[mgarblik]

Has anyone actually installed one of these units and a new ring and pinion from fabcraft. Just wondering what you think of the product quality, how well the posi works and how quiet the gear set was. I had some noise in the rear of my Catalina and pulled it apart to inspect. The axle bearings were lousy, which I expected. What I didn't expect in a million years was what I found in the carrier. The pinion shaft, not the bolt broke at the bolt hole and the little end bounced around in the housing chewing the absolute crap out of everything in there including the pinion. I think the only thing I can save is the pinion yoke and the carrier. Everything else is shot. It's not even a POSI! I thought these things were supposed to be good?. I have never seen a shaft break like this. Bolts yes, but not the shaft. With Fabcraft stuff, it's going to take $1500.00 in parts to fix this mess. Tempted to throw a Ford 9" in it and be done. Appreciate some feedback. That's allot of coin to fix a rear end.

[tom s]

the gears are Richmond.Tom

[hurryinhoosier62]

Originally Posted by mgarblik

Has anyone actually installed one of these units and a new ring and pinion from fabcraft. Just wondering what you think of the product quality, how well the posi works and how quiet the gear set was. I had some noise in the rear of my Catalina and pulled it apart to inspect. The axle bearings were lousy, which I expected. What I didn't expect in a million years was what I found in the carrier. The pinion shaft, not the bolt broke at the bolt hole and the little end bounced around in the housing chewing the absolute crap out of everything in there including the pinion. I think the only thing I can save is the pinion yoke and the carrier. Everything else is shot. It's not even a POSI! I thought these things were supposed to be good?. I have never seen a shaft break like this. Bolts yes, but not the shaft. With Fabcraft stuff, it's going to take $1500.00 in parts to fix this mess. Tempted to throw a Ford 9" in it and be done. Appreciate some feedback. That's allot of coin to fix a rear end.

I looked into building a 9" for my '64 Cat. $1500 wouldn't even make a dent in the costs of building a custom 9". The axle housing alone was nearly $1,000, not to mention the cost of the third member ($1500). You have to remember that every component in your diff is approaching 60 yrs old. ANY mechanical device that old WILL corrode, fatigue and break. Another thing to consider is in a modified form, the 9.3 stood up to blown Hemis on nitro. That's WHY Fabcraft had to start making parts: too many 9.3s were used up in racing.

[warriors revenge]

it is great that the parts are available for the 9.3, but i am looking at making bolt in 9" housings for the early big cars because i would rather spend the money on a 9"
i am surprised to hear about this issue....
kal

[Ragtop Man]

There is a payback issue for whoever develops a 9" - there just aren't that many takers, esp. when the '57-64 Pontiac/Olds is bomb-proof and still fairly plentiful in their normal state.

What WOULD bring down the house for the '65-70 guys is a legit 12-Bolt that would actually bolt into the Pontiac/Olds which could use all the commonly available GM posi units, ring and pinion, etc. that Chevy guys have piled like cordwood under their workbenches.

To 99% of show judges it would look stock as a rock; 12 bolt cores are out there by the ton, the parts are not expensive or hard to come by.

[Willshire]

I put a JD Race posi in my GP with fabcraft gears (i think JD and Fabcraft were working together....kinda). Easiest setup i've ever done. It's a little bit noisy but i have a bonneville driveshaft in that needs to be balanced.I got a series 2 carrier because the ring gear from fabcraft is super thick. but, now that fabcraft sells the posi they should mate right up. Back in the day, ford guys were putting these in because they were just plain tougher than the 9"

[Willshire]

http://forums.maxperformanceinc.com/...d.php?t=741207

Here is my install. Make sure you get the rear end book from fabcraft too. worth every penny!

[hurryinhoosier62]

Originally Posted by warriors revenge

it is great that the parts are available for the 9.3, but i am looking at making bolt in 9" housings for the early big cars because i would rather spend the money on a 9"
i am surprised to hear about this issue....
kal

When I talked to the guys at Quick Performance(2011), they quoted an ESTIMATED price of $875 for a 9" axle housing for a '62-64 Pontiac B-body. It was estimated because they had never built one. Upon their (Quick Performance) review, the cost became closer to $1,000. As Ragtop Man has stated, the real market would be in the '65-70 "B" bodies. Top fuelers, funny cars and fuel altereds ran the 9.3" Olds/Pontiac for decades. It's NOT weak by any means of measurement.

[mgarblik]

I have had a chance to completely disassemble and clean my 9.3" rear. I have carefully studied how it was made and how they oil the bearings and so forth. I can see why it was a favorite in it's day. It is quite a hunk of nodular iron. Looks like it should be strong. It is easy to see how it was much less expensive to manufacturer than a Ford 9". Not having a removable drive pinion support greatly reduces cost, fewer parts and fasteners. It does make setting up the pinion slightly more difficult. But without having a separate part stack-up tolerance there, it should be fairly easy to hit the right pinion depth shim. I have no idea why mine is so torn up. Just my luck I guess. This car just doesn't look like it was ever abused and it's an open rear. You would think it would just roast one tire long before killing the rear. But I guess if you think about it, if it regularly roasted one tire and the other was barely turning, that does really work the spider and side gears. For reasons I can't explain, those gears look very good. I will post some pics of the damage. It's interesting, just wish it wasn't MY car.

