'75 A model 8.25 worth upgrading or leave as is?

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Joe Dart

Joe Dart

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I picked up a 8.25 rear end out of a '75 dart from my local pick your part.The tag on the cover says 2.45 ratio.I'm want to install the diff into my '69 dart,but since the ratio in the '69 dart are lower compared to the taller '75 gears it's gonna bog down the /6. So pretty much I just wanted to take care of it before it goes in.
My plan's in the future is to install a V8 in the '69.
Street/Strip 3.55 gears
Richmond Gear posi unit.(Peg legging get's boring real quick)
Is it worth investing or do I leave as is?

Frank
 
your problem is the 2:45 ratio is the only one that will work in that rear, I have read that if you change the carrier you will be able to use a different ratio in your housing, but other sources state that the housing's themselves are different so the carrier's do not interchange, so you are going to have to do some research, hopefully some one here will chime in with more advice or you could contact a good differential shop
 
caferacerx said:
your problem is the 2:45 ratio is the only one that will work in that rear, I have read that if you change the carrier you will be able to use a different ratio in your housing, but other sources state that the housing's themselves are different so the carrier's do not interchange, so you are going to have to do some research, hopefully some one here will chime in with more advice or you could contact a good differential shop
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yea i hear the same two things.. also heard if you grind the housing some you'll be fine. wish i could find a definate answer.
 
I did one in 98, cost $700 for a posi 3.91. Oh it looked so pretty, they washed the whole axle and painted it all black. Carrier must be changed even for 2.73's

I still have it today, doing alright.

Wished I would had built a 8 3/4 and by now have two ratios to swap out for long trips.
 
abodyjoe said:
yea i hear the same two things.. also heard if you grind the housing some you'll be fine. wish i could find a definate answer.
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dodge freak said:
I did one in 98, cost $700 for a posi 3.91. Oh it looked so pretty, they washed the whole axle and painted it all black. Carrier must be changed even for 2.73's

I still have it today, doing alright.

Wished I would had built a 8 3/4 and by now have two ratios to swap out for long trips.
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Holy smokes! Didn't expect that response.It would be great if some one has definite insight of the proses of modifying the carrier.I have a friend that work on diffs on the side and I was gonna have him set me up with the new gears.I'm gonna ask if he's familiar with this 8.25.
 
I have an 8.25 with 2.45 gears also. Came out of a 75 dart too. I put it under a 72 duster so i could use BBP wheels. I consider it a temporary rear until i build an 8.75 for it. Investing in a 8.25 is a waste of money, i feel. Actually, a Dana 60 might not be too much more to build. Often times you can find one out of a 3 /4 ton truck pretty cheap and they usually have 3.54 or 4.10 gears. May or may not have limited slip. Minimum to get the truck dana under your car: figure $150 for housing narrowing, $80 for ends, $400 for axles. If it has a good useable limited slip , you may need the proper side gears to mate up with the axles. If the ring and pinion is in good shape and is the ratio you want you can reuse them. I don't know what the prices are for 8.25 parts, maybe a little cheaper, but when you are done you still have a small rearend with c clip retained axles.
 
Thanks forphorty.
I have searched and came up with the same result too.Considering that I bought the complete diff for only $85 and for the 4 1/2 bc.I just wanted to freshen it up before it gets installed in to the car.

Can I at least change the ring and pinion? According to the '69's original ratio. It is lower than the '75 2.45.
There is no tag on 69's diff,but upon my research it say's that it would probably have a 2.73 or 2.95 ratio.I would be fine with that.
 
Yep, the 69 rear will for sure have a lower ratio than 2.45. The 2.45 crap was a way to improve fuel economy in the 70s since they weren't using overdrive transmissions yet. If your buddy will do it cheap enough, the gear swap might be worth the trouble if you already have the parts.
 
If you want to change the ring and pinion your going to need a carrier for 2.73 and higher, the 2.45 carrier wont work. The 8 1/4 is fine for street cruising even with a strong v8 but if you're going to drag race or run slicks you'll want a stronger rear.
 
daliant said:
If you want to change the ring and pinion your going to need a carrier for 2.73 and higher, the 2.45 carrier wont work. The 8 1/4 is fine for street cruising even with a strong v8 but if you're going to drag race or run slicks you'll want a stronger rear.
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Does a later model 8.25 that has the 2.73 carrier fit in the housing that I have.If you say yes,I'm going hunting for one.
 
