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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 16 Jul 2008 :  2:40:00 PM  Show Profile  Reply with Quote
I'm currently in the process of rebuilding the front end on my 72 Lemans. (suspension and disk brake converion) After the front is complete I plan on rebuilding the rear suspension. While I'm back there I want to go ahead and put a positive traction differential in it, and upgrade to a 3:73 gear.

The trouble is i'm not exactly sure what size rear end i currently have. I know it's a 10-bolt, but not sure whether it's the 8.2" ring gear or the 8.5" ring gear. from what little i can tell just by looking, and after extensive research, i believe it to be an 8.5" 10-bolt. I learned that the best way to find out is to remove the rear end cover and put a wrench on a ring gear bolt - if it takes a 7/16 wrench, it's the smaller 8.2, and if it takes a 9/16 wrench, it's the 8.5. i haven't gotten around to doing this yet.

I just wondered if anyone might know what would have been stock for this year/model? (i'm pretty sure that this is the original rear end)

*72' Pontiac Lemans* - Work in Progress

Brian R
Crazy Horse

USA
1676 Posts

Posted - 16 Jul 2008 :  2:49:01 PM  Show Profile  Reply with Quote
My 71 was an 8.2. I went with 3:55's when I did it about 7 years ago.

Been honking on it for years with no issue. Be careful with 3:73's. If you have even a moderately built 400 or more you really don't need all that gear unless you plan to do nothing but race. Highway travel
will be terrible because of the RPM's. My 3:55's are at around 4000 at 75 - 80. Not good for any length of travel. 3:73's will drive you nuts.

Again, not sure how you plan to use the car - just my 2 cents.
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Christ
Howling Wind

USA
1808 Posts

Posted - 16 Jul 2008 :  2:59:52 PM  Show Profile  Visit Christ's Homepage  Reply with Quote
Q. How can I tell the difference between a GM 8.2 10 bolt, Buick/ Olds/Pontiac 8.2 10 bolt, and a GM 8.5 10 bolt?
A. Each of these has a different spline.
GM 8.2 = 25 spline shaft
Buick/Olds/Pontiac 8.2 = 27 spline shaft
GM 8.5 = 30 spline shaft
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hugh
Cochise

USA
430 Posts

Posted - 16 Jul 2008 :  3:18:53 PM  Show Profile  Reply with Quote
If you are removing the cover, look on the edge of the ring gear and the gear ratio is stamped on it and it will look something like 48:16, where 48/16 = 3.00.

Also, there is a code stamped on front side of the passenger side axel tube which will tell you what it was originally and it is a two or maybe a 3 letter code, like PS or GPS. You can look the code up here or online.

Do not use a 3.73 unless you are drag racing or you have an over-drive transmission. Otherwise a 3.08 or 3.23 will be plenty.
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 16 Jul 2008 :  4:44:08 PM  Show Profile  Reply with Quote
Got a 400 going to be built into a 461: plan on using Perfomer RPM intake, Comp Hydraulic Roller cam (236\242 @.050" lift, .520/.540 lift, 110 Lobe seperation), haven't decided on a carb yet. Have a set of 6X heads (not sure, but i think they're 6X-8) I'd like to use, after some work (like to get them to flow 250 cfm, if possible). Not sure on a transmission yet, the car had a chevy 350/TH350 in it when i acquired it. can't bolt up the chevy TH350 to the pontiac 400, so have to buy one i suppose. probably go with a pontiac TH400. I like TCI's streetfighter, probably go with it. no idea with a converter yet, think cam called for a 2800 stall.
Not primarily a drag racer, but will be run down the track on occasion. intentions are a street/strip car. will drive to local car shows, won't see highway beyond 55-60 mph.

with this information, still think 3:73 is too much?

and anymore ideas about rear end size?

*72' Pontiac Lemans* - Work in Progress
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Brian R
Crazy Horse

USA
1676 Posts

Posted - 16 Jul 2008 :  4:58:56 PM  Show Profile  Reply with Quote
Personally, yes, the 3.73's are too much for me. With the combo you are building that thing will go like a r@pp$d ape even with 3.23's and still be a good car for an occasional road trip. If they are too low for what you want, go for the 3.42/3.55 range.

