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Dart 7 & 1/4" Rear #855729
11/17/10 12:28 AM
11/17/10 12:28 AM
Joined: Nov 2004
Posts: 1,601
Hatfield,Pa.
bigD Offline OP
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bigD  Offline OP
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Hatfield,Pa.
Will this stand up to a mild 273?,D

7 &1/4 poll
single choice
Votes accepted starting: 11/16/10 11:26 PM
You must vote before you can view the results of this poll.
Last edited by bigD; 11/17/10 12:29 AM.

2015 Chrysler200s,2008 Charger R/T R&T,1999 Dakota R/T,1999 Viper ACR,1968 Charger R/T.
Re: Dart 7 & 1/4" Rear [Re: bigD] #855730
11/17/10 01:46 AM
11/17/10 01:46 AM
Joined: Feb 2007
Posts: 612
Nampa, ID
None2Slow Offline
mopar
None2Slow  Offline
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Posts: 612
Nampa, ID
A few things will determine if it can hold up.

1. How will you drive it?

2. Auto or Manual?

3. What gears?

If you have a manual and dump the clutch, it wont last long at all. If its an auto and you drive it like an old lady, it will last behind a big block for a very long time. If you have 2.73 it takes more work to get the car moving, thus more abuse. If you have 3.73 its a little easier to get moving. Need a little more info, but for the most part, nope, wont last long.

Re: Dart 7 & 1/4" Rear [Re: None2Slow] #855731
11/17/10 02:04 AM
11/17/10 02:04 AM
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog Offline
Striving for excellence
Kern Dog  Offline
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Posts: 18,493
Granite Bay CA
The 7 1/4 axle was the standard axle behind slant 6 and 318 cars. Its a decent unit with great reliability. Yeah, they break, but I have seen 8 1/4 axle shafts break at the hub without being abused. It really comes down to how the axle is treated.
Even using a 3 or 4 speed trans doesnt spell instant death. These axles came behind 318 3 speed cars too.
What kills these and other axles ? Abuse and neglect. Rev it up and dump the clutch? Peel out alot? Buy some good shoes. Also, and this also applies to early transmission failure...When spinning the tires on loose surfaces,(Water, dirt, gravel) LIFT off the gas when approaching an area with better traction. Its the sudden shock loads that cause the greatest damage.

Re: Dart 7 & 1/4" Rear [Re: bigD] #855732
11/17/10 02:17 AM
11/17/10 02:17 AM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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RapidRobert Offline
Circle Track
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Circle Track
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
supposedly the spider gears are the weak link & Randy's sells them & maybe Doc does also. I'm gonna try a welded spider &&1/4 on a circle burner & see if it holds up. The ~100 lbs?? or so less unsprung weight (from an 8&3/4) will be very nice.


live every 24 hour block of time like it's your last day on earth
Re: Dart 7 & 1/4" Rear [Re: RapidRobert] #855733
11/17/10 02:31 AM
11/17/10 02:31 AM
Joined: Feb 2007
Posts: 612
Nampa, ID
None2Slow Offline
mopar
None2Slow  Offline
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Posts: 612
Nampa, ID
Yeah, I agree about the sudden shock loads. My brother was driving my dads 83 Ford 1/2 ton. Had the 300 6 and a 4spd with the 9". Spinning in the gravel to pavement. When i caught it took out hte rear and the trans. Split the case down the middle. The 9" had some broken teeth. The 300 isn't known as a horse power machine especially for 83. Anything short of a weekend cruiser thats driven nice, this rear don't have much hope. I killed 3 with a stock 318 and 4spd. Of course I wasn't easy on it.

Re: Dart 7 & 1/4" Rear [Re: None2Slow] #855734
11/17/10 03:34 AM
11/17/10 03:34 AM
Joined: Oct 2008
Posts: 1,894
Mira Loma, CA
69B3GT Offline
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Mira Loma, CA
Ive seen one take more abuse then it should. The one in my buddies 73 dart, burnouts all day long, no gear oil in it ( no joke is howls and grinds like you wouldnt believe) But its getting worse and i can see it failing soon. Personally id just step up the rear for peace of mind

Re: Dart 7 & 1/4" Rear [Re: bigD] #855735
11/17/10 11:18 AM
11/17/10 11:18 AM
Joined: Nov 2004
Posts: 1,601
Hatfield,Pa.
bigD Offline OP
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Heres some more info: 904 auto,2.73 open rear. Plan on freeway drives and crusin,no racing.D,


2015 Chrysler200s,2008 Charger R/T R&T,1999 Dakota R/T,1999 Viper ACR,1968 Charger R/T.
Re: Dart 7 & 1/4" Rear [Re: bigD] #855736
11/17/10 07:45 PM
11/17/10 07:45 PM
Joined: Jan 2003
Posts: 20,179
Park Forest, IL
slantzilla Offline
Too Many Posts
slantzilla  Offline
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Posts: 20,179
Park Forest, IL
I had one in my Duster when I started racing it. I used to do big funny car burnouts and always waited to hear the "CLUNK!" when I came out of the water. Never did break it. It did eat an axle bearing or two though.