DusterKrazy said:
Not to hi-jack, but do they make a sure-grip unit that will work with a 2.45 ring and pinion??
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I think there is.Check out the link I posted on #6.The guy talks about how he bought the 2.45 carrier and couldn't use it.
Hey, he might sell it to you.
 
Joe Dart said:
Does a later model 8.25 that has the 2.73 carrier fit in the housing that I have.If you say yes,I'm going hunting for one.
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Yes, all 8 1/4 2.73 and higher carriers are interchangable up to 1996(splines changed from 27 to 29) ,also 76 and newer uses larger carrier bearings so if you want use a 76 up carrier you'll have to swap to the smaller bearings.
 
daliant said:
Yes, all 8 1/4 2.73 and higher carriers are interchangable up to 1996(splines changed from 27 to 29) ,also 76 and newer uses larger carrier bearings so if you want use a 76 up carrier you'll have to swap to the smaller bearings.
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HaHa!It never fails with my luck on stuff like this.I was just 1 year away from having the carrier without the head aches.
Thanks for confirming on the interchangeability.
 
Also not trying to hijack the thread but I called Randy's yesterday to get some info about sure grip units for my 8 1/4 & the guy made me feel like I was an idiot for even wanting to use an 8 1/4. I am building a mild 350 +/- hp 360 for my '65 Barracuda & unfortunately just don't want to play all the over-priced 8 3/4 games. I would rather put money elsewhere. It is $500+ just to find an a-body 8 3/4 than start adding in sure grip & gear ratio prices, it can easily hit $1000 or more. It was actually funny how much guys were asking for 8 3/4 chunks at the Nats this weekend, of course very few of them were selling so....
The 8 1/4 should be more than strong enough for a street driven cruiser with the hp I am hoping for. The guy from Randy's also told me that he did not know where their units were made & chuckled as he stated that he didn't think any of them are made in USA anymore.
Am I wasting my time with this rear end? Do I really need a suregrip? $450 for the only unit they sell seems like too much money to just be able to lay down 2 tracks of rubber once in a while, especially not knowing where it is made.
 
phish1270 said:
Also not trying to hijack the thread but I called Randy's yesterday to get some info about sure grip units for my 8 1/4 & the guy made me feel like I was an idiot for even wanting to use an 8 1/4. I am building a mild 350 +/- hp 360 for my '65 Barracuda & unfortunately just don't want to play all the over-priced 8 3/4 games. I would rather put money elsewhere. It is $500+ just to find an a-body 8 3/4 than start adding in sure grip & gear ratio prices, it can easily hit $1000 or more. It was actually funny how much guys were asking for 8 3/4 chunks at the Nats this weekend, of course very few of them were selling so....
The 8 1/4 should be more than strong enough for a street driven cruiser with the hp I am hoping for. The guy from Randy's also told me that he did not know where their units were made & chuckled as he stated that he didn't think any of them are made in USA anymore.
Am I wasting my time with this rear end? Do I really need a suregrip? $450 for the only unit they sell seems like too much money to just be able to lay down 2 tracks of rubber once in a while, especially not knowing where it is made.
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why not buy a cheap c or b body 8 3/4, have it cut down to a-body size. i'll bet you come out ahead of the game. then it comes down to gears and a clutch pack.. 8 3/4 has a tom more options.

a 8 1/4 will hold up fine even at the track to certian power limits. do you need a sure grip? only you can answer that one. an top of it i prefer the 8 3/4 because i can change rear gears in less then a hour.
 
i have had a 8 14/ in my car since i got it only thing i did was change the oil its got 2.95 gears highway it runs great its been raced many times also nvr had a problem 81/4 i beleive are good and easy to find parts for and mines a 74
 
You only need to change the carrier to change from 2.45's. The housing are the same. No suregrip available for the 2.45's. There are tons of pre '76 8 1/4's around. Look in 1/2 ton trucks and vans. I got my 3.21's out of a '74 Dodge van.