Others will chime in I hope, but with 3.73's you could never hook up for a decent time anyway. One of the nice things about a Pontiac is it's not a small block. Pontiacs have tons of torque down low and don't require the high RPM's to make them go.

Good luck with it, sounds like a fun project.
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drobe2
Cochise

USA
333 Posts

Posted - 17 Jul 2008 :  02:27:09 AM  Show Profile  Reply with Quote
http://www.drivetrain.com/GMtrkratio_posidata.html
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 17 Jul 2008 :  08:37:13 AM  Show Profile  Reply with Quote
I'll definitely keep that in mind about the rear gear ratio Brian. Thanks.

I forgot to mention earlier that, from what i've found, this car was built in canada. I already mentioned that it had the Chevy 350. This past winter i got curious about the engine, so I scraped off the paint and found the numbers on the block. turned out the numbers on the block matched the vin number on the car, this was the original motor. For the longest time i couldn't figure out why this was, then someone told me that, for a certain period of time, canadian built pontiacs were equipped with chevrolet drivetrains.

With that in mind, would this be a Chevrolet rear end, a Pontiac rear end, or are they all simply considered GM rear ends, with no differences between makes?

*72' Pontiac Lemans* - Work in Progress
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Mr. P-Body
Running Bear

USA
2258 Posts

Posted - 17 Jul 2008 :  09:22:06 AM  Show Profile  Visit Mr. P-Body's Homepage  Reply with Quote
Matt,

Virtually all Canadian Pontiacs of the era had Chevy engines in them...

I would recommend Torker II over RPM for the big-cube engine. Traction is going to be at a premium as it is, but a dual plane intake will compound the problem. We generally recommend the AED 850HO carb for these, but one of Cliff's Q-Jets fills the bill nicely as well.

We've moved away from the hydraulic rollers, as well. Too many lifter issues. Using the hydraulic roller cam with solid roller lifters works, but if you haven't already bought a cam, get a solid roller instead. There are several on this board with that setup and they can attest to the effectiveness. There are a couple that have changed over, too. Forget the mythology of solids. They're fine for street engines and do NOT require adjustment often. The kicker is the solid setup is a tad less expensive!

250 CFM from the 6X is no problem for a good porter. Don't fall for the "CNC is the only way" line, either. A real pro will get them right by hand. Consider filling the crossovers while you're at it. DO NOT buy the hardware for the heads based on price. Get the "good stuff". We use SI Valves "Competition Series", but Ferrea are quite popular as well. Use only the "6000" series if you go Ferrea. Using the valves from the '67-'70 heads will give you more installed height for a better choice of springs.

If your rear axle uses "C-locks" to hold the axles in, it's a Chevy rear. If not, it's a "BOP" rear. The code is the best way to find exactly what you have.

Jim
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i82much
Cochise

USA
220 Posts

Posted - 17 Jul 2008 :  10:41:42 AM  Show Profile  Reply with Quote
I thought you could tell just by looking at the housing - the 8.5 has a more circular cover whereas the 8.2 has indentations at 9 and 3 o'clock in the cover. Seems to me the old summit catalogs used to have a diagram of the bolt pattern and gasket that would make it obvious without pulling anything apart.

Steve
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i82much
Cochise

USA
220 Posts

Posted - 17 Jul 2008 :  10:43:22 AM  Show Profile  Reply with Quote
See if this helps, click the links:

http://www.richmondgear.com/01gm.html

Steve
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mike mcarthur
Pony that Jumps

USA
2475 Posts

Posted - 17 Jul 2008 :  11:56:39 AM  Show Profile  Visit mike mcarthur's Homepage  Reply with Quote
Ditto the gear recommendations. I have 3:55's and they suck on the highway. Stick to the 3:08, or 3:23

It's the stuff you learn after you know it all that's important
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 17 Jul 2008 :  2:28:31 PM  Show Profile  Reply with Quote
Jim,

Thanks for the info. I do have more questions about the engine suggestions, but i'll bring them up at a later date, in a different post.

i82much,

Yes, I've seen the diagrams in the summit catalog. Mine is round, it does not have the indentations. however if you look at that link, or most any diagram, you'll see that both the 8.2 and 8.5 have both round and indentated rear covers. I appreciate it, but I've found that you can't tell for sure what it is just by appearance.

