I have a 53 plymouth two door cranbrook, anyone do one piece custom axles and have measurements?

[DavidJose1]

Trying to figure out the length and measurement needed for custom 1 piece axles, I'm gonna try to do a custom disc brake conversion and I'm running a 360 twin turbo. I hear these tapered and keyway axles will shear off

Edited June 22, 2022 by DavidJose1

[Sniper]

I am sure any custom axle maker will make what you want, for a price.  Back in the old days they used to cut another keyway and run two keys.

 

All that said, it'd be cheaper to swap in a newer style axle.  Cherokee and Explorer axles seems to be the favored ones and they can be had with discs as well.  Not sure if they can handle a twin turbo 360 though.  Might need to go 9" because even if you get a set of one piece axle shafts made up something else in the stock axle will fail, probably strip the teeth off the ring gear.  Not to mention no limited slip options short of welding up the spiders as a sort of spool.

 

But i don't know of anyone making one piece axles for our rides.  I think the M37's have that aftermarket option, but I dunno how relevant it is to the pass car side.

[kencombs]

That axle design was used behind the super stockers of the 60s.  I wouldn't worry about them unless you have excellent traction, like huge sticky tires and suspension to match. 

[andyd]

I used an Oz 1962 Chrysler rear axle which was basically a 55/56 Plymouth rear axle for 30 yrs with a home made rear disc conversion.......used a front vented 11 rotor hat from an Oz late 60's Valiant and attached it to the rear drum brake hub held onto the axle with the large centre nut which then had a custom made caliper bracket using 4 of the 5 rear axle brake drum backing plate bolts and the caliper bracket held the 1975 Oz Ford rear disc caliper..........worked fine of 30 yrs or so but I eventually swapped it for a complete 1990's Oz Ford disc brake rear end..........I would NOT use the original rear axle unless that was all that was available, which back in the mid 1970's was pretty much all I could afford...........lol...........andyd 

[Plymouthy Adams]

spline axle shafts are often not a problem at all if you do the maintenance per the specs.....this axle style continued with the 8 3/4 till along the 64 model year and held up to some beefy machines....the max wedge for one....the Salisbury is the Euro version of Dana and put these rear axles in a number of their performance cars.....I have this axle setup in a couple factory 440 powered setups all in positive traction might I add.  The hardest drums I have ever encountered to remove of this style was my Volvo PV544..

[Sniper]

What other axles assemblies do is really irrelevant.  The OP isn't talking about running an 8 3/4 or any other axle.  So we need to stick with the issues relevant to the specific axle being contemplated.

[Plymouthy Adams]

read again please...not talking 8 3/4,  but talking same as he....then comparing the same axle style, tapered with keyway as is the 53 to that of Mopar through 64.....and the very ability to stand up to the punishment of the max wedge with its 420 HP factory output.....further, I mentioned also that this style taper with key continued way past 64 in many other makes and models still running factory big blocks....there is no fault in the design...

[James_Douglas]

I ran a long ram 64 Chrysler 300K convertible hard in high school. I purchased new hardened keys from someplace on someones recommendation. That 413 was 390HP and a lot of torque. I never busted a key. Same basic axle.

 

The only reason I am going to go to a 9 inch ford for the 1947 Desoto is the big desoto uses a larger rearend, 12 bolt ring gear, and I have not been able to find a NOS 4.11 ring and pinion. The 4.3 works but is a little too much in town in second OD.

 

I also want to get a 12 inch drum brake that is self adjusting. A pinion that never leaks is another plus... Currie can make one up but in the end it will be like $4k.

 

James

[kencombs]

4 hours ago, Plymouthy Adams said:

read again please...not talking 8 3/4,  but talking same as he....then comparing the same axle style, tapered with keyway as is the 53 to that of Mopar through 64.....and the very ability to stand up to the punishment of the max wedge with its 420 HP factory output.....further, I mentioned also that this style taper with key continued way past 64 in many other makes and models still running factory big blocks....there is no fault in the design...

That was my rationale for my first response also.   I can't pass judgement on the differential, but the axle design is not flawed in any way.  Well, except for brake maintenance accessibility and that is fixable without changing the thing out.   I ran a 413 in a 58 Dodge for several years.  Beat on it hard too.  Never an axle/hub issue.

 

Edit to add:  My Dad owned and operated a salvage from 1960 though 1990.  I spent many hours working there, removing, selling and installing parts.  I saw exactly one failed Mopar rear end.  The pinion was driven back so hard it broke the case and carrier.  But that was due to a high speed collision with an immovable concrete object.  Hit the front of the crankshaft and broke everything from there back.

