Rear axle switch - Impala Tech
Transmission & Driveline Transmissions & Differentials

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  • 1 Post By jayoldschool
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post #1 of 10 (permalink) Old 11-20-2019, 10:46 AM Thread Starter
 
 
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Rear axle switch

Just curious if its feasible to swap in a rear axle from a 73 impala into my 66 2dr hardtop. Have a lead on one real close that has the gears im looking for. Im swaping out an axle that the PO put in from a much newer car(bigger bolt pattern forcing to run 2 diff lug patterns). Just wondering how much its different dimensional and how much fab work would have to do to make it work. Guy only wants $125 for a posi 10 bolt. Also, im building an engine projected for 350-400 hp, just street, no track use. Thank you!
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post #2 of 10 (permalink) Old 11-20-2019, 11:45 AM
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Quote:
Originally Posted by jmiller1119 View Post
Just curious if its feasible to swap in a rear axle from a 73 impala into my 66 2dr hardtop. Have a lead on one real close that has the gears im looking for. Im swaping out an axle that the PO put in from a much newer car(bigger bolt pattern forcing to run 2 diff lug patterns). Just wondering how much its different dimensional and how much fab work would have to do to make it work. Guy only wants $125 for a posi 10 bolt. Also, im building an engine projected for 350-400 hp, just street, no track use. Thank you!
Be a lot easier to just swap the axles if the rear end is the same length and the rears are both 10 bolt corporate rears from a 1970-'96 car. After 1996 the axle spine count (diameter) changed from 28 splines to 30.

Big Dave
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post #3 of 10 (permalink) Old 11-20-2019, 09:51 PM
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The 73 impala has the larger 5x5 bolt pattern, all 71-76 full size do.
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Two doors, four doors, wagons, and ragtops.
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post #4 of 10 (permalink) Old 11-20-2019, 10:32 PM Thread Starter
 
 
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Thanks guys, i was thinking that it was going to be the 5x5(although ive seen many wheel company websites say its still 5x4.75 as stock for 73 impala)guess ill keep looking, junkyard has em for $100 open and 125 for posi but it might be a project for next spring, getting chilly here in mn
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post #5 of 10 (permalink) Old 11-21-2019, 12:43 PM
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Originally Posted by jmiller1119 View Post
Thanks guys, i was thinking that it was going to be the 5x5(although ive seen many wheel company websites say its still 5x4.75 as stock for 73 impala)guess ill keep looking, junkyard has em for $100 open and 125 for posi but it might be a project for next spring, getting chilly here in mn
You are right it could have either bolt pattern. It depended upon the shipping weight of the vehicle; so a lighter Biscayne would get the 4 inch bolt pattern and the heavier Impala or Caprice would get the 5 on 5 (which is actually a 5 bolts on a metric 120 mm). After 1973 all used the metric bolt pattern as GM went totally metric with body parts. It wasn't until they introduced the LS-x in 1996 that the engine and trans went totally metric.

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post #6 of 10 (permalink) Old 11-21-2019, 09:25 PM
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No.



- all 71-76 full size use 5x5
- they are 5x127 (5x5)

- they all use imperial thread lugs
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post #7 of 10 (permalink) Old 01-26-2020, 05:35 PM Thread Starter
 
 
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So i just got a deal at the junkyard close to where i live, was looking for a 10 bolt rear axle and he said $150(drum to drum with coils and arms) I told him to cut it out. He calls back an said to come back as he had some questions. I get there and he shows me a car he already had tipped on its side(sitting in 2ft of snow) its a 12 bolt that im getting for the same price! Seemed nice and tight, no posi but no biggie. I didnt get the numbers off the axle but im sure its going to be a pretty low ratio. My question is what gear ratio would be a good choice? Car is 66 impala 2dr hardtop, 355 with projected 400 hp, xe268h cam, vortec 062 heads 650 edelbrock. Will get a beefed up TH350 and 275/60/15(28" tall). Live in rural MN, will be driving alot off 55mph county roads60mph hiways and maybe a 20 mile jaunt on a 65mph. I want the rolling burnout type of car, but not screaming down the hiway. Any opinions or suggestions? Also planning on getting a stall converter as well, how high should i go?
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post #8 of 10 (permalink) Old 01-26-2020, 07:03 PM
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Suggestions? Yes. Make sure it's not a truck 12 bolt before you waste time and money on it.


IF it's a car 12 bolt... 3.08s, 3.23s... MAYBE 3.42s if you aren't going to hit the highway much. 2500 stall converter.

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post #9 of 10 (permalink) Old 01-29-2020, 11:46 AM Thread Starter
 
 
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Thanks! Got the numbers, it is a 69 police axle(surprised it didnt have limited slip)but has the the 2 top control arms instead of just the one. Popped cover off and got to see it had 3.31 gears so even better, i plan on keeping those for now. Got it sanded down ready to paint. Will be replacing axle bearings and seals, wondering if i should bother with carrier bearings as lash looks good. At some point it will be getting a posi carrier but not anytime soon.
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post #10 of 10 (permalink) Old 01-29-2020, 03:44 PM
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Clutch style limited slip differentials are not used by police for the same reason you don't find them in road race cars. If you get one tire on grass or dirt with the other on pavement you will find yourself going side ways if you get on the gas. Limited slip and lockers (two different beasts) are designed for use at the drag strip or off road entirely when you are knee deep in mud or loose sand. On the road way they can be dangerous if you are half asleep or two cans past the legal limit. You have to drive all the time with a posi, not texting or be talking to your significant other. It is why I grew tired of my 582 powered Impala and took it apart before crushing the car. You never ever run a spool on the street, that is for a drag strip only.

I was coming off an interstate at 85 mph on a wet road when I hit the gas on my 582 BBC to accelerate. Believe it or not I spun out while I had a Posi (that magical device that gives you the ultimate in traction). News flash: a limited slip will not give you any traction on a curve (cornering) and it will add instant understeer pushing you to the outside of the road; and off it if you have a limited traffic lane. On dry pavement the car cornered like a slot car, but not on a wet road or while getting on the gas (I could punch it driving at 70 mph on the interstate driving in a straight line and light up both rear tires on dry pavement, which also gets old after a while, and expensive, having to constantly replace the rear tires).

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