*72' Pontiac Lemans* - Work in Progress
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i82much
Cochise

USA
220 Posts

Posted - 17 Jul 2008 :  4:10:13 PM  Show Profile  Reply with Quote
Matt - news to me but I've been wrong before. Seemed to me I never looked under a chevy and found the indentations but they were plentiful under pontiacs. sounds like you've seen otherwise.

Steve
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 17 Jul 2008 :  4:36:09 PM  Show Profile  Reply with Quote
Not saying you're wrong i82much, it may very well be that i am the one who is wrong. All I know for sure is that i've looked, and looked again and mine is definately round - no indentions. I'm hoping that means 8.5, i'd much rather have the 8.5 than the 8.2 because
1. posi traction differential is about $100 cheaper for 8.5 2.http://www.chevyhiperformance.com/techarticles/48518_posi_10_bolt_upgrade_install/index.html

*72' Pontiac Lemans* - Work in Progress
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i82much
Cochise

USA
220 Posts

Posted - 17 Jul 2008 :  7:38:51 PM  Show Profile  Reply with Quote
Hmm. I thought there was a Chevy 8.2 and a GM (all makes) 8.5 - both with round covers, and a BOP 8.2 with the indentations. But even if I'm right about that I don't know how to tell the 8.2 Chev from the 8.5 GM. However - found this site - check out the differential ID link on the left hand side and see if that helps:

http://www.jdrace.com/

Steve
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Mr. P-Body
Running Bear

USA
2258 Posts

Posted - 18 Jul 2008 :  08:15:41 AM  Show Profile  Visit Mr. P-Body's Homepage  Reply with Quote
Steve,

You're right, but... The '71-'77 era is pretty fuzzy when it comes to rears. There are a mish-mash of variations, and it's prudent to be certain. There's even a BOP "12-bolt" that's really a 10-bolt in disguise... It has 12 bolts holding the cover but only 10 on the ring gear.

Jim
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i82much
Cochise

USA
220 Posts

Posted - 18 Jul 2008 :  08:23:19 AM  Show Profile  Reply with Quote
Hey Jim,

Yeah it DOES seem like that era always has a lot of questions associated with it - more so than earlier years. Heck even with my old BOP 8.2 there were "good" and "bad" 4-pinion and 2-pinion posi units so you had to open the case to see what was in there. But at least it was easy to tell what basic rear I had since in 65 things weren't so fuzzy!

I've seen the 12 bolt cover/10 bolt ring gear before but can't remember what car that was on, maybe an Olds. Was probably shopping for rears after I broke my 8.2.

Steve

Steve
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 21 Jul 2008 :  2:15:40 PM  Show Profile  Reply with Quote
hmmm, sounds like the only true way to find out is to research the numbers or open 'er up. ok, that works, I'll be in there anyway. Thanks for the help everyone.

*72' Pontiac Lemans* - Work in Progress
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 07 Sep 2008 :  7:27:25 PM  Show Profile  Reply with Quote
Finally got the rear out and opened it up. The ring gear bolts took a 9/16" wrench. So to the best of my knowledge, I've got an 8.5" 10-bolt rear end.

Thanks again!

*72' Pontiac Lemans* - Work in Progress
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dr. Rick Riviera
Cochise

Belgium
214 Posts

Posted - 08 Sep 2008 :  06:30:18 AM  Show Profile  Reply with Quote
Hi PontiacMatt,

Some more circumstancial evidence is the pinion nut size:

8.5" 1 1/4"
8.2" 1 1/8"

Very best regards,

Rick
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 09 Oct 2008 :  12:20:48 AM  Show Profile  Reply with Quote
Finally got a guy to put in my new Eaton posi differential in the rear. he reassured me that i do have the 8.5" rear.

He called last night with a slight problem though... I bought some new carrier bearings at the local O'Reilly's, and upon assembly, he found that while these bearings fit the carrier just fine, they are too large to actually fit into the rear end.

?!? wierd, but he said he'd see what he could find out. hopefully only a minor setback.

*72' Pontiac Lemans* - Work in Progress
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i82much
Cochise

USA
220 Posts

Posted - 09 Oct 2008 :  08:28:50 AM  Show Profile  Reply with Quote
There is a truck rear that uses "heavy duty" bearings, maybe you got those instead of the "standard" 8.5 bearings.

