8.2 upgrade options
 

I'm starting to do some research into upgrading from my 8.2 into something more durable.

I see a few paths:
- Find an 8.5 or a 12 bolt locally
- Moser 12 bolt or 9"
- Strange Dana S60

What I've found locally in terms of 8.5 or 12 bolts have been overpriced and in need a full rebuild/gear swap anyway, so it's making sense to spend a little more to get exactly what I want from the get go.

I'm leaning towards a new Moser 12 bolt since my local options are few and far between. I'm assuming a 9" would be overkill for my application, but I do like the idea of being able to swap pumpkins easily. I haven't heard a lot of folks running S60s.

My car will stay mostly on the street. I just want to the option to take it to the drags occasionally or beat on it without fear that the diff is going to grenade. What should I be considering in terms of carrier type (Eaton, Auburn, TrueTrac), axle splines, etc?

Moser 12 bolt, your combination is pretty well establish so The option to change gears, don’t think is necessary.

Leave the gear change consideration out of the equation.
It’s far easier and cheaper to change tire height to fine tune the gear ratio.

If the axles for now are usable in the local 12 bolt I would go with stuffing new parts in that if it will bolt right in.

If your RAII heads are not heavily ported I don’t think you will harm the 12 bolts stock axles without slicks and a lot of runs.

If you're already inclined towards an aftermarket rear, the Moser 12 is a good choice. I have one in the back of my '69 bird. It's one of their muscle pack rears. TruTrac, 31 spline axles, big ford bearings with the chevy special housing ends. It would work really well in your combination.

If you are aiming for more in the future, spec it with a slightly better axle package and upgrade the pinion yoke to a 1350 instead of the 1310 it will come with. The housing itself is good for a lot of power, just limited by the axle and pinion yoke used. Even the basic package is capable of around 600hp or so per my conversations with moser.

Heads are not heavily ported. Based on my last chassis dyno session, I estimate I'm putting out about 425-435hp and 500tq at the crank (Mustang Dyno numbers were 355hp/450tq w/conservative timing) so nothing too crazy. This combo will likely stay this way for a while since I just built it. I could see moving on to a set of ported Edelbrocks at some point.

With the local stuff - the asking price for the 12 bolts I've seen are $1500 on the low end (non posi) and $2500 (posi) on the high end. By the time I got done building it, I'd likely be in close to what a Moser would cost.

I was looking at the MusclePak setups - looks like the main difference is that they come with brakes?

"Leave the ease of changing ratios out of it", great advice......:D That advice is given because changing ratios in a Salisbury style rear axle is a royal pain in the ass. There are different series of differential carriers depending upon what ratio your trying to use. Expensive, and time consuming.

The guys that invented the quick changes decades ago should have listened to that advice............LMAO

If you want to drive a long distance via the interstates, are you going to fine tune it with tires, and wheels off of a semi?

Swapping a third member in a ford 9 inch takes maybe an hour, how long would you guess it takes to change a ring, and pinion in a Salisbury style axle, and at what cost? Even if you only set up one ratio, the cost, and ease of setting up a ford is cheaper initially.

As I have posted previously, the availability, and pricing of parts, and pieces for 9 inch fords make them the SBC of rear axles. There are tons of used stuff floating around that can be bought rather cheaply.

The ford are also easier to set up a ring, and pinion as they are adjusted by screw adjuster inserts, rather than shims to move the ring gear into the pinion for proper clearence, and backlash. I've done both, the ford is easier, and cheaper. especilly if you're paying to have someone do it for you.

My advice would be to price out all of the options, make your decision after checking out the options. You're the only one that knows your plans for your cars usage in the future.

It's your car, your money, and ultimately, your choice.

It all comes down to the PURPOSE OF THE BUILD.

Read your build thread, I see a footbraked T400 backed 9.5-1 464 with a mild hyde roller cam & what appears to be stock flow '68 RA II heads...

Here's what you got to answer. Is this goal for the GTO a street/occasional strip pump gas low 12 sec 3850 +/- lbs mainly StreetCar????

OR, is your proclivity for the car to be a continual "upgrade" deal where the future eventually years down the road holds low 10's in the quarter mile with a trans brake & slicks?

