Ok Im going to be rebuilding my first rear end. I am going to be researching as much as I can before I start. So I came to this section looking for advice, help, and combined knowledge. I am going to be rebuilding a 10 Bolt out of an 85 camaro, 3.08 current ratio, open differential, drum brakes. I want to put a nice LSD in it, and raise the ratio a little bit, I know that I have a Series 2 Carrier right now, what does changing to a 3 series entail? I have also heard of using spacers, is this viable for high power? I will also being converting it to disc brakes, I have no idea what to do there. I want this rear end to be strong, I recently swapped in a 9 bolt as a temporary fix (big mistake not spending the extra money on the PBR brakes). Thanks in advance for the help.

 

There's a tech article here on the site somewhere that explains how to modify your outer axle flanges to accept the disc brake backing plates. It's really not too hard to do. Basically you cut off the upper part of the flange where the big hole that your brake line for the wheel cylinder passes through, then you have to measure and drill two upper holes in the flange, and grind or cut the ends of the flange to a 45 degree angle where you made the cut. Most guys say there's no major problems using a ring gear spacer to run 3 series gears on a 2 series carrier. Most aftermarket gear companies make a "thick", 3 series ring gear that eliminates the need for a spacer though. On top of that, if you're going to be buying a new LSD carrier, just get a 3 series one, and you won't have to worry about the thicker ring gear, or using a spacer. As far as posi units go, my recommendations would be a Zexel-Torsen unit that came stock in the 98-up f-bodies, an Eaton clutch style unit, or a Detroit True-Trac. The Eaton Gov-Loc ("grenade lock") is weak, and self-destructs far too easily, so definitely avoid those. The Auburn units work ok, but their achilles heel is the fact that they're not rebuildable like the Eatons. The big advantage to the Zexel-Torsen and the Detroit True-Tracs is that they use gears for their limited slip capability, so there's no clutches to wear out. I've seen the True-Trac unit brand new on ebay for $350, and you can get a used Torsen unit dirt cheap on ebay if you search on there regularly enough. Be aware that the Torsen was available in both 2 and 3 series, so make sure to ask which one they're selling. The other thing with the Torsens is they use 28 spline axles, so you'll need axles from a 90-92 thirdgen. 89-down are 26 spline. The other things you can do to help strengthen up your ten bolt would be welding the axle tubes to the center section, using a T/A Performance cast aluminum rearend cover, and definitely use a solid pinion spacer instead of the commonly used crush sleeve. Hope this gives you some ideas.

 

If you're buying a new posi, you buy it in 3 series, and you buy gears that are 3 series (3.23 and above) and you're done, now you have a 3 series rear.

Do a search on my name in the tranny forum about 10 bolts. I think i've started 2-3 threads that went on for a while. I rebuilt mine (twice, going on 3 times now), and have some good info for a newbie. ie, what tools you'll need, what hassles you may run into (I got them all). etc.

FYI i'm putting in 3.73 gears and a detroit true trac right now.

 

Well thanks for the help, my main problem was my not understanding the whol carrier business. I will look on ebay for a while to see what I can find. What gear ratio should i get? I was thinking 3.42 would be nice, but I plan on eventually changing to a t56, so I could go with more gear. Any ideas? Im strengthening everything before I go with an engine build.

 

A t56 really needs 3.73 or 4.10's. Since you have overdrive now with your 700R4, go for 3.73's.

Make sure you use the solid pinion spacer and a girdle.

 

Any idea on how much a 3.73 would cut down on my top speed?

 

Top speed ? Probably none. I doubt your car has enough power to hit top speed with any gearing.
Just as a comparison, I have 3.73 gears with *no overdrive*. I could hit my top speed, but it's 135mph or so.
Yours is probably 160mph or so, and I doubt the engine has enough power to hit redline in top gear. Chances are your top speed will increase, because you now have enough power to get going faster with the deeper gears.

Here's a spreadsheet I made to calculate that, including speedo-gear
https://webdisk.ucalgary.ca/~jmknopp...eed%20calc.xls

 

If you're really serious about going to a T56, 3.73's would be considered entry level gears for that trans. 3.42's are great with a 700r4, but you'd regret using them once the T56 goes in. Most guys with 4th gens that have the T56/3.42 combo say they hardly ever use 6th gear, unless they're going about 80 mph. Hey Sonix, I was thinking of you when I mentioned the true trac. You'll have to post up and let us know how you like it once you get it in. As a Christmas present to myself, I just ordered up a solid spacer and a stud kit for my T/A cover. I've got a brand new set of GM 3.42's sitting in a box, and I was thinking about installing those, along with the Torsen I've got on the workbench, when I put the solid spacer in. Running 3.23's with the factory Auburn unit at the moment.

