I acquired a 8 3/4 center section out of a Dodge truck, 741 open and was told 355 gears. I counted the teeth on ring gear and pinion gear and came up with 3.91. The number stamped on the ring gear is 3.58. Just a little confused. What is proper way to determine EXACT ratio. Thanks for any help.
Gear Ratio
- Thread starter Stockdog
- Start date
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Bulldozer
free ice cream sandwiches
im betting the number on the ring gear is actually 3.55, just a crappy stamping. this is the number to go by.
Count the teeth on the ring gear, count the teeth on the pinion then divide the smaller into the larger number.
Dusterdude72
IN MOPAR MUSCLE MAGAZINE
If you have it all visible,count the teeth on the ring and the teeth on the pinion and divide the ring number by the pinion number. For example, mine is 41 tooth ring divided by 9 tooth pinion. Which makes for a 4.56 gear.
OldmanRick
Well-Known Member
You do see the 741 cast into the chunk right?
Coould possibly be an late 50's early 60's gear set.
Make sure your axles will slide in the side before puttin much money in the center.
Make sure your axles will slide in the side before puttin much money in the center.
That's what I'm wondering. Double check the numbers on the third member. Is it this? [SIZE=-1]Casting # 1820657[/SIZE]
OldmanRick
Well-Known Member
Reason i asked Bruce and dog is because toyota uses a 3.58 ratio in a drop out chunk that i saw by googling....
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[SIZE=-1]8 3/4 CASTING NUMBERS
[/SIZE][SIZE=-1]1820657 AKA "657"
The 657 is as equally weak as the 741 described below but nowhere near as common. It is a 1 3/8" pinion shaft unit like the 741 and was discontinued in 1964. This was the year when Chrysler dropped the tapered axle shafts that had the brake assembly attached to the axle with a keyway and large nut. If you see this rear end....RUN! However, the pumpkin can be swapped into a later housing or rear end.
[/SIZE][SIZE=-1]I wonder if they took the guts and put them in a 741 housing[/SIZE][SIZE=-1]. [/SIZE][SIZE=-1]Or if they would even fit.[/SIZE][SIZE=-1]
[/SIZE]
[/SIZE][SIZE=-1]1820657 AKA "657"
The 657 is as equally weak as the 741 described below but nowhere near as common. It is a 1 3/8" pinion shaft unit like the 741 and was discontinued in 1964. This was the year when Chrysler dropped the tapered axle shafts that had the brake assembly attached to the axle with a keyway and large nut. If you see this rear end....RUN! However, the pumpkin can be swapped into a later housing or rear end.
[/SIZE][SIZE=-1]I wonder if they took the guts and put them in a 741 housing[/SIZE][SIZE=-1]. [/SIZE][SIZE=-1]Or if they would even fit.[/SIZE][SIZE=-1]
[/SIZE]
I would run it if everyting seems tight, that is why I threw in late 50's early 60's
If you think about it there were alot less resources for parts back then, and people used what they had to keep something running.
If you think about it there were alot less resources for parts back then, and people used what they had to keep something running.
OldmanRick
Well-Known Member
I've seen the early funky style rears before, but i had no idea about a carrier earlier then the 741. Thanks Bruce, you taught me something today.:thumblef:
Bulldozer
free ice cream sandwiches
great detective work Bruce
Also, 8.75 were used before 1957, I had a 1/2 ton 1956 dodge truck with an 8.75 with tapered axles, 40K original miles bought off the original owner.
I found a 3.31 in a 65 plymouth /6 3 speed,(741) never heard of such,looked it up in the FSM,sure enough,,optional ratio. I just got a 1958 1/2 ton 8 3/4 truck rear complete that has 3 something gears. Have not pulled it apart yet to see actual numbers. Carrier # 1820657 also a number that was unknown (to me).Maybe it is a 3.58 too.
I wouldn't be surprised if it is. That would be nice to know fer sure.
Was it a later in the year build? What I have read the banjo style rear was introduced in 57. That's pretty interesting.
[SIZE=-1]8 ¾[/SIZE][SIZE=-1]
The only Banjo axle produced by Chrysler.
Introduced 1957 DOA by 1974
Last year in A bodies: 1972
Last year in E bodies: 1974[/SIZE]
Beware because some 657 rears actually had 8 inch ring gears! I'd measure the ring gear to be sure. Could be a swapped gear set.
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