[strato gto]

Just change the drop out center with a used one.Non posi centers are cheap and it is a bolt in.Easy fix!

[mgarblik]

I was led to believe that the #3 case that caries the 3.42 factory gears and higher ratios are VERY hard to find, even the open ones. That was why the replacement gear sets have the thicker ring gears for the #2 case. Was told that less than 10% of all the old 9.3" cases were the #3 case. Could be wrong, as I am just learning about these for the first time. With my future plans, a new posi unit is the right way to go. Just an unexpected very large expense. Especially 5 miles after getting the transmission back in the car. I guess the good news is there aren't many major components left to fall apart after this.
Unfortunately for me, this car turned out to be the typical trailer queen/show car/auction car. Looks great at the car show, even won a concours de' elegance show years ago....... but it wouldn't make it around the block without falling to pieces. I won't have a car like that. It's going to run when I am done with it, and look decent too.

[mgarblik]

Here are some pics of the "mighty" 9.3" rear end. Hope for better luck with the new stuff.

[tom s]

If you run across a broken posi I have a couple sets of side gears avail for much cheaper than a new set from Brad.Tom

[mgarblik]

Thanks Tom. I already pulled the trigger on the Fabcraft stuff. Here in the Mid-West we really only have about 6 months a year to enjoy these cars. I really want to DRIVE this car some before it's -20 degrees F and I am waist deep in snow! The ring gear is in good shape and the pinion is OK, It's slightly gnawed-up on the very inside face where it doesn't really contact. The side gears and spiders seem to be fine. Go Figure. It's a 3.42 gear. I would be happy to sell off these parts to help finance the new stuff if anyone is interested. Let me know. I would have used the ring and pinion over but the Fabcraft Posi is made to work with their extra thick ring gear or a factory #2 case.

[Hillard]

I might be interested Mike. 3.42 is what I really want for my wife's 62 wagon. Need anything else? maybe do some trading? If not, let me know how much you want.

[mgarblik]

I will call you next week. I'm sure this car needs something.....the way things are going!!

[Engine-Ear]

Interesting thread.

As for the culprit that lead to the damage, maybe it was built with subcomponents whose tolerances were on the loose end of acceptable range and/or the metallurgy / hardening wasn't to-spec.

I have hammered the HELL out of these diffs (all were peg-legs, like yours) when they had already seen 30 to 45 years of daily service and have never had a problem.

Hope you keep the rear end PMD.

Kal, I agree that the '65-'70 is where it's at (R.M.'s post #5) instead of the '64 & back.

[Deadhead]

On your side is the fact that hardly anyone is buying these parts right now. Whatever is left can be bought for less than premium prices. There are plenty of viable positraction rears for these cars still in yards and garages. Maybe 10% of Pontiacs had them, but you have a period of 5 years and the other marques where the internals fit, making it a little less scarce than your statistic appears. The headaches and expense surrounding aftermarket parts and or custom fabrication are exponential compared to finding and setting up a factory unit. Ask anyone who has done it on one of these cars or read any thread regarding the same. I did one recently and had a machinist do the carrier swap. My total cost was around $1200.

[mgarblik]

Quick up-date: Got all the new parts yesterday. Came quickly, very well packed and all the parts carefully marked. As some know, I am in the automotive education business so I also bought the manual they promote. Gave the whole book a read last night. I would say to anyone not familiar with rear end work and especially anyone who has never worked on a 9.3", this book should be required. It's textbook quality and the book itself is very high quality. Best specific rear end manual I have ever seen. The 9.3" does have some weird and unique set-up procedures, not difficult, but not like any Dana, 10 or 12 bolt or Ford. The strangest part is the case bearing preload adjustment. Rather than using rotating torque on the case bearings like every other rear end I have ever worked on, they use " holes of adjustment", no torque reading. This is very well covered in the manual. I plan to build the rear end this weekend.

[mgarblik]

Well it's been a real battle with this rear end. I probably have 12-14 hours in this rebuild and I am still not really happy with it. Here is where I am so far. Fabcraft Trophy Track limited slip unit is really nice. It's an Alburn Gear unit made to their specs. Nicely finished, less than .001" ring gear runnout. My unfortunate issue is with the new ring and pinion. My understanding is Fabcraft had an exclusive deal with Richmond Gear to make these sets for them. Not sure what they used for blanks or how they cut the gears, but I can't get a really nice pattern on the drive and coast side of the ring gear. I have set-up hundreds of rear axles and this one kicked my ass. I tried 11 different pinion shim thicknesses after gauging the housing for a starting point. No matter what I do, the pattern still wants less pinion depth. Eventually, you run out of tooth area on the face which will break teeth. I finally decided to go back to the gauge size which gave a nice drive side pattern and let the coast pattern fly. I anticipate this gear set being noisy when you let off the gas and coast. But we will see. Richmond gears are always the most difficult by far to get a really nice pattern on. For racing, this set-up would be just fine. For a street car, probably noisy. I will take a few pics before I button it up tomorrow. The people at Fabcraft have been super nice and helpful by the way.