I have a 8 1/4 diff out of a 73 duster that has 2.45 gears. I have read that the carrier is different than any other gear ratio. My question is if I get a carrier for 2.71-4.10 can I put it into my housing or is it different also?
8 1/4 diff with 2.45 gears
- Thread starter 340derek
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pishta
I know I'm right....
I think the really low carriers had some big *** pinions and some thin gears. I dont think they are compatible. IMHO....
There is a thread on here about this very subject. I don't know but I'm not convinced that what your trying to do is not possible.
i thought that as long as you got a carrier that would take the gears, per say a 3.55 from a pre '96 8.25 rear, it will work in your housing.
lilnoah
Supercharged slant six with 4 speed and 8.25
If you have the carrier for the 2.76 and up it will work. I have the same problem but I have the carrier and am going with 3.23 gear ratio
Mike your slipping we beat this one to death here
The 8 1/4 thread
post 1 shows the difference between them
The 8 1/4 thread
post 1 shows the difference between them
I looked for it and could not spell your user name, Hop's is all I could come up with at the time , Thank you super member and friend
spohxafilah?
QuickDart360
Well-Known Member
My dart sport came factory with 2.45 granny gears. Bought a new auburn gear carrier and 3.91s. Went in like they belonged there!! No issues. Friend of mine that does rears and trannys did it. He said everything went in smoothly without a fight.
I'm thinking of going the "new" route also. My car is a '75 318 Scamp with an open 2.45's. The only upgrades so far are a 4bbl and dual exhaust with the stock manifolds. I've read all these threads about upgrading 8 1/4's and I'm still confused, probably because I'm in uncharted territory!
1. If I buy a new sure grip carrier and new ring and pinion gears am I good to go? (I found a Mopar Performance 8 1/4 sure grip on Summit or Jegs for $386.) I'm looking at 3.21 or 3.55 gears.
2. Thinking about 3.21 gears, more highway than city driving. I did not find any 3.23 gears for an 8 1/4 read end, only 3.21's. Were 3.23's for early years than 1975?
3. My rear end is offset, can this be done? My rear end is off the car now so this may be the time to do it. Thanks in advance for the help.
Woody
1. If I buy a new sure grip carrier and new ring and pinion gears am I good to go? (I found a Mopar Performance 8 1/4 sure grip on Summit or Jegs for $386.) I'm looking at 3.21 or 3.55 gears.
2. Thinking about 3.21 gears, more highway than city driving. I did not find any 3.23 gears for an 8 1/4 read end, only 3.21's. Were 3.23's for early years than 1975?
3. My rear end is offset, can this be done? My rear end is off the car now so this may be the time to do it. Thanks in advance for the help.
Woody
1. 3.21's are a great all around gear especially for me since I have a A999 (wide ratio gears) transmission so it does have a decent getup and go.
2. 3.23 gears I believe are not an option in 8 1/4's. They are in 8 3/4's and Dana's. I just came back from a round trip drive to Louisville CO, from Utah (500+ miles one way) I have 245/60R15's in the back and at 3,000 rpms I was cruisin' about 72 mph. Mileage ranged from 14.6 (50 mph crosswinds + uphill) to 17.4 mpg's. With the previous tires (255/60R15's), I was going 74mph at 3,000 rpms. Also I converted the A999 to non-lockup (I did this so I didn't have to shell out a lot of cash for a high performance high stall LU TQ-convertor)
3. Offset? Since the rear is is off the car I'd say yes. But keep in mind once you take all the guts out and re-install everything with the near gears you have to set the preload, do the correct ring/pinion alignment with shims, etc... My knowledge of these rears is moderate at best, I did attempt to do all this once I gave up after a week, I got close according to the local gear shop, even then it still made noise.
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QuickDart360
Well-Known Member
Had 2.45 gear in my 8.25. Bought a auburn sure grip unit from Randys Ring & pinion. I went with 3.91s from US gear. Found these new on ebay. Everything went right in fine!
Thank you all
1st, Welcome to the site !!
2nd, I don't have a tach in my 360/904 with 2.45 gears, but I can tell you it's plenty relaxed at 60 mph, and it's like racing a power glide at the drag way as I can cross the line in 2nd gear
A good chunk of the RPM also depends on the overall size of the wheel/tire, namely the rear tire if they're the offset front/rear size.
So I calculated the estimate (automatic trans slip included) with 245/60R15 (26.5 inch diameter tires) to be approximately around 2200-2300 RPM at 70 mph.
I'll put a tach in my car, but I'd guess you are about right. I have 235/60R15 is the only difference.
Love it on the road, though....
I'll put a tach in my car, but I'd guess you are about right. I have 235/60R15 is the only difference.
Love it on the road, though....
2200-2300 at 70mph would be awesome!
Hopefully once I get to it, I'll rebuild that A500 OD trans I got and put in 3.55 rear gears (a lot of work for both).
Then, I'll be cruising the highways like I had 2.45 gears! 3.55*0.69=2.45
Powerflite
Well-Known Member
Can anyone tell me how many teeth were used on the ring & pinions of the 2.45 and 2.26 gear sets?
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