Steve
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Bill Boyle
Horse Feathers (Charter Member)

USA
4869 Posts

Posted - 02 Apr 2009 :  2:04:28 PM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Drobe2 reference above--the link has changed to: http://www.drivetrain.com/parts_catalog/positraction

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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Punisher
Sitting Bull

174 Posts

Posted - 02 Apr 2009 :  11:46:37 PM  Show Profile  Reply with Quote
How did it turn out Matt?

Edited by - Punisher on 02 Apr 2009 11:49:31 PM
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 03 Apr 2009 :  11:23:27 AM  Show Profile  Reply with Quote
haha, uhh...

Well turned out the rear was the 8.2" rear.

After I found that out, just decided to go ahead and purchase a 12 bolt housing.
Got it and the axles for $600, (supposedly out of 69 chevelle?)
I sent back the 8.5" eaton carrier i had purchased and had it exchanged it for a 8.875" (12 bolt) eaton posi carrier. also bought new 3.42 richmond ring and pinion. had a local professional shop rebuild it (completely gone through). everything seems to have come out nicely, but haven't had a chance to drive it yet, working on building the motor right now.

So, I've got an 8.2" rear end (disassembled, but have all parts) just sittin around... If anyone needs one, let me know. (non-posi, somewhere around a 2.73 gear)

I'll see if I can't figure out how to put some pictures of the 12 bolt on here.

*72' Pontiac Lemans* - Work in Progress
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 03 Apr 2009 :  12:55:36 PM  Show Profile  Reply with Quote
[URL=http://img441.imageshack.us/my.php?image=1000532q.jpg][/URL]

[URL=http://img441.imageshack.us/my.php?image=1000536.jpg][/URL]

[URL=http://img441.imageshack.us/my.php?image=1000542u.jpg][/URL]

*72' Pontiac Lemans* - Work in Progress
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Phil
The Great White Buffalo

USA
7236 Posts

Posted - 05 Apr 2009 :  12:54:09 PM  Show Profile  Reply with Quote
Matt, It's hard to tell from the pics. but did you have the tubes welded?

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 05 Apr 2009 :  8:51:25 PM  Show Profile  Reply with Quote
no i sure didn't Phil... after all the work had been done is when i actually started noticing it being discussed in the forums.

Think it'd be necessary? Can it be done with the rear end in the car?

*72' Pontiac Lemans* - Work in Progress
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Punisher
Sitting Bull

174 Posts

Posted - 05 Apr 2009 :  11:04:59 PM  Show Profile  Reply with Quote
I knew it would be a 8.2" if it was factory but had it pegged when your guy said the bearings wouldn't work that fit the 8.5" carrier... 8.5" rears also have LH thread bolts for the ring gear. first year 8.5's (1970) have 9/16 bolt heads but later 8.5" rears have 11/16 head LH Thread...
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Phil
The Great White Buffalo

USA
7236 Posts

Posted - 06 Apr 2009 :  6:11:51 PM  Show Profile  Reply with Quote
Matt, I wouldn't worry about it at this point unless you are making alot of power. If you have to pull it apart for any reason though, I would take the opportunity to weld the tubes.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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PontiacMatt
Many Ponies

USA
1410 Posts

Posted - 06 Apr 2009 :  6:24:25 PM  Show Profile  Reply with Quote
Phil, how much power are we talking here? I'm just gettin started on the engine, hopin to have around (give or take alittle) 400 hp, and 500 ft.lbs with a 467, 6X heads. (was to be a 461, now goin 467, block was already bored .040. got me held up at the moment tryin to get the pistons exchanged...) will probably never see more than 550-600 hp with this engine, if that much. (aluminum heads in a few years maybe.)

*72' Pontiac Lemans* - Work in Progress
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Phil
The Great White Buffalo

USA
7236 Posts

Posted - 06 Apr 2009 :  8:34:36 PM  Show Profile  Reply with Quote
Too many variables with each car to assign a specific number.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Taman
Red Bird

USA
844 Posts

Posted - 07 Apr 2009 :  2:47:44 PM  Show Profile  Reply with Quote
I run 3.73's and took it on the power tour long haul. I ran at 3000rpm @65 mph with 28" tall tires. I run a 562hp 462" 400. I am switching back to my 4.33's. With 3.73 I run 11.50@116. With 4.33 I should go 11.30's @118mph. 3.73's are not to bad for me. Even when I cruise on the freeway. I only run 60-65. Traction is not a problem for me.

