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Location: Muskego, WI | Help me identify this rear diff, not sure what I have. I purchased the entire rear end (axle housing, axles, diff, bearings, everything but the brakes) from a gentleman in Minneapolis about 5 or 6 years ago, he had the rear end under his 1961 300 G (which I saw in his shop). He said he was informed the rear end was incorrect for his car at a show so he desided to make his car correct, that's when I picked it up. I had the entire rear end mounted in my 1956 Imperial until this fall when I installed an 8 & 3/4 with 3.23 Sure Grip from a 1967 Coronet. The rear end has been sitting in my storage shed since, but as you can see some of the gear teeth are quite pitted (it's shame too, the rest of the unit is in good shape). It's definitely a 3.36 Sure Grip, but what year/version is it? What car was it originally in?
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Location: Chestertown, NY ( near Lake George) | Looks like the diff from myy 55 New Yorker. The diff case is damaged as well as the spiders, of course you knew that.
Edited by Shep 2012-02-06 3:10 PM
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Exner Expert 19,174 posts. Neil passed away 18 Sep 2015. You will be missed, Neil!
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Location: bishop, ca | The P/N is 14xxxxx, which indicates an initial application for the 1954 model year.
Any particular part (and its P/N) can continue to be installed, un-changed, onto subsequent model years, and,
sometimes, a P/N's second digit can PRECEDE its actual initial MY application, so, possibly, this "14xxxxx" P/N might
pertain to the 1955 (and beyond) MY production.
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Location: WHEELING,WV.>>>HOME OF WWVA | i don't know why but neither the ring nor case numbers are in any of my book sources ------------------------------------------later |
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Location: NorCal |
The 1409101 ring gear was used in any one of several rear ends all dating from '37-'56, this is an 8 1/4" rear end. |
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Location: Muskego, WI | It is absolutely an 8 3/4 ring gear, I've measured it multiple times. Below are pictures of the diff in question in the factory original Imperial rear axle housing (8 3/4 housing). The splines on the ends of the axles have 16 teeth and are identical to the axles that were originally in the car. The mystery continues...
Edited by jboymechanic 2012-02-06 6:58 PM
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Location: The not-so-great, dirty-white North ( Michigan) | This is truly a "mystery" axle assembly.
16 tooth splines is definitely 56 and down model years.
Yet the differential is a Shure-Grip type.
You have an interesting axle here!
I guess the next thing to do is to measure the housing stud pattern to see if it is "later" or "earlier" 8 3/4" type.
Easiest way is to get a 1957-up 8 3/4 gasket and place it on the carrier and see if the holes line up or not! |
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Location: Muskego, WI | In my 1956 factory service manual, the last section is dedicated to the 300B. Standard axle ratio was 3.54 for both 3 speed manual or 2 speed PF auto. However, the following ratios were optional:
3.07, 3.36, 3.73, 3.91, 3.9, 4.0, 4.1, 4.3, 4.56 and 4.89
No mention of Sure Grip though, but I would think that would be assumed in a 300?
Edited by jboymechanic 2012-02-06 9:24 PM
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Location: WHEELING,WV.>>>HOME OF WWVA | for sure not an 8 3/4 ---------------------------------------------------later
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Location: WHEELING,WV.>>>HOME OF WWVA | doesn't a 8 1/4 come out the rear and have 11 studs --------------------------------------------------------------------------later |
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Exner Expert 19,174 posts. Neil passed away 18 Sep 2015. You will be missed, Neil!
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Location: bishop, ca | Jon, no....those rear gear ratios would not be "assumed" as being Sure Grip assemblies, on any car, 300 or no.
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Location: Muskego, WI | Not sure why people keep saying it isn't an 8 3/4. When people say it isn't, do they mean not a 1957 and later 8 3/4? The ring gear is definitely 8 3/4, but it is an older style. I did confirm that this diff does have a different 10 bolt pattern than the later 1957 and up 8 3/4 diffs. So we know this is 1956 or older. It appears I'm not the only one to have had one of these, see the old link below:
http://www.forwardlook.net/mail-archive/msg26771.html |
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Location: Big pimpin' | Jon, the 8 3/4 diff didn't exist until 1957. Anything earlier would almost have to be an 8 1/4 which looks Almost IDENTICAL in appearance. I can't tell you how many have PM'd me here looking at a 1956 8 3/4 rearend, only for me to have to tell them this same thing..Not an 8 3/4. Looks to be an early 8 1/4 unit. Unless you physically measure that ring gear OUT OF the rearend, then the 8 1/4 looks JUST LIKE the 8 3/4 by the naked eye.
