8 inch ford +bbc

working on a 41 ford cpe. have 496 bbc rated at 480 hp and stage 2 th350. car has an open 8 in. ford rear. can get a 8" trutrac pig on ebay supposidly rated to 550 hp for around 800 bucks. will this hold up to occasional thrashing on the street or shall i start shopping for a 9 inch?

 

It's not the center section that will fail as much as the skinny axles. If you get the rear to hookup things begin to happen quick. I'm a supporter of 9 inch trac loc rear with 31 spline axles. I've had very few failures.

 

Might as well swap out the rear end now and save the towing charges later. Skinny tires will spin before hooking up enough to break the axles but the kid with the Honda Civic will blow your doors off.

A good 9" or 8.8" out of an Explorer will handle all of the power and most come with limited slip and 3.73 gears.

 

Depends on what you mean by thrashing on the street. Big Sticky tires and a trans brake? NO it won't last. Average street tires and the occasionall burn out? Problably last a long time. Shock is what breaks rear ends and that comes from traction, if you don't have any, you won't have a problem.

 

How long that axle will last depends on your car and how it is driven. Unless something isn't right in the engine or trans, there's no question the 8" is the weak link in the drivetrain.

 

Having a weak link in the drivetrain is not a good idea.

 

If you ever hook up the 8-inch will break. BTW 8-inch 28 spline axles are same as small bearing 9-inch 28 spline axles, so they are not really the weak link. It is the center section ring and pinion and other small parts inside it.

If you have your current 8-inch, get a small bearing 9-inch housing narrowed to fit and you can use your current axles as long as you get 28 spline 9-inch center section. Yes, 31 spline or more is stronger and better, but you could do a low-budget upgrade with your current axles and a narrowed housing. Either way you are buying a new center section. This should hold up fine and not break unless you have slicks and transbrake.

 

i thought as much. thanks. have a line on a 9" at dimension i need 51" with axles. its as good as bought. thinking on running 325 gear. all street use some highway. any thoughts?

 

Should be just fine, The 496 has enough torque to overcome the 3.25 no problem. You could run a bit looser (higher stall) converter and it would work real nice.

BTW, now that you have got rid of the 8-inch rearend, your next weak link is the Turbo 350 trans. Even if you put the hardened intermediate sprag, which helps, it is still a matter of time. I broke two T350's in my drag Camaro before getting mad and putting a PG and transbrake in, and I was running about 450 hp 454. Never happier, made it real easy to race then. But you are driving on street, just don;t let off gas in second gear, that loads the weak sprag.

 

thanks for the off the gas advise did not know. have 2800 converter. would have to chop up x frame to accomidate th400. tailshaft is in tunnel with 350.

 

We had a client with a 69 Mustang at one time, it was a "girls" version with an 8" rear axle. The guy put in a 390 with a mild cam and aluminum intake, headers, blah, blah, blah. He came back 2 days later for the 9" we recommended. The pinion drove right out the front of the case and he was running Pro Trac N50 tires (remember those?) so I don't think he had ultimate traction. Your 496 will make a wee bit more TQ than that 390 did, at least I think it will

 

Do what you want ... But consider this

Back when Ford started with the Mustang ... Ford installed the 8 inch rear end. BUT when they upgraded the 289 to the Hi Po 289 (271 HP soild lifer engine ) Ford installed the 9 inch. In the later models ... whenever the HP was more than 250 or so ... Ford installed the 9 inch. If the HP was less than 250 or so, they installed a 8 inch.

It was very common for a early 4 speed Mustangs ( V8 ) to break a 8 inch rear end ... in the 60's and early 70's. Most with any horsepower ended up with a 57/58/59 Ford car rear end ( the big bearing one ) The big bearing ones have the larger, better axle shafts.






Not my opinion ... just the facts.

 

WONT LAST , But may be a blast breaking it. When i first put my duece together I was on a budget,asked a ton of questions and was told a 8 inch would be fine ,well the first summer i went through 4 center sections breaking cross pins and exploding the rest of the of the guts, with a small block no slicks on the street . Put a 57 wagon 9 inch in stock carrier 389 gears and a track lock . Worked great till i put on slicks and took it to the track and exploded the single rib carrier[and drive shaft ,1 muffler,and twisted i axle.] now its a nodular section and NO issues . SOOOO again a 8 inch will be a shit load of fun exploding behind your big block PLEASE send footage !!!

 

I cant believe no one has said anything about the th350, even "stage 2" or whatever, those things are super weak.

I'd expect it to go before the rear.

