[besserspat]

Hi guys, what is the real world strenght for a Safe T Track 4 Pinion Nodular housing HD forged axles differential?

The PO of my 73 Bird had swapped a 3.36 Sate-T-Track HD diff from a 68 Bird to the 73, after relocating the spring perches for second gens. The diff being first gen F body is still slightly narrower but honestly cant really see the difference with the rallye IIs.

The 73 is getting completely new power/drive train this winter. so I thought re-using the Safe T Track in my '80 Camaro which is also getting a new engine this winter.

Do you think the Nodular Safe T Track HD differential can survive a 550-575 hp BBC 454 with a 4 speed? I dont baby my things but I dont plan on using slicks but maybe some DRs on the street. The Camaro should be around 3850 lbs with driver.

I dont want to destroy that somewhat rare diff.

Thanks
Peter

[hgerhardt]

Back when Pontiac Drag Days was a thing, we had a racer with a '67 GTO with I think a 421 with a Doug Nash 5-speed and a 4-pinion diff in the '67 rear end. His favored launch technique was to side-step the clutch at 6k rpm. He broke axles in that car almost every month, but never hurt the 4-pinion. One year he decided to "step up" to a 12-bolt with unknown internals. First pass, blew it up.

Obviously, that's one data point and YMMV...

[25stevem]

I would not risk grenading it with a 4 speed and what will likely be 580 ft lbs of torque.

[Formulajones]

Short answer is no

[Half-Inch Stud]

Dry clutch is <\= Engine TQ, while Converter can be 2x engine TQ.

I think the axles will bust 1st, the stock Yoke 2nd, then the pinion splines, then the 4-Pin posi.

[Tom Vaught]

As long as you street race and never put a tire on the car it will be fine.
Example Wanger's 4.33 4 pinion 10 bolt rear axle he ran in the 64 GTO red car and
Bill Sherman ran for a short while.

I swapped some parts for the Wangers Rear Axle and ran it on the street all thru college.
Then I moved to the East side of Detroit (Grosse Pointe Mi area) and the car sat for several years.
Eventually I put a Moser 9" rear axle under the car and stored the Wanger's rear until Tenny bought
the rear and put it back under the Red Car.

Never hurt it on the street with a regular tire on the car.

Put slicks on the car and I do not think it would survive.
I had a 12 bolt under the car for a short period of time which I blew up so I went
to the Moser 9" Ford Rear. I destroyed several regular 10 bolts, the single 12 bolt
before the 9". SO IT DEPENDS OF IF YOU ARE GOING TRACK RACING AND, PUTTING
A GOOD TIRE ON THE CAR.

Tom V.

[geeteeohguy]

What Tom said. The tires are the safety fuse in the drivetrain. Once they get super sticky, stock parts become the 'fuse' and give up the ghost.
Run stock-ish tires and drive normally, not an issue.

[PONTIAC LARRY]

Why would you go backwards from a superior 8.5 Corp in 73 down to a 8.2 ? Pinion diameter reduced also from 1.625 to 1.438 .. A 8.5 should merely have the center fully welded to tubes and upgraded to 33 spline axles and a 33 spline Eaton Tru Trac would hold up to the new drivetrain... if your not launching at a drag strip it may survive a while OK with 8.2 but don't understand going backward considering what's stock in a 73 and the simple upgrades available

[242177P]

Originally Posted by besserspat

I dont want to destroy that somewhat rare diff.

I think you have your answer right there. Build an 8.5 and you can choose another ratio as well. Recoup some coin after you sell the nodular rear.

[besserspat]

Just to get things straight, its the previous of my 73 bird that swapped a 8.2 HD Safe T Track rear end in the 73, not me I got the car like that with healthy rebuilt P350, leaky Th350. and the 3.36 Safe T Track HD read end.

The car is a really nice driver, rust free ( desert car from Palm Springs area) but Id like this thing a little faster, so I got a 500-525hp 461 Stroker, JH Continental converter , built Th400 and a 30 spline True Trac 3.08 geared 8.5 10 bolt going in this winter.

