3rd gen guys? Need advice on a rear end swap...

[Charger1973]

Im going to pull an 8 3/4 rear end from a 72 Charger to put under my 73.  The rear is still under the car and I will need to remove it.  I know there are some differences in the 72-73 suspensions as far as rubber bushings etc.  I need to know how much to get from the 72?  Should I just cut it at the shackles and take the leaf springs and all?  Or is there even a difference in 72-73 springs?  Id rather not take what I dont need so if they are the same I will leave them.  Any help would be great!

And if it makes a difference, the 72 has a rear sway bar I will be getting as well. 

[bordin34]

I think that the rear-ends should be the same. I don't see why or how they could change them to give a better ride.

[Nacho-RT74]

I know 71/72 spring front bushing is round, and 73/74 is elongated. A buddy's mine installed  71 springs on 74 without problem. So even is different, measure from center to center of bushing it should be the same. Rear bushing and shackle definitivelly is the same

Stud guide on spring is the same, and should it be located on same place

Plates. sway bar is different because the isolated clamp assembly on 73/74. if you install a 71/72 rear sway bar plates on 73/74 you wont be able to use those isolation clamps. Also will need to use the lower spring clamp to shock absorver, since U bolts holes on plates doesn't match between 71/72 and 73/74.

Axle pedestals. 71/72 has a small guide hole to fit the spring stud, for a while 73/74 has a big hole to the isolation stuff. If you try to fit a 73/74 axle on spring without iso clamps, axle will be floating around since guide will be floating on big hole. Another difference is the pedestals are shorter on 73/74 to compensate the extra height because the iso clamps asembly.

Rear sway bar itself... 71/72 are straight, and 73/74 are bended to save from hit the axle cente section because the different pedestal height

another sutff is 71 R/T spring are with more leafs, and one more on passenger side because engine torque

[Nacho-RT74]

hehehe found it
http://www.dodgecharger.com/forum/index.php/topic,1673.0.html

[Charger1973]

So it sounds like if I take the whole assembly it would be a direct bolt in, otherwise I will have trouble getting parts to match.  Thats no problem.  The one peice that I would like to know about is this front leaf spring hanger.  Does anyone know if they the same or not? 

[Nacho-RT74]

On both pics are the same assembly but the right side pic is not the right spring to 73/74 as far I know... or at least not te one mounted on mine. It is a round bushing being really an elongated one the correct

[Charger1973]

On both pics are the same assembly but the right side pic is not the right spring to 73/74 as far I know... or at least not te one mounted on mine. It is a round bushing being really an elongated one the correct

Those are the springs under my 73, I dont think anyone has changed them..  I will look at the rest of my cars tomorrow, i'll let you know if any of them are different than this one. 

[Charger1973]

Do you have a picture of yours?  Or at least one that is elongated?

[Nacho-RT74]

not of mines, but will search... to take a pic of mine will have to wait tomorrow at day light. Anyway is a fact you can interchange the complete assembly, and also keeps the front hanger and also spring on the donor parts car, just take axle, lower and top plates and sway bar

[andy74]

when i swapped my 8 1/4 for an 8 3/4 the rear end i got had the larger holes for the spring mount,a local spring shop had the metal bushing to compensate for it,i just welded them in,everything else swapped over,including the rear brakes-ive been driving it like that for damn near 2 years,and everything seems fine,but i dont have a rear sway bar

[Charger1973]

By larger hole you mean the one at the rear end where the large rubber bushing is on the 73/74s?  SO your rear was from a 73 but you used your 72 front hangers and it worked fine?   

[Nacho-RT74]

No, he is talking about the pedestal holes that fits on to spring stud

You know what ? I have doubts now... here is the pic of my front spring hanger. DOES LOOK THE SAME you posted... but I'm pretty sure is elongated, unless is allmost unnapreciable difference.

Now I don't remember what exactly did happen. I think I could trade the springs I bought when I was replacing. I could be bought a wrong one what did have elongated hole the first time and had to go to dealer to trade, don't remember why. was long time ago, in 2001.

Really I don't know/remember right now. But also could it be the elongated difference is pretty unnapreciable mounted.

well in fact if you see side by side... 71/72 spring mounting bushing is SMALLER than the 73/74. but definitelly the hanger looks the same so center to center, 71/72 springs are the same distance that 73/74, so interchangeable

Mopar catalogs are some confusing on PN description on 71 and 74

[Charger1973]

Hmm 

[dukeboy_318]

I think that they should fit okay, might have to just try it and see, my charger has 71 super stocks on it, and they fit fine with no mods according to the owner, but mine already has the 8.75 rear so that might have helped some. hope this helps

[Charger1973]

I think it will all work out fine.  I will try and get everything and I will update when I get ready to do the conversion. 

[Nacho-RT74]

trust me you won't need to get the springs or hanger, you can use the ones you already have, and install the new axle with taller pedestal and smaller guide hole and sway bar plate with matching lower shock absorver plate.

