Olds/Pontiac Rear vs 9" Ford

What case did you have? I hope it wasn't a three rib.

 

A little late to this thread but I noticed that the issue of horsepower to turn came up. None other than the Chevy hero Bill Jenkens answered that years ago. While competing in Pro Stock he never missed a chance to keep the advantage over the competition. He had all of the then popular rearend combinations tested in an effort to see if any power could be saved. The result was the 12 bolt was the least power robbing design.
The only problem is that to make a 12 bolt live in that environment you spend big bucks to flesh out the total package.

Frank

 

Ok, A lot different opinions. First the application must be considered. High power soft hit, high power hard hit, mid power hard hit and mid power soft hit.

High or mid power hard hit is going to break stock axles and posi parts fast. High power and mid power soft hit will survive a long time with stock parts, but will fail eventually.

Examples: 1. My black 62 (550 HP) will break any posi in one run with after market axles. It hits really hard. With 16lbs in the slicks it crushes the tire down to one inch off the rim on launch. Picture available of tire. Stock housing with back brace.

2. The green car in the picture showed earlier, I have raced against for 40+ years has only broken stock 31 spline axles. His car hits softer than mine. Mine pulls wheels in first and second , he barely gets them off in first.

3. My red 62, 532" blown, injected street car (1000 HP dyno tested) has never broke anything. But it has a 3" heavy walled axle tubes, 3 rib Eaton posi. and back brace. It does not hit anywhere as hard as the black car.

I do not how you would pull the pinion gear out, as I have not in 40 something years beating the crap out of my cars.

I spoke to Fabcraft 2.5 years ago on the subject of Alum. housings and if there were a demand for them, But I hope they come out with them.

Please note: Never use a Dana Posi. Too weak for any thing. None were used in the examples above.

 

Why would you in a 2000 lb car with an automatic? You could run an 8 3/4 mopar in a combo like that without any problem. I would be much more concerned about an 11 second G/MP car.

 

There seems to be some real misconceptions floating around about what sort of combos are hard on rear-ends. LOTS of front engine fuel cars ran 8 3/4 mopars and earlier small housing Olds rears @ 2000hp without any problems. Gave more room for the drivers legs. Minimal shock loadings, breakage is not an issue.

Heavy car=breakage Light car=easier on parts
Stick= breakage Automatic=easier on parts
Heavy flywheel= breakage Light flywheel=easier on parts
Trans brake=breakage Foot brake= easier on parts
No marcel=breakage marcel=Easier on parts
lower first gear=breakage taller first gear=easier on parts
Hard hook=breakage tire spin= easier on parts
mettallic pads unsprung hub=breakage slipper clutch=easier on parts.

 

..... which is why you can buy a Ford diff housing that accepts 12 bolt internals.

 

What's marcel?

 

There is a reason you see 9" ford rears in most serious high perf. applications, and as said much easier to get parts for. Mike

 

The marcel is the wavy piece of spring steel you see in between the facing material on most clutch discs. It absorbs some of the initial hit, softens engagement, and reduces chatter.

 

The reason you see so many 9' fords is most car guys are monkey-see, monkey-do. Its like small-block chevies in everything, and powerglides in race cars. I have actually seen guys on the internet talking about wanting to pull 8.5" ten bolts to replace them with 9" fords in 12 second cars. Why? cause it said so in the magazines...

 

Bump, still hoping to hear about the 9.25 Mopar swap...

 

Amen to that.

 

When people talk about the Olds/Pontiac rears, how old are we talking? I have one that I'm thinking about using that I think is a '49 or '50, were those early ones good too? Or does a guy have to get up into the 60's?

 

um,, sorta.

if your building a rear end for a car its cheaper to build a 9", and you end up with a stronger rear end as a bonus.

for the powerglide thing,, the reason everyone uses them is because they work perfectly and are fairly hard to break if built to suit the application. most cars under 3200 lbs will pick up a .10th or more when switching from 350/400 to a glide.

Its also nice because if you break something the guy in the pit next door will probably have what you need.

I have seen 12 second cars spin the pumkin on a dana style rear end, and it fucks things up real bad. why spend that kind of money to build something that has some many weaknesses engineered in.

yeah there are some monkey see monkey doo guys, but when the monkey is smarter than you, you should do what the monkey does.

 

The '57-59 Ford rear isn't a bad looking rear either.

I started building Fords way before I built GMs for myself. But we even swapped the Olds rear into those if that makes any difference.

I'm putting a 9" Ford in my project because I have it but if I had an Olds or Pontiac with a locker I'd use that instead and save the Ford for something else.

If you can find the pieces and maintain it well you will like the Old/Poncho rear real well.

Something I found out on here a couple of years ago; for a housing you can use the easier to find '59-'64 Chevy with the olds punkin. You'll have to trim all the junk off of it but its another avenue to get you where you want to be.

