sparafucile17

Forgive the dumb question, but did the '91 Z28 with 305 engines come with a 2.73:1 rear end with posi? What what I can tell on the web, all 90+ Camaros went posi, but my Helms manual say the rear should have a metal tag on it. I looked and don't see the tag. Any ideas?

I want to beef up the rear gear this summer and need to know what parts to order. I have a friend who's done this type of work before to help out.

Also, what gear ratio would you guys recommend? I was leaning towards a 3.73:1 but wasn't sure if that's too high for a 305. Currently the car has a new exhaust from headers back and some small performance tweeks. Probably somewhere in the 275 HP range.

Thanks
Jeff

87DJP2001

Check for RPO G80 (limited slip) option. Also with your 2-series carrier make sure you buy the correct gears or use a spacer. And with a Stock set-up (your mods are not increasing the HP to that number) a gear swap is a waste of money.

89Vert

you need a high rev'er for 3.73 to be effective and TPI ain't a high rev intake,

I went to 3.45 from 3.08,

my trap speeds were higher but my time was no different, cause of the extra shift,

I've since gone back to 3.08 and find the car likes that gear better

sparafucile17

Ok, I'll check for the RPO code when I get home. When you say 2-series carrier, what does that mean? I'm pretty dumb when comes to rear-end work, so excuse my ignorance.

That's kinda why I'm asking what do I need to know before I go to the performance shop to order parts. Posi Yes/No, 10-bolt, desired gear ratio, anything else? I plan to get a complete rebuild kit with it to redo seals bearings etc. I know the front seal is leaking for sure, so I think it best to re-build it with my more experienced buddy at hand.

And yes, I do understand at this power stage I'm not gaining any HP with a gear swap. My pan is to work from the back forwards so I don't have to worry about damaging parts or choking the life out of my mod with wimpy parts down the line. I want to do rear ==> driveshaft ==> T56 trans ==> 383 engine in this order.

Jeff

sparafucile17

So does that mean the higher the ratio, the higher up your power band must be in order for it to be useful? Also what would happen to drivability if you put too big a gear on a TPI engine?

My goal is to make it a street car and I'm not too interested in high end power since I won't be going much faster than 60 mph on most days. *VERY* rarely I'll bring it to the track, but that's just for fun and I don't care too much about my time slip. (as long as it's not a wussy 17sec!!)

I just want this thing to sound and drive like a mean son of gun on the street!

Jeff

sparafucile17

Any ideas anyone?

Jeff

Anniversary-Z-man

The 2 series carrier is what you have because you have 2 series gears....you can't just swap in 3 series gears (3:08, 3:45, 3:73) and replace 2 series.
Also if you plan on going with a 383 at some point (depending on power levels) you may want to forget rebuilding the 10 bolt and going with a 12 bolt or 9".
I spent about $1500 building up my 10 bolt with all the best parts and reinforcing it etc....and then later on in the project decided to do a 383 as well (makes about 550hp) so intead of worrying about trashing the 10 bolt I built up I went and picked up a Moser 9"....(so unfortunately I'll be selling thr 10 bolt).

89_Irocz

My 92 305 TPI came with a 2.73:1 Posi. so yeah most 91's did also, most 305 tpi's in 91&92 also came with drum brakes on the rear.

sparafucile17

So, if I understand this right the carrier is the rear end housing? Right? Basically what I see in my head is that the carrier is everything around the rack & Pinion.

Once you guys clear me up on this issue, what's the deal with a 3 series gears not working in 2 series carrier? Is it because the 3.08, 3.45, and 3.73 rack and pinion are too large to fit inside the housing(carrier)?

Reasoning aside, what do I need to do in order to swap in a 3.73 gearset into my 10-bolt for the least amount of money? Can I just buy a 3 series carrier and new gears are rebuild with remaining parts from my original 2.73 setup?

Help!

Anniversary-Z-man

Actually...I said the 3 series is for 3.08 and higher...that's incorrect...2 series are 3.08 and lower, and 3 series start at 3.23. The carrier is not the housing, it's what the ring gear bolts to. I believe the difference between the 2 and 3 series gears is ring thickness...so spacers may be required if possible to convert. All the 3rd gen camaro 10 bolt housings were pretty much the same. Also FYI...it's RING & Pinion gears....RACK and Pinion is steering.
To build the 10 bolt definitely try to determine how you need it built...what kind of power do you need it to handle? If you're going to be pushing 350-400hp then you're going to want the good stuff. Heavy duty differential (like the HD Zexel/Torsen), good brand gears, possibly larger pinion yoke, stronger axles, stronger cover etc.....Then there's welding the axle tubes, and strengthening/reinforcing them.
If I were you and $$$ is a problem, then you might want to wait on a rebuilt if it's not necessary now until you know what you're going to need from the rear (or just buy my 10 bolt I had built up LOL).

sparafucile17

Ok,

I'm a little more clear on what a carrier is. So my next question is how do you know what the spline count is for my application? I looked on eBay and found 10-bolt 3 series carriers that have either 26 or 28 splines.

Is it worth getting this off eBay or should I buy a brand new carrier when I get the gears? If so what is a good brand for gears and the carrier? BTW I finally checked my car and it WAS a posi. Do I need to buy any special now that I know it's a posi?

Also, does anyone know of a good resource for changing out a 2 series to a 3 series?

Thanks, you guys suggestion have been really helpful so far!!
Jeff

Kevin91Z

Get yourself a set of used 3.42 rear end gears and posi from a 4th gen 6-speed car, or buy a new set of 2-series gears and use your existing posi. 3.42's is a great ratio for a stock TPI and it'll be great for what you want out of your car. Your 91 will have 28 spline axles.

sparafucile17

Ok,

I found two different used 3-series carriers from two different 4th gens. They are:

• Posi (Limited Slip) - '98 Z28
• Torsen (Torque Sensing) - '98 SS

Which one is better and why? Also what do you think a good price for a carrier is? $200??
Is one better suited for street use?

- Jeff

rudyt5000

i'd go for the posi (limited slip) from the 4th gen if you really want to push power cause these things been handling power from the Ls1 and im pretty sure thats more power than what you'd be capable of a stockish 383. I'd just switch the whole differential with brakes and everything WHOLE cause its a direct replacement anyways...but you would have to switch to new REAR wheels from a 4th gen camaro

not the torsen sensing- (~since it sounds like a bunch of computer stuff~)
AND is this mostly back in the day -Corvette parts- If you're going to be pushing 350-400hp then you're going to want the good stuff. Heavy duty differential (like the HD Zexel/Torsen). I heard parts are hard to find and are very difficult to replace or upgrade

sparafucile17

Ok, good tips. I read up a little more on the Torsen carries and found out the following:

It just sounds like it is better that the limited slip counterpart. But you bring up a good point if this is an outdated carrier then it may be difficult to find parts in the future.

Does anyone more details on the Torsen Carrier? How much better is it than the regular limited-slip?

I guess what I'm worried about it that the limited slip came from a non-LS1 Z28 and it isn't designed to handle that level of power (which is more than I need but feels good to know I can go there if I want to.)

Jeff