8 1/4 rear end pros and cons

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cowboyup1107

cowboyup1107

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Wondering how a 8 1/4 would hold up. What are some of your experiences with them. Is it a night and day difference between a 8 3/4 and a 8 1/4. I have one in my sights for a killer deal and the cheapest 8 3/4 ive found is $700 out of a satelite so it would need to be narrowed but it is a suregrip.
 
Mine works fine but I don't drag race and often let up on the gas a bit when shifting--its a full manual valvebody "auto" trans


Only thing is I'm stuck with the 3.91 gears. I would love a 8 3/4 and then I could have a set of 2.94 gears for long drives from home. It cost more thou.

I'm almost thinking of getting another 8 1/4 axle and swapping axles for long drives but where do I store the axle in a nice clean 2 car garage ?

Wished I just bit the bullet and got an 8 3/4
 
The 8 1/4 is a decent axle, but to know if it would work for you, we'd need to know more. What car? What mill? What trans? Drag racer or cruiser?
An a body with a mild small block and an automatic? Certainly. Plenty of Mopars were built that way.
 
frankenduster: The car is a 72 dart I have a 318 in it now and a 904 tranny. However it dosent have enough poop to her. My plans are to make it a saturday night special that can still get me back and forth to work. The 8 1/4 rear end I can get my hands on is only a housing for $25. I can get that now but whats holding me up is will it cost more to put this thing together rather then getting the 8 3/4?
 
Certain year Dakota and Durango 4wds had 3.55 and 3.91 gears WITH Sure Grips! I pulled 2 from the local Self Serve yards and had them installed in 8 1/4 axles.
I ran an 8 1/4 in a 360 Dart and it performed great. I hammered the car and the axle held up fine. It is a beefy design that should be able to handle plenty. The killer to any setup isn't just horsepower, it is "shock loading". This is a condition where the driver imparts sudden loads to the axle. A 4,000 rpm slam into gear with slicks ? NOT good. A decent automatic on street tires? much safer.
 
I'm kind of curious also. I'm hoping to have my 422 together soon, and it will have a man vb 904. The car is a 73 Dart Sport 340 and it still has the original 8.35 rear (I think). I thought about just taking it out and cleaning it up and using it for now, but I'd hate to just tear it to shreds. I probably won't be getting any traction for now, and I know that would help it last a little. I just want to drive the thing, and I'm running out of cash for a rear.
 
These questions have been asked many times,and always seem to get the same answers.It is a package-not just a component.The factory did a very good job of putting out packages for different types of performance wants.The reason 8 3/4 comes up in conversation is because it is the all around great performance rear.You will hear all kind of stories about how I got this part cheap and threw it in and did all kinds of mods and it is still going strong.Key word is what did it really cost?Believe all the bench racing stories that you want,but it really comes back to what works and what makes you walk back home after a few holeshots.My money goes with the 8 3/4
 
If I'm not mistaken the 8-1/4 has a larger input shaft diameter than the 741 does. Not that the input shaft is the weak point, it's just nice to know. There's a lot of guys out there running 8.25s with enough grunt to pull the wheels off the ground. I really don't think you'll ever damage one with street tires. Especially in a light A-Body.
 
a suregrip 8 1/4" rear is a pretty good rear dont know the limits of them but mine has been behind a slightly warmed over 340 with alitle over 3000rpm stall and a firmshifting 904 for about 8years only streetdriving but most of the driving and plenty of good launches on the street on sticky tires and no complaints so far.
 
d5667 said:
These questions have been asked many times,and always seem to get the same answers.It is a package-not just a component.The factory did a very good job of putting out packages for different types of performance wants.The reason 8 3/4 comes up in conversation is because it is the all around great performance rear.You will hear all kind of stories about how I got this part cheap and threw it in and did all kinds of mods and it is still going strong.Key word is what did it really cost?Believe all the bench racing stories that you want,but it really comes back to what works and what makes you walk back home after a few holeshots.My money goes with the 8 3/4
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I agree, I added up some prices for stronger parts, and it was more to build than an 8 3/4. There are aftermarket axles, gears, sure-grips, etc, but the cost was ridiculous. I'm just curious as to how long it would last if I didn't really hook up. Without any mods to it.
 