 

When you buy your T56, just remember that there are at least 2 versions (can't remember if there were 3 versions).
1993 T56 cars had the option for 2.73 and 3.23 gears and 94-97 had 3.42 gears, so the gearing in the trans is slightly different for most of the gears, 4th being the same on all of them.
4.10's are perfect for the 94-97 T56, but may be too much for the 93 2.73 T56.

 

Good point Zepher. The 93 T56 has a 2.97:1 1st gear, almost identical to the thirdgen T5, and the 94-97 models have a 2.66:1 1st gear. 3.23 or 3.42 would work great with the 93 T56. I'd probably run 3.42's with the 93 model. Wow, I just did a quick search on T56's, and apparently there was two versions available in 93. One had the above stated 2.97 1st, and the other one had a stump-pulling 3.36 1st gear!

 

What about the 6th gear? I would be picking the rear gears based on top gear, rather than first gear of the trans. If it still has the .5 6th gear overdrive, then you'll never use it with 3.23 gears. Go up in gear until your top gear is a useful highway cruiser. Worst case scenario is your first gear is a tractor creeper gear - No biggie, you can skip it when toodling around town, or use it to jump off the line when you want to.

 

Granted, my last response was all about 1st gear ratios, but read the one I posted before that. I agree, and I was trying to recommend a rear gear that would give the best compromise on both ends of the spectrum. That's why I mentioned 3.73's or 4.10's earlier, otherwise 6th gear is just there for decoration. Starting line ratio is an important factor, but not necessarily the main deciding factor.

 

Well in the next few months Im going to be exploring junkyards, looking for a nicely totalled 4th gen to buy, just the whole thing, get the t56, maybe and lt1/ls1? and the interior. I Have alot of plans for my car, its getting done slowly, its down for the winter, so Ill be working on it.

 

Found all the gear ratios for the T56's.
GR - M28 -- M29 -- 94+
1 -- 3.36 -- 2.97 -- 2.66
2 -- 2.07 -- 2.07 -- 1.78
3 -- 1.35 -- 1.43 -- 1.30
4 -- 1.00 -- 1.00 -- 1.00
5 -- 0.80 -- 0.80 -- 0.74
6 -- 0.62 -- 0.62 -- 0.50

 

Don't forget that you want the later 28 spline axles to match your 4th gen zexel torsen... You pretty much want the 28 spline pieces no matter what...

 

Ok I have another question, 4th gen rears are basically the same exact thing but wider correct? are they a direct bolt in? Because when I do find a fourth gen, Im hopefully going to drag the whole thing out of the salvage yard. I was thinking about this due to the fact the 4th gen will have disc rears already where as my stock 10 bolt would need converting.

 

Yep, direct bolt in.
Since you're upgrading from drums you'll need to:
-tweak the e-brake cabling
-reset the brake line pressure so the discs work. Wilwood proportioning valve I think is "the" fix
-You may need a brake line adapter, i'm not sure if the 4th gen one uses the exact same line fitting.
-Springs, shocks, control arms, etc all will work fine.

Good luck finding a 4th gen in the salvage yard. It's probably with all the Corvettes and Maserati's eh?

 

Well, theres alot of salvage yards in my area, and even more idiots driving fast cars. So I figure I should be able to find atleast one.

 

Since his car is an 85, the center brake line will bolt right up. Another alternative that would be cheaper/easier for the proportioning valve would be to use the stock, drum brake valve from an 89. 90-up valves use a different thread pitch, but the 89 valve is the same threads as the 85 lines. The 89 drum valve provides adequate pressure for the PBR's without having to cut and reflare the lines for a Wilwood valve. Or even better would be to get the 89, 1st design 1LE valve. It'll hook right up to the 85 brake lines. I'm using my stock 89 drum PV with PBR's, and it works pretty good. I've got a brand new 1LE valve sitting in a box, just been too lazy to put it on and bleed all the lines.