Power limit of a 12 bolt? - Chevelle Tech

Transmission & Driveline Transmissions and Differentials

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post #1 of 28 (permalink) Old Mar 25th, 07, 2:03 PM Thread Starter
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Marcus
 
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Power limit of a 12 bolt?

Have a reubild 12 bolt rear everything except the housing is new. New Eaton 3 series posi, Richmond 3.73 gears, Tom´s KA 30 splines c-clips axles and offcourse new bearings. How much horsepower will it hold up for? Know that I should have changed the ends to Ford style ends. Have another 12 bolt laying around to build up later. The car is a 3400 heavy chevelle 64 with aut. and 2500 in stall. The engine will be a 489 with at least 500 hp, not planing on slicks with this rear but who knows?

Marcus

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
12 bolt Eaton posi Us gear 3.31 Toms KA 33 splines axles
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post #2 of 28 (permalink) Old Mar 25th, 07, 2:05 PM
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Freddie
 
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Re: Power limit of a 12 bolt?

The 12 bolt is usually good to around 600 HP. You should be fine with it at 500 HP and the automatic.
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post #3 of 28 (permalink) Old Mar 25th, 07, 2:07 PM Thread Starter
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Re: Power limit of a 12 bolt?

Thanks for the quick reply.

Marcus

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
12 bolt Eaton posi Us gear 3.31 Toms KA 33 splines axles
Malibu ss 64 is offline  
post #4 of 28 (permalink) Old Mar 25th, 07, 2:52 PM
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Gary
 
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Re: Power limit of a 12 bolt?

My 3200 lb. 70 runs 9's with a 12 bolt
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post #5 of 28 (permalink) Old Mar 25th, 07, 3:12 PM Thread Starter
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Re: Power limit of a 12 bolt?

Quote:
Originally Posted by gnicholson View Post
My 3200 lb. 70 runs 9's with a 12 bolt
But not with c-clips 30 splines axles and Eaton Posi?

Marcus

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
12 bolt Eaton posi Us gear 3.31 Toms KA 33 splines axles
Malibu ss 64 is offline  
post #6 of 28 (permalink) Old Mar 25th, 07, 3:30 PM
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Re: Power limit of a 12 bolt?

Your setup sounds great and will handle 500+ with an automatic. Im sure a few people here can give you the limitation of some 12 bolts, but the worst I have seen was an axle tube bend at the housing - the spool and gearset were okay. It was in a 10.0's 68 Malibu. There has been one pinion gear breakage in my expirience but thats not because it was a 12 bolt, I'm guessing the gears may have had a defect.
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post #7 of 28 (permalink) Old Mar 25th, 07, 3:47 PM
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Gary
 
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Re: Power limit of a 12 bolt?

No ,I have a spool ,bigger axles, ford bearings,steel caps, and a braced housing.I was just trying to tell you that the 12 bolt will take a lot of power properly modified. I think your combo is more than adequate for what you have.
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post #8 of 28 (permalink) Old Mar 26th, 07, 8:52 AM Thread Starter
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Re: Power limit of a 12 bolt?

I forgott I also have a TA aluminium cover with studs for the posi bearingcaps, so you think it can handle some use even with slicks? Will build the other rear I have when money comes around .
Thanks

Marcus

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
12 bolt Eaton posi Us gear 3.31 Toms KA 33 splines axles
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post #9 of 28 (permalink) Old Mar 26th, 07, 10:12 AM
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Gary
 
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Re: Power limit of a 12 bolt?

the axles are the weak point and you replaced those.If you foot brake with slicks I dont see a problem.
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post #10 of 28 (permalink) Old Mar 26th, 07, 11:09 AM
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Re: Power limit of a 12 bolt?

Quote:
Originally Posted by Malibu ss 64 View Post
so you think it can handle some use even with slicks? .
Thanks

Marcus
You are really taking a big chance running slicks and c clip axles.
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post #11 of 28 (permalink) Old Mar 26th, 07, 11:32 AM Thread Starter
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Re: Power limit of a 12 bolt?

Quote:
Originally Posted by covertolds View Post
You are really taking a big chance running slicks and c clip axles.
Life is a big chance . I know that the c-clip axles can break and ruin my quarters. But I won´t use it with slicks often just a few times/year, and will build up another 12 bolt with ford style ends and 33 splines bolt in axles and 1350 yoke, but then will the posi be the weak line? (going to change the spider gear in the one that I´ve already have) it´s a carbon clutch eaton posi a year old.

Marcus

Chevelle Malibu ss 64
489 BB with parts from Lewis racing
Alumitech radiator with dual spals
Th 400 Edge 9.5" converter
12 bolt Eaton posi Us gear 3.31 Toms KA 33 splines axles
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post #12 of 28 (permalink) Old Mar 26th, 07, 11:57 AM
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Gary
 
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Re: Power limit of a 12 bolt?

The only way to find the absolute limit of a part is to push it to the limit. As long as you dont use a trans brake your not going to have a problem.You bought good quality axles,right. slicks and foot braking will not hurt it unless you got a hold of some bad parts.i.e. metalurgy, heat treat ,etc.
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post #13 of 28 (permalink) Old Mar 26th, 07, 4:31 PM
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Re: Power limit of a 12 bolt?

Quote:
Originally Posted by gnicholson View Post
As long as you dont use a trans brake your not going to have a problem.You bought good quality axles,right. slicks and foot braking will not hurt it unless you got a hold of some bad parts.i.e. metalurgy, heat treat ,etc.
Whatever.
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post #14 of 28 (permalink) Old Mar 26th, 07, 8:29 PM
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Gary
 
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Re: Power limit of a 12 bolt?

Whatever what, instead of being an as#@*&% why don't you tell me where i'm wrong .I'm sure your much smarter with a ton more experience so lets here it. I've only been building differentials for 25 yrs. so I might be missing something.
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post #15 of 28 (permalink) Old Mar 26th, 07, 9:12 PM
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Re: Power limit of a 12 bolt?

I copied this reply that I posted in a previous thread so I didn't have to type so much.

I bought a set of Henry's Machine axles in 1973 to put in the 12 bolt in my 3450lb. '67 Camaro that had a 427, 4 speed, and 4.88 gears. The car ran mid 11's at 118 on slicks back in '73-'74. It was a stick car, and was launched at 6500-7000 on slicks. This car was my daily driver and street racer for years and had plenty of hard miles on it when I retired it in 1978.

The older guys should remember that, back then, the major aftermarket axle manufacturers were Summers Bros. and Henry's Machine.

These axles were standard length 30 spline axles with stock c-clips holding them in.

I ran the same pair of Henry's axles in various Nova and Camaro projects I built since that Camaro over the years and beat the snot out of all of them.

About 1992 or 1993, I sold them to a buddy that was building a street/strip '55 Chevy with a 468. He put a Camaro 12-bolt in it, and needed axles.

These same axles that I bought in 1973 have been in his '55 for the last 13 or 14 years of street driving and high 10/low 11 second passes at the track.

These axles have never EVER given 1 minute's problem, although he told me that the splines are FINALLY starting to wear a little bit. I think that could be expected after 33 years of hard use.

Remember, this pair are only the stock 30 spline with stock c-clips and bearings, so form your opinions from there.


Randy

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