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So I have a 1984 Camaro Z28 with a 350 swap. Brand new engine, not sure what has been done to it though. Brand new 650 cfm Edelbrock carb. It has a T5 NWC tranny, and a 10 bolt rear diff cover.
So the question is... Rear diff housing casting number is GM 22522676 (Is that a 7.5?). I pulled the rear diff cover and took down the numbers I found on the end of the axles - being 4117. From what I've found, 41:17 is a 2.41 geared axle. Am I wrong? If not, are they any good? And if not, what kind of swap can I do? (I'm looking for a bit more of a performance axle that can handle a bit of a 350 build. I plan on getting a bigger cam in the future). Do I have to change the ring & pinion too? Easier to just get a different rear end all together?
Thanks
Last edited by ShaneTrain; 05-12-2016 at 01:30 PM.
A 3.42 or a 3.73 would wake it up nice. Most of the ring and pinion option list the same part numbers whether it's a 7.5 or 7.6...also get an install kit too.
All of the '84 Camaros had the 7.5 10 bolt with 26 spline axles. The 7.5 and the 9 bolt were the only factory installed rear ends in the 3rd and 4th gen Camaros and Firebirds. You could get a Dana 44 from GM but you had to put it in yourself. SLP installed these in their cars too.
I would recommend an after market rear end if you want to be sure that you are not going to break it. You can do several upgrades to the 7.5, but there is no guarantee that it will not break. A 7.5 is always going to be a 7.5, no matter what you do to it.
You can upgrade to 28 spline axles and a 7.6 ring & pinion set. You can also upgrade to a Eaton Posi, Eaton Truetrac, Yukon Dura Grip, Torsen or a few other stronger differentials. But in the end you still have a 7.5.
Yes that's a 7½". ALL 84 Camaros came with that model.
Gear ratio #s are found around the edge of the ring gear.
84 Z28 w T-5 should probably have come with a 3.23, if it was LG4 to begin with. (VIN code H) Of course, "come with" and "has in it" are often 2 VERY different things. Markings on the ring gear for 3.23 are "42:13". Looks like 13 on the pinion there but I'm too lazy to try to guess where half of the ring is and count that.
No that is not a posi. If you look in the window you have hidden from us, a non-posi will have nothing but 4 gears w 2 of them on a shaft; a posi will have 2 plates and a bunch of little springs between them. But since I know what a Saginaw carrier looks like, and what an Auburn WOULD look like if you had one, I can tell you, that's not a posi.
That is some SERIOUSLY DISFRIGGINGGUSTING fluid you got there. Looks about 250,000 miles overdue for a change. Axles are probably smoked. Might want to pop em out and have a look while you're there.
Best course of action will depend on how much of what you have left is any good.
Yea I'm slowly learning that the guy I bought it from didn't take too much care of this thing. I just bought it a few weeks ago and have already thrown quite a bit of money at it. BUT, it runs for the most part haha. It drives ok once it's warmed up, so I would only assume the axles are ok for now.
So being an open diff, the question asks of what to put in it. I was going to go with 75/90 with LSD additive. Still a good idea?
As for ring and pinion, I gathered it is a 3:42:1 from what I could get from the numbers on the ring.
3.42 is 41:12. Probably just fine for most street performance purposes, at least, not so bad that it's worth the money and effort it would take to change it.
Pull the axles and look at em. Just do it. Only takes about 5 seconds a side if you're slow like me; more likely you can do it quicker. Post pics of the outermost 3" or so of the shaft, just inside of the wheel flange, if you don't know what you're looking at/for.
So I went to take out the bolt that holds the pin in, and it snapped. Looks like just before the pin starts and the threads end. Lovely... Apparently this is common...
Any ideas how to get it out without destroying the pin?
Blow it away. Torch it. Evaporate it. Use nuclear fusion on it. The replacement cost is worth the enjoyment.
Especially since, I'd BET MONEY (if I was the betting kind... which I'm a university statistics teacher in some of my spare time, so I'm NOT the betting kind...) that your cross shaft is DESTROYED already. And even more especially after seeing the fluid.
Frankly, I doubt you have ANYTHING there worth worrying about. Not even the housing. Since in 1984 there was only drum brakes, or Saginaw discs; neither of which rear end housing core is worth putting A DIME into.
Now that you've got em out, what do the axles look like?
So I managed to save the lock pin by using a scribe and wd40 to slowly ease out the broken bolt. Just gotta buy a new bolt now. Anyways, here's the axles
No grooves. Smooth all the way to the drop. Looks pretty good to me! Guess I got lucky I suppose
Left side
Right side
Last edited by ShaneTrain; 05-12-2016 at 11:26 PM.
Thanks for all the info guys. Very helpful!
I checked the entire ring gear probably about 4 times and can't find a number on it. I can see one etched in to the pinion gear, which has that 3:42:1 on it. Maybe I've had this gear ratio wrong all along. Might already be somewhat half decent, or at least enough to do its job for now supporting the 350. Those other numbers I had found were on the bracket pieces that hold in the ends of the carrier unit. I'm assuming that has nothing to do wit the gear ratio itself? Those numbers were 4117. Strange how the ring doesn't have ANY numbers on it though.
I heard another way to do it is to spin the tire 2 full rotations and count how many times the drive shaft spins and divide by 2. I put bigger tires in the rear, so would that still work? They are 235/70R16's
Last edited by ShaneTrain; 05-13-2016 at 08:53 AM.
No, the #s on the carrier bearing caps are just the casting number of the caps. Not related to the gear ratio in any manner way shape form or fashion.
As Big said, just count the teeth and divide.
I wouldn't sink money into that rear, no matter what... 26 splines, drum brakes. Wrong core to build up. Even though the axles aren't trashed yet. (however the lower pic does appear to show the beginnings of brinnelling or spalling on the bearing surface; you can see acoupla roller prints on it)
Counted the teeth, turns out its a 3.23 gear ratio. Put her all back together, filled her up, mounted a brand new 650 cfm edelbrock carb, tuned it best I could by ear. Pulls pretty good for what it is now!
Thanks for all the help guys!
05-12-2016, 01:14 PM
