8&3/4 Axle questions

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225Cuda

225Cuda

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OK I bought a Complete 1963 Chrysler Newport with an 8&3/4 Axle, a 361 (B) big block(Im boring 60 over for 372 Cubic inches) I went 60 over at the suggestion of the machine shop( engine has just over 3/8" cylinder wall thickness), and a 727 matching the engine, now I went to rock auto to se what parts were available for the Axle it said it was a 742 Case for the 63 newport, but when I pulled it out of the car today it says 741 on the case, I will be narrowing the housing to Abody standards and getting A body axles, to put into my 67 B'cuda I will be putting the 372ci engine and 727 trans in my B'Cuda, also Im wondering if the 741 case will handle the 400+ HP from the engine, for "Hot street" useage, and maybe some low track use.
 
The weakness of the 741 case is finding r&p for it. The pinion is smaller, but doesn't have the stress risers of the larger pinions. And a 741 uses the exact same suregrips as the other cases. The pinion isn't the weak point in a 8 3/4 case anyway.
 
33IMP said:
The weakness of the 741 case is finding r&p for it. The pinion is smaller, but doesn't have the stress risers of the larger pinions. And a 741 uses the exact same suregrips as the other cases. The pinion isn't the weak point in a 8 3/4 case anyway.
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So, " almost" the bigger is better, but the more the is kinda deal?
 
Been running a 741 in the 470 automatic cuda for years now, it has 10x28 slicks on it. Not a day goes by without at least one full throttle launch. I don't baby it, ever, and I don't worry about it. I do have concern over the splines on the right side axle shaft which I inspect every year. When you twist one of those off during a 2-3 shift @ 90 MPH you turn your muscle car into a high speed corn picker.
 
Col_Steve said:
Been running a 741 in the 470 automatic cuda for years now, it has 10x28 slicks on it. Not a day goes by without at least one full throttle launch. I don't baby it, ever, and I don't worry about it. I do have concern over the splines on the right side axle shaft which I inspect every year. When you twist one of those off during a 2-3 shift @ 90 MPH you turn your muscle car into a high speed corn picker.
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MAN THAT'S COOL *** HECK!!!!!!!
The daily Launch... It sounds as though You've " Picked some Corn" though!
 
Col_Steve said:
Been running a 741 in the 470 automatic cuda for years now, it has 10x28 slicks on it. Not a day goes by without at least one full throttle launch. I don't baby it, ever, and I don't worry about it. I do have concern over the splines on the right side axle shaft which I inspect every year. When you twist one of those off during a 2-3 shift @ 90 MPH you turn your muscle car into a high speed corn picker.
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Op is planning on narrowing the housing. I'm hoping good axles are part of the plan.
 
741 does have a smaller choice of performance gears.
Staying with the A-body OEM brakes & bolt pattern?
Upgrading the front brakes & suspension to handle the extra weight & power? (Including master cylinder.)
 
Just a thought . . . . . don't the pre 64 8 3/4's have the tapered axle shafts with a different spline count ??
 
slickchick said:
Just a thought . . . . . don't the pre 64 8 3/4's have the tapered axle shafts with a different spline count ??
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Pre-65 have the tapered axles, (but the spline count of ANY 8 3/4 is 30) but the op is gonna narrow the housing. Gonna need new axles anyway
Edit. There is one exception, spool rear-end 8 3/4 can have 35 splines.
 
You'll be fine with a 741.
How do you plan to run a '63 727 (pushbutton shift, ball & trunnion output) in a '67 Barracuda?
 
33IMP said:
Op is planning on narrowing the housing. I'm hoping good axles are part of the plan.
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It happened to us at Imlay City in 1971. Terry and I were running a 64 Fury Gasser. The week before I'd removed the 4.88's and installed 5.13's which I think was the tipping point. At any rate we made several runs Terry launched hard, and stuck good every time, and had another fine run going. 1-2 shift no drama, 2-3 shift and the car turned right. There weren't any barriers or guard rails after the grandstands and the local farmer had corn right up to the strip. It was August so the corn was high and eared out. The car instantly disappeared into it sending a column of corn skyward. He and the car emerged onto the track a couple hundred yards downrange with wet tires and got all crooked but stopped safely. The grille smashed, fiberglass hood mostly missing, and windshield all busted up. When that axle broke in the splines all of the torque was applied to the left tire and what with the light and high front end was easily able to overcome the grip of the skinny front tires. After that episode we pulled the right axle for inspection/replacement after every third run, more often than not it would be a half spline off already. We should have had a Dana in it, and we should have been buying Strange axles, but we were way underfunded and stock axles were nearly free.
Steve
 
