1965 Dodge Dart stock differential advice

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Stumpy

Stumpy

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Just throwing this out there.

After considering replacing the stock whiny 7.25 open diff in my mostly original 273 Power Pack, 4-speed 65 Dart with an 8.25, I decided that given how much I'd be spending to put in an 8.25 and things I have to change, I'd rather put a period correct diff in it. The car is a nice survivor and mostly stock and I'd like to keep it closer to original if I or someone ever wants to restore it.

I don't mind spending the money on a diff but am unsure which way to go. I wanted to go with an early a-body 8.75 from a similar year but they are practically unobtainium at any price. Open would be fine. Original 8.75 Housings are tough to find. Would a reproduction housing like from Moser be a possibility? I was also thinking that a 7.25 Sure Grip might be a better fit given the lighter unsprung weight and my driving style.

I've had many, many 7.25s. (at least 5) and not one has blown up on me. I'm well aware of the reputation of the 7.25 and the lack of availability of parts and gear ratios. I don't street race the car and I don't go to the track. I don't granny it, but I don't romp on it...well much... and I don't do many hard launches.

I could also find someone that will rebuild the rear AGAIN after only 3 years and take the time and care to work the whine out of it. Could I or should I just replace the open carrier with a 7.25 Sure Grip if I can find one? Parts again seem to be the problem. I'd like more cruising friendly gears than 3:55s and the shop that rebuilt my 7.25 last time said that was the highest gear available.

Thoughts? Pic of the car so you know what we are talking about.

IMG_4626.jpeg
 
Nice car! IMO, there's not a thing wrong with going to the 8.25. I mean, it won't be original with any other rear but the 7.25, so it really makes no difference. The 8.25 will be much more budget friendly in any event. OR you could try to find a 7.25 sure grip unit. That would add a lot of strength to what you have.
 
Unless you’re going for 100 point resto or true survivor status. A reversible upgrade (better rear/disc brakes) will never affect a vehicle.

As a 66 Dart 273 4bbl/4 speed owner who like to have fun with his car put the 8-3/4 in be it an original housing or Moser. My car is an original 8-3/4 car and I’m modifying it. I’ll be buying a moser house& axles (I’ll retain the original if I ever sell it goes with the car)
 
Stumpy said:
Just throwing this out there.

After considering replacing the stock whiny 7.25 open diff in my mostly original 273 Power Pack, 4-speed 65 Dart with an 8.25, I decided that given how much I'd be spending to put in an 8.25 and things I have to change, I'd rather put a period correct diff in it. The car is a nice survivor and mostly stock and I'd like to keep it closer to original if I or someone ever wants to restore it.

I don't mind spending the money on a diff but am unsure which way to go. I wanted to go with an early a-body 8.75 from a similar year but they are practically unobtainium at any price. Open would be fine. Original 8.75 Housings are tough to find. Would a reproduction housing like from Moser be a possibility? I was also thinking that a 7.25 Sure Grip might be a better fit given the lighter unsprung weight and my driving style.

I've had many, many 7.25s. (at least 5) and not one has blown up on me. I'm well aware of the reputation of the 7.25 and the lack of availability of parts and gear ratios. I don't street race the car and I don't go to the track. I don't granny it, but I don't romp on it...well much... and I don't do many hard launches.

I could also find someone that will rebuild the rear AGAIN after only 3 years and take the time and care to work the whine out of it. Could I or should I just replace the open carrier with a 7.25 Sure Grip if I can find one? Parts again seem to be the problem. I'd like more cruising friendly gears than 3:55s and the shop that rebuilt my 7.25 last time said that was the highest gear available.

Thoughts? Pic of the car so you know what we are talking about.

View attachment 1716144108
Click to expand...
Looks awesome. For my latest build Dart Charger I have bought NOS bearings and shims for around usd 250. Then a new 3.23 gear ratio in NOS box for another usd150. I just bought new seals and gasket. Took me 6 month.

I bought factory stuff for quality purpose.
 
65dartcharger said:
Looks awesome. For my latest build Dart Charger I have bought NOS bearings and shims for around usd 250. Then a new 3.23 gear ratio in NOS box for another usd150. I just bought new seals and gasket. Took me 6 month.