This is exactly the goal. I don't forsee ever aiming for low 10s at the race track or significantly modifying this combo. For as long as I've owned this car, the goal has always been to keep it a stock appearing car that can handle an occasional runs on drag radials at the Wednesday night drags. This car mostly sees around town cruising and and car shows for which the 8.2 in it would likely serve fine.

Quick Performance 9 inch and done.

Is your head spinning now on making a choice. LOL

It was already spinning. I never really paid much attention to diffs because I never had anything powerful enough to potentially break one!

a 12 bolt would have to be a lot cheaper than a 9 for me to go that route. how much less is a 12 bolt than a 9 inch?

No matter which one you choose this is your chance to get it built to the exact width that centers your wheel and tire assembly inside the confines of the wheel wells for optimum clearance. This allows you to go up by a size or two on the same wheels if you decide to later on.

You will be wearing out a few sets of rear tires I’m positive of that. :D

If they’re a little too close to the fender lips which is usually the case you now have a chance to move them inward exactly the right amount.

Analyzing the factory-look theme of your build I see the Moser 12-bolt as the one that best fits your car.

Good luck and have fun. :thumbup:

ah ... so the appearance is why people go with the 12 bolt instead of a 9 inch or 60 ...

Or maybe it’s the stigma of Ford 9”. Just suggesting.

Sometimes perhaps.

Some people put the 9” in their cars just for bragging rights and just to say they have one, whether they need the upgraded strength (there are many versions both weak and strong) or just like to run the same style rear as many full-on race cars.

I can remember calling up the H-O Racing tech line back in the early ‘90s where Ken Crocie would answer technical questions for his customers. I was telling him about my car and mentioned it had a 9” and he said he didn’t like them and preferred the 12-bolt. If he did tell me the reason I’ve forgotten it, but anyway everyone has their preferences.

Both myself and my friend who I traded one of my cars to for my first Pontiac (which was a 1964 GTO I later learned was a clone) were really into drag racing and having a Ford 9” we thought was the greatest thing in the world. The GTO when I got it in 1989 had a narrowed Currie 9” with a 31-spline Traction Lock and 3.25 gears, a Doug Nash 5-speed behind a ‘69 RAIII 400. All top-shelf stuff for the time.

After a few years I started bracket racing the GTO running a 455 and TH400, it wasn’t long before the clutches inside the Traction Lock were worn to the point where where it wouldn’t burn both tires anymore. I pulled the pumpkin and paid someone to install a Detroit Locker and 3.89 gears. After that I never messed with it, racing it for about another 9 years before finally selling the car.

The 9” fit the theme and purpose of the car and at the time it was a better rear end than a GM 12-bolt but times have changed and now the aftermarket complete new rear ends afford you many more choices. Back then everything was built off of junkyard housings and center sections for the most part, not brand new upgraded components like you can buy today.

A moser 12 bolt would be the way to go if you want to throw money at it and keep it looking stock. OEM 12 bolts are generally too pricey, by the time you make upgrades to a 1200 open rear end with 2.73s your most of the way to the cost of the Moser, and the Moser is quite a bit stronger.

If you have a N case 8.2 I would get a TA cover and run it and not replace it until something breaks, in the 12s with drag radials, that might be never. But it could be the first pass too, that is drag racing..LOL

The 3.36s seem to be the toughest gear set in an 8.2, a little stronger than 3.55s. Also versus OEM gears, the aftermarket gears also do not have some of the tapers on the pinion machining and are a little stronger. See the photo..

The offset of the 9” rear end is pretty noticeable under an A body. If your going after a OEM type look, it does not fit that. We fabricated had a 9” in a A body before all the kits were available. We did an 8.75 Mopar in an A body also. The 9” with upgrades for power get’s pricey pretty quickly, nodular case with the bigger front bearing support are pretty important upgrades.

For the money, it is hard to beat buying a 8.5, then depending on how quick it is do other upgrades. I bought a 8.5 a few weeks ago from a 72 Cutlass for $350. There was a salvage years that had several 8.5s from 72 Chevelle’s and Buicks, he wanted $350 also. I have seen some asking $500. There were several million of those 8.5s made in 71 to 72, you just have know where to look for them, they put them in every 2 and 4 door combo of A body there was later end of 72. They cost a fraction of the price of a 12 bolt, parts are cheap too.