Everything Under The Sun Is Intune
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72 GOAT RULES
Tribal Scout

USA
6 Posts

Posted - 31 Dec 2017 :  4:47:35 PM  Show Profile  Reply with Quote
I'm wanting to do the same thing that Pontiac Matt is trying to do. That is update my 10 bolt rear end to a posi. I know I have 278 gears right now with a limited-slip. That based off the PHS documents I obtained on the car. I'm hoping it won't be too difficult or expensive to convert this over to a posi. I would be open for suggestion on a link to a video or a name brand of posi that will work for my 10 bolt application. Not sure if I have the 8.2 or the 8.5 either. I have to find that out now that I know what to look for thanks to this discussion.

Edited by - 72 GOAT RULES on 31 Dec 2017 4:50:57 PM
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67drake
Sitting Duck

Azerbaijan
1510 Posts

Posted - 01 Jan 2018 :  3:44:35 PM  Show Profile  Reply with Quote
quote:
Originally posted by 72 GOAT RULES

I'm wanting to do the same thing that Pontiac Matt is trying to do. That is update my 10 bolt rear end to a posi. I know I have 278 gears right now with a limited-slip. That based off the PHS documents I obtained on the car. I'm hoping it won't be too difficult or expensive to convert this over to a posi. I would be open for suggestion on a link to a video or a name brand of posi that will work for my 10 bolt application. Not sure if I have the 8.2 or the 8.5 either. I have to find that out now that I know what to look for thanks to this discussion.



IF it is the original rear,it's an 8.2. Anything could have changed over the last 45 years though. A few tips on how to ID the rear here-
http://www.jdrace.com/diff_id/10bBOP_Pontiac.htm

Best bet is to pull the cover to count the teeth as far as gear ratio goes.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires
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67drake
Sitting Duck

Azerbaijan
1510 Posts

Posted - 01 Jan 2018 :  3:53:01 PM  Show Profile  Reply with Quote
Also,parts are not crazy expensive,but the labor is what you usually get hit for. I'd check your local Craigslist for a 68-72 GM A body posi rear that is already set up with a ratio you want. If it is from a 71-72 Cutlass/Skylark it will be an 8.5. 8.5's are a lot stronger if you beat on it,race,or run sticky tires. You would have to shorten the driveshaft a a little to run an 8.5 though.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 01 Jan 2018 3:53:36 PM
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72 GOAT RULES
Tribal Scout

USA
6 Posts

Posted - 03 Jan 2018 :  3:34:19 PM  Show Profile  Reply with Quote
I have some certainty that it is a 8.2, with NON c clip. I have the 4 bolt axle. Not sure why I'm getting Ames saying its a 27 spline when others are saying 28. Will verify by taking cover off. Meanwhile Summit says this is a good fit for a position p#19674 After looking at it, my only concern is "limited slip" kinda told the guy I wanted the non clutch locker model. Is looking to be complicated in translating from English to English lol... does anyone know of a Eaton None clutch posi that would work. The fine print says you will enjoy this for life. Says nothing about wear of clutches, but I'm not sure, it why I wanted the locker with no clutches.... face Palm.....
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72 GOAT RULES
Tribal Scout

USA
6 Posts

Posted - 03 Jan 2018 :  3:38:10 PM  Show Profile  Reply with Quote
Detroit Truetrac
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cortcomp
Coyote

USA
5361 Posts

Posted - 04 Jan 2018 :  12:02:22 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Non clutch is pretty much locker type or cone posi type, which wears also.
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72 GOAT RULES
Tribal Scout

USA
6 Posts

Posted - 04 Jan 2018 :  06:53:28 AM  Show Profile  Reply with Quote
This is the place to go for all b o p information anyone ever needs. Buick olds and Pontiac 10 inch rear ends from 72 back.

www.hemmings.com/magazine/mus/2013/01/B-O-P-Rear-Axles/3720371.html%3famp=1" target="_blank">https://www.google.com/amp/s/www.hemmings.com/magazine/mus/2013/01/B-O-P-Rear-Axles/3720371.html%3famp=1

This information was great took any guesswork out identification and gave the best explanation about everything.

