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Rear End
#1
Okay guys, give me the low down on swapping rear ends.

Right now i have an 8" with 2.79 gears. I am thinking of swapping the whole assembly with my other project mach that has the 9" 3.25 traction lock.

Is it just as easy as just swapping the whole rear end out or is there other things i need to look out for? I am thinking the drive shaft will be an issue. I do have a spare drive shaft if needed.
These are drum brakes also.
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#2
Not an area where I have a lot of expertice in. I doubt the drive shaft is an issue, the U joints might be different. Brake line shouldn't be too much of an issue, mounting plates are probably the same. I would think this is a pretty straight forward swap.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#3
Hi Matt,

I had the same problem, a 8" rear end using 2.75 gear with Conventional style differential, i.e., only one wheel would spin at a time.

I got a 9" rear end at a salvage yard and had the third member rebuilt with 3.50 gears and new differential, Traction-Lok is a good choice.

I didn't have any problem with the driveshaft length, I rebuilt the drum brakes and replaced the leaf springs. This was a great upgrade!

(One thing I have been thinking of recently is swapping C4 for AOD transmission and using 4.11 or 4.86 gear instead of 3.50 -- maybe next car after more research.)

Chris

1971 Mustang
Grabber Lime with black deluxe interior
302 engine with C-4 transmission and 9" rear end with 3.50 gears
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#4
Chris

If i do the swap i was planning on doing my leaf springs along with it (hence my other thread). I think the 3.25 will be a good fit for me.
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#5
Won't you have to recalibrate the speedo?

[Image: 1z21rv4.png]

Mike

"If I were you...... I´d rather be me."  Tongue

Check out my video:
http://www.7173mustangs.com/thread-my-mustang-in-action

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#6
Matt Peetz;65778 Wrote:Okay guys, give me the low down on swapping rear ends.

Right now i have an 8" with 2.79 gears. I am thinking of swapping the whole assembly with my other project mach that has the 9" 3.25 traction lock.

Is it just as easy as just swapping the whole rear end out or is there other things i need to look out for? I am thinking the drive shaft will be an issue. I do have a spare drive shaft if needed.
These are drum brakes also.
Matt..I just finished a complete rear end swap in my camaro..Check my fb page..I went from 3.73's to 3.08's big improvement & I think your planned swap to 3.25's should be fine ..The only issue you may run into is the u joint at the rear may be different..I had that issue in my swap..Check the yoke on the pinions to see...If they are different no fear..they make whats called a combination u-joint..http://www.dennysdriveshaft.com/c130_uni...oints.html A few things very worth while to do besides all new brake hardware is new rear axle bearings & seals..Also check the axles themselves..new brake lines.[url]http://www.inlinetube.com/[/url]..I had my drive shaft balanced WORTH EVERY PENNY !!!! & you want to check your pinion angle [url]http://www.hurst-drivelines.com/files/Un...111606.pdf[/url] Doing all the above will make a HUGE improvement in the way the car drives & feels..

LOVE OF BEAUTY IS TASTE..THE CREATION OF BEAUTY IS ART
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#7
I too replaced the leaf springs with rear end upgrade, and replaced the gear attached to speedometer cable inserted in the transmission to recalibrate speedometer. If you are going from Conventional to Traction-Lok differential it is well worth the swap. The 3.25 gears will be fine, moreso if you plan on driving on highway.

I don't recall any issue with u-joints.

1971 Mustang
Grabber Lime with black deluxe interior
302 engine with C-4 transmission and 9" rear end with 3.50 gears
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#8
luxstang;65843 Wrote:Won't you have to recalibrate the speedo?

Yes, whenever axle ratios are changed the speedometer driven gear must also be changed. A good way to calculate the new speedometer gear size (number of teeth) is divide the new axle ratio by the old ratio and multiply that by the old number of speedometer gear teeth. If you also change tire sizes at the same time more calculations are required.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#9
Trans swaps, rear gear changes, tire size changes all affect the speedometer. I'll be doing all 3 so i'll wait until the changes are done to recalibrate. Short term I'll get some speed differences between the speedo and a GPS. Big Grin

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
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#10
Chris Womack;65816 Wrote:I got a 9" rear end at a salvage yard and had the third member rebuilt with 3.50 gears and new differential, Traction-Lok is a good choice.

What are good donors for this?

[Image: 11jmcuc.png]
351C Bold Manners, Brash Attitude
Favorite Teams: Michigan Wolverines and Whoever Is Playing Ohio State.

When I drive past a herd of cows, the cows MOO at me
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