 

Never encountered a slipped hub.  Some guys used hardened keys but IMO they are not needed.  But for the system to work as intended they must be assembled as speced in the shop manual.  Clean, dry tapers!  No rust, scratches or lube as the resistance to spinning comes mainly from the interference of the tapered joint.  Keyway is only secondary.

Edited June 23, 2022 by kencombs

[Sniper]

9 hours ago, Plymouthy Adams said:

read again please...not talking 8 3/4,  but talking same as he....then comparing the same axle style, tapered with keyway as is the 53 to that of Mopar through 64.....and the very ability to stand up to the punishment of the max wedge with its 420 HP factory output.....further, I mentioned also that this style taper with key continued way past 64 in many other makes and models still running factory big blocks....there is no fault in the design...

I read what you posted.

 

I used to own a 64 300.  It had an 8 3/4 with tapered axles. Chrysler DID NOT use the same axle as a 3 Plymouth behind a Max Wedge, they used an 8 3/4.  The 8 3/4 came out in 57 for a reason. 

 

The fault in any design is exceeding that design.  A twin turbo 360 will exceed that with the axle in a 53 Plymouth.

[Plymouthy Adams]

29 minutes ago, Sniper said:

I read what you posted.

 

I used to own a 64 300.  It had an 8 3/4 with tapered axles. Chrysler DID NOT use the same axle as a 3 Plymouth behind a Max Wedge, they used an 8 3/4.  The 8 3/4 came out in 57 for a reason. 

 

The fault in any design is exceeding that design.  A twin turbo 360 will exceed that with the axle in a 53 Plymouth.

again you failing to see what was said and you are even now ignoring the original post and the idea that he was concerned over the taper axles and keyways.....they were not a problem on the early mopars and not AGAIN as mentioned when the design continued with the production of the 8 3/4 and putting the muscle to the pavement behind some very powerful engines, again no problem with taper axle and even after Mopar dropped the tapered axles other companies continued yet with taper axles again with no problem...the only problem here is you are not able to comprehend the concept of an axle design...not a an actual axle classified by a ring gear size...as I said from post one...the taper axle are not an issue....that have withstood the test of time.   And while the 53 axle may well fail within the carrier.....the post was not questioning the gears,  the man was concerned with the taper axles failing.  

Edited June 23, 2022 by Plymouthy Adams

[Sniper]

The assembly AS USED IN THE OPS CAR is a light duty, low power axle.  It shreds keys and key ways with any sort of added power and traction.  The fix back in the day was to add a second keyway, that fix was abandoned as soon as newer, strong axle assemblies became available for a reason.  I don't care what other axles or axle manufacturers might have done, we are not talking about them. 

 

The ADDED point was that even if he got a one piece axle made up to fix the key way issue all that would do is move the failure point to the next weakest link in the axle. 

 

In the OP's case, wanting to run a twin turbo 360, the stock 1953 axle assembly IS THE WRONG CHOICE, period.  Unless the choice you are making is to spend money needlessly.  In which case, have at it.

[Loren]

Keyed tapered axles were used successfully for a very long time.

If the parts are in good shape and axle nut is tight with a cotter pin in it, they are more likely to stay together than come apart.

The Halibrand quick change axle Hot Rodders still use has keyed tapered axles.

Its the taper that does the real work. The key offers added protection.

In machinery tapers are used in lots of torque applications. Drill chucks for one. Jacobs the drill chuck manufacturer has their own spec tapers.

The biggest complaint about the stock axle is that it requires a really good hub puller to get them apart.

I like the design of the stock 8.25 axle but if you find you can break it, then the next axle MoPar made is the 8.75 and it is highly respected.

It has the same excellent design, is much stronger (not that the 8.25 is weak, but the 8.75 is larger) and has lots of ratios and limited slip differentials.

It bridges the era of keyed tapered axles and the flanged axle shafts, so if you wanted to look “Old timey original” you could.

My thoughts on most things mechanical is that you don’t change anything until you find you can break it.

Then strengthening one component will almost certainly lead to the breaking of others. The weak link keeps moving.

The 8.25 axle was used clear up to 1956 and it was strong enough for the first V8s.

If you have an 8.25 axle shaft out of the car take a look at the necked down area between the wheel bearing and the differential splines. Notice how long it is.

If you look at a flanged axle shaft, look at the smallest diameter and how short it is. I was looking at a Dana 44 the other day and I swear the smallest diameter was less than 3/4 inch long. You don’t need an engineering degree to tell where that axle will break. That long necked down area was intentionally design to spread the torque load over the largest possible area. That’s a good design feature. I have to admit I haven’t seen a flanged axle shaft from an 8.75 but I haven’t heard of any breaking either.

[Sniper]

6 hours ago, Loren said:

The 8.25 axle was used clear up to 1956 and it was strong enough for the first V8s.

 

One could argue the point that if it were strong enough the 8 3/4 would not have been developed to replace it.

