i was wonderin if my 1/4 mile times would improve from changing the rear end from 2.77 to 3.23? my engine is a stock 88 L98 i messed up the borg warner 9 bolt (2.77) so instead of paying alot i found a rear end in a junkyard 10 bolt (3.23). it was very hard finding this rear end because my car is equpied with rear disc's breaks. my current 1/4 mile time is 15.06

 

2.77 is a horrible gear ratio. Even swapping to 3.08's would give you a better 1/4 mile. I'm guessing by swapping to 3.23's you might pick up half a second.

 

Go to 3.42s

 

I second the 3.42 recommendation. I went from 2.77s to 3.42s in my car, and it picked up like . in the 1/8. I went from a 10.1 to a 9.7. That was w/ crappy 60's too.

 

probally not maybe change to a real man gear like a 4.10 or a 4.56 now your talking

 

that much gear with a stock motor with a 700r4 will be a slow turd!!!!!!!!!!!!3.23-3.42 auto,3.42-4.10 6-speed with plenty mods to rev and make power 5800-6500rpm..

 

to answer your questin, yes your times will improve, unless you are already redlining your 1:1 gear , or with your new gears, if you red line before the finish, then u have too high of gear.

 

I had the same gear and with a shift kit and going to a 9 bolt 3.23 rear i went from 14.9 to 14.3 in the quater.

 

I have a 89 IROC 5.7 and it to has the 2.77
I hate it. The second gear is so slow, But, I like the long first gear run..... I've learned to perfected my tire spin.
But, I'm soon going to say goodbye and go prob 3.42
Will the rear disc bolt to any old 3rd gen rear.
I've been looking at mostly the v-6 cars they seem to be easier to get a-hold of.. I don't know if they will bolt thou.
But, any info on what you find would help..??

 

It will make a big difference.

We recently swapped out a 2.73 axle for a 3.23 axle that was pushed by a 305 TPI. No tracks times with either but the SOTP difference was very evident.

 

A quick Desktop dragstrip shows(with a stock L98/700r4)

2.77 gears 14.5 @ 93.0mph
3.23 gears 14.3 @ 94.8mph (my car has 3.23 gears and runs 14.4 @ 94-95 all day, so its close)
3.42 gears 14.7 @ 94.8 (goes into 4th gear)

 

I honestly doubt you'd be shifting into overdrive in the quarter. In my crappy little 305 i can do 125 without being anywhere near redline. With 3.42's and more powerful engine it wouldn't change THAT much.

Ahhhhh my bad. I did indeed mean 3rd gear.

 

I'm sure he ment 3rd gear.
Mine w/ the 2.77 has this

0-40 1st
42-80 2nd
81-120 3rd
121-140+ feathering Pedal in OD
I believe I used to run 140mph at just around 4k also.

But, changing to 3.42 should get me about a 1/2 sec quicker....ballpark...??

And, How much top end am I really gonna lose..???

What about the v-6 cams/pont rear ends. Will those fit up under a IROC...??

 

3.42 might be too short of a gear ratio for a mostly stock LTR setup. You'll rev the motor right out of its powerband. I think 3.23 would be the most desirable gear unless you plan on moving your powerband up another 1000 rpm to match the LT1 or LS1 peaks ~5800. GM put 3.42 gears in those cars for the performance rear, but for our TPI cars, the performance axle was 3.23.... I had 3.23 and went to 4.10 for my stealthram (initially was going to be a miniram), and my car was faster with the 3.23 until I changed the intake.

 

My car stock went 14.3 w/2.77 gears.
Switched to 3.73's yielded 14.1 .
13.78 w/drag radials.

3.23/3.42's are just about perfect for LTR setup, I was thinking ahead

 

I ran a 14.2 in the 1/4 with 4.10s and a 305tpi/auto. So i'd just go with 3.73's or 4.10's.

 

Sorry, 4:10's is way to much gear for a stock LTR setup. Remember the L98 will run out or rpm before your 305 using same intake.
If he traps 100 MPH that 5350 RPM's with converter locked, unlocked its about 5600. Stock L98 makes peak @ 4400.

Now if you plan some intake changes, go for it.