the right brackets. There are 2 or 3 applications that look similar but aren't the same. If there's a part number stamped on the plate or bracket, it helps ID it. For example, the large C-shaped alternator plate should have 499749 stamped on it.

And as I mentioned, if you don't have the 3 spacers, let me know and I can measure mine and you could make some.

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Old 04-09-2019, 08:48 AM
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Quote:
Originally Posted by Grand73Am View Post
I'm sure some did, but my 79 TA with 403 and heated back glass/rear window defrost came with the 63 amp alternator. Both items are on the build sheet.
My experience with high amp alternators came from selling auto parts for 13 years. A customer comes in store needing an alternator, car is broken down at home. Question comes up of which amperage...99 percent of the higher amp alternators I experienced had a rear window defroster.

I would have thought a 63 amp unit would be standard...interesting, thanks for sharing!!! as always!!!

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Old 04-09-2019, 12:40 PM
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My 81 T 301 had the 80 amp -no rear defroster, it won't fit the brackets for a 400. They do make higher amp alternators that bolt right in.

Problem with the 301 brackets is it is a "short deck" block and many brackets bolt to the timing cover and the head and the distance is different.

You can use the rotary AC compressor bracket as it just bolts to the head. Be sure and get pulleys that match the brackets. The 301 pulley do not.

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Old 04-09-2019, 07:43 PM
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Quote:
Originally Posted by Grand73Am View Post
Hopefully you have the right brackets. There are 2 or 3 applications that look similar but aren't the same. If there's a part number stamped on the plate or bracket, it helps ID it. For example, the large C-shaped alternator plate should have 499749 stamped on it.

And as I mentioned, if you don't have the 3 spacers, let me know and I can measure mine and you could make some.
I have got tons of spacers in a bin...probably 50 in there. If you would like to save me some time searching and trying I would like that. Thanks for the replies guys!!

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Old 04-09-2019, 11:08 PM
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Okay, no problem. I'll measure them tomorrow and post the results.

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Old 04-09-2019, 11:31 PM
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I just remembered that I had already written and saved this info a couple years ago. So, this has the spacer measurements, and a few more things you might like to know. Also, in my first post(post #2) above, the drawing has the bolt sizes listed below it:

There are 3 brackets or plates that you need. The GM part numbers are: Alternator plate #499749, P.S. front plate #482195, P.S. rear bracket #485992. And there's a spacer that goes between the alternator and the head which is 69 mm long, part #526968. And there are 2 more short spacers. The spacers may be hard to find and you might have to make them. You'll also have to figure out what bolts to use if the seller doesn't provide bolts with the brackets. I just noticed that the bolt sizes are on the illustrations, so that'll make it easier. The part numbers for the brackets/plates won't do much good with GM since the parts are obsolete, but sometimes the sellers on eBay will put the part number in their listing, so knowing the numbers will help make sure it's the right part.

More info: Measurements for the 2 short spacers for the power steering pump. The front one is .606" long, 13/32" ID, 3/4" OD. The rear spacer is 1/4" long, 13/32" ID, 3/4" OD.
Measurements for the long alternator to head spacer: 69mm long, 1" OD. I don't have an ID, since it's still on the car, but it just has to accommodate the 3/8 bolt that goes through it, so probably about 13/32" ID like the other spacers.

Also, if you buy a rebuilt power steering pump, it won't have the 2 threaded studs on the back. If you don't have an old pump to take studs from, you'll have to find some or make some. Each stud has a shouldered base that is about 11/64" thick. You have to have that shouldered base there, since it's part of the spacing with the brackets. The length of the threaded stud above the surface of the base is 13/16" for the upper stud, and 1-1/16" for the lower stud. The threaded studs are 3/8"-16 thread.

And if you get a new p.s. pump, it doesn't come with a pulley, so you'll need one for a 77. They're the same for 75-79 Pontiac V8's. The part number is 496411. So, that should make it easier to find.

New p.s. hoses can also be ordered from your local parts store.

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Old 04-10-2019, 02:18 PM
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As I recall.....last year for the large case alternator...on a 400/455...was 76.....

I'm thinking it used an aluminum mount....and an idler pulley...for tension.

Don't recall EVER seeing one on a 77-79 400..in a bird......and I've looked at ALOT of these cars...in the last 40 years.

Also thinking that the 80 amp alt...used on the 80-81 turbo cars was an oddball/different case...than the earlier ones

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Old 04-13-2019, 10:58 PM
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Thanks for the replies guys. Green Hornet I bought an aluminum mount on ebay thinking that was what I needed....... only to find it a week later in a milk crate. So I got it all on there today ....worked perfect. 73GA I had the brackets off of an old pump and threw the 301 brackets in the crate ..LOL. The .606 and the .250 spacer I had in the bin. I found a chevy alternator bracket with a little arm on it so I ground it off, cut it, and filed it as flat as I could to 2.71 inches. I had the long bolt and had to cut a couple more. Looks like it belongs now.

I mocked it up with an older alternator I just gotta get a new one tomorrow. If your looking at the alt from the front it should be a 9 oclock? If your sitting in the car it would be 3 oclock? Thanks again!

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Old 04-13-2019, 11:19 PM
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Glad to hear you figured it out.

The alternator clocking should be about 2 o'clock from the front, like in this pic:

187-8753_IMG by grand73am, on Flickr

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