 

I would surmise that a twin turbo 360 would make 500+hp, well beyond anything Chrysler put in a 50's car.  At that level the original axle is a bad choice, even without tapered axles as the OP is thinking about doing.  Which is the point, within the original design parameters, or near to them, the 53 axle is a fine unit.  When you exceed those parameters by multiples it is no longer a fine axle.  It is a grenade without the safety pin in it.

[Loren]

24 minutes ago, Sniper said:

 

One could argue the point that if it were strong enough the 8 3/4 would not have been developed to replace it.

 

I would surmise that a twin turbo 360 would make 500+hp, well beyond anything Chrysler put in a 50's car.  At that level the original axle is a bad choice, even without tapered axles as the OP is thinking about doing.  Which is the point, within the original design parameters, or near to them, the 53 axle is a fine unit.  When you exceed those parameters by multiples it is no longer a fine axle.  It is a grenade without the safety pin in it.

It all depends on how its driven.

If you are going race anything, you can break it.

Some folks drive like they intend to break things.

As Colin Chapman said of Mario Andretti, “That man could break an anvil”
Chapman, it should be noted built cars that killed a lot of good drivers by breaking under stress.

 

I understand Sniper’s point, the weak link in the 8.25 rear axle is not the axle shafts, it is the fact that it is undersized for the torque load anticipated.

For serious loads there are bigger stronger axles available. The ones usually used for axle swaps in vintage Plymouths, ie Cherokee & Ranger are not on that list.

Number 1 Ford 9 inch. It has the removable differential carrier like the MoPar 8.25 & 8.75 but for strength and a lower drive shaft hump it uses a “straddle mounted” pinion gear. Meaning the offset of the pinion to the ring gear centerline is so extreme it practically straddles it. This gives the 9 inch a lot more tooth contact and thus strength. That extra strength however comes with a parasitic drag cost.

Number 2 MoPar 8.75. The 8.75 has the removable differential carrier but not the straddle mounted pinion. Thus it doesn’t have the parasitic drag. It isn’t as strong as the Ford but all things being equal you’d go faster with it.

Number 3 Dana 44. Used in more cars than you’d believe! Doesn’t have a removable differential carrier, isn’t a straddle mounted pinion type. The guy who now owns Joe Walsh’s Maseratti is a friend of mine (the one he sang about “my Maseratti does 185, I lost my license now I don’t drive”) and so I’ve looked it over pretty closely. There lives a Dana 44 in those cars just like my International Scout!

Clearly the MoPar 8.75 has some compelling advantages over its competition.

Even this well designed axle can be broken with enough power and hard use. I am reminded that Plymouth used the Dana 60 in the Superbirds.

Which takes us right back to the concept of not changing anything until you break it. Once you’ve proven you have the power and the difficult operation to break it, then you change it. The average guy in his 70s is not going to stress his car like he did when he was a teenager. We simply don’t want to pay the tickets (Jay Leno being a notable exception. I’ve seen him driving his 1912 Stanley twice the posted speed limit, with no seat belts and 1912 brakes!). So its back to the need vs want argument. If you need it there is no question but how do you know you need it? You gotta break it under use. If it is just something you want, then that is the justification. Engineers work on needs not wants.

[Adam H P15 D30]

On 6/22/2022 at 4:32 PM, DavidJose1 said:

Trying to figure out the length and measurement needed for custom 1 piece axles, I'm gonna try to do a custom disc brake conversion and I'm running a 360 twin turbo. I hear these tapered and keyway axles will shear off

With that mill don't waste time or money on modifying the stock axle.  You are in 8.75, 8.8 Ford or 9" Ford territory, don't cut corners at the rear axle...  Probably spend less $$$$ putting something better in verses trying to strengthen what's there, not to mention ample gear, carrier and other parts availability.

[Los_Control]

I have to agree with @Adam H P15 D30 I can see trying to stay period correct with your build .... with your 360 that bus left a long time ago.

You could pick up a Ford Explorer 8.8 with disk brakes and many many options of gear ratios, you can get your parking brake back, you can buy brake parts from any local auto parts store.

 

The swap is pretty straight forward, buy a rear end from the bone yard, try to get all the E-brake cables that go with it to modify to your use. Grind off the spring perches and weld on new ones .... Tractor supply use to sell spring perches for $20 ... I dunno about now and sure there are other options .... The U-joints depends with what you have now. I could name many more reasons to make the swap .... While I can not honestly think of 1 reason to modify your original rear end.

 

IMHO .... agree or disagree .... Beefing up a stock rear end is like putting lipstick on a pig.

[DavidJose1]

Good words dear sir, got 8.8 now having to find exact length center to center perfectly and grind rest, measure out and weld rest in