swapping my 373 open diff for a 327 LSD this week. The car currently has a very mild 350 and T5.

I know the gas mileage is going to go up but im hoping my stop light antics will be more impressive as well...... hear me out

With the 373's i cant even use 1st gear for a hard launch, it just melts the tire. I know the 327s will hurt the 1/4 miles times but the first 3 gears should still pull pretty hard. Especially with both tires gripping.

Future mods are going to include a vortec roller engine with nitrous and a t56 or TKO 600, i think i can worry about more gear when that combo breaks the 9 bolt.

What do you think? More seat of the pants feel through the first 3 gears since i can use 1st more effectively? Im hopin so.

 

I'm in the same type of dilema. Currently I have a 10 bolt with 4.11 non-posi in my car. I'm in the middle of assembling a BW 9-bolt to put in it. The gears in the 9-bolt are 3.27. I am having a hard time deciding if I want to keep them or shell out a pile of cash to put 4.11 back in. I like the torque of the 4.11, but gas mileage sucks since I have some mods on the engine. But the beauty is when I pass someone, I don't even have to bother down shifting. Just apply more throttle and off like a racehorse I go. Sad part is at 70+, the motor starts really cranking hard to maintain the speed. Been searching around for posts regarding preferred ratios to get a better idea on what to do.

 

bump

anyone else have any thoughts on this?

I have a tpi 305 with some mods a T5 and 2.73 gears. I want to go to 3.73's. I live in the mountains and do about 45mph most of the time. I think 3.73's would be a lot of fun in the mountains.

 

If I was stuck to mountain roads all the time, my choice would be 4.11. They're not the greatest for open road cruising, but they are choice when it comes to windy turns and steep inclines. I swapped out my 4.11 rear for a BW 9-bolt 3.27. I travel quite a distance for work and 4.11s were killing my mileage.....but they were fun. I wasn't sure I was going to like the 3.27 ratio, but now that it's in my car, I love it. But I travel a couple of big mountains going to and from work and I really enjoyed the 4.11s for that.

 

How many miles are on your motor I have a couple friends who had 80's cars with 305's with 50-60 thousand on them and switched from 2.73's to 3.73's and both threw a rod right threw the block in about a month.

To answer the original post I would think your thought sounds right if you can't use 1st now with the 3.27's you will be leaving the line the same you would think.

 

[quote=///DAN///;4288914]How many miles are on your motor I have a couple friends who had 80's cars with 305's with 50-60 thousand on them and switched from 2.73's to 3.73's and both threw a rod right threw the block in about a month.


Sounds coincidental to me. Mine is an 88, TBI 305, few external mods, different cam the only internal, has 119,000 miles on it, and I pretty much run the ***** off of it every chance I get. Haven't thrown a rod yet and I consistently run it up to 5000 - 5500 RPMs. I've actually been hoping it will blow apart so I have an excuse to finish building my 383 to drop in. So far it runs like a champ.

 

coincidental maybe but they were two cars that "we ran the ***** off" the one car was mine that I sold to a friend ran the hell out of it he blew the stock rear doin neutral drops he put in a 3.73 posi two weeks later rod right threw the side and after talking to a couple different mechanics a motor gets used to running at certain RPM's and when you go from 2.73 to 3.73 you move the normal RPM range up to a range it is not used to and won't like . That is just my experience with it you wanted an opinion and I gave you mine do with it what you want .good luck hope it stays together for ya.

 

Just for the record, I didn't ask for your opinion.

And your mechanic pals must think it's 4:20 all the time. Your engine doesn't get used to running at a certain RPM. If that were the case....there'd be no accelerator. We'd be buzzing around in Briggs & Stratton buggies if that were the case.

Did the light from heaven shine down on you at any point and give you the clue that maybe....just maybe....the neutral drops may of had something to do with the rod letting loose? I know its a stretch to think something so good for your car could do so much harm, but it's true.

 

sorry it wasn't you that wanted an opinion my fault but SOMEONE did it's really nice how people ask for an opinion and someone else has too pick apart everything because they know soo much. Yea all the mechanics I know are high all the time they know nothing you are GOD forgot to ask you first if I could give my experience / opinion on anything I will make sure I check next time. Again sorry about using the board for the way I thought it was for .

 

I'm not GOD, and I don't know everything....but I do know a hell of a lot about cars. And I DAMN sure know that neutral drops are one of the dumbest things a person can do.

Using this site for what it's intended for is fine. Although, I didn't think it was to cry like a baby just cause SOMEONE knows more than you and your high mechanics.

 

whooooa, ok it's all good, maybe we can bring this around to the original post. if i was to commute or just spent a lot of time on the highway i might like 3.27 gears. i can tell you that 2.73 are way too tall. i have to really ride the clutch just to start moving and under light throttle i grab 4th about 70 mph and feel like I am lugging in 5th unless i am going really fast.

i was hoping to hear from ian1320 or anyone else on their thought of tall gears or low gears. my car is not a daily driver and i wouldn't mind if i could boil the tires at will with 3.73's and after spending some time with a tire/gear/mph calc i thought i might like 3.73's in these windy mountain roads where i live and i think i could still cruise on the freeway decent, better than 4.10's anyway. oh and i'm not johnny racer anymore, too many speeding tickets, so i really don't care about top speed besides that's what i have a sport bike for, it'll do 160 if i want to.(which i'm not sure if i want to do)

 

I have a 3.27 9 bolt in my car with an auto and love the combo. Its just the right gear to cruise comfortably on the highway while still being fun stoplight to stoplight. The only problem i will forsee for you is when you go to a T56 in the future. Your 5th and 6th gears will be almost useless. What i would do is do the 9 bolt for now and then save up and built a rear with 3.73s or even 4.10s for when you do the t56 down the road.

 

Update, I kept the 3.73 rear and replaced the worn LSD so now both tires hook. I also switched to a wider wheel and a stickier tire so first is actually usable and alot of fun. Overall im pretty satisfied with the 3.73 and im glad i didnt switch to the shorter gear.

Here is a link to a helpful calculator that may help you determine what gear you want to run.

http://www.angelfire.com/fl/procrastination/rear.html