I have broke quite a few 9” rear ends. I split one grey case open and broke the back pinion support off with a 300 6 cylinder. Split the carrier in 2 on another. I have 2 friends that have broke pinion shafts. JMHO. The Ford 9” are the most expensive rear end to build properly. They run pretty hot compared to other rearends, the worst part of the 3% loss in efficiency shows up in the form of heat.

For a RA II, I'm leaning towards the 8.5" - purely because aesthetics. Take a grinder to one and most folks won't know it isn't an 8.2, "whoa, it still has a 10 bolt". Sneaky. Assuming Ol' Pinion head has one on his racks, he could be a one-stop shop for you. Road trip?

12 bolt is my second choice. Period correct upgrade. Still GM, nobody is going to hold their nose. Perfect if you're wanting to impress the folks who are impressed by the number of cover bolts. The 9" just screams "I've been modified", and the bread and butter parts aren't bulletproof.

I have a '69 XH code 3.55 4-pinion posi with a nodular case right now that's not original to the car. It was rebuilt about 10 years ago. The conundum is it's a relatively valuable rear for someone restoring their car. Would a $200 TA cover really add that much strength to it? It would be a shame to blow it up when I could sell it and recoup some of the cost of a more stout rear end.

If I could find a core for that price, the decision might be easier. I was thinking they'd be easier to find around here, but maybe I'm not looking in the right places.

Agree on a 9" screaming "modified: which is why I was leaning towards the 12 bolt. "Keep your GM car all GM" ;)

What is a TA cover?

https://www.taperformance.com/products.asp?cat=48

I have a TA cover that I need to install on the 8.5 in my Tempest. I chose the 8.5 for a little less unsprung weight than a 12-bolt and a little less internal friction, my car is built for cornering rather than straight line performance. Still rivals the strength of a 12-bolt just in a little lighter package.

I currently have the original 8.2 housing with 3.36 Yukon gears, Eaton posi and B&M cover behind a 461 stroker in my 68 FB. Original plan was to build it for cruising and get a couple time slips. Wound up pulling the numbers matching engine and TH400, storing them under my bench and having a completely new engine and trans built. Had a lot of fun at the track last year. I plan to hit the track more often this year so I recently ordered a new Moser 12 bolt with 3.91 gears, 33 spline axles and Trutrack carrier. Car already has a Stage II TH2004R from Extreme Automatics. Wanted to keep the car GM appearing plus I had bad experiences with Ford rears almost 50 years ago. Granted they weren't 9" but the stigma is still there.

The TA cover girdle or other comparable 10 bolt girdle covers for an 8.2 is the same as a 8.5. You can get it and run it on an 8.2 10 bolt and move it over to a 8.5. Some knock offs are only about $150 new. It both keeps the case from flexing for better teeth contact under a load, and reinforces the carrier caps. With a valuable N case and more than 400 HP in front of it I would want to run one. I like the deeper cover versions that add extra strength and also add an extra quart of oil.

The cheapest upgrade for an 8.2 in an A body is by far the 71 and 72 Olds and Buick 8.5s. The 8.5 have bigger U joints and bolt in axles that do not taper down like a 12 bolt or a 8.2. The driveshaft usually has to be shortened some, same as running a 12 bolt. The stock axles are 28 spline but they do not taper down like a 8.2 or a 12 bolt, the stock the 71 and 72 bolt in axles are strong enough to get a street car deep into the 11s. For drag racing you do not need the c clip eliminators either. The 8.5s weak spot is the stock carrier, but can also be upgraded to a 28 or 30 spline axles and better carrier, or even 35 spline and spool for drag racing. You can also upgrade the 8.5 to newer style 8.6” ring gears. From what I understand the 8.5 carrier’s are Nodular (not completely sure on that though), but I know all the OEM A body 12 bolts are grey iron. The two have the same pinion dimensions, so the nodular 8.5 has more pinion support than a 12 bolt. Find someone that is parting out a 72 Buick or Cutlass and you will find a cheap 8.5. The Cutlass does not have the typical 8.5 markings, and get passed off as Chevy 8.2s. Easiest to find and usually price the same as an 8.2 cause they don’t know what it is.

I run the TA cover on a 3.90 N unit . I’m not a drag racer and have a more modest 420hp 406 . I also bought thicker axle
retaining plates from Jim at http://www.jdrace.com/ in Ohio . They are supposed to provide more support for the sealed axle bearings . You can’t find a 8.5 unit anywhere around my neck of the woods . I’m really considering a moser instead of a rebuild of my 8.2 when the time comes .