Unless the spring you will get are stronger and better that the ones you already have

[Nacho-RT74]

I found these two diagrams I made LOOONG time ago. and posted but have no idea where, so I repost... illustrations without sway bar plates. You can notice different pedestal height and different holes width to U bolts on plates. Also why are those differences.

[Nacho-RT74]

edited and made new draw to a direct compare. Pedestal height is shorter on 73 and laters because the extra assembly height on isolation assembly... plus the guide hole size ( x measurement ) ... Isolation clamps also made wider assembly between C clamps, what would make a "problem" if you try to fit one kind sway bar plate on the other one, beside also the guide hole of course and Isol Clamp shape ( not plain ).

Another problem that I already found and I couldn't save when I got wrong sway bar plates and tried to modify ( earliers ) is the taller pedestal heigh also makes a taller sway bar plate side reinforcement that meets with axle on laters one, so imposible to fit. ( green boxed on second draw ) Will need a HEAVY modificationg that will make probably a weaker plate. The U bolts clamp holes are not that hard since can be elongated and will need to fill the space of the iso clamp shape  and modify the hole to the spring guide... that is pretty easy to do really ( 3rd pic ). Never could fit anyway.

So conclusion... to make the easy job, with springs exception, you need to match complete assembly from one to the other year, including sway bar parts, both plates ( lower and top ). Bar itself also recomended.

Spring you can use the same except if you want to change for a more leafs one or bigger or smaller isolation front bushing. So as wished, but not mandatory.

[74Charger]

I did a swap about a year ago or so.  I took a 8 3/4 rearend from a 72' Road runner and put it on my 74' Charger.  Which had a 8 1/4 rearend.  Aboslutely no problems what so ever.  I reused my springs, shackles,shock mounts and my whole brake assembly.  The only thing I took off the 72' Road runner was the axle housing.  All the bearings, drop out, and axles I bought new.  It was actually pretty easy to do.  I was a little nervous.  Never having done a rearend swap before.  And I wanted it to be as painless and easy as possible. I did my homework and found one exactly the same size as my old 8 1/4 rearend.  The rest is history as they say.

[Charger1973]

I got the rearend home last weekend.  I got a chance to work on it a couple days this week and its not finished but its under the car anyway.  I got the 8 3/4 rearend complete with the leaf springs and all hardware.  I was even able to get the front hangers.  I also got the rear sway bar.  All this came from a 72 Rallye.  The benefit of doing it this way, is that I completely did away with all that rubber isolator stuff in the rear of the car.  (The front is next in line  )

[73ChargerSE]

I have a question:

I may be getting a C-Body rear for my Charger.  The perches are the same width as 3rd gens right?  If i plan on keeping the rubber isolator stuff, how would I modify the perches, could I just bore them out a little bit, or would I have to get new perches with the larger opening?

[Charger1973]

I think they are the spring perches are the same width, but im not 100% sure on that. 

I dont see why you couldnt enlarge the hole to fit, if the guys who do the opposite swaps sometimes just weld in a washer to take up the gap.     Do they even make the spring perches with the large hole?  I always see them with the small hole. 

[Charger1973]

Ok I almost have this thing back together but I have a couple questions.

1.  How do I adjust the rear axles with the adjuster on the passenger side of the 8 3/4?  Im not sure how tight is needs to be. 

2.  My driveshaft is for a small U joint and the 8 3/4 yoke is for the large U joint.  What do I do?  Can I swap in the small yoke from my old 8 1/4?  If I can, is it a good idea?  Do I need the larger U joint for a car with more HP?

[74Charger]

Ok I almost have this thing back together but I have a couple questions.

1.  How do I adjust the rear axles with the adjuster on the passenger side of the 8 3/4?  Im not sure how tight is needs to be. 

2.  My driveshaft is for a small U joint and the 8 3/4 yoke is for the large U joint.  What do I do?  Can I swap in the small yoke from my old 8 1/4?  If I can, is it a good idea?  Do I need the larger U joint for a car with more HP?

Not sure on the adjuster.   

If I remember right,  They make a universal u-joint you can buy.  That adapts the 7260 to the bigger 7290 yoke.   

http://www.mopar.com/m_perf_subcat2Check.jsp?SubSubSubGrpID=466&dummy5=1182290413065

[Charger1973]

Ok I almost have this thing back together but I have a couple questions.

1.  How do I adjust the rear axles with the adjuster on the passenger side of the 8 3/4?  Im not sure how tight is needs to be. 

2.  My driveshaft is for a small U joint and the 8 3/4 yoke is for the large U joint.  What do I do?  Can I swap in the small yoke from my old 8 1/4?  If I can, is it a good idea?  Do I need the larger U joint for a car with more HP?

Not sure on the adjuster.   

If I remember right,  They make a universal u-joint you can buy.  That adapts the 7260 to the bigger 7290 yoke.   

http://www.mopar.com/m_perf_subcat2Check.jsp?SubSubSubGrpID=466&dummy5=1182290413065

Looks like this is what I am going to use for now.  Id like to get the right driveshaft though so next time I can use a standard U joint.  I wonder if my local parts store would have the combination U joints or if thats something I have to get through a catalog...