"Everybody funny, now you funny too."
Re: Dart 7 & 1/4" Rear [Re: slantzilla] #855737
11/17/10 08:34 PM
11/17/10 08:34 PM
Joined: Feb 2007
Posts: 612
Nampa, ID
None2Slow Offline
mopar
None2Slow  Offline
mopar

Joined: Feb 2007
Posts: 612
Nampa, ID
If you treat it right, it will treat you right.

Re: Dart 7 & 1/4" Rear [Re: bigD] #855738
11/17/10 11:17 PM
11/17/10 11:17 PM
Joined: Apr 2010
Posts: 1,216
Under My Car
Mopar_Country Offline
pro stock
Mopar_Country  Offline
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Under My Car
Quote:

Heres some more info: 904 auto,2.73 open rear. Plan on freeway drives and crusin,no racing.D,




If you follow this recipe, it will be fine. Keep in mind they won't handle to many burnouts as a rule.

Re: Dart 7 & 1/4" Rear [Re: bigD] #855739
11/18/10 09:54 AM
11/18/10 09:54 AM
Joined: Jan 2003
Posts: 353
Chesterfield, MIch
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Cuda67 Offline
super street
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Posts: 353
Chesterfield, MIch
The thrust washers on the side gears wear out which alows the side gears to move to far out. To much clearance and it breaks. Replace the washers once in awhile and your good to go. This info from the axle lab at Chrysler Engineering.

Re: Dart 7 & 1/4" Rear [Re: bigD] #855740
11/18/10 11:01 AM
11/18/10 11:01 AM
Joined: May 2003
Posts: 3,068
N.W. Florida
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Fat_Mike Offline
master
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Posts: 3,068
N.W. Florida
My old '65 Dart came from the factory with a 7.25 behind a 273/4 spd. Can't say how many times it was gone through before I got my hands on it, but it had a ton of miles on it and was still there.

Last edited by Fat_Mike; 11/18/10 04:44 PM.
Re: Dart 7 & 1/4" Rear [Re: Fat_Mike] #855741
11/18/10 01:31 PM
11/18/10 01:31 PM
Joined: Jan 2003
Posts: 3,122
Auburn WA
Dave_J Offline
master
Dave_J  Offline
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Posts: 3,122
Auburn WA
I pulled the DORF 9" out of my 65 Cuda and replaced it with a LBP 7 1/4 2.94:1 SG from a 74 Dart Swinger. It stayed behind the 383 Magnumn for 2 years when I heard a loud grinding noise on the way home from work. I made it home and dug out my 8 1/4 - 8 3/8 hybred with 3.55:1 SG. Hung it on the springs ok. when moving the 7 1/4 around the garage, the left brake drum popped off and the brakeshoes were delamanated and that was the grinding noise I had heard.


Retired, US ARMY 1973-1994
ASE mechanic, Electrical 1994-1997
Retired GTE/VERIZON/FRONTIER 1997-2015


Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.

03 Suzuki Burgman 650(Burger King) Scooter
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Re: Dart 7 & 1/4" Rear [Re: Dave_J] #855742
11/18/10 08:32 PM
11/18/10 08:32 PM
Joined: Jan 2003
Posts: 4,588
St. John's Newfoundland
440newport Offline
master
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Posts: 4,588
St. John's Newfoundland
my 2.76 geared 7 1/4 lasted about 2 weeks behind a mild 360 before it started clunking. I wasn't babying it sure, but I wasn't exactly trying to kill it either.

Re: Dart 7 & 1/4" Rear [Re: bigD] #855743
11/19/10 01:05 PM
11/19/10 01:05 PM
Joined: Nov 2004
Posts: 1,601
Hatfield,Pa.
bigD Offline OP
top fuel
bigD  Offline OP
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Posts: 1,601
Hatfield,Pa.
Thanks for the replys .I have a bunch of smallblock stuff left over from the Coronet and a couple of 273s(one with 904 trans) that were given to me,slant is smoking so I'd thought I use up all my leftovers on this project,D.


2015 Chrysler200s,2008 Charger R/T R&T,1999 Dakota R/T,1999 Viper ACR,1968 Charger R/T.






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