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#1
01-16-2018, 11:43 AM
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8.2" rear end defects and fixes? 1969 FB
I have an 8.2" rear factory posi OE rear end with 3:55 gears in my 1969 FB. I am planning on increasing the power output to 550-600 torque. I hear my rear end may not live with that level of power. I would like to know before I oil a track.
Would welding the tubes into the center full circle, and replacing the ring carrier with an Eaton unit resolve the failing rear end issues? Or is there something fundamentally weak about there rear ends that can not be corrected? Axles? I realize the 8.5" is a stronger rear end and can substitute in, as a will a 12 bolt. I would like to keep the original rear end in there and just possibly upgrade the weak pieces....unless they are all weak. I'm not sure what typically fails on these? Is anyone running 600 foot pounds of tq or more thru an 8.2 with drag radials and having it live? This is a street car with some visits to the track. Thanks in advance. |
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#2
01-16-2018, 01:04 PM
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Oh, and this is a Nodular rear end, denoted by the big N cast into it. I am unsure when they refer to "grey iron" rear ends if this includes nodular rear ends.
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#3
01-16-2018, 08:14 PM
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I haven't tried to beef up an 8.2. I just heard from enough knowledgable people to not bother with it. I beefed up a 1972 Nova 8.5. It's holding up well behind an aluminum headed 455, without drag radials.
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- Tom |
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#4
01-16-2018, 08:53 PM
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Contact PY member 'Ol Pinion Head. He's an excellent resource for information on Pontiac differentials. Strengths, weaknesses, etc.
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1969 TA RAIII M40 Auto Cameo White/ Std Blue Int 1970 TA RAIII M21 4-spd Lucy Blue/Std Black Int 1971 TA 455 HO M22 4-Spd Lucy Blue/Deluxe White Int |
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#5
01-17-2018, 07:50 AM
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If it is the original rear I would take it out and replace it with an 8.5". I have broken a Pontiac 8.2" on the strip before.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
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#6
01-17-2018, 01:04 PM
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Gray Iron or Nodular
Quote:
I have learned I have the 4 pinion HD Nodular rear end in my 1969, likely with forged axles. Has anyone broken or had any experience with the Nodular rear ends breaking? They are pretty rare compared to a standard 8.2" rear I believe. |
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#7
01-18-2018, 11:28 AM
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Because of it's rarity I would not use it, it would be difficult finding another one. The weak point in your rear is the 8.2" diameter ring gear, the N housing and posi are fairly strong. Try to find an 8.5" and upgrade the posi and axles for your power level.
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
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#8
01-22-2018, 03:19 PM
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The "N" nodular rear ends didn't as a rule include forged axles. The exception is the higher numerical ratio units used on 69 HO GP's but they were only produced in handfuls.
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My Break Away Squad 1969 Fbird (Base, 350, 400HO & Sprint Cvt’s - 400HO & TA Hardtops) 1969 LeMans (2dr & 4dr Hardtop and a Cvt) 1969 LeMans Safari 2 seat Wagon 1969 GTO (2 Cvt, 2 Hardtops & Judge Hardtop) 1969 Catalina (3 Cvt’s & a 2dr hardtop) 1969 Ventura 2 Seat Wagon 1969 Executive 4dr Sedan 1969 Bonnie Cvt 1969 Bonnie 3 Seat Wagon (2 of them) 1969 Bonnie Brougham (4dr Hardtop & Cvt) 1969 Grand Prix SJ (2 of them) 1969 2+2 2dr Hardtop (Canadian model) |
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#9
01-28-2018, 05:07 AM
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I also went with a Nova 8.5 rear end. It was a pretty easy swap, and building the guts is significantly less expensive than sourcing the limited amount of available 8.2 BOP parts. 8.5 stuff is sooooo much more available.
I agree with AG. I kept my 3.23 BOP rear for my FB parked away for later. If I frag the rear end at the track, at least I will have something to fall back on once my "speed bug" subsides.
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"...ridge reamer and ring compressor? Do they have tools like that?" |
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