FWIW my 78 TA stock 8.5 axles have a lot of low 11 high 10 runs on them. just recently upgraded to 30 splines in it. Many of the bearings in an 8.5 are identical to 12 bolts.

If you plan to hire someone to rebuild and set up a 8.5 or 12 bolt, cost wise it becomes close enough you are likely ahead getting the complete aftermarket 12 bolt that drops in.

i went strange S60 years ago. pretty sure i did that because they didnt have a 35 spline truetrac for the 9 inch, only dana 60 at the time. my car is only 550 hp or so and is a street car so probably way overkill. but honestly i never thought once about how it would look under the car, just that it was the strongest diff available and they were all about the same price from what i remember.

i definitely get that the 12 bolt will be plenty for your intended use and look "right" under your car ... but what if you decide to do a procharger or turbo one day? these cars are never finished .... like guns and roses said, "i used to do a little but a little wasnt doin' so a little got more and more ..."

That is some good overkill..aftermarket block and a 35 spline S60 for 550 HP. That’s awesome. Did your grandparent’s build brick outhouse’s for a living. Lol

i broke a couple 8.2's and a muncie years ago ... i was a little gun-shy when i put the car together.

Maybe I'll add a T/A cover as cheap(er) insurance while I gather funds for a 12 bolt. Not sure I trust it enough to save the rear on a 1/4 mile run, but it's not going to hurt anything.

Speaking of JD Race, he's got a few 8.5s on his eBay store for under $2k. Seems like an economical path from a trusted source.

So for you 12 bolt 33 spline guys does the bigger axle and spiders make the case thinner and break there?

That’s where I had mine built. Kinda hard to go wrong, just be sure to upgrade to an Eaton posi with 30-spline Moser axles if you do decide to do the 8.5. Also make sure it’s the ‘71-‘72 Buick/Olds version with the bolt-in axles and tapered roller axle bearings.

Also you’ll be able to reuse the TA cover since the same one fits 8.2 and 8.5 BOP rear ends.

Back in my racing days I remember seeing an 8.5 under Jim Wanger’s red 1974 T/A running nitrous that was driven by ‘Dirty Ed’ Dufrene. The T/A was a stealthy street race car with no really visible traction aids (pinion snubber and probably clamped leaf springs) and it was running in the 9.40s at over 140 mph at LACR’s 2700 ft altitude.

Jim's got a '71 Cutlass 8.5 with a 3.42 Eaton setup ready to go that looks like a pretty good option. I wanted to keep with 3.55s, but I don't think stepping down to 3.42s would upset my combo.

Mine has 3.42 gears as well, that’s a decent gear for street and not too bad on the highway with a tallish tire. You really won’t notice the difference, 464 cubes doesn’t really need any gear steeper than 3.42 on the street and in fact 3.08 would be plenty.

I’m running mine behind an overdrive auto trans so the highway RPMs will be pretty low.

A 12-bolt would be nice but if you’re trying to keep within a budget the 8.5 is not only priced right it’s also plenty strong for your needs.

Not everyone is planning on building a 6 or 700 horsepower beast in the future. If you ever did well then changing the rear end out to something stronger wouldn’t be a big deal.

What kind of HP/torque are we looking at before it's time to worry about breaking a stock, nodular Pontiac LS rear? 3.55 for instance.

Once you start using sticky tires is usually when you start spitting out the stock limited slip 8.5 diffs, I’m sure they will handle 400 horsepower no problem if the tires can spin.

Your guess is as good as mine when you’re talking about 8.2 cone-type posi units. I had a decent 3.36 posi 8.2 and I sold it so the next guy could deal with whatever might happen to it in future. The later clutch-type posi units are much better.

I plan on upgrading my Le Mans convertible with a Buick/Olds 8.5 factory limited slip and 2.73 gears to replace the one-legger 2.56 8.2 rear. My 421 HO is a mild build making maybe 350 horsepower.

I know its not cheap but definitely going with 12 bolt and the TA is cheap insurance especially if you want to play once in a while. In the end we all want to add more power, specially if down the road you want to Boost that baby up to 500 hp, and put some stickies on that baby. Coming up through ranks of muscle car error, and seeing 10 bolts weather the 8.2 or the 8.5 grenade when you least expect it. Everyone hunting for 12 bolts to replace them.

