So what happens if you keep the old /6 rear end after 360 swap?

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myasylum

myasylum

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I have a feeling I may run out of cash doing this...
So, what would happen if I kept my old stock rear end in (From the /6) after the 360 swap?
Would I just not be able to really stomp on it with out breaking something, or what would happen? Thanks!
 
Nice guide dude! Thanks! Yea... I think it's a 7 1/4... Damn it!
The car is in starage right now too, so I can't check for sure.
What about the stock /6 tranny? Are those junk too?
 
If it's an auto trans it won't work with a V8 but I think the manual transmissions will bolt up to the bellhousing. Don't know how sturdy a manual trans from behind a 6 would be. Might work.
 
myasylum said:
Nice guide dude! Thanks! Yea... I think it's a 7 1/4... Damn it!
The car is in starage right now too, so I can't check for sure.
What about the stock /6 tranny? Are those junk too?
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904s are cheap and easy to find, simple to build too. The shift kit will cost you more that the trans. Do be careful with the rear though. Find you an old BroncoII and take the 8.8 posi out of it, they change pretty easy and most were 3.73's.
 
My 73 Scamp came stock with a 318/904/7 1/4 I put on a 4bbl and a set of side pipes, drove to the carwash, washed my car, pulled out of the carwash without getting on it I just pulled out onto the road and KACHUNK!!! I limped it home and found a 8 1/4 at the local yard.
 
renegadebuck said:
904s are cheap and easy to find, simple to build too. The shift kit will cost you more that the trans. Do be careful with the rear though. Find you an old BroncoII and take the 8.8 posi out of it, they change pretty easy and most were 3.73's.
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a 904 built to stand up behind a 360 that's going to see some lead foot action is MORE than your BASIC rebuild .
 
Bought a 74 Duster with a 318/904/7.25 last week and it came with a tore up rear with Big bolt. Went to the field and got another from a 4 dr dart donor and cleaned it up and installed it. I think the issue and the longevity of the unit is very closely related to ones ability to use it as a driver and not a racer. It might last a granny for many years but i'm sure you aren't a granny. The Duster i bought with the bad rear did come with 12" tires on the rear with a 7 1/4 in the back. I wonder what happened? Duh.... The small unit will last you until you have the ability to afford the change you want but you will have to keep your foot out of it and run not so big tires.
 
My 8 1/4 takes a beating pretty well, just never stomp on it from a dead stop....

I have a 318 2bbl, with hookers, duals a 904 and the 81/4.
 
JohnRR said:
a 904 built to stand up behind a 360 that's going to see some lead foot action is MORE than your BASIC rebuild .
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I've been shifting mine at 8k for years, never a problem, It's beefed up a little with some Fairbanks goodies, but for the weight difference and the ability to stay together, a 904 is plenty tough enough for a 360. My 340 is taken about as far as I can go without juice or a blower, and it's taken all I could give it.
Offy intake, 636 Lunatti solid, 207 intakes, 180 exhausts, Intake and heads matched ported to about a hair between ports, 850 dominator, 4k stall, MSD, Accel dis.
 
my 7 1/4 lasted to the paved rd one mash on the gas pull it home with the tractor . not ring an pinon, but the spider gears went through the back cover
 
The 7-1/4 is marginal with a slant 6 and inadequate with a 273. Add any additional torque and the chances of a 7-1/4 living are reduced. IF you avoid stressing it with unequal wheel traction in such conditions as rain, snow, sand on pavement, acceleration around corners etc. it might live for a while. If you think you are going to exercise the torque of a 360 you will most likely be able to examine your spider gears from outside the case. Drive it easy and it may last for a while, but plan on an upgrade to, at least, an 8-1/4 sometime in the future.
 
myasylum said:
I have a feeling I may run out of cash doing this...
So, what would happen if I kept my old stock rear end in (From the /6) after the 360 swap?
Would I just not be able to really stomp on it with out breaking something, or what would happen? Thanks!
Click to expand...

Not much if 7.25 lol
 
myasylum said:
I have a feeling I may run out of cash doing this...
So, what would happen if I kept my old stock rear end in (From the /6) after the 360 swap?
Would I just not be able to really stomp on it with out breaking something, or what would happen? Thanks!
Click to expand...

I'm not even going to read the thread. I'll answer it in one word.


BOOM!
 
BOOM? Not necessarily. The 2 8.25's I killed died with a horrible CUH-LANK! and then a whole lot of other horrible noises...
I killed one rocking a $700 Volare Road Runner out of a snowdrift, and grenaded the one in my Aspen R/T beating the snot out of it. (Only after I had an B body 8.75 ready to replace it).