I bought factory stuff for quality purpose.
Click to expand...
I never really considered accumulating NOS stuff. That's a possibility.
 
At least with the 8 3/4 you'll have a rear that your car could have been ordered with and you'll still have small bolt pattern. They are damned well indestructible in a case like yours, and adding a Sure Grip won't solve the inherent weaknesses in the 7 1/4.
 
in1965, mopar said the 8 3/4 rear end will be offered, in 235/273 four speed cars, as they paid out lots of money for warranty on 7.25 rears. i ended up changing mine to 8 3/4. just food for thought
 
Stumpy said:
Just throwing this out there.

After considering replacing the stock whiny 7.25 open diff in my mostly original 273 Power Pack, 4-speed 65 Dart with an 8.25, I decided that given how much I'd be spending to put in an 8.25 and things I have to change, I'd rather put a period correct diff in it. The car is a nice survivor and mostly stock and I'd like to keep it closer to original if I or someone ever wants to restore it.

I don't mind spending the money on a diff but am unsure which way to go. I wanted to go with an early a-body 8.75 from a similar year but they are practically unobtainium at any price. Open would be fine. Original 8.75 Housings are tough to find. Would a reproduction housing like from Moser be a possibility? I was also thinking that a 7.25 Sure Grip might be a better fit given the lighter unsprung weight and my driving style.

I've had many, many 7.25s. (at least 5) and not one has blown up on me. I'm well aware of the reputation of the 7.25 and the lack of availability of parts and gear ratios. I don't street race the car and I don't go to the track. I don't granny it, but I don't romp on it...well much... and I don't do many hard launches.

I could also find someone that will rebuild the rear AGAIN after only 3 years and take the time and care to work the whine out of it. Could I or should I just replace the open carrier with a 7.25 Sure Grip if I can find one? Parts again seem to be the problem. I'd like more cruising friendly gears than 3:55s and the shop that rebuilt my 7.25 last time said that was the highest gear available.

Thoughts? Pic of the car so you know what we are talking about.

View attachment 1716144108
Click to expand...

I went through this same conundrum with my dart as well. Having a almost all original, begs the question, what do I do with it when the spiders in the 7-1/4 break... had originally thought a 7-1/4 suregrip carrier was my answer. Till it came to finding/affording one. Then finding parts to rebuild it if need be after that, is also a huge issue.

Though I've never seen full documentation that it was done to a 273-4bbl dart, supposedly you could order add-ons from the 65 performance catalog, which included an 8-3/4. I've heard of barracuda that have the option from 65. Don't see axle differences noted in the build docs that I have for the dart.
20230920_092512.jpg

It's all besides the point. When it breaks, you have a broken rearend... no drive, no fun...

When mine broke, had already picked up a 8-3/4 housing and a few different pigs by then. 2.76, 2.93, 3.23 and 3.55 l for when it eventually happened. Sold the 4.10s and 3.91s that I had picked up a couple years before that.

The price of 8-3/4 housings has tripled since 2010, but can still find them for less that $1000. See one in for sale section with axles for less than $800 right now. Sure grip centers run a bit more than $500 used. New/rebuilt for much more.

If I had to make the switch over again, I'd do it with today's prices, and complain a bit, but figure the way forward to make it move again.

Just my $0.02. Hope it helps.
 
just as a fact check, any A-body 8 3/4 is a direct bolt in up to 1972 correct? I got the idea the OP was specifically looking for an early a-body 8 3/4...
 
I know you want to keep things original, but do you have disc brakes up front? Have you though about upgrading? Might keep that in mind and go with BBP instead of SBP. I don't think the 8 1/4 ever came SBP.
 
SSBC makes small/large pattern disc brakes that bolt on 10 inch drum spindles - hub drilled for both, so you choose, change later is easy peasy...
 
SIX225 said:
I know you want to keep things original, but do you have disc brakes up front? Have you though about upgrading? Might keep that in mind and go with BBP instead of SBP. I don't think the 8 1/4 ever came SBP.
Click to expand...
Those that have done this with SBP and didn't want to convert just have the axles drilled to 5x4 opposite the4-1/2 circle.
 
eekvonzipper said:
Does a 7 1/4" Sure-Grip just drop-in to the same Open-Rear Axle?
Click to expand...
No simple drop-in differential changes for 7-1/4. Need before and after measurements, a housing spreader, arbor for more measurements and possibly different shims. Bearing and seals may need changed, also require additional tooling todo.
 