Not trying to thread jack but I'm in the same position as the OP, rear end options.

606tq/569hp 462ci on 295/55/50 possible 295/65/15
I've got the 69 XH nodular rear with 3.55, part of me wants to upgrade this since..
I've got rear disk brakes on it already.
This rear end is factory and nice, I'm not dragging the car but at 4000lbs and possible 30" Street R tire to hook, it'll get some abuse.

What if me and the OP wanna keep the 8.2...
Moser 31 spline and what new gears etc, can the 8.2 handle the torque and occasional street launch for us???

I'm thinking it can and if we update the parts with only the level of hooking the tq comes into the equation. Street tires add no real load on the rear end but dead hooking is now a big change, 30" x 12" Street R tire.

Thanks and sorry OP if this Jack's your posts.

Don’t keep the 8.2 rear.

Upgrade to something better rather than waste money hoping the 8.2 will withstand 570 horsepower’s worth of abuse for any reasonable amount of time.

Hooking up will break the 8.2 so sell it before you make that mistake and just move on to something better, you’ll be money ahead in the long run.

While I don't have an answer for you. I would have to guess that rear ends like transmission (both manual and automatics) would be rated in torque capacity.

Stan

One quick follow-up question and I'll end the hijack... Stock 1969 GTO nodular LS rear...
8.2 or 8.5?
Cone or clutch?

8.2 cone type. :)

Thanks Bart!

If your putting power to an 8.2 in an A body you probably should have something like a QA1 anti hop bar to make the rear end dig in and not have wheel hop. Wheel hop with a stock suspension A body seems to kill the 8.2 as much as anything. I don’t have a qA1 setup, we created ours, but my center control arms are raised up on the rear end like a QA 1 set up. It made a big difference, eliminated wheel hop completely using a 30” tall drag slick.

We put a Moser 12 bolt in my buddy’s 69 gto not to long ago. The rear came from JD we just ordered new backing plates with brakes and had him install them before he installed axles so we didn’t have to redo it. With brakes it was less that $3500.00. It is far better than any rebuilt stock 12 bolt you’re going to find. With that said take a better look at your 10 bolt it might be a nodular center section. The 10 we pulled from his car is a N center section with 3.55 gears. Now it sits on jackstands in the corner. The purestock car he races has a 8.2 with a good posi unit and aftermarket axles it’s been getting pounded on for 20+ years now still going strong I’m talking hundreds of track passes.

I got in touch with Jim at JD Race. Given my specs, he recommended a 12 bolt as it's a direct bolt in. He said I'd need a shorter driveshaft with the 8.5. Another difference - while the 8.5 has bolt in axles, it's 28 spline (like the 8.2). The 12 bolt is 30 spline. He recommended rear discs with the 12 bolt setup to act as c-clip eliminators.

You're lucky that he's right around the corner from you. The cost of shipping from OH to CA isn't cheap - about $425. Even still, it might come up less than a Moser which is pricing out around $4600 after tax and shipping ($450). If I wanted the rear powder coated it would push me close to $5k.

The 8.2 in my car is a Nodular housing with the 4 pinion carrier. I put new aftermarket axles in it when I had the carrier rebuilt, but I can't remember what brand they are. I'm less worried about the housing or axles and more concerned about the carrier or 55 year old gears giving up. When Jim rebuilt the carrier 10 years ago, he said to go easy on it.

I went ahead an ordered a T/A girdle for now while I make up my mind on a new setup.

Aren't 12 bolts still a C clip axle? Do the aftermarket units come with bolt in ends?

Ive never understood why anyone would pay Moser aftermarket prices for a 12 bolt, when a 9 inch is basically the same price.

If you are sourcing locally and trying to stay cheap then a C clip 8.5, 12 bolt or 8.8 make more sense.

Factory 12 bolts are c-clip. The aftermarket 12 bolts have the option of bolt in or c-clip.

I figured they had to be. But they flat out change the ends and use custom axles right? Not like one of the C clip eliminator kits?

There is an absolute 0% chance I would pay $2000+ dollars for a C clip axle.

And I say that as a guy who regularly defends 8.5s as a budget option.

With what those moser 12 bolts cost, I'd take a long hard look at a nicely built 9 inch from a place like quick performance.