Edited by dukeboy 2012-02-07 12:55 PM
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Location: Muskego, WI | dukeboy - 2012-02-07 11:39 AM
Jon, the 8 3/4 diff didn't exist until 1957. Anything earlier would HAVE to be an 8 1/4 which looks Almost IDENTICAL in appearance. I can't tell you how many have PM'd me here looking at a 1956 8 3/4 rearend, only for me to have to tell them this same thing..Not an 8 3/4. Looks to be an early 8 1/4 unit. Unless you physically measure that ring gear OUT OF the rearend, then the 8 1/4 looks JUST LIKE the 8 3/4 by the naked eye.
The 8 3/4 diff as it is commonly known didn't exist until 1957, but Chrysler made rear ends in the same style and with 8 3/4 ring gear prior to 1957. This is one of those rear diffs. I measured it at 8 3/4, my 1956 factory Chrysler service manual states that all Imperials, 300s and New Yorkers used 8 3/4 rear ends (only Windsors used the 8 1/4). |
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Exner Expert 19,174 posts. Neil passed away 18 Sep 2015. You will be missed, Neil!
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Location: bishop, ca | OK...so, there is an "old" and a new version of the 8 3/4" differential.
You've got one of the rare 'old' versions of the 8 3/4.
Now what?
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Location: Muskego, WI | d500neil - 2012-02-07 1:22 PM
OK...so, there is an "old" and a new version of the 8 3/4" differential.
You've got one of the rare 'old' versions of the 8 3/4.
Now what?
Now that we've established that it is the old style 8 3/4, what year is it? What vehicle did it come from? If it was possibly factory original/optional on my Imperial I'd keep it. If not, I'd probably sell it to some one that is looking to make their restoration correct or add period, make and model correct sure grip to their project. There's also the full of all this robust conversation.  |
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Location: NorCal | jboymechanic - 2012-02-07 8:01 AM
Not sure why people keep saying it isn't an 8 3/4. When people say it isn't, do they mean not a 1957 and later 8 3/4? The ring gear is definitely 8 3/4, but it is an older style.
Regardless of the physical measurement of the ring gear it is an 8 1/4". As I stated several times, this gearset dates back to '37 and up to '61 and every credible source calls it 8 1/4". The 8 3/4" housing has two bolts at the top and yours has one. The only cars that used that 8 1/4" gearset after '56 were 6 cylinder. |
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Location: The not-so-great, dirty-white North ( Michigan) | John...
Can you tell me with a straight face and sincerity that something that has an 8.75" diameter ring gear (crown wheel) is an 8.25" (8 1/4") rear carrier?
Especially when the bolt hole pattern for the early 8 1/4" rears was 11 bolts(studs) and the 8.75" rears was 10-bolts (studs)?
How do you think axles get their designation, up to and including GM, Ford and Dana rear ends?
I think you are hung up on anything that has 8 3/4" HAS to be a "modern" 8.75" rear.
That is patently false.
I have a 1956 DeSoto Adventurer, that has a 3.73:1 rear gear axle assembly with a PRE-Modern 8.75" axle assembly in it.
The ring gear measures 8.75" in diameter.
Does it fit a 1957-up housing? Hell NO! The 10-hole pattern to attach it is different.
It also has 16 spline axle shafts. And an interesting companion flange for the "winged" u-joint carrier cups.
So it is NOT a modern 8 3/4" carrier. But it is not a 8 1/4" carrier either, as I had one of those from a parts donor Firedome I got rid of several years ago.
Both were third member rearends. But size was visibly different.
You need to acquire a few pre-1957 Shop Manuals and read up......... |
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Location: Williams California | Imperials and senior series Chrysler and DeSoto used different carriers in '55-56 than their junior counterparts.
---John |
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Location: Muskego, WI | Pictures as proof of my statements. Let's all try to keep cool and focus on figuring out what this diff belongs to, I appreciate all helpful comments (but still enjoy the not so helpful ones). For reference, C-71 = Windsor, C-72 = New Yorker, C-73 = Imperial, C-70 = Crown Imperial (limo) and C-300B should be pretty obvious.