 

I ran a 8" with a lock right and stock axle's into the low 10's in the .25 at the drag strip in a 65 ford falcon for 3 seasons of street and drag Luce. Car was making 500rwhp and on a 8"slick and a food brake.

That said it was a time bomb and on borrowed time but it lasted for me.

 

Here is what happened to my (b/4 & after) 1957 28 spline (Posi) 9" Ford rear end behind a 1972 Corvette 454 BBC w/450 hp & M21 4 sp Muncie (and engine mount) after street racing but beating a Toyota Supra by 6 car lengths...I suggest you go to Strange or Currie..this cost me $1150 to fix...

 

I have been running a 8" for years the turns out the 700R4 was the weak link

 

This is your answer.

 

What , specifically about a T350 is "weak" ?

 

496 and 8" Ford combo is a big spend on an engine and not wanting to upgrade to what it twists on. It will stay together for a little while if the tires don't have much traction capability.
A stock 9" without upgrades will splatter just the same with good traction and engine torque.
Need part numbers and dollar figures on what the driveshaft part will cost because of failures to happen? I like Dutchman stuff because of a 1200 hp street truck that MY driveshaft lives in. I like traction capabilility that will let you know when the tires and suspension give up and rattle your teeth.

 

I have never broken a Ford 8" on the street,.. (maybe I was just lucky) I have however tore up a couple GM 10 bolts,... I mean "really tore up !".

Now for a little grumpy old man statement,... I have always had a lot more fun with a mild built engine in a street driven Hot Rod,.. Than a big horsepower rig,... They need more attention, they draw more attention (The unwanted kind),... and they usually have more problems, when you drive them on the street a lot,.... IMHO.


"Everybody today wants to choooose there rear axles,... Whats the strongest ?, whats the coolest?,...what looks the best ?!!!,...

Why,..Back in my day,. We didn't haaaave any choices,.. we used what ever junk we could find,.. we made it work !,.....And that's the way it was,..... And we liked it !,.. weee Loved it!,...There we were, a bunch of crazy punks driving up and down Woodward,.. Big engines with blooowers sticking through the hoods,... Rumpty-Rumpty,.... open headers so loud you couldn't think straight, So loud it would make your ears bleed!,... Racing alllll night, until our rear ends exploded !!!!,... throwing shrapnel in every direction,... wounding alllll the other street racers,...... Aaaaand we liked it !!!!!

Soooo there we were,... A bunch of deaf, bloody punks, handcuffed in the back of squad cars heading for the "Pokey" with our rear ends blown to smithereens !!!!!

AND WEE LIKED IT !!!!,...... WEEEEE LOVED IT !!!!!!!!"



(Alright guys,.... Ah,... I'm sorry,.. just couldn't help myself,... )

 

I run that ratio/9" behind a sbf--65 is right at 2350 rpm. I don't drive it hard but it runs real well down the road....

 

I'm thinking ,after the first problem, you should have found a new trans builder.

The hardened int. sprag race is a $30 item . The sprag race and int. clutches stop the direct drum ,which is spinning in reverse at roughly twice engine rpm, in low gear. If it doesn't break then, certainly letting off the gas in second gear isn't going to do a damn thing.
There are other minor things that need attention to make one bulletproof , but they very dependable for a STREET car.

I've seen 8 sec Super Stockers never have a problem.

 

Ha!

LOL!

 

thanks. trans builder is 76 and pretty knowledgeable. not to concerned with trans. how about a coil spring rate for must.2 to hold big block

 

I am not the trans builder, but after breaking TWO of the hardened sprags and not weanting to get the real high dollar T400 style sprag, I went to a PG and never had any trouble. I was told letting off the gas in second was hard on the sprag, could be my memory not correct.

Not saying a T350 can not be built to take some power, but for the orig thread starter, after getting rid of the 8-inch, that T350 is next weakest link. Spend enough money on custom parts and it may not be.

 

It may be hard on the sprag wear, but jacking the line pressure up out of this world is hard on them too. There are other ways to make a T350 shift firmly.

The point is ,the OP has a STREET car. You're talking about a drag race car with ,what sounds to me like questionable mods to the trans.
You had a bad experience. Many people don't.

Here's one: 4400 pound Pontiac station wagon, 455 GTO engine, T350 trans.
For the most part, this was a tow vehicle for the open trailer and race car.
But ,it was also bracket raced regularly. Ran in the mid 14's, with 2.73 gears.
Only non stock part was the hardened sprag race. After 8 years of abuse, the fluid would always stay bright red, and we didn't change it all that often. No issues whatsoever.
There's nothing at all wrong with a T 350 in the poster's application, if it's built properly.