Use the bottom link because the first link has an air on it. Click both one will work for you.

Edited by - 72 GOAT RULES on 04 Jan 2018 06:56:30 AM
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67drake
Sitting Duck

Azerbaijan
1510 Posts

Posted - 04 Jan 2018 :  08:43:41 AM  Show Profile  Reply with Quote
What's the car going to be used for? How many miles driven per year?
I'd read up on Detroit Lockers for street use if that's what you want to run. I've never run one myself, but a lot of guys hate them on the street.
I don't know of anybody personally who has worn the clutches out on an Eaton posi.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires
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72 GOAT RULES
Tribal Scout

USA
6 Posts

Posted - 04 Jan 2018 :  09:59:30 AM  Show Profile  Reply with Quote
Cool, that's good advice and after talking to Summit I will probably use the 3.36 posi. And it's a Eaton. https://www.summitracing.com/parts/etn-19674-010

Yeah I won't be putting a ton of miles on it. It's mostly a weekend driver. In good weather

Edited by - 72 GOAT RULES on 04 Jan 2018 11:08:44 AM
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67drake
Sitting Duck

Azerbaijan
1510 Posts

Posted - 04 Jan 2018 :  10:23:17 AM  Show Profile  Reply with Quote
I run an 8.5" in my '71 GTO. When I built and set up my rear end I used the same Eaton posi as the one you posted in the link (except it's the 8.5 version of coarse). I've beat the heck out of it on the street and track for the last 5 or so years with no problems.


71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 04 Jan 2018 10:24:59 AM
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wakesupremo
Crazy Horse

United Kingdom
687 Posts

Posted - 17 Jan 2018 :  02:41:42 AM  Show Profile  Reply with Quote
I have the post unit that came out of my BOP 8.5" if thats any good to anyone on here. Needs shipping from UK though. My local speedshop supplied me with the gears and pinion kit etc to go to a 3,55 set up only to find that they supplied me with them to fit the 8.2" but wouldn't have them back as they said it was my fault for telling them it was the 8.2". I said it was an 8.5" but they replied by telling me there was no such thing in BOP so it must be an 8.2. I was well and truly 'had over' by them. Ive now got a F**d 9" under there !!!!
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Phil
The Great White Buffalo

USA
7236 Posts

Posted - 17 Jan 2018 :  08:46:04 AM  Show Profile  Reply with Quote
I'll never buy another cone type posi unit after the POS Auburn I had that wore out in less than a year. And that was in a 5.0 truck so overpowering it certainly wasn't an issue. I've had Eaton clutch type units that have never failed. One of them is from 1972 and still works perfectly. Clutches can be sourced for them too unlike the factory GM ones with the S-clip springs.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Cobrabill
Talking Dog

Aruba
3136 Posts

Posted - 17 Jan 2018 :  6:31:00 PM  Show Profile  Reply with Quote
quote:
Originally posted by wakesupremo

. I was well and truly 'had over' by them. Ive now got a F**d 9" under there !!!!



Wakey- GM rearends are the weakest of the Big Three. Your rearend issues are over.

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wakesupremo
Crazy Horse

United Kingdom
687 Posts

Posted - 18 Jan 2018 :  02:03:50 AM  Show Profile  Reply with Quote
Thanks for that Bill. I was told when I bought my firebird 12 years ago that the rear end was the one every racer wanted back in the day. It had some abuse for 11 of those 12 years and stood it ok. It was only when looking to change the 2.73 rears to 3.55's that I realised how difficult it was for anyone to recognise what rear it was over here in UK. I was certain, after advice on this forum, that it was an 8.5" but was told that there wasn't such a thing. It ended up costing a small fortune to get the gears etc but they were never fitted as the axle went 'kaboom' the following weekends racing. It wasn't until I started to strip the axle that I realised the size of the new parts were minuscule compared with the broken parts in my original axle, also that they wouldn't have fitted anyway. the speed shop refused to take them back!!!!
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