Could you tell me if it's true, that in 1982 1983 1984 it was possible to have a 3.73 posi-traction with aluminium drum brake?

If yes, what was the RPO?

 

If the original owner opt'd for the limited slip rear it would be RPO G80. Also the Aluminum Drums were stock in those years.

 

Yes.

Rather ordinary in the L69 cars. Very very rare in 82, since there were no L69s that year.

One of the reasons that those 83-85 L69 cars are among the primo ones to try to find.

 

Thanks for the info guys

The reason why I asked this question, it's because I found one (suppose to be a 3.73 ,but not seen yet)and the guy said to me that it was very rare... and I was not sure!!

 

Don't pay for it until you pop the cover off and count the teeth and verify the presence of a posi carrier. If it isn't what you want, be prepared to walk out right then and there, don't even bother haggling or feeling like you "owe" the guy something for showing it to you; if he said it's a 3.73 posi and it's not a 3.73 or it's not pois, he lied. No point in you feeling guilty or obligated, because he lied.

There's no "almost as good as" or "it laid down 2 stripes" or "it felt like 3.73s". It's all BS at that point.

Kind of like buying a car, and the owner tells you it's a 350, "It's gotta be, it runs too strong to be a 305". Yeah right.

RPO codes are worthless. Liars use RPOs. The truth lives in the parts themselves.

 

Ok but ...how many teeth I must count for a 3.73?

 

41 on the ring, & 11 on the pinion (41 divided by 11 = 3.72727272727272....) It's probably also stamped on the edge of the ring gear.

 

Ok thanks, I'm going to see that tomorrow morning.

 

I have met the guy and here's the differential



And like RB83L69 has mentioned, I have pop the cover off and...suprise it's not a 3.73 like he told me but a 3.42!!!




But a 3.42 and my Th350 it's a good combo...what do you think...I buy or not?

 

I wouldn't buy it.... it's an Eaton Gov-Lock, affectionately known as the "Grenade Lock" by the S truck people; and it's drum brakes.

The way the Gov-Lock works, is that it acts like an open diff until the RPM difference between the 2 axles exceeds some value, I've been told 100 RPM; at which point the little weights operate the clutches. It's really not appropriate for high-power cars; it's more for trucks and mud. They grenade when they lock up suddenly on pavement.

 

I'm disappointed

It's not easy to find one...and weird this differential was in a Camaro Z28 1984???

And for the drum brake that ‘s what I already have.

Which one is the best for me ?

 

THE ONE to look for, would be a 90-92 disk brake rear with 3.42s. Or 3.23; you could then put 3.73s in it.

The early rears have the smaller axles. The early (88-back) disc brakes suck, and their hydraulics are not compatible with yours which means you'd have to replace the master cyl and prop valve in order for them to have any chance of working right; and then modify the prop valve and add the caliper recall kit to get them closer to right. The 90-up rears with discs use a system that has the same hydraulic requirements as drums; in fact, in those years, the MC and PV were the same part # for discs and drums. That rear will bolt right up into your car as if it was meant to go there. The only adaptation you'll have to do, is to get the end of the steel brake line off of the donor car, maybe the last 6" or so, and splice it onto the end of your steel line; because 84-up rears use a metric bubble flare line where yours (and mine) uses a SAE fitting. You would have the same issue with that 84 rear. Your car's parking brake actuator, unlike the ones in certain later cars, will hook right up to the cables on the late rear.

I have a 91 or 92 disc rear in my 83. It came to me with 3.23s. I had the axle tubes welded, added LCA lowering brackets, put in 3.73s (which was actually the stock gear in my car, being a HO) with an Eaton high-perf posi, and used a crush sleeve eliminator. I am still using my 83 MC and PV with SAE fittings, and the parking brake is perfect.

That one in the pic might be better than what you've got, and if it's cheap (like less than $200) it might be worth doing; but it's not the best choice of parts.

 

Thanks RB83L69 for your help

It's exactly the price (200.00$CAN)what the guy ask for and I think I'll buy it and someday if I can find one like you said...I will resell!!

Last thing... RB83L69 how did you know all those things about the differentiel...I'm impressed :hail: