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John Lewis (guyopel) came up with a super simple way to quite literally bolt a GM 105 amp alt to our Opels to provide more power for lights, stereos, etc. He kept to parts that you can easily find at most any parts houses. One part is the bracket that mounts the alt. It's a "dress up" chrome "F" bracket from SPECTRE # 42273, but the problem is, they're breaking. You'll know why if you ever see one, but, John and I were wondering what would be the cost to get a small run CNC milled out of solid steel or aluminum. Right now we're just looking for possible "ball park figure" for making a program and price for material. I have a spare bracket on the way that can be used to get the ball rolling, if you're interesting in looking into this with us.
 

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John Lewis (guyopel) came up with a super simple way to quite literally bolt a GM 105 amp alt to our Opels to provide more power for lights, stereos, etc. He kept to parts that you can easily find at most any parts houses. One part is the bracket that mounts the alt. It's a "dress up" chrome "F" bracket from SPECTRE # 42273, but the problem is, they're breaking. You'll know why if you ever see one, but, John and I were wondering what would be the cost to get a small run CNC milled out of solid steel or aluminum. Right now we're just looking for possible "ball park figure" for making a program and price for material. I have a spare bracket on the way that can be used to get the ball rolling, if you're interesting in looking into this with us.
Gene,
You may remember that I had one break on me, but I had another one in my bag of spare parts, from a different manufacturer and it has been on my car now for 4 years with no problems. The other thing is that they break due to the sharpness of the bend in the cheap steel that they use. If they used good steel with less carbon in it the problem would not exist. Anyway, another way to solve the problem would be to take a new bracket and remove the chrome from the corners and run a bead of weld in there. Then you could either just paint the bracket or have it re-chromed.
 

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I made mine, bent two L brackets and welded them together.

Pat
 

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John Lewis (guyopel) came up with a super simple way to quite literally bolt a GM 105 amp alt to our Opels to provide more power for lights, stereos, etc. He kept to parts that you can easily find at most any parts houses. One part is the bracket that mounts the alt. It's a "dress up" chrome "F" bracket from SPECTRE # 42273, but the problem is, they're breaking. You'll know why if you ever see one, but, John and I were wondering what would be the cost to get a small run CNC milled out of solid steel or aluminum. Right now we're just looking for possible "ball park figure" for making a program and price for material. I have a spare bracket on the way that can be used to get the ball rolling, if you're interesting in looking into this with us.
I own a metal shop and I can make them out of stainless, will be quite strong however the cost might not be too appealing. To CNC this bracket will be even more expensive due to the amount of material that is wasted. Once the CNC is done, you still need to make holes and bore out for the through bolt.

Just not worth the time and expense.
 

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I used one made for a chevy 235 engine. used it for many years and when the Manta got hit the alternator broke but the bracket remained intact. Ron
 

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I was lucky so far but I carry the spare one in a tool box .
One of the reasons why that bracket often breaks is that it is wider than the alternator, so the space between the bracket and alternator must be properly shimmed. Failing to do that puts immediate stress on the F-bracket which is squeezed with alternator mounting bolt and bent during installation. After that, it does not take long for the bracket to fail.
 

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Discussion Starter · #7 · (Edited)
but I had another one in my bag of spare parts, from a different manufacturer and it has been on my car now for 4 years with no problems.
Do you remember the manufacturer?

@ PJ If you can remember how much shimming or provide a picture, it would be a key piece of info needed.

These brackets are not just breaking on us, they're doing it to Chevy owners too, I found out that due to these "failures" some of the parts houses are not carrying them.
 

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Just Some Dude in Jersey
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must be properly shimmed. Failing to do that puts immediate stress on the F-bracket which is squeezed with alternator mounting bolt and bent during installation.
Hmmm...I never thought of that as the cause for those brackets breaking, but it makes sense. I guess someone could decide not to go to the trouble of shimming that extra space and just tighten the bolt until the bracket bent enough to make the extra space go away. Then you would be bending that part of the bracket in the reverse direction from how the company bent it. As many know, that is how you make metal crack, especially hardened metals.

When Markandson had brought this subject up a year or so ago, I was doing my alternator upgrade. Through the process I had discovered that there appears to be two styles of that F-bracket out there, both with the same part number. I think they improved the design. The newer one has an oversized hole at the top of the "F" and the bolt now has a long sleeve with a flange at that end. Unfortunately, there are still a lot of the older style out there and people might not know that there is a redesigned style available.

I had always thought that the breakage was partly due to most of the weight of the alt being on that middle position part of the bracket and that the metal was just too thin for the job. But Markandson's suggestion that the metal is brittle where they bent it and PJ's suggestion that bending it back by over tightening the bolt because of no shims both make sense.

Either way, a better solution would be nice to find. It isn't comforting to know that your alt bracket could fail at any time. An adjustable design with slots or alternate holes at the various mounting places would seem a good idea to me. Possibly having the new design angle upwards, instead of sticking straight out, might add some more adjustability or adaptability to the design. It also seems to be shame that those nice rubber shock isolators in the oem brackets get eliminated with the F-bracket mod. Now every single bit of motor vibration is transmitted by metal on metal contact to the alt. I swapped out the older style for the newer style and noticed a tremendous amount of wear during the brief time I had the older style bracket on there.
 

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I found this item which is readily available. Welded on the outside rather than however they do with the Spectre Bracket. It is not available on their website. But you could call them 800-442-4601.

1967 1968 Camaro SB Lower Alternator Mounting Bracket | eBay

1966 1967 1968
Chevy II / Nova - Camaro - Chevelle
Lower Alternator Mounting Bracket - Small Block
Replaces General Motors part # 3878256
 

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I found this item which is readily available. Welded on the outside rather than however they do with the Spectre Bracket. It is not available on their website. But you could call them 800-442-4601.

1967 1968 Camaro SB Lower Alternator Mounting Bracket | eBay

1966 1967 1968
Chevy II / Nova - Camaro - Chevelle
Lower Alternator Mounting Bracket - Small Block
Replaces General Motors part # 3878256
A good effort but no, it will not fit our application.
How about creating a set of bushings to allow the alternator to be installed instead?
I will take a look at that option today.
 

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That's right. You'd have to slot the hole into an area that doesn't provide security.
 

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How about creating a set of bushings to allow the alternator to be installed instead?
I will take a look at that option today.
That's the way I've been doing it for the past 20 years for the most part. For some racing applications I just make a new lower steel bracket from scratch, but for street cars I use the OEM lower bracket and some delrin bushings to create the proper offset.
 

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Super Moderator
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Gene,
You may remember that I had one break on me, but I had another one in my bag of spare parts, from a different manufacturer and it has been on my car now for 4 years with no problems. The other thing is that they break due to the sharpness of the bend in the cheap steel that they use. If they used good steel with less carbon in it the problem would not exist. Anyway, another way to solve the problem would be to take a new bracket and remove the chrome from the corners and run a bead of weld in there. Then you could either just paint the bracket or have it re-chromed.
It stands to reason that the cheapo bracket broke because it was either a grade of steel with high carbon which work-hardened during the forming process, or the chroming process was done incorrectly. Any plating process (nickel and chromium included) induces hydrogen embrittlement to some extent. And that can make the material overly brittle, enough for it to crack.
 

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Yeah, Bob, . . .

Gene,
You may remember that I had one break on me, but I had another one in my bag of spare parts, from a different manufacturer and it has been on my car now for 4 years with no problems. The other thing is that they break due to the sharpness of the bend in the cheap steel that they use. If they used good steel with less carbon in it the problem would not exist. Anyway, another way to solve the problem would be to take a new bracket and remove the chrome from the corners and run a bead of weld in there. Then you could either just paint the bracket or have it re-chromed.
It stands to reason that the cheapo bracket broke because it was either a grade of steel with high carbon which work-hardened during the forming process, or the choming process was done incorrectly. Any plating process (nickel and chromium included) induces hydrogen embrittlement to some extent. And that can make the material overly brittle, enough for it to crack.
. . . lately I've had a lot of problems with that choming process as well!
:haha:
 

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It stands to reason that the cheapo bracket broke because it was either a grade of steel with high carbon which work-hardened during the forming process, or the chroming process was done incorrectly. Any plating process (nickel and chromium included) induces hydrogen embrittlement to some extent. And that can make the material overly brittle, enough for it to crack.
I have to agree with you. Some people buy a $10 bracket and want to get $35 worth out of it. You only get barely what you paid for with items made by ACME!

The bushing idea is more inclined to be the proper way to go.
 
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