Contrary to popular opinion, you can blow up a Dana 60, but just like a Torqueflite, it's ugly when it lets go.
My 3/4 ton 77 D250 had a 440 in it, and one or more of the spider gears exited through the rear cover at 60 mph on the interstate. I coasted to the shoulder, got out and looked underneath, and saw what looked like the Alien had exited someone's ribcage...a real ugly hole blown outwards with jagged shards of metal surrounding it. Brrrr.
Made a BOOM! sound first, then another sound like someone kicking an several cases of empty Pepsi bottles off the back of a truck....
If you intend to beat on your 7.25, take a cell phone with you and prepare to walk! Hope your friends are home!
Best of luck to you,
alan627b
 
That,s funny,but I think I got one on ya.My 8 1/4 behind a 450hp 340,4 speed.I launched off the line in and hit 2nd gear and ka-thunk,ka-thunk,ka-thunk.I thought I blew a ujoint cause of the repeated sound and then wham!Looked out the window,and there goes my wheel with 1/2 the axel still attached.Well I,ll tell ya I touched cloth in my shorts!LOL!Thank god I didn,t cavein my 1/4 panel(no c-clip eliminators)Now have 8 3/4 4.10,s.A 71/4 would be like riding on toothpics with a 300-350hp 360.When it goes,you could do some serious damage!Don,t even attempt it!!My 2 cents.

Picture 010.jpg
 
Alan, that was funny, not at the time I bet, but a good tale.

Petty, nice axle shot! Yikes!
 
I must've had better luck than most.. I converted from slant six to a 360 2 years ago.. wasnt enough money in the project for a new rear, so the 7 1/4 stayed in.. Its a sure grip 7 1/4 and I drove the car for 2 seasons this way.. and I was in no way gentle. Even drove it on a 3 hour, one way trip to the Mopar Nats last August. Burnouts in the alley, you name it (with the exception of something rediculous like a neutral drop) and it just kept taking the beating.. Decided 2 seasons was enough pushing my luck though and bought a complete 8 3/4 at the Nats... 7 1/4 was still good when I pulled it out.. must be a fluke.. All I have ever heard is that they cant take any punishment LOL .. this thread confirms it.. lol
 
SpeedracerX said:
I must've had better luck than most.. I converted from slant six to a 360 2 years ago.. wasnt enough money in the project for a new rear, so the 7 1/4 stayed in.. Its a sure grip 7 1/4 and I drove the car for 2 seasons this way.. and I was in no way gentle. Even drove it on a 3 hour, one way trip to the Mopar Nats last August. Burnouts in the alley, you name it (with the exception of something rediculous like a neutral drop) and it just kept taking the beating.. Decided 2 seasons was enough pushing my luck though and bought a complete 8 3/4 at the Nats... 7 1/4 was still good when I pulled it out.. must be a fluke.. All I have ever heard is that they cant take any punishment LOL .. this thread confirms it.. lol
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yes you were lucky , I blew the 7 1/4 in my dad's 72 duster when I was 17 and it had the stock 318 with a 2 bbl and a shift kit in the stock 904 still .

The first 489 3.23 chuck didn't last long when the car was switched to a 340 and a 4 speed
 
I even put a shift kit in the 727 while the 7 1/4 was still in there.. guess I will thank the mopar gods for the fluke rear end... my 8 3/4 has a 742 case with 323's ... that should be plenty for all I intend to do with the car.. I really only want a cruiser for my honey and I, but when Im at a light, if I want to smoke the tires off a little I shouldnt have to worry as much as I did with the 7 1/4 LOL ...
 
It's funny...the fastest vehicle I have yet owned only ran a 14.80 et, and most of them were mildly modified at best...but I still have manged to break a lot of stuff! Ah, youth...
The same 440 equipped D250 grenaded a 727 in spectacular fashion, a horrible BANG! and that case of pop bottles sound again...I think the over running clutch exploded.
At any rate, it wasn't pretty looking under the truck and seeing it bleeding ATF all over the place...the 727 came out in at least 5 ugly pieces, and that was what i could find!
I am a firm believer in blast shields now, after this fiasco. There is a reason the NHRA requires a blast shield on 727's and turbo 400's a second before any other auto trans, or at least that's what the rule book used to say.
Any T-flite is a grenade with the pin pulled, if the u-joints ever fail, or so say the good transmission guys. A u-joint failure under power can cause the over-running clutch to fail the next time you beat on it. A bolt in sprag is always a good upgrade at rebuild time.
Let's be careful out there!
alan627b
 
Pettyblue,I saw a guy at our track do that exact same thing in a 70 Duster, his 1/4 panel wasn't so lucky as yours!
Speaking of Dana's...after I blew the Dana 60 up in the Dodge, I got another one at the junkyard and a buddy helped me stick it in the bed of the truck. Sometime later, I got the blown rear end out,and went to get the replacement out of the truck bed. I couldn't lift that big old pig out by myself, so....I got in the box and pushed it out with my feet!
That Dana hit the driveway pretty hard, but didn't get hurt a bit! Took one hell of a chunk out of the driveway though!
I guess they're pretty tough! 2 tons of fun...no wonder they last in dump trucks so well! LOL!
alan627b
 
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