Power limit of a 12 bolt? [Archive] - Chevelle Tech

: Power limit of a 12 bolt?


Malibu ss 64
Mar 25th, 07, 3:03 PM
Have a reubild 12 bolt rear everything except the housing is new. New Eaton 3 series posi, Richmond 3.73 gears, Tomīs 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

big gear head
Mar 25th, 07, 3:05 PM
The 12 bolt is usually good to around 600 HP. You should be fine with it at 500 HP and the automatic.

Malibu ss 64
Mar 25th, 07, 3:07 PM
Thanks for the quick reply.

Marcus

gnicholson
Mar 25th, 07, 3:52 PM
My 3200 lb. 70 runs 9's with a 12 bolt

Malibu ss 64
Mar 25th, 07, 4:12 PM
My 3200 lb. 70 runs 9's with a 12 bolt

But not with c-clips 30 splines axles and Eaton Posi?

Marcus

Nicks406
Mar 25th, 07, 4:30 PM
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.

gnicholson
Mar 25th, 07, 4:47 PM
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.

Malibu ss 64
Mar 26th, 07, 9:52 AM
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 :D.
Thanks

Marcus

gnicholson
Mar 26th, 07, 11:12 AM
the axles are the weak point and you replaced those.If you foot brake with slicks I dont see a problem.

covertolds
Mar 26th, 07, 12:09 PM
so you think it can handle some use even with slicks? :D.
Thanks

Marcus

You are really taking a big chance running slicks and c clip axles.

Malibu ss 64
Mar 26th, 07, 12:32 PM
You are really taking a big chance running slicks and c clip axles.
Life is a big chance :D. I know that the c-clip axles can break and ruin my quarters. But I wonīt 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 Iīve already have) itīs a carbon clutch eaton posi a year old.

Marcus

gnicholson
Mar 26th, 07, 12:57 PM
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.

covertolds
Mar 26th, 07, 5:31 PM
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.

gnicholson
Mar 26th, 07, 9:29 PM
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.

ToyzRMe
Mar 26th, 07, 10:12 PM
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

covertolds
Mar 26th, 07, 10:41 PM
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.


Geez, with your 25 years experience, you should know better than to say something as ridiculous as what you said. The guy said he has a car weighing 3400lbs. (assuming no driver), at least 500 hp, and a 2500 stall.

I sure wouldn't want to take the chances with a c clip axles and slicks. Stupid!!!

But hey, you seem to be very knowledged on the workings of a differential. I mean with 25 years experience and all.:thumbsup:

betcha618
Mar 27th, 07, 3:25 PM
Every car i get the first thing i do is a C-Clip eliminator. I don't think the C-Clip design is really good if you ever race at the track with slicks, and i think when you use slicks at the track you have to have C-clip eliminators.

Nicks406
Mar 27th, 07, 4:58 PM
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

I agree. C-clip elimnators are, to me, considered a rulebook saftey upgrade. The only stock axles I have seen shear/twist off at the splines are 55-64 GM 17 spline, 40 Buick axles, and some corvette stubs. Personally I have never seen a c-clip button "pop" off or a c-clip fall out or shred....maybe I am just lucky, but to me it's along the same lines as everyone who says all 400 sbc overheat. :bsflag:

There was a nifty test some rag did back in the early 70's with a chevelle or camaro, you know how it goes. Anywho, there rearend upgrade at the time was the GM Heavy Duty service pack spiders and side gears, a few more discs, and new GM axles. They ran the car into the mid 10's yanking the front wheels in the pics. I'll have to find it for the pictures alone!!


Again, your setup sounds perfectly fine for your combo. Post pics of the car and lets hope for one wheels up shot :D

big gear head
Mar 27th, 07, 11:52 PM
I built an 8.2 10 bolt with 28 spline Moser c clip axles. The car was a stock body '69 Camaro with a 383 and a 4 speed. I told the owner to take it easy on the rear end, but he didn't listen. He put slicks on it and raced it sevral times. The front wheels were in the air several times and the 28 spline c clip axles held up fine. The rear end is still in the car and working fine. I don't think a good after market 30 spline c clip axle is going to cause any trouble with an automatic transmission, street tires and 500 HP.

gnicholson
Mar 28th, 07, 1:08 AM
Thats what I was trying to say earlier.Iv'e seen a lot of people beat the hell out of the stock 12 and even 10 bolts without mishap in 11sec range st. cars. I think its a little risky but if you have a forged good quality c clip style 30 spline axle I think the risk is minimal ,but I may not have learned anything in 25 yrs. and am probably spewing stupid s#@*% again. Can I get an amen covertolds?

70 SS LS-5
Mar 28th, 07, 1:47 AM
I definitely agree that c-clip axles are not the "part-waiting-to-break" like many people want you to believe. I've built many very fast cars with mucho HP, slicks, etc. that used c-clip 12 bolts and never had one break.
mike

covertolds
Mar 28th, 07, 8:03 AM
You guys can believe whatever you wish. I think it's pure foolishness to run c clip axles and slicks with any kind of power. Why run the risk of snapping an axle and having the wheel and axle come out of the rear only to take the quarter panel with it.

It's your cars, so do whatever you want and I hope it bites you in the a$$ someday!

Calibu
Mar 28th, 07, 9:28 AM
It's your cars, so do whatever you want and I hope it bites you in the a$$ someday!Lets not wish or hope for bad things to happen to people, huh?

Wally
Mar 28th, 07, 10:22 AM
Lets tone this down a little and treat each other with a little respect please:cool: :cool:

Just for the record I used stock axles in my 68 Z/28, raced the car in E/stock, went 10.90s on 9 inch slicks. It twisted the ends of the axles, checked them on a regular basis.

I knew I was living on borrowed time so when they began to twist I replaced them. I had lots of stock axles and used them.

I have seen the axles come apart, breaking in strange places but never have I seen the C-clip fail. I think the minor diameter of the axle is just to small for a heavy car that really works, like low 1.30 60ft times.

Be nice to each other, that is one of the rules of Als place.

:yes: :yes: :yes:

covertolds
Mar 28th, 07, 12:08 PM
2 things:

I'm not saying that a C Clip is going to fail. I'm saying that if you break an axle with C Clips, good luck to ya.

Second, I am being nice.

betcha618
Mar 28th, 07, 12:51 PM
He is correct. No one said the C-Clip itself is going to fail. But if you snap an axle with c-clips the trire and half of the broken axle will come right out of the rear. if you have the c-clip eliminators and you break an axle it will not come out of the rear. Much better for it not to come out. imo.

Wally
Mar 28th, 07, 2:17 PM
2 things:

I'm not saying that a C Clip is going to fail. I'm saying that if you break an axle with C Clips, good luck to ya.

Second, I am being nice.

I know what fails when the axle breaks, I've seen the tire tear the quarter out of the car. Bad choice of words.

Your definition of nice and mine are some what different.

Wally
Mar 28th, 07, 2:23 PM
He is correct. No one said the C-Clip itself is going to fail. But if you snap an axle with c-clips the trire and half of the broken axle will come right out of the rear. if you have the c-clip eliminators and you break an axle it will not come out of the rear. Much better for it not to come out. imo.

For the work necessary to install the c-clip eleminators and the leaks that will soon begin, I would whink guys might be better served doing the housing ends and use the ford style bearing and retainer, or just by a good set of c-clip axles. They are less expensive than stock axles and a good solution.

I think that we have said about all we need to say on this.