7 1/4 rear work with 318?

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mkayers

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Will a 7 1/4 rear end live with a 318 as long as I'm not beating on it all the time? I'll eventually switch to the bigger rear end but would at least like to use this one to cruise while I'm looking for one.
 
My 318 '73 Dart parts car came with a 7.5 from the factory. Surprised me when I looked under it. Thought I would have at least scored an 8.25 rear. Ended up finding an 8.25 in the local scappie for $100 or so for the car I'm working on.
Cheers
 
mkayers said:
Will a 7 1/4 rear end live with a 318 as long as I'm not beating on it all the time? I'll eventually switch to the bigger rear end but would at least like to use this one to cruise while I'm looking for one.
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I have a 318 with Comp XE268 cam and 904 with a shift kit in front of a 7 1/4. It should hold up as long as you don't do any neutral drops, excessive burnouts, or launch extremely hard. You can get on it once and a while and it will hold up, but don't expect it to last a long time if you are ricky racing all of the time. I think this goes for any rear really, as anything can be broken. This all is true if the rear is in decent shape,of course, with no vibrations or noises at the moment. Over time, sometime in the future, you may want to shop around for a 3.23 or 3.55 geared 8 1/4 rear or a 8 3/4, although the 8 1/4 would suffice and be much cheaper in the end. Im on the lookout for a 8 3/4, as I will be at the track occasionally. As long as you are not thrashing on it and maintain it, it should hold up ok. Have fun.

-Justin:toothy10:
 
I still have the original 7 1/4 under my 72 4 dr. dart. Its held up to a lot of abuse, lately its been making a winding noise though. LOL. I am planning on swapping in a 8 3/4 w/ a 2.94 suregrip & sm. bolt axles this winter. I use the car daily so I don't need a low gear.
 
Beat The 7 1/4 To Death! Chances Are There Is Someone In You Area That Is Scrapping One Right Now. They Are All Over And Were The Standard In Most Abodies /6 Or 318 Until 72 Or So. Heck If You Lived Close Enough I Would Give You The 2 I Have Waiting For Their Time In The Shredder Right Now....
 
My wife's '72 V8 Scamp came with one from the factory. I also have one in my '72 Duster with a 318 and 4 speed. I have been known on occasion to bang a gear or two and it is still fine. I have an 8 3/4 to put in eventually but for right now I'm gonna stay with the 7 1/4.

Chuck
 
Anyone want to take bets on how long the 7.25 last in my Scamp behind 500hp ?
 
I bet it will last longer than we think or expect it to as long as you use street tires.


Chuck
 
It Will Probly Do Just Like The 8 1/4 Did Behind The Stock 72 440 I Had In My Old 85 D100 Truck. The King Pin In The Carrier Will Decide To Become One With The Universe And Scatter Itself To The Far Corners Of The Earth. And That Was With A Stock Tranny, Colum Shifting At 4500rpm....
 
WONTGETDUSTED said:
I $10 Bet Less Than 1000 Miles!
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Like Chuck was saying, it will last longer than we expect, as long as prudence is taken while driving the car. I have seen folk with not much experience in Mopars or automotive mechanics,mind you, that just want two things: lots of power and a big engine. What they don't look into is that the rear differential plays an intrigal part in the whole system and often disregard it. For instance, I have seen individuals who have placed big blocks in A bodies and left the 7 1/4 in place. No breakage. Like said, its not a guarantee that anything will break or survive. It all depends on the conditions its subject to. I romp on my ride fairly hard at times and the diff never howls or vibrates and is visably spotless from the outside. I run premium oil in it and its well maintained. I also have a 76 Valiant with a slant and A-833 4speed. I bang the gears pretty hard sometimes to get it up to speed and ut holds up great. It has well over 300,000 miles on it and the motor was rebuilt with a hotter cam. I bet it holds up well, even behind the 500 horsepower motor that Adam has. Well, at least until the deadly thrashing begins.:snakeman:
 
I have to be nice to it till I can afford to build another rear so no sticky tires or beating on it for awhile.
 
Years ago my older brother had a 66 Cuda with the 235 horse 273 and a 4 speed. The first time he dropped the clutch at 4000 with 14" street tires the 7-1/4 broke. Is it abuse? I don't know, but I never trusted one to last after that episode. At least we found another one cheap to put back in.
 
66dartman said:
Years ago my older brother had a 66 Cuda with the 235 horse 273 and a 4 speed. The first time he dropped the clutch at 4000 with 14" street tires the 7-1/4 broke. Is it abuse? I don't know, but I never trusted one to last after that episode. At least we found another one cheap to put back in.
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Even though its a 7 1/4, that a hard launch, regardless. Any rear could of broke really. But that sucks though. I think i'd rather grenade mine by doing a long smoky burndown. Lol.:cheers:
 
The original 7.25" in my Vart lasted 10 years behind the original 273, then another 5 years behing a really hot 318, until I did a brake (Break?) stand one evening and everything went "CLUNK, CHATTER, CHATTER". :) I installed another 7.25" from my 67 Dart and ran it for about a dozen years behind a healthy 360/727 combo, but never did a brake stand, or a tire roaster on a 90* corner. It was still going strong when I started my restification, although there's an 8.75" with a 3.90 sure grip, (with a spare 3.23 peg legger) going in this time. Treat the 7.25" rearend with a little respect and it will probably last a lot longer than you might think.
 
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