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#1 |
Registered User
![]() Join Date: Feb 2008
Location: Omaha, NE 68144
Posts: 333
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Rear End ID help
About a year ago, I got a 72 Burb with 400ci/TH400/posi SPID options. Well, I finally got around to working on it this last month. Have been noticing some odd things on the rear end lately.
1) the brake shoes are worn on the outer 1.5" of the 2" shoe - drum also doesn't encapsulate the backing plate either & matching odd wear. 2) DS drum was real gunky so figured the wheel cylinder needs replaced. 3) jacked up & spun 1 wheel forward to see the other side reverse. Decided to remove the cover to confirm the G80 has been stolen in it's previous life. ![]() PS housing tube says HA 1202 W. Not sure how to decode this. Think the gears & housing are from a 1968 & they just swapped the 6 & 5 lug axles - explains the odd brake pad/drum wear. Same with the drum & it doesn't sit all the way down around the backing plate. Also measured 55.25" from back-to-back plate on the rounded outer edge. Wheel mount surface with drums on was 63.75". Any info would be appreciated & might help others.
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Bryan '52 Bel Air 2dr HT - in pieces '68 C10 - 6cyl/4spd REMOVED, LT1/T56 to be installed “Any society that would give up a little liberty to gain a little security will deserve neither and lose both.” - Benjamin Franklin "And those who know what's best for us, Must rise and save us from ourselves" - RUSH lyric (mockery) |
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#2 |
Registered User
Join Date: Mar 2003
Location: San Francisco, CA USA
Posts: 2,454
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Re: Rear End ID help
I think you nailed it. Your PO did a complete rear end swap and then put the 72 shafts in the earlier housing to keep it 5 lug. He wasn't worried. No buyer was ever going to look.
Ray |
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#3 |
425hp409
![]() Join Date: Oct 2008
Location: Prosper Texas
Posts: 841
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Re: Rear End ID help
I did the exact thing your PO did before I was "Enlightened" in this forum. I put 72 5 lug axles in my 68 6 lug diff not knowing that they were different widths. My brake drums stuck out too far not engaging the shoes properly causing a soft pedal and poor stopping as the brake shoes were flexing upon application. A quick fix to keep your existing differential and axles is to install brake drums for 2.5" shoes. The NAPA part number is ND4401234 for the drums. You will then have full contact of the shoes to the drums, with a little left over.
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Charles 68 SWB, Dad bought new, now 396 & factory ac 64 Impala SS, 409 425HP, 4 speed AC 64 Bel Air Wagon, 400 Small Block 57 Bel Air all original 283 w/Factory Air 77 GMC Sprint, 454/425HP 67 Olds 442, all original 90 ZR1 Corvette |
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#4 |
Registered User
![]() Join Date: Feb 2008
Location: Omaha, NE 68144
Posts: 333
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Re: Rear End ID help
Charles,
Thanks for that insight. That would allow them to function normally & could get me by without doing an entire rear end swap. My local NAPA sells those for $66.49/ea so I'll keep it in mind. Great info!! On the other hand, if I can find a correct 3.07 posi rear in my neck of the woods for a reasonable price, I'd probably jump on that since the gears would help mileage a little & restore it to OEM. Here's an extra question: What should the STD ratio be in a 1-leg 71 truck rear end?
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Bryan '52 Bel Air 2dr HT - in pieces '68 C10 - 6cyl/4spd REMOVED, LT1/T56 to be installed “Any society that would give up a little liberty to gain a little security will deserve neither and lose both.” - Benjamin Franklin "And those who know what's best for us, Must rise and save us from ourselves" - RUSH lyric (mockery) Last edited by 68C10HotRod; 09-22-2010 at 11:21 AM. Reason: ratio |
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#5 |
Registered User
Join Date: May 2009
Location: Eliot, Maine
Posts: 1,314
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Re: Rear End ID help
i personally like the 3.42-3.73 range gears (with an overdrive) but if you go hi-po and stroke out that 400 big block some day the 3.07 will be a reasonable on the highway. i'd also suggest you run the wider rear axle for better stability and looks.
Last edited by capev86; 09-22-2010 at 02:46 PM. |
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