Edited by jboymechanic 2012-02-07 9:10 PM
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Location: NorCal | DeSotohead - 2012-02-07 4:55 PM
John...
Can you tell me with a straight face and sincerity that something that has an 8.75" diameter ring gear (crown wheel) is an 8.25" (8 1/4") rear carrier?
The 1409101 ring gear in the subject rear end identifies it as 8 1/4" (common nomenclature regardless of what it might actually measure) and is interchangeable with gearsets that date to 1937....taking your argument to the logical conclusion the 8 3/4" dates back to 1937. Otay.
The 8 1/4" gearset is found in three distinctly different third member assemblies, the most common have 11 attaching holes but that's just one of three and the the C-72 and C-73 you cite aren't one of them. My comments are about THE SUBJECT REAREND IN THE OP |
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Location: The not-so-great, dirty-white North ( Michigan) | I stand by what I say. You may have a mistype in your literature.
Rather than referring to it, it might be nice to show the source.
Jon did his part, and John (Big M) has substantiated my statement of larger than 8 1/4" axles in senior vehicles. |
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Location: Muskego, WI | 57chizler - 2012-02-08 1:02 PM
DeSotohead - 2012-02-07 4:55 PM
John...
Can you tell me with a straight face and sincerity that something that has an 8.75" diameter ring gear (crown wheel) is an 8.25" (8 1/4") rear carrier?
The 1409101 ring gear in the subject rear end identifies it as 8 1/4" (common nomenclature regardless of what it might actually measure ) and is interchangeable with gearsets that date to 1937....taking your argument to the logical conclusion the 8 3/4" dates back to 1937. Otay.
The 8 1/4" gearset is found in three distinctly different third member assemblies, the most common have 11 attaching holes but that's just one of three and the the C-72 and C-73 you cite aren't one of them. My comments are about THE SUBJECT REAREND IN THE OP
John, if this 8 3/4 (as measured) ring gear is actually commonly known as a 8 1/4 as you say, what would the 8 1/4 (as measured) ring gears be commonly referred as? It seems very odd to me that there would be two different sizes of 8 1/4 ring gear. Keep in mind the parts books aren't always right. My Imperial had an odd radiator part number in it as well (1686000) that was original to the car but didn't match the parts catalog's part number for the car.
On another note, does any one know what the numbers and letters after the ratio stand for. In this case, 7 55 23+MIX? |
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Location: ZH, Switzerland | Thanks for your information and Jon for opening this thread. I checked the rear axle (differential) at my Chrysli. It's the same 1404 number at the front and at the same position (like a real 8 3/4" rear end) there is a flat area with the ratio 3.36 stamped in. The carrier inside looks like a Sure Grip, but it isn't. It's an open carrier. It's pictured in the 1956 Service Manual exactly this way. Common to the later 8 3/4 are both adjusting disks to adjust the clearance of the bearings.
Happy Motoring!
Dieter
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Location: Muskego, WI | It behaves like a sure grip though, when the assembly was mounted in the car and the rear tires were lifted off the ground and you spun a wheel in a certain direction the opposite wheel matched the direction of rotation (not the opposite like an open carrier). Is there a condition that would cause an open diff to act this way? |
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| Hello...I am looking to repair or replace the differential on 56 Chrysler New Yorker. It is a "front loader" like the pics at the top of this thread. What is it? It has never been opened since 1956 and I have a new fresh built 392 going in. Does anyone make a replacement bolt in 3rd member? or a siutable entire rear axle replacement? Also, where can I get some new leaf springs? Should I run it first and then decide?? Any help will be greatly appreciated> .. Thanks, Alan
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| Correction....It looks identical to the LAST photo in this thread. Thanks!! |
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| Correction....It looks identical to the LAST photo in this thread. Thanks!! |
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Location: So. Cal | There are no replacement 3rd members for the '55-'56 Chrysler rear, nor for the early 8 1/4 either. Another used gear is your only option with them. There is no good reason to swap it out unless you don't like the gear ratio in it, or if it is bad. So if the gear ratio is good for you, and it works, just leave it. Otherwise, you can swap in a later 8 3/4, but I'm not sure what length the '56 New Yorker uses, so you will have to measure it out first to figure out a good replacement. Best to measure from drum-drum, which is from the wheel mounting surfaces to compare. But replacing it will require welding on new spring perches, new lines & a new driveshaft. |
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Help identify this rear differential
