8 1/4 rear end questions

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H22A4

H22A4

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My Scamp currently has a 7 1/4, 904 tranny with the big bolt pattern. Originally I considered an 8 3/4 rear end but I'm not keen on sourcing/cutting down axle shafts from a B Body to fit in an A body 8 3/4. So that's turned me to looking for an 8 1/4. From what I've read, I should stay away from a 8 1/4 rear ends with a 2.45 gears since I would need to buy a new carrier when installing a higher ratio. I'm not concerned if I find one with a sure grip or not since it would almost certainly have to be rebuilt/replaced.

I'm heading out on a treasure hunt for a few parts next week and will be hitting a few wreckers.

1) Do I need to be concerned with casting numbers for an 8 1/4 rear end since casting numbers on an 8 3/4 are a big deal?

2) What would be a reasonable price range for a 2.76 & up 8 1/4 rear end from a wrecker?

3) Anything else I should be looking out for when getting an 8 1/4 rear end?
 
I run one in my '75 Duster with no problems...not much in the line of different #s...correct that you do not want the 2.45 ratio...I have one of those sitting in the next room...the yokes came in 7260 and 7290 u joint flanges...You dont want an open one...they're weak...the sure grip carriers are much stronger, and available in auburn cone and flat clutch models...
 
Sanguine said:
I run one in my '75 Duster with no problems...not much in the line of different #s...correct that you do not want the 2.45 ratio...I have one of those sitting in the next room...the yokes came in 7260 and 7290 u joint flanges...You dont want an open one...they're weak...the sure grip carriers are much stronger, and available in auburn cone and flat clutch models...
Click to expand...

Thanks for the help so far....

You lost me with the 7260 vs 7290 yokes; are both types open or just one (the 7260)? Are carriers different for 2.71 & above ratios if it was sure grip equipped or not? What was different? I'm budgeting having to buy a new sure grip so why would I want to buy one from a wrecker when it will quite likely be worn/need a rebuild (if it can be).
 
7260 and 7290 are U joints
carriers are the same except for the 2.45 one
cone sure grips are not rebuildable per say(although i have some machining trick to breathe new life into one)
clutch types are rebuildable
 
If you are going to install a Suregrip, then the gear ratio shouldn't matter, since you will be replacing the whole carrier anyway. I have 2.45s in mine, but a new Suregrip and 3.55s waiting to be installed.
 
You should be able to find an 8 1/4 for around $100. Look for trucks or 80's cop cars for a sure grip. I got mine for $50. If you can't afford new gears...the trucks and vans with 6 cyl.'s usually have 3:55's.
 
I would not be concerned about finding an 245 ratio A body unit. The key here is to find an A body unit that is a serviceable piece. You can always change the gears/differential.

I have not seen anything of use in the scrap yards here in years, but then I live in chicago too, there arent any A bodies in the bone yards. Having said all this - I'd guess 150 $ is what I'd be willing to pay for one.
 
Being a newbie to all of this, I want to add a question to this thread regarding 8 1/4 rear end. I am in the proccess of getting a donor car (a 1976 Duster will be delivered this Saturday) and the owner tells me it has an 8 1/4 rear end on it. Now I have not confirmed this, nor have I even seen the car but in pictures only (I know you guys are shaking your heads on that one, but the car is located about 200 miles away and he is going to deliver it to me) I have told him that if it does not have what I want on it (8 1/4 rear end, front disc brakes) then I will refuse delivery and I will be out only $100 for his gas and time to deliver it.

Now on to the question, how can you tell if the rear end has suregrip or what gears are in it???

Thanks for any help!

John
 
The only way to tell if its a sure grip for certain is to lift both rear wheels and spin the tires. If they turn the same direction then its a sure grip if they turn opposite directions then its an open diff. To check the ratio turn the tires one revolution and count the number of turns the pinion makes. 1 tire revolution to 3.25 or so pinion turns - its a 3.21 to 1. For 200$ I wouldnt turn it down as long as it has the disc brake set up, these are getting pricey these days. Besides you can get alot of other scrap parts off it. If you get the 8.25 then its a great deal. You didnt have to do much just pay to get it dropped off, in my .02.

Best of luck with it....
 
i know this post is old but i just wanted u to know i went to the mopar vs. the world nats. last may in vald. ga. bought an 8 1/4 rear with new 355 suregrip complete exc.for drums for 300 dollars there was bout 10 of them there for less than 400 dollars even seen an early abody 83/4 for 550 i try to find a swapmeet somewhere close u can get a good deal theres nothing in the junkyards here either goodluck
 
My question is does anyone make aftermarket axles for an 8 1/4? I have one in my dart that I upgraded to 3.73 and a sure grip. I have no complaints so far. Check your widths too when looking. I originally got one out of a dakota but it was too wide. All I ended up with was the 3.73 gears. 2852905, 3723598, 3723599 are direct fit A-body housings that will bolt right in. 7 1/4 to 8 1/4 may require a shorter driveshaft.
 
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