School the rookie on 8.25 rears

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67CudaBob

67CudaBob

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I am converting my 67 Dart GT ragtop over to BBP. Street cruiser only, eventually with some mild horsepower. I have been talked into (by many here) saving some money and going with a less expensive 8.25 from my high mileage 7.25.

I have access to (2) complete 8.25 axles, drum to drum, both with BBP. One is a mid 70's "A" body one-legger. The second is a mid-80's police car sure grip.

If I can buy both of them for the right price, can I simply remove the sure grip unit (and gears) from the mid 80's axle and plug-n-play it into the mid 70's axle housing? Will the sure grip work with the existing axles in the mid 70's housing?

Or, am I better off holding out for a complete "A" body 8.25 sure grip drum to drum so I know everything is set properly and working together?

I appreciate your thoughts-
 
It depends on the gear ratio in the 80's cop car rear and the ratio in the A body rear, if they are both 2.76 or numerically higher then yes you can plug and play, also if both gears are 2.41 or numerically lower you can mix and match. The 2.76 and higher carrier isn't compatible with the numerically lower gear set, also the carrier bearing size changed in '75 so depending on what year the A body rear is you might have to change bearings on the carrier.
 
All 8.25 carriers fit any 8.25 case of any year.

HOWEVER: 2.45 and numerically lower gears require a special carrier. All gears 2.76 and numerically higher will fit a "standard" carrier.

If you choose to swap the gears AND carrier between the cases you won't have any issues. In any case, you will need to re-shim the pinion gear against the case.

Also, depending on the year of the case, the carrier side bearings may be different outside diameters. The inside diameter is the same, and Autozone carries both in Timken. I think everything 1973 and older is the larger bearing, and 1974-up was a slightly smaller outside diameter.

Note that if are playing with carriers 1997 and UP, they will be a higher spline count, and will use larger C-clips. Since your potential donor axle is from the 1980s, this will not be a problem for you. All axles prior to 1997 were 27 spline, so your 1970s axles should fit right in to a 1980s carrier.
 
Thanks guys! Was an Oldsmobile guy for 25+ years, then I bought a Cuda that was mechanically done, so this is my first stab into mechanically modifying a Mopar. I wouldn't want to do it without the knowledge of the members here. Thanks again.
 
What police car? Mine came out of an F Body and I just moved the perches. Got some wheels with 5 inches of back spacing and it works just fine. If you don't feel like going into the guts that may be the way to go.
 
Leadfoot said:
What police car? Mine came out of an F Body and I just moved the perches. Got some wheels with 5 inches of back spacing and it works just fine. If you don't feel like going into the guts that may be the way to go.
Click to expand...

I am waiting to hear back from the guy on what it came out of.

I am having trouble finding axle width dims online for F/M/J bodies. One site said they are all the same width - do you know if this is true, and if so what the width is? I have seen both 54.34 and 53.34 for flange to flange listed on the internet for the 8.25 F body.
 
Like the above mentioned stay away from the 2.45 housings they are junk when you want to change gearing, found that out the hard way.
 
It is not the housing that changes for 2.45 gears, only the carrier.

My '75 housing came factory with 2.45 gears and open diff carrier. I installed a late model Trac-Loc with 3.55 gears, no problem.

BTW - Don't waste your money on the side bearing adjustment tool ($100).

Go to the hardware store, and for $15 you can get a length of pipe and two large huts that will fit the adjusters perfectly. I used a 36" length of pipe, because the tool works the same for 8.25 AND 9.25 axles.
 
superdart said:
It is not the housing that changes for 2.45 gears, only the carrier.

My '75 housing came factory with 2.45 gears and open diff carrier. I installed a late model Trac-Loc with 3.55 gears, no problem.

BTW - Don't waste your money on the side bearing adjustment tool ($100).

Go to the hardware store, and for $15 you can get a length of pipe and two large huts that will fit the adjusters perfectly. I used a 36" length of pipe, because the tool works the same for 8.25 AND 9.25 axles.
Click to expand...

Yeah ment carrier sorry
 
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