Then I have another car a 1980 plain jane Camaro that currently has rebuilt 350/Th350 and 2.56 open rear, its rust free but a little rough and never ran to its full potential. So the original plan was to swap the Th350 for a 4 speed that I have on the shelves here ( 2.64 Super T-10) and put the 8.2 Safe T Track that will be removed from the 73 Bird this winter.

But Now my daughter needs a new 350 for her 79 C10 , so I first thought Ill put the Camaro's 350 in her truck and build one of the cores SBC 400 I have here. But you know how things are, one things leads to another , I also have numerous 454s including a 454 LS-7 XCH short block sitting on the shelves , I have everything to make it street friendly , steel flywheel, lakewood bellhousing, iron case Super T10 ...I was just wondering if using the 8.2 Safe T track would have been OK. But seems like it isnt lol ...

Whats funny is I am trying to re-use the parts I have lying around in the shop , but looks like I will end with even more parts on the shelves... LOL

[lust4speed]

From what I remember most of the BOP 10-bolt failures around here were caused by the case spreading and allowing the pinion and ring gear teeth to end up at the bottom of the case. Never saw a 4-pinion carrier fail, but any failure point is a failure of the 10-bolt.

[turbo69bird]

I asked bill Eckstrom who raced the Stephens Pontiac drag cars , this exact question he ran one in. A GTO and a firebird in stock class in 68-69 keep in mind on 6 inch casler slicks most likely and tracks weren’t as sticky back then.

He said he never once blew up the factory 10 bolt, Of course they were brand new in low mile new cars at the time, but that was his answer.

[besserspat]

Sounds like a pretty tough differential then ! But let's keep it secret before everyone starts swapping their 12 bolts for 8.2 10 bolts lol

Peter

[Bruce Meyer]

I blew the spider gears on a posi 8.2 with a 400 and a 4 speed on street tires. The 400 was pretty mild. Maybe 400 HP. There is no way it will hold up under your combo.

[geeteeohguy]

Originally Posted by Bruce Meyer

I blew the spider gears on a posi 8.2 with a 400 and a 4 speed on street tires. The 400 was pretty mild. Maybe 400 HP. There is no way it will hold up under your combo.

I disagree. It all depends on how he drives the vehicle.

My dad's Toyota 4Runner went through 3 clutches in 80,000 miles.
My 4Runner still had the factory original clutch when I sold it at 210,000 miles.

If you don't drive like a teenager, should be fine. Many of us don't beat on our cars like we used to and they seem to hold up a whole lot better.

[carcrazy]

I've blown up every 8.2 I've ever had when used on the track with some sticky tires...even my turbo 400 cars.

[i82much]

i blew up a couple two pinion 8.2's behind a 350 chevy with a muncie on street tires, then switched to a four pinion and it held up just fine.

[mchell]

My 4 pinion lasted longer than expected when run with a diff girdle……that being said, after getting into the 1.5x 60 foots on slicks it blew up the ring and pinion gears. Never had a problem with the axles.

[Sirrotica]

Originally Posted by lust4speed

From what I remember most of the BOP 10-bolt failures around here were caused by the case spreading and allowing the pinion and ring gear teeth to end up at the bottom of the case. Never saw a 4-pinion carrier fail, but any failure point is a failure of the 10-bolt.

This is also my experience, the 8.5 is stronger than any 8.2 is. Ran an 8.5 under a second gen on the dragstrip with slicks, and a 455 in front of it, it never broke while the guy owned it.

I've seen many many 8.2s broken with street tires, as Mick has said, the ring and pinion breaks most often. I broke the bolts holding the posi carrier together with a 4 speed, and street tires. Automatics are much more forgiving when it comes to the 8.2, side step clutch dumps are what I've seen that breaks them most often.

If you ever knew any chevy guys that hot rodded the 55-64 chevys with the drop out third members, they are also 8.2 ring gears, and use some of the same parts as the later 8.2 GM series do. They were known for blowing up when behind a stick with a powerful engine in front of it, such as a 409.

On a 8.5 if it's going to see abuse, put some extra welds on the area where the axle tubes go into the center casting. I've seen more than one rotate the whole center casting breaking the factory spot welds, weld them before they break the welds think of it as preventative maintenance.

[Half-Inch Stud]

Just remembered the popular Read failure mode: the stock 7/16" Wheel Studs shear-off. gotta have the Half-Inch Stud