I hate to be a Debbie Downer but the transmission in the 63 is push button shift and has the ball & trunion drive shaft joint. You would be farther ahead by using a latter model transmission with the newer input shaft and slip joint yoke. The .060 over 361 pistons will be expensive since they are custom made. You might be farther ahead by starting with a 383 and gaining some extra cubes. The rear end needs to be shortened and requires new axles. You might be farther ahead by using a 65-67 B-body rear and just relocate the spring pads.
 
Most machine shops are prone to getting you to spend more money. Just get an old motorhome smogger 440 and put the 361 heads on it. Get a 727 with a PK number higher than 3600000 to get the wider direct bushing, common input splines, and part throttle kickdown and conventional yoke. And run an 8.8 Ford rear end.
 
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Locomotion said:
741 does have a smaller choice of performance gears.
Staying with the A-body OEM brakes & bolt pattern?
Upgrading the front brakes & suspension to handle the extra weight & power? (Including master cylinder.)
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Going with bbp disc all around
 
mcodecuda said:
I hate to be a Debbie Downer but the transmission in the 63 is push button shift and has the ball & trunion drive shaft joint. You would be farther ahead by using a latter model transmission with the newer input shaft and slip joint yoke. The .060 over 361 pistons will be expensive since they are custom made. You might be farther ahead by starting with a 383 and gaining some extra cubes. The rear end needs to be shortened and requires new axles. You might be farther ahead by using a 65-67 B-body rear and just relocate the spring pads.
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This, in addition to the 361 having the early small diameter crank pocket that will keep you from running a later 727, at least without extra crank machining or a custom convertor.
 
mcodecuda said:
I hate to be a Debbie Downer but the transmission in the 63 is push button shift and has the ball & trunion drive shaft joint. You would be farther ahead by using a latter model transmission with the newer input shaft and slip joint yoke. The .060 over 361 pistons will be expensive since they are custom made. You might be farther ahead by starting with a 383 and gaining some extra cubes. The rear end needs to be shortened and requires new axles. You might be farther ahead by using a 65-67 B-body rear and just relocate the spring pads.
Click to expand...
Yeah got the console shifter out of a 65 b body with cable shift
 
mcodecuda said:
I hate to be a Debbie Downer but the transmission in the 63 is push button shift and has the ball & trunion drive shaft joint. You would be farther ahead by using a latter model transmission with the newer input shaft and slip joint yoke. The .060 over 361 pistons will be expensive since they are custom made. You might be farther ahead by starting with a 383 and gaining some extra cubes. The rear end needs to be shortened and requires new axles. You might be farther ahead by using a 65-67 B-body rear and just relocate the spring pads.
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rebuilders choice has them in stock an readily available.
 
CudaFactHackJob said:
Most machine shops are prone to getting you to spend more money. Just get an old motorhome smogger 440 and put the 361 heads on it. Get a 727 with a PK number higher than 4900000 to get the wider direct bushing and part throttle kickdown and conventional yoke. And run an 8.8 Ford rear end.
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Machine shop I went to was $250 for a cleaning new freeze plugs and the bore over
 
225Cuda said:
Machin shop I went to was $250 fo

The 361 had the same stroke as a 383 and it's a easier revving motor because it's got such a short stroke
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?? That has nothing to do with my comment on the crank pocket (recess) for the convertor...
 
Riiight....$250 plus the markup on the pistons = $1,000. Easier revving??? You can only beat cubic inches with cubic dollars. You picked a bad motor, trans and rearend to start with. Better off to resell that car and start over. Unless it's really a 413; which most 63 New Yorkers were? What are the block casting numbers and stamped pad numbers?
 
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CudaFactHackJob said:
Most machine shops are prone to getting you to spend more money. Just get an old motorhome smogger 440 and put the 361 heads on it. Get a 727 with a PK number higher than 3600000 to get the wider direct bushing and part throttle kickdown and conventional yoke. And run an 8.8 Ford rear end.
Click to expand...
The machine shop I went to is only charging me $250 for The bar over new freeze plugs and full cleaning
 
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