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Being something of a novice in the thirdgen world, I didn’t take much notice of the details on this axle, I was pumped for posi, 3.42 gear and disc brakes.
speaking of brakes, those rotors seem large…
11.5” diameter. is it a G80 1LE axle?
Last edited by theraymondguy; 11-09-2021 at 05:47 AM.
No; it's a 93-97 4th gen. The disc brakes used on those are essentially the same as the 89-92 3rd gen ones. 98-up also got the parking brake that is a mini drum setup inside the center of the rotor. Yours of course won't have that.
Housing prep: remove EVERY PIECE from it. Take pictures if necessary. Brakes, brake lines, axle bearings & seals, pinion & carrier bearings & seals, vent, ABS sensor (you can do away with that altogether of course), old control arm nubs, etc. Clean it up CLEAN at the quarter car wash with engine degreaser, a wire brush, and something to swab out the axle tubes. Or maybe even, have it tanked. Take it to someone who can weld on cast-iron; not that that's "hard" or whatever in and of itself, just, they need some sort of oven to heat the pumpkin up uniformly and evenly to at least brown-hot. Have them straighten the housing (rod inserted through it, maybe using something like those "puck" things wheel balancers use) PERFECTLY straight, and weld all the way around the axle tubes, and fill in the plug welds the factory used so that they stop leaking. (looks like both of them you can see in the wide photo leeeeeek) Have it sandblasted. When I did this to mine, I got it powder-coated; you could use that, paint, ceramic, or whatever peels your banana.
Last edited by sofakingdom; 11-09-2021 at 07:23 AM.
No; it's a 93-97 4th gen. The disc brakes used on those are essentially the same as the 89-92 3rd gen ones. 98-up also got the parking brake that is a mini drum setup inside the center of the rotor. Yours of course won't have that.
Housing prep: remove EVERY PIECE from it. Take pictures if necessary. Brakes, brake lines, axle bearings & seals, pinion & carrier bearings & seals, vent, ABS sensor (you can do away with that altogether of course), old control arm nubs, etc. Clean it up CLEAN at the quarter car wash with engine degreaser, a wire brush, and something to swab out the axle tubes. Or maybe even, have it tanked. Take it to someone who can weld on cast-iron; not that that's "hard" or whatever in and of itself, just, they need some sort of oven to heat the pumpkin up uniformly and evenly to at least brown-hot. Have them straighten the housing (rod inserted through it, maybe using something like those "puck" things wheel balancers use) PERFECTLY straight, and weld all the way around the axle tubes, and fill in the plug welds the factory used so that they stop leaking. (looks like both of them you can see in the wide photo leeeeeek) Have it sandblasted. When I did this to mine, I got it powder-coated; you could use that, paint, ceramic, or whatever peels your banana.
Awesome, thanks Sofa. There’s obvious signs of seeping at the seals etc, it does need some attention. It measures 64 1/4” inside of flange to inside of flange.
I’m wondering if I’d be happier with a 3rd gen housing and axles? There is a 91 drum axle at the same pick n pull… I plan to run ‘90 formula 16” rims, 5/8” positive offset for the rears. Either way I’ll gut the housing and drag it to our commercial truck shop, take it for a spin in the hotsy if they’ll allow it. If not the heated power washer does nice work too.
The 3rd gen wheels won't fit a 4th gen rear properly. They'll stick out about 1-3/4" too far on each side. Besides merely looking goofy, they may hit the fender lip.
4th gen or Vette wheels fit perfect since they're the right offset.
Any 3rd gen rear you get that isn't $$$$ is going to either be destroyed too uselessness, or have drum brakes, or both. You can put those brakes on a drum rear but it's not trivial. Not impossible, or even very hard, but not trivial.
Your choices are to either build up and install the 4th rear, and then either get wheels that fit or deal with ones that don't; or, tackle the brake swap on your existing rear, and move as much of the 4th over as you see fit. I can definitely tell you though, the "posi" in that 4th is almost certainly an Auburn, and therefore JUNK. But don't worry about that yet: get your housing issues sorted out first, then worry about the carrier later.
I have researched this thoroughly today, lots of numbers on the forums for 4th gen axle width:
I’m here to tell you that this 4th gen axle is 65.0” axle face to axle face.
It is my understanding that the 3rd gen axle measures 61.75 axle face to axle face, leaving the claims of 4” increased width somewhat exaggerated.
with the 16mm positive offset from the formula rims, that reduces the increased wheel lip to wheel lip width to 3”, which will (barely) tuck under the fenders… it might not be horrible.
Last edited by theraymondguy; 11-09-2021 at 09:06 PM.
Well, if you wish to make karma laugh, tell it your plans.
I mounted the 4th gen axle and felt sick. God it looked awful.
There’s only one thing to do, parted the 4th gen axle took the proceeds and squandered it on this mess:
10 bolt 26 spline Third member out of an ‘86 firebird (2.8, auto), 3.42 gear set, about 115000 Miles according to the oil change reminder. I dare say original to the car.
I’ll be transferring the bigger sway bar, drum brakes etc. from my 9 bolt. New bearings, seals, Annnnnd (make sure you’re seated, air sickness bag handy…)
An EBay Posi.
Nothing but the finest. 26 spline, of course.
I’m $450 CDN into it now for the third member, posi (screaming deal, $250 CDN delivered), bearings and seals. I’ll be parting with another $100 or so for paint, shims, pinion bearings, seal etc.
Still much less expensive than a delivered used 9 bolt from Australia or a $700 Kijiji used third member with a 3.08 gear and will be fully refurbished at that price. Should handle all the grunt the mild cam 5.0L / TH700r4 can muster and hopefully not blow one tire off at ever launch. At 2000 miles a season, I hope to have it last many.
I have no viable dreams of an engine swap or manual trans in the near future. If it comes to pass than a “real” axle swap will be in order. In our market every viable part sells and will move this lot on too.
Last edited by theraymondguy; 03-06-2023 at 04:03 PM.
The posi groaned like crazy and really wasn’t drivable. Draining the gear oil and adding fresh with Ford FM made all the difference. Quiet, smooth - it’s just a pleasure to run.
The swap from 3.27 to 3.42 should not be as notable as it is - I believe most of that is from the significantly worn 9 bolt.
You actually crawled under there - and are still alive?
Maybe the camera angle makes this look worse than it really is.
Originally Posted by T.L.
I was thinking the same thing...
I too like to live dangerously… 😀
Camera angle not helping. Jackstands on the torque boxes, Wheel chocks are present if not hard to see. Safety wiggle before and a thorough “that’s not going anywhere”.
I’m a heavy equipment guy, most everything is sketchy.
Wow, those were some clumsy, accident-prone guys!...
Lol, some dramatization for effect I’m sure. I can identify with parts of it - walking out on the boom to replace a hose etc. It is called “field” work for a reason, it usually happens in a field.
11-08-2021, 04:33 PM
