I just came across a 3.73 posi for my 89 RS tbi camaro. I was wondering how hard it would be to put it in my car. The guys will sell me the axle, gears and posi unit as one thing. Can I just drop out mine, put my brakes on it then put it in? Whut do I need. If some one can help me out I owe ya big time. By the way both my car and this new rear are brake drums. Thanks


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89 RS Camaro
Hedman Headers, Highflow Cat, Flowmaster 80 Series
180 Degree Thermo
Open Air Element with K&N Air Filter
Custum Burned Chip

So Many Mods......so little time

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Both setups are drums? Hell yeah, go for it; you can switch axles easily! You don't have to change the master cylinder or prop valve at all... your job consists of:

1. unhook rear brakes (fluid line, e-brake cables)
2. unbolt old axle
3. bolt in 3.73 axle
4. hook up 3.73 axle's brakes

Do yourself a favor though, and buy a new body-to-axle brake line! It'd be much easier to do now than a couple years down the road. When you unhook the rear brakes, though, make sure you plug that rear brake line (on the body)! You don't want your master cylinder to run dry, otherwise, instead of bleeding "just" the rear brakes, you'll have to bleed the master cylinder... and that's a pain in the butt.

An easy way to do this is instead of unscrewing your old body-to-axle brake hose, cut it in half... since you're buying a new one, anyway! Then, as brake fluid pours out, stick something in it, like a bolt, or golf tee, or chewing gum... something to plug that hole and keep the brake fluid in. Or, you could even take vise-grips, and clamp them on the hose so it squashes the hose shut. Then, take your time switching the axles around...

When it's time to hook up the 3.73's drum brakes, hire a friend to watch your master cylinder. He must watch the FRONTMOST reservoir on the master cylinder!! Don't have him stare at the one closest to the firewall- that's for your front brakes. As he watches the frontmost (towards the bumper) master cylinder reservoir, have him/her armed with a bottle of brake fluid. Tell him/her to keep that reservoir full while you work, and to warn you if they run out of brake fluid. (Buy a big bottle or three.)

While they're doing that, you can unscrew the old half-a-hose from the steel brake line on the car, and insert the new hose between the car and axle. Then you just do a "textbook bleed" of the back brakes.

Make sure to use your torque wrench on all the bolts that hold the axle to the car. You shouldn't tighten the bolts down while the axle's in the air. Either rest the back on it's tires, or support the axle with a hydraulic jack under the center, and THEN tighten the bolts all the way. Otherwise you'll induce an upward preload in the bushings, and your handling will be a bit funny.

And finally, remember to re-check the torque of all those bolts a day or two after your swap. I forgot to do that, and lose the panhard-rod-to-body-bracket bolt while driving- luckily, I was right outside my house. Good thing I wasn't doing 80 MPH!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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Oh- and yeah, you could put -your- drum brakes on the 3.73 axle. You might want to do that, since you know your current drum brakes work. You probably don't know how well the 3.73 axle's brakes were working... the Haynes 82-92 Camaro manual will have all the torque specs you need for the job. If you don't encounter any rusted-solid or broken bolts, I'd say it should take you the weekend. If you want to make this into a "restoration project", look into replacing the rear axleshaft bearings (parts stores mis-name them as rear wheel bearings) and seals, and you might want to paint the axle with POR-15. I used it; great stuff. http://www.por-15.com I used their Super Starter Kit (Semi-gloss black, $20), and it was just enough to coat my 3.73/posi/disc axle.



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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!