Is this the right alternator bracket?

[Patrick B.]

Re: Is this the right alternator bracket?

Patrick------


Yes, but we have to keep in mind that this may be a bracket for a non-Corvette application. I think that some of the pre-1969 other Chevrolet brackets were similar.

Joe ---

My 1970 parts book for non-Corvette Chevrolets shows 3863138 as a 1965 only bracket for 396's in big Chevies, and 3925526 for 66-68 396s in everything but Corvettes. 3940939 is shown for all 69-70 big blocks. I know the 69 up brackets are sheet metal rather castings. If anyone knows whether 68 396 Chevelles and Camaros, for example, used a sheet metal or cast bracket, it could identify the bracket in question. The book listed a whole different series if brackets for 62 amp generators, so they must have been a considerably different from the 37, 42 and 55 amp generators seen in Corvettes.

[Joe L.]

Re: Is this the right alternator bracket?

Joe ---

My 1970 parts book for non-Corvette Chevrolets shows 3863138 as a 1965 only bracket for 396's in big Chevies, and 3925526 for 66-68 396s in everything but Corvettes. 3940939 is shown for all 69-70 big blocks. I know the 69 up brackets are sheet metal rather castings. If anyone knows whether 68 396 Chevelles and Camaros, for example, used a sheet metal or cast bracket, it could identify the bracket in question. The book listed a whole different series if brackets for 62 amp generators, so they must have been a considerably different from the 37, 42 and 55 amp generators seen in Corvettes.

Patrick------


The 63 amp alternator was a completely different alternator than the 37, 42, 55, and 61 amp units. The latter units were Delcotron 5.5" type 1D. The 63 amp was a Delcotron 6.2", type 2D. Its larger frame size is what required the different mounting brackets and it was always used with a transistorized external voltage regulator. The 63 amp unit was never used on a Corvette (although some Corvettes did use a transistorized voltage regulator).

The stamped steel bracket was used for applications using the long waterpumps. For passenger cars and light trucks this began for the 1969 model year. For Corvettes, it never occurred.

I believe the 3925526 bracket is a cast iron bracket but I'm not 100% sure. If it is, it's most likely the bracket than Dan has.

[David L.]

Re: Is this the right alternator bracket?

I was just at the Rhinebeck, NY, swap meet yesterday and there was a vendor with two very similar brackets for $40 each. Both had the "GM" casting but only one had a part number which was "3882810". When I compared the two brackets side by side the "3882810" bracket would mount the alternator in a slightly lower position when bolted to the engine. I did not buy the brackets so the brackets are probably still available for sale.

Dave

[Joe L.]

Re: Is this the right alternator bracket?

Joe, no numbers anywhere. The only marks in the casting are the capital letter E inside of a triangle and in another location the marking "G.M."

Dan-----


I did a little more research. I'm now virtually certain that what you have is the GM #3925526 passenger car bracket.

[Patrick B.]

Re: Is this the right alternator bracket?

Dan-----


I did a little more research. I'm now virtually certain that what you have is the GM #3925526 passenger car bracket.

I asked Jerry McNeish whether the 68 396 Camaro alt brakets were cast iron, and he just responded that they were. That confirms your thought that the 3925526 brackets were cast and are likely what Dan has. I will take a photo of the 3863138 and 3882810 together. The biggest difference between them is that they place the alternator pulley in alignment with different grooves on the crank pulley.

[Patrick B.]

Re: Is this the right alternator bracket?

IMG_0705.jpgIMG_0706.jpgIMG_0707.jpgHere is a comparison between the 65 396 Alternator bracket and the 66 up 427 bracket. The "810 "427 bracket (top bracket in the first picture) moves the alternator forward and the alternator belt runs in the outer groove of the crank pulley. The 396 bracket is less beefy and runs the Alternator belt in the innner groove of the crank pulley. It has a GM marking and possibly a manufacturers marking but no part number like the 427 bracket. Dan's bracket looks more like the 65 396 bracket to me.

Rereading Dan's post I am sure his is the rare 65 396 part. He notes that it has an E in a triangle and G.M. with periods like the 396 part.

IMG_0708.jpg

[Joe L.]

Re: Is this the right alternator bracket?

[ATTACH=CONFIG]39553[/ATTACH][ATTACH=CONFIG]39554[/ATTACH][ATTACH=CONFIG]39555[/ATTACH]Here is a comparison between the 65 396 Alternator bracket and the 66 up 427 bracket. The "810 "427 bracket (top bracket in the first picture) moves the alternator forward and the alternator belt runs in the outer groove of the crank pulley. The 396 bracket is less beefy and runs the Alternator belt in the innner groove of the crank pulley. It has a GM marking and possibly a manufacturers marking but no part number like the 427 bracket. Dan's bracket looks more like the 65 396 bracket to me.

Rereading Dan's post I am sure his is the rare 65 396 part. He notes that it has an E in a triangle and G.M. with periods like the 396 part.

[ATTACH=CONFIG]39556[/ATTACH]

Patrick-----


The "E" within a triangle manufacturer's ID mark is also seen on some examples of the 3925526. Although it's a little hard to say for sure from Dan's photos, it appears to me that the arm section of the bracket has the offset ("downturned") end at the mounting hole boss. This is a characteristic of the 3882810 and the 3925526 but not the 3963138.

[Patrick B.]

Re: Is this the right alternator bracket?

Joe -----I should have taken pictures from the same angle as Dan's pictures to make this easier. Dan's bracket has the rear ear of the alternator bolt hole in the same plane as the part of the bracket that fits againt the head. This puts the alternator in the rearward location consistent with the 65 396. I don't think any of the later engines had the alternator belt on the inner groove of the crank pulley, did they?

[Joe L.]

Re: Is this the right alternator bracket?

I don't think any of the later engines had the alternator belt on the inner groove of the crank pulley, did they?

Patrick------


Yes, there were some that did. A lot were light truck applications but there were some passenger cars, too.

[G A.]

Re: Is this the right alternator bracket?

at Joe L.'s request...........

[Joe L.]

Re: Is this the right alternator bracket?

at Joe L.'s request...........

Dan-----


Thanks. As can be seen from the configuration, this bracket is almost certainly the 3925526 passenger car bracket. Based on the configuration of the "arm" section, it could not be the GM #3963138 1965 L-78 bracket.