Rear-end rebuild questions

Author Topic: Rear-end rebuild questions  (Read 2291 times)

Offline ff6849

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Rear-end rebuild questions
« on: January 11, 2012 - 06:09:15 PM »
I have 440 in a 1973 barracuda that was originally a 318 car, so I was told. I believe that the 8 ¾ rear-end with a 2.73gear is the original. I am gathering the pieces to rebuild my rear-end. The car has Air-Shocks at the moments that have a very slow leak when the air leaks down the car sags quite a bit. I have a 742 case with a sure grip unit and a 3.55 gear. I have a new set of KYB’s, I am going to replace the rear wheel bearings when I replace the third member, add a rear sway bar, new brake shoes, brake springs and wheel cylinders. 


My questions are: :clueless:

1.   Are the axles different from a Big Block to Small block?
2.   Is the sagging from air shock leak an indication that my springs need to be replaced?
3.   Is there anything else I should do while I have the rear-end tore apart.
(__________]]]]]}~~~~

73 440 Cuda'
915 heads (mild head work, stock bottom end 10/9:1 compression)
A518 2600-2800 Stall
4.10 rear gear
TTI headers with 3' exhaust with  X pipe 
comp XE274H cam
Hughes Roller Rockers
Holley Sniper EFI
Holley Street Dominator intake
MSD ignition




Offline ted

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Re: Rear-end rebuild questions
« Reply #1 on: January 11, 2012 - 06:31:50 PM »
replace the springs
74 cuda, 70 challenger r/t

Offline Katfish

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Re: Rear-end rebuild questions
« Reply #2 on: January 11, 2012 - 06:36:34 PM »
Put the new shocks on before you tear it apart.  You'll see how it sits and whether you want/need new springs.

Offline brads70

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Re: Rear-end rebuild questions
« Reply #3 on: January 11, 2012 - 06:39:37 PM »
IMO the rear shock support/bracket wasen't designed to hold up the weight of the car. A better way is to get rear springs that are arched the way you want them.
I got mine that way from Spring n things( ESPO ) www.springsnthings.com
You can order them plus 1" , plus 1 1/2" etc....
Lots of members have got there springs here. My car had air shocks when I bought it. ( it's a 70's thing) this was the first thing I removed.
I belive the axles are all the same. no difference big block vs small block.
If your going to build a 8 3/4 for strenght you might as well step up to a Dana 60. Thats next on my list.Dr Diff is 2K everything new for a Dana 60, you can use the brakes off the 8 3/4 on the Dana. I have a 440/727 and it has held up fine so far ( just don't use slicks) but I'm building a 451" stroker and the 8 3/4 .... well I don't want to push my luck!  :grinno:
Hope that helps?
Brad
Brad
1970 Challenger 451stroker/4L60 auto OD
Barrie,Ontario,Canada
Proud to own one of the best cars ever made!!!!!

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Offline MEK-Dangerfield

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Re: Rear-end rebuild questions
« Reply #4 on: January 11, 2012 - 06:47:05 PM »
Your car was originally a small block car. The springs you have in the rear now, are not able to support the additional weight of the big block.

I went with Springs n things too, with a 1" over stock height.  No more saggy butt syndrome.   :2thumbs:

Mike

1970 Challenger - SOLD
2016 SXT+.  1 of 524 SXT+'s in Plumb-crazy for 2016.

Offline dodj

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Re: Rear-end rebuild questions
« Reply #5 on: January 11, 2012 - 07:01:01 PM »
replace the springs
:iagree:
The extra torque of a big block requires heavier rear springs to help control axle wrap. I like my Mopar XHD's relatively stock ride height.

IMO the rear shock support/bracket wasen't designed to hold up the weight of the car. A better way is to get rear springs that are arched the way you want them.
:iagree:
Springs for ride height, Shocks for controlling/dampening the spring's oscillation for keeping the tire in contact with the road.
Scott
1973 Challenger  440 4 spd 
2007.5 3500 6.7 Cummins Diesel, Anarchy tuned.
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Offline BS CUDA

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Re: Rear-end rebuild questions
« Reply #6 on: January 11, 2012 - 09:59:47 PM »
8 3/4 - 4.10 with an Auburn limited slip. Mickey drag radials at the track. Fryem in the box and hook at the lights. Stock springs. Roughly 150 passes and no troubles... yet  :cooldancing: Should probably mention 520hp and 610ft lbs.
« Last Edit: January 11, 2012 - 10:01:34 PM by BS CUDA »

Offline ff6849

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Re: Rear-end rebuild questions
« Reply #7 on: January 12, 2012 - 07:11:08 AM »
looks like I am calling ESPO, axles should be ok or should they be replaced too.
(__________]]]]]}~~~~

73 440 Cuda'
915 heads (mild head work, stock bottom end 10/9:1 compression)
A518 2600-2800 Stall
4.10 rear gear
TTI headers with 3' exhaust with  X pipe 
comp XE274H cam
Hughes Roller Rockers
Holley Sniper EFI
Holley Street Dominator intake
MSD ignition

Offline Chryco Psycho

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Re: Rear-end rebuild questions
« Reply #8 on: January 12, 2012 - 09:54:57 AM »
looks like I am calling ESPO, axles should be ok or should they be replaced too.
the diff is the same small block or big block the axles will be fine unless you can see a twsit in the splines of the axles , the wheel brg shouldbe OK just clean them , look for scoring or discoloration , if they are ok repack them with grease & keep going

Challenger - You`ll wish You Hadn`t