3.91 Gears, Sticky Tires, & Stock Axles

[2010BlackCamaroSS]

So, after swapping to 3.91 gears, I was unable to hook in 1st or 2nd gear. I knew the tires were an issue. After all, I was running almost the cheapest tires you can buy in 315/35/R20 (Lexani). They're a great budget tire, especially if you're putting big tires on the rear, just don't expect to hook.



I just mounted a pair of NT555RIIs today; but I'll be honest, I'm hesitant to try launching on them. I'm scared I'm going to break an axle, and I don't have the dough right now to replace them if I break them.


Other mods to the car: 2" headers, 3" exhaust, CAI, truetrac, & DynoSteve tune. Car is an auto.



What do you folks think? Are the stock axles up to the task? Should I wait until I upgrade axles or send it?


I have a feeling I'm going to get plenty of "send it" replies...

[CamaroCracka]

I ran the vert at the track with crappy tires (old 305 Goodyears) and it's around 500 wheel with a 3.91 and it's a manual. I've since upgraded to 1LE axles, but I still would not try the slicks on it. The fact that you're auto will help a lot, but chit breaks. Never race anything you can't afford to set on fire and roll off a cliff.

[OmniCamaro]

Originally Posted by CamaroCracka

I ran the vert at the track with crappy tires (old 305 Goodyears) and it's around 500 wheel with a 3.91 and it's a manual. I've since upgraded to 1LE axles, but I still would not try the slicks on it. The fact that you're auto will help a lot, but chit breaks. Never race anything you can't afford to set on fire and roll off a cliff.

Great advice on racing! Good chuckle.

Did you both do the gears yourself? I've wanted to install the 3.91's for years but am afraid it's over my depth of knowledge.

[CamaroCracka]

Years ago I tried putting 3.91s in a SS diff. It was not complicated, but without a case spreader to hold the housing still, I could not apply enough torque to get the sleeve to crush. I ended damaging the yoke because I did not see it getting dinged up as tried to tighten the bolt with an impact. I could not imagine what it would take to rebuild a ZL1 rear. There were a number of guys who did it successfully, and I have since heard of guys pre-crushing the sleeve in a press a bit, making the process easier.

Both the diffs in my cars are factory pieces, which is the most reliable way to go if you can find them. They were much cheaper back then and I kind of got the Z28 diff free because I bought an entire Z28 suspension and sold everything but the diff for more than I paid for it. In hindsight, I should have kept the axles.

[olblue75]

Yeah Z28 axles are like chickens teeth!!

[oldman14ss]

so are 1le axles unless they are the same as z28? thats a good question

[CamaroCracka]

Originally Posted by oldman14ss

so are 1le axles unless they are the same as z28? thats a good question

They sure look the same, but are not priced the same and have different part numbers. Not sure what makes the Z28 units worth double the 1LEs.

[bottletalk]

Originally Posted by CamaroCracka

Years ago I tried putting 3.91s in a SS diff. It was not complicated, but without a case spreader to hold the housing still, I could not apply enough torque to get the sleeve to crush. I ended damaging the yoke because I did not see it getting dinged up as tried to tighten the bolt with an impact. I could not imagine what it would take to rebuild a ZL1 rear. There were a number of guys who did it successfully, and I have since heard of guys pre-crushing the sleeve in a press a bit, making the process easier.

Both the diffs in my cars are factory pieces, which is the most reliable way to go if you can find them. They were much cheaper back then and I kind of got the Z28 diff free because I bought an entire Z28 suspension and sold everything but the diff for more than I paid for it. In hindsight, I should have kept the axles.

I'm dumping the crush sleeve and going with a solid pinion spacer.

[CamaroCracka]

Originally Posted by bottletalk

I'm dumping the crush sleeve and going with a solid pinion spacer.

I saw that, but I'm thinking that might be a bit beyond my skill level.

[bottletalk]

Originally Posted by CamaroCracka

I saw that, but I'm thinking that might be a bit beyond my skill level.

if you can do ur own brakes u can do this, just has more bolts and u have to measure stuff! watch a couple vid's, it's ez...just requires sum work.
set ur pinion depth according to the original pinion measurement, set ur bearing preload boom the pinion is done. use the same shims off the original ring assembly and toss it in, check for backlash and slap a shim on the side that needs adjusting while taking out the same size from the other side to move the ring over. back lash in spec then check the contact patch. If you can't get the right backlash spec with a good contact patch u have to adjust your pinion. this where spacer is better then the crush sleeve and it won't move under sum spirited driving!

[2010BlackCamaroSS]

Originally Posted by CamaroCracka

Never race anything you can't afford to set on fire and roll off a cliff.

For sure. This is not my only car; so I wouldn't be without transportation if it broke. But still, I like to conserve money when I can. Breaking stuff is expensive.


Anyway, I've launched it several times since I started this thread. No issues. I still get some wheel spin; but then again, I don't always do a burnout before launching because tires are expensive. Also, I don't always air down the tires because I'm lazy. I also think that being on the stock converter gives me some protection as well, as I can't launch at higher RPMs.