 

'57-'64 is preferred, beefier and posi's available. Earlier rears are fine for hot rod use.

 

i can tell you first hand if you can get set up with the olds stuff and get the gears you need the olds is far stronger than the ford ! BUT if you have nothing and are not sure what your needing and having trouble finding the olds parts run the ford its cheaper in the end some guys think the olds parts are gold

 

Yes, I hear this all the time, it says so in Car Craft. First off, if you head out to your local auto wrecker and buy a 9" ford for a couple hundred bucks. 90% of the rears you find are going to have a single rib carrier, which is a REAL weak POS(ask me how I know). Even the 2 rib WAR cases are REALLY hard to find now, and you can FORGET about finding a nodular case in the wreckers. So right from the get-go you have to go out and buy a new nodular carrier which is going to cost you $250-$300. Then you have to buy a pinion support, because the one that came with your single-rib carrier wont work thats another $100. Posi, gears and axles are a wash, because you are going to need that stuff for any rear. So if you have a Nova with an 8.5" ring gear ten bolt, which properly set up is a DAMN strong rear, you are into the 9" for $550-$600, and you havent even STARTED yet.
If you REALLY do have a car with enough power to break a decent 8.5" ten bolt(think nines here), you can buy a Dana 60 out of a truck, and weld Mopar ends on for less than a hundred bucks, and most of them will already have a usable limited slip in them. Whatever rear you use, axles and gears are a wash, you are going to have to buy them anyway, because most tracks arent going to let you run any car that is quick enough to warrant a rearend swap without aftermarket axles anyway.

 

Its down to these two housings for my project. I am starting to gather parts for a circa '67-'69 period hot rod build, either the smooth-back 9" or the Olds is the ticket. An earlier olds would work well too,and have the period look I am after, but I think parts are even harder to find. I havent been able to find ANY source of gears for the earlier rear, and I am planning on 4.88s, so the gears it comes with are not going to work. I am still hoping to hear more about the 9.25 mopar swap, as these rears are really common in the wreckers with posi's and this would be a really good way to go. But I have been checking on this and getting no-where.

 

Only if the chassis is junk. If you put the line at 3200lbs, REALLY junk. The tall first gear is more forgiving if you dont have the ability to hook the car. Anyway, I dont want to turn this thread into a Car Craft dogma debate, so I will drop it here.

 

George you can stuff the 9" punkin in the '57-'59 rear. They were actually an 8 3/4 rear from the factory but the 9" stuffs right in there. May make finding bits easier.

the '58 and '59 were actually a dimple back as opposed to a true smooth back like the '57. I have a '58 housing hangin on the wall. Its chopped down pretty short.

I look at it this way, I got ford stuff out the wazoo (I'm absloutely sure what a wazoo is I think its like a ying yang) and would like to have Olds/poncho stuff. You might as well be on the other side of the planet from me so you must be loaded down with olds/Poncho stuff

 

Which is stronger in stock form?

1) O.P. vs. ford 9

2) O.P. vs. chevy 12 bolt

3) O.P. vs. chevy 14 bolt (semi or full float i'm not even sure if it came both ways?)

 

The reason fords are so much stronger is the overlap and angle of the dangle....basicly ford 9 has 3 teeth in contact at all times...here is a very good wright up on rear ends that exsplains everything...
http://www.truehi9.com/gears2.html

Personaly.. id go ford 9..

 

Its called hypoid angle. Same reason why they take more power to turn. And there are many more factors that enter into the strength of any given rear. I have a buddy that pulled the pinion right out of a single rib 9" carrier filled with new parts on the third pass. Not a real killer car either, 3300lb 12 second small-block/4speed car. Broke the nose right off the casting. He was shocked. We werent...

 

Whats a 9-1/4 mopar? Do you mean a Dana 60. Dana 60s are the heaviest rear on the market and do not have a drop out center. But if you want to run them they are strong.

Pat

 

No, the 9.25 is Mopars in-house replacement for the Dana, it is a pretty strong rear in its own right, and parts are REALLY common. It has been used in tons of Mopar pick-ups for the last 3 decades, so limited slips are REALLY common in the wrecking yards. It is a salisbury type rear, we are talking about weather the diff (and ring and pinion) itself can be swapped into the olds, not the whole center-section.

 

Good to know. Thanks for the tip. I am still hoping to do the mopar diff into the olds, if that turns out to be do-able, it will be a matter of which housing I can dig up. I am pretty sure I can come up with an early 9" housing I know a few guys with fords from that era, a couple of them have parts cars.
I thought all the early housings were smooth back. Can you send me a pic of the back of your '58 housing?

 

Consider it done. I'll post one here besides if it helps anyone.

 

boy you sure sound like an expert.

 

If I remember correctly, pre-'57 Pont. had smaller diameter axles also.