SIX225 said:
I know you want to keep things original, but do you have disc brakes up front? Have you though about upgrading? Might keep that in mind and go with BBP instead of SBP. I don't think the 8 1/4 ever came SBP.
Click to expand...
I already upgraded to SBP Dr Diff discs up front and right hand lugs all around.
 
chewy said:
I went through this same conundrum with my dart as well. Having a almost all original, begs the question, what do I do with it when the spiders in the 7-1/4 break... had originally thought a 7-1/4 suregrip carrier was my answer. Till it came to finding/affording one. Then finding parts to rebuild it if need be after that, is also a huge issue.

Though I've never seen full documentation that it was done to a 273-4bbl dart, supposedly you could order add-ons from the 65 performance catalog, which included an 8-3/4. I've heard of barracuda that have the option from 65. Don't see axle differences noted in the build docs that I have for the dart.
View attachment 1716144383
It's all besides the point. When it breaks, you have a broken rearend... no drive, no fun...

When mine broke, had already picked up a 8-3/4 housing and a few different pigs by then. 2.76, 2.93, 3.23 and 3.55 l for when it eventually happened. Sold the 4.10s and 3.91s that I had picked up a couple years before that.

The price of 8-3/4 housings has tripled since 2010, but can still find them for less that $1000. See one in for sale section with axles for less than $800 right now. Sure grip centers run a bit more than $500 used. New/rebuilt for much more.

If I had to make the switch over again, I'd do it with today's prices, and complain a bit, but figure the way forward to make it move again.

Just my $0.02. Hope it helps.
Click to expand...
This is for 65 Valiant. Note the standard 7.25 and optional 8.75. The right side column is 273 only.
1695235287945.png
 
str12-340 said:
just as a fact check, any A-body 8 3/4 is a direct bolt in up to 1972 correct? I got the idea the OP was specifically looking for an early a-body 8 3/4...
Click to expand...
Correct, a few minor changes, like brake hardware and vent location. No big deal. In the long run, if running the SBP, bite the bullet and just swap in the A-Body 8 3/4 and be done.
 
str12-340 said:
just as a fact check, any A-body 8 3/4 is a direct bolt in up to 1972 correct? I got the idea the OP was specifically looking for an early a-body 8 3/4...
Click to expand...
All A-body rear axle assemblies with bolt into any A-body. They all are around the same width and have a 43" spring to spring measurement. The differences between 7 1/4, 8 1/4, and 8 3/4 will require some other changes when swapping. To go from a 7 1/4 to an 8 3/4 requires changing the U-bolts and shock plates, and to shorten the driveshaft. Depending on which wheels are used, sometimes the wheels have to be changed too. The '64 and earlier 13" wheels will likely not bolt down flush with the 10" drums due to the wide wheel slots. The 14" wheels are not a problem. Other combos may require several other mods/changes as well. As an assembly, The 8 3/4 A-body rears were pretty much identical from '66-72, except for the flared drums that started in 1970. The 3rd member housing casting numbers, and u-joint sizes varied depending on application, but, those are minor and easily adapted if needed or desired.
 
toolmanmike said:
This is for 65 Valiant. Note the standard 7.25 and optional 8.75. The right side column is 273 only.
View attachment 1716144411
Click to expand...
What is the source of that chart? I've heard forever that you could get a factory 8 3/4 in 1965, but, I've yet to see a build sheet or window sticker with that option. Dealer installed at a later date, sure, I've seen paperwork for several of those, but, not a factory installed one. Anyone have that proof?
 
I decided to go 8.75. Shipping costs are redonkulous so on the hunt for a local housing in PAC NW. WA, OR, ID. If anyone has a lead on one let me know.

No huge hurry.
 
Wildcat in Oregon. They were pricy from quotes given to me years ago compared to othere near where i lived back then. In person that may be different.

Ron's Wrecking in WA. They were a lot of GM but had some other makes' cars and parts avaliable. Never dealt with them peraonally.

I am sure there more.

Old car yards down here don't exist anymore after cash for klunkers. Last one I went to was in Ogden, UT.
 
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