Formal Rear Axle Dimensions

[1970FuryConv]

I have a question for the axle experts. Will a formal 1974 – 1978 rear axle fit on later fuselage cars? In other words, did Chrysler change dimensions spring center to spring center and drum to drum when the formals were introduced? Or are the formal rear axles interchangeable with the 1972 through 1973 Chrysler/Dodge/Plymouth cars.

Thanks, Ben

 

[CBODY67]

One thing would be to compare the rear track measurements.

 

[1970FuryConv]

One thing would be to compare the rear track measurements.

I have a rear track measurement for 72-73 of 63.4".
I don't have one for formals.

 

[3C's & a D?]

I would think dimensionally they would be very close, if not the same. Most formals I have encountered were equipped with the 9 1/4 axle, whereas most fuselages have 8 3/4's, 318 and slant six cars had the 8 1/4. So, there maybe some fiddling with the driveshaft/U joints.

 

[bigmoparjeff]

I believe they are either the same or very close.

My '71 Town & Country has a formal rear axle in it. I will get back with more info later on.

Jeff

 

[marko]

63.4 is the rear track of a 78

 

[69CoronetRT]

Please thank Big John for this info if it is helpful. They are original supplier documents from the 70's he so kindly passed on to me.

 

[1970FuryConv]

Appreciate the feedback. Thanks!

 

[1970FuryConv]

I would think dimensionally they would be very close, if not the same. Most formals I have encountered were equipped with the 9 1/4 axle, whereas most fuselages have 8 3/4's, 318 and slant six cars had the 8 1/4. So, there maybe some fiddling with the driveshaft/U joints.

Agree. I think the driveshaft will need to be shortened to use the 9.25. My current axle is 8.25. With Jeff & Marko's info, formal should fit. We can wait to see what Jeff adds.

 

[bigmoparjeff]

My photo didn't come out as clear as I hoped.

At least as far as my eyeballs can tell, the spring is sitting straight on the axle housing. The u-bolts are cockeyed, as they were hastily installed by the previous owner.

The rear axles were swapped between the '74 Monaco and '71 T&C.

Considering that the track is identical from 1972 to 1978, it's pretty likely that the spring center to center measurement is the same too.

Jeff

 

[1970FuryConv]

My photo didn't come out as clear as I hoped.

At least as far as my eyeballs can tell, the spring is sitting straight on the axle housing. The u-bolts are cockeyed, as they were hastily installed by the previous owner.

View attachment 476329


The rear axles were swapped between the '74 Monaco and '71 T&C.

View attachment 476330

Considering that the track is identical from 1972 to 1978, it's pretty likely that the spring center to center measurement is the same too.

Jeff

Thanks Jeff!
Did the driveshaft have to be shortened to accommodate the 9.25? Was a u-joint conversion required on the driveshaft? Ben

 

[bigmoparjeff]

Thanks Jeff!
Did the driveshaft have to be shortened to accommodate the 9.25? Was a u-joint conversion required on the driveshaft? Ben

That I can't tell you. I wasn't involved with the actual swap. I traded a set of formal seats and some cash for the Town & Country. I drove from the Philadelphia area to Chicago to pick up the car and didn't spend a whole lot of time at the guy's house, since I needed to make tracks to get back home in a reasonable time.

I do know that the distance from the front spring hanger to the axle is longer on the formals. He used the springs, hangers, brackets, and everything from the T&C, so he had to fabricate spacers to go between the body and front spring hanger in order to center the tire in the wheel opening on his Monaco. With the formal springs installed in the T&C, the tire is too far back in the wheel opening.

Jeff

 

[1970FuryConv]

That I can't tell you. I wasn't involved with the actual swap. I traded a set of formal seats and some cash for the Town & Country. I drove from the Philadelphia area to Chicago to pick up the car and didn't spend a whole lot of time at the guy's house, since I needed to make tracks to get back home in a reasonable time.

I do know that the distance from the front spring hanger to the axle is longer on the formals. He used the springs, hangers, brackets, and everything from the T&C, so he had to fabricate spacers to go between the body and front spring hanger in order to center the tire in the wheel opening on his Monaco. With the formal springs installed in the T&C, the tire is too far back in the wheel opening.

Jeff

Why would he switch springs? That makes no sense to me.
Are the formal axle spring perches different from 1972-1973?
1972 Fury rubber insulated spring perch