Chuck
 
Why not look into the for 9" rear from an Explorer easy to find gears, rear disc and pretty common to find , 4 1/5 bolt pattern and the right width. Planning on putting one in may 72 Scamp, just easier to build (parts and price) 8 1/4 are good for street strip 300hp will hold up if build right, but have the c-clip issue (not an issue till they brake..). I have a buddy who races chevs 9sec car and runs the Ford rears because they hold up great, easy to find parts are alot of gear options and a heck of alot cheaper and easier to find then a 8 3/4. You could sell your 8 1/4, and use that money to pickup a Ford 9" for...
 
slantysix said:
Why not look into the for 9" rear from an Explorer easy to find gears, rear disc and pretty common to find , 4 1/5 bolt pattern and the right width. Planning on putting one in may 72 Scamp, just easier to build (parts and price) 8 1/4 are good for street strip 300hp will hold up if build right, but have the c-clip issue (not an issue till they brake..). I have a buddy who races chevs 9sec car and runs the Ford rears because they hold up great, easy to find parts are alot of gear options and a heck of alot cheaper and easier to find then a 8 3/4. You could sell your 8 1/4, and use that money to pickup a Ford 9" for...
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Just a small correction....the rear end you are referring to is actually an 8.8...

I know that's close to 9" but they are very different rear ends.

The 8.8 was used in many Mustangs, full-size and Ford trucks. The Explorer version is nice because it has 31 spline axles...Mustang version has 28.
 
I just spent over $1100 totally reconditioning an 8 3/4 sbp for my 70 Dart.
the COMPLETE used REAREND drum to drum cost $325
a used742 case sure grip w/ 3.91 richmond gears with a new yoke cost $250
Parts to rebuild entire rearend,all wear items replaced except ring / pinion $300... replaced all bearings,clutches, seals, brakes,wheel cyl's,,hardware.... found new drums for 40 bucks on craigslist
Labor to rebuild chunk and set lash $125

I consider that I got the rearend cheap and "stole" the chunk (I shopped and scrounged for a year and a half) and still have over a grand wrapped up in it when I was done. . If I hadn't gotten the rearend with u bolts, shock plates, brake line tee, backing plates, e brake cables, the right yoke, and all the other bits, I would have been nickel and dimed to death before it was all over.

If I had to pay full price or close to it for everything, and scrounge for used bits, (for example shock plates $50, e brake cables $40 etc.)and buy a new ring/pinion, I could have easily spent close to $1800.

If I was doing it all over again and had the large bolt pattern, I would go with the 8.8. If youre in the situation I am with the small bolt pattern, its either get new axles AND 73 and up front disc set up to go to large pattern,(yes I know some have redrilled for large pattern but I would not trust that especially in a high horsepower situation) or stay sbp which SERIOUSLY limits tire selection.

you might be able to pick up the entire 8.8 rear for $200 or less and put that much or less in it to recondition it which would be 1/3 the price of an 8 3/4 rebuild. I heard a mustang motorhead say once that there were a lot of 3.73 gears put in the 8.8's.
 
I don't see what is so bad about the 8 1/4 rear end. I know a lot of guys on here are looking at it from a racing standpoint but I picked up an 8 1/4 out of a Satellite with 2.73 gears for free. The price of cleaning it all up, chrome diff cover, brake shoes and drums was about $150. That's for the entire rear end complete and ready to go. I don't know how anyone who is on a budget can consider an 8 3/4. I was looking at some and the best price was $400 for one that needed to be gone through. That's crazy! Hopefully one day I can be an idealist when it comes to the best parts, but if you already have the rear end just make it work and thats all that matters. Don't sell it and wait for a deal just get goin on the rear you got!

my 3 cents.
 
I am rebuilding an 8 1/4 for my car this winter and doing the same setup as yours. I will use a 3.55 gear set and a clutch type differential. I've seen Dana diff's for under $300. I think there the same as a Chrysler factory unit.
As far as the durability of a 8 1/4, it does have a 1 5/8 diameter pinion and there are people racing them with slicks.
I think with a street car and radial tires, it will be fine. At least that's what I'm hoping. Plus they are lighter too!
 
This is great info, I'm looking to swap a '75 8 1/4" I got for free into my Duster and also need to swap the 2.45:1 open carrier for shorter gears and a Sure Grip. However I'm thinking of using a 3.07:1 ring & pinion from a Jeep Cherokee rear end since they are basically overflowing out of Jeep parts shops and junkyards around here. Anybody know what the options are for limited-slip or locker setups for 8 1/4s? I'm looking for best bang-for-the-buck whether it's LSD or Locker...
 
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