According to my Magic 8 Ball, 450 horse with street tires, it will last 2 years. Also according to the Magic 8 Ball, I will win next weeks lottery.
 
metallidart said:
I agree, I added up some prices for stronger parts, and it was more to build than an 8 3/4. There are aftermarket axles, gears, sure-grips, etc, but the cost was ridiculous. I'm just curious as to how long it would last if I didn't really hook up. Without any mods to it.
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YepThe old addage still holds-if you put a million dollars into a VW bug-you will have the fastest bug around.You may not want to spend the money for a A body 8 3/4 rear but one way or another you will not get a better all around rear for the money.I have pulled 8 1/4 out of cars that had 150000 miles and they were still good.Of course if you don't run a suregrip they will last longer.Torque and hookup is your worst enemy.Either way you go-good luck
 
The 8.25 has been in production longer than any other Chrysler rear end. It has been used in Jeeps almost since Chrysler acquired Jeep and there is extensive after market support. I rebuilt mine with all new bearings, ring and pinion for less than $250. even upgrading with stronger parts is less than an 8.75.

I have over 50k miles with many hard launches and smokey burn outs on my 8.25.

In general you can buy an 8.25 and rebuild it for a lot less than an 8.75. If aren't going racing with slicks and a torquey big block you can save some money that can be used else where. If you are building a big power big block an 8.75 may not be enough and stepping up to a Dana 60 might make more sense.
 
This thread got me curious about my 8.25, so I went out and took the cover off last night. It has 3.21 gears, but I don't know what the sure grip in those rears are supposed to look like. I looked on ebay, and they look like normal open carriers. I think I'll try mine for a while. Maybe just for a summer.


A38Valiant said:
According to my Magic 8 Ball, 450 horse with street tires, it will last 2 years. Also according to the Magic 8 Ball, I will win next weeks lottery.
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I need a magic 8 ball. Congrats on the lottery win!! If I had one, I could ask it if someone was being sarcastic. LOL! haha.
 
I'm no expert on rears but I would think 3.21 would be pretty good if you're commuting with it. I think the bigger question here is what's the best compromise between fuel economy and between Saturday night cruiser. I know it's very risky but sometimes I love to go from 65 to 120 mph on the hwy for just a few seconds and blow past someone who thinks his car is fast. Just saying the ratio is important also. Just depends what you are looking to do with it. FWIW, Some very trusted people have told me 8 1/4's are nearly indestructible. When My 7 1/4 blows up, I'll probably go for the 8 1/4.
 
I agree with you guys on the 8 3/4. If you can get one, build one. I personally have a 8 1/4 in my 72 dart. Total rebuild with new sure-grip, 3:55 gears, bearings, and brakes (11in drums for some reason) ran me about $1200. I don't regret it tho, this rear end has held up pretty well with my constant beatings (318 mild build).
 
8 1/4 rear end-How much is it good for? torque/horsepower

http://forums.moparmusclemagazine.c...ow-much-is-it-good-for-torque-hors/index.html

me-I have noticed that the rear ends in a lot of late model jeeps are similar to the 8 1/4 in my 76 volare road runner (E58) {360}
how much can I throw at it?
I found an 8 1/4 pinion snubber and a package sale of bearings and a sure grip unit on ebay. I want to keep using this rear in my Aspen F body.

drmopar-This is a surprising decent rearend that has been overlooked by most. Just beware when buying the posi, there are two different units. One for 2.41 and higher gears and one for the others. My brother has a 8 1/4 in his 14 second Duster. No issues. I have also seen them in a 12 second Aspen. The guy ran it this way for yrs. without any issue.
He has a 360 making 450 horse with slicks.
The C-clips on the mopar rear end cannot drop out like a chevy unit, so no need to worry about spitting out an axle.
Good Luck.

68440Barry - I have an 8.25 posi in my 74 pickup with a 67 440 and about 400 h.p. So far so good.

yvdz - Keep that 8 1/4, they are strong enough to handle a potent small block. Besides, they are WAY easier to find than a 8 3/4

RBolig - I have a 4.10 geared 8-1/4 in the Dart Sport with a 400 hp small block and a four speed, and it's having no problems.
 
My friend Rodney had an 8 1/4 in his Demon runnin 11s leavin with the wheels in the air until he changed to a different engine and then upgraded to an 8 3/4. He never broke the 8 1/4.
 
cowboyup1107 said:
frankenduster: The car is a 72 dart I have a 318 in it now and a 904 tranny. However it dosent have enough poop to her. My plans are to make it a saturday night special that can still get me back and forth to work. The 8 1/4 rear end I can get my hands on is only a housing for $25. I can get that now but whats holding me up is will it cost more to put this thing together rather then getting the 8 3/4?
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is this the one down in pueblo? if so , thats Kens, great guy, and i think the axles and gears are in it, no brakes or backing plates. but a great deal
 
I ran 11.50's and my brother was running 11.70's both 8 1/4 and slicks cutting 1.70 60 ft. With a mild small block I would'nt sweat it at all.
 
Yeah Its the one on the list in pueblo. I just need a weekend to go take a peek at it and it will probably follow me home for that price.
 
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