well guys my rear end leaks due to a worn out pinion bearing,so im gonna go and order new gears and a install kit.but i wanted to know wat to get 3.42 or 3.73?i have a 700 r4 that just got freshly rebuilt with goodies.my car is a daily driver but im not to picky on the gas.so wat should i get.look at my sig for my mods i also have the lt1 so that helps out.my car feels slow out of the whole with them 2.73

 

When I bought my car it had 3.73's--not too bad on the street, about 2250 rpm at 70 mph cruising in 5th. But with the stock 305 it's kind of short winded, runs out of steam in each gear pretty fast--would be much better with 3.42's or even 3.23's. Still, as it is it gets about 25 mpg. If the motor had a power band good to 6000 rpm the 3.73's would be just right.
If I were heavy into racing from light to light I'd keep the 3.73's but I enjoy more canyon carving stuff, being able to downshift into turns, and they're just too low for that. I've just about decided that I'll end up with a 350 built for 2000-5500 rpm and 3.23's--it won't have the launch of the 3.73's but it'll be much better than 2.73's, plus it will give a great midrange through the gears and an estimated cruising rpm of 1900-2000 rpm at 70 mph, right at the bottom of the power band and easy on everything.

 

sure it doesn't leak because of a bad seal? you'd need a new carrier, shim, or special gears to fit your carreir. i'd go for a posi carrier. which gears you go with depends a lot on your engine combo. either would work but WAG i'd go with 3:42s.

 

i already have an lsd.and i will purchase the gears for my 2 series carrier.i can rev my motor till like 5800 rpms because of the lt1 cam

 

OK--with that cam I'd go with the 3.42's.

 

not that this helps, but i run a lt1 cam in my 305 and also run 3.73's, i love them but as mentioned they run out a bit short on the highway........ as for being able to rev til 5800 .....i rev my car til 6800 lol then again....i pinned the hell out of my heads and the valves/heads are fresh 416's. ported, polished, carbed....so my car doesnt exactly run out of steam at 4500 like most of the cars.......my car can breath til about 7 k .....

ive seen people go 3.23 and wish they went 3.73.....and vice versa.......all depends on if you like off the line power or like highway power......bottom line.

just a helpful idea, bearings do not seal anything. if anything is leaking its the rear seal / pinion seal......if bearings sealed.....then the fluid would not be distributed thru the rear end to every bearing.

anything 3.23 and above is going to require a 3 series carrier (posi/lsd)

installing gears is tricky and time consuming on the first run. ive seen people eat up brand new gears installing them too quickly and not being precise......i was able to install mine without a hitch on the first go and they still run great 1 year later.....but i took my sweet time and spent 2 weeks making sure everything was correct.

In the long run till cost you about as much in tools as it will to have them installed (in most placeS) places here were charging 500 bucks to install gears so i just bought the tools and did it myself for about 200 including the press.

 

how will 3.42 be out the whole and in the highway?i have a 2 series carrier w/ an lsd already.i can just purchase gears for a 2 series carrier

 

a lot better than what you have now.....

just to give you a good estimate..... the gear ratio *3.42* will be EXACTLY 3420 rpm @ 70 mph in drive.

Same goes for ALL gears.... 2.73 will be 2730 rpm @ 70 in drive etc etc etc...

plus what your car does on the highway has more to do with what you have done to your car than the gear ratio.

cam, heads, intake, torque converter, fuel injection system ignition..... all go together in the grand scheme of what your car will do under certain circumstances.....

ALL the gears mean is, lower ratio, more off the line *power* and less TOP end.

3.73 will get you off the line faster but you will lose about 15-20 mph on your absolute top speed

gears do not make your engine faster, or slower.....it doesnt gvie or take power, it just allows the power made to be transfered to the wheels faster OR slower.

 

Interesting--as far as the contrast of 3.23's v. 3.42's in actual street use, my current 3.73's are a lot of fun around town and with the T5 the cruising rpm is acceptable--but I know that eventually I'll want a taller rear end just because I like using the motor on mountain roads for entering and exiting turns and, with 3.73's, I'm all done shifting in the first four gears by 40 mph unless I want to run really hard, which usually I don't.
So, if the 3.73's are gonna go, I'd rather make a bigger jump down to the 3.23's than to the 3.42's to better justify the time and expense of a gear change. I can't afford to make changes in gradual steps.
With a little casual math, from 3.73 to 3.23 is a loss of .5 in ratio, or about 1/7th of the rpm I was turning with the 3.73's, so if I was turning 2250 rpm at 70 mph with the 3.73's, reducing that rpm by about 1/7th would be a little over 300 rpm which would give me a cruising rpm of about 1900. This would drop the rpm's in the first four gears, too and make them really useable on mountain roads. As it is, I can start from a dead stop easily in 2nd, almost like 1rst with 2.73's, so the 3.73's are fun but really geared to drag racing.
Finally, the Factory Five spec racers are lobbying their santioning body to let them go to 3.27's in their replica cars. The rules insist they must stay with the 2.76's that came in their donor cars, an inferior off-brand pony car of some type. These knowledgeable racers say the 3.23/3.27 ratio is ideal for road racing with a streetable motor. Hmmm....

 

yeah, i noticed a huge huge difference in how long i was abhle to hold gears going my my stock 2.73 to the 3.73......took me a week or two to get used to the shift points.....

i like hard launches from a light.....all there is to it, in fact im almost considering going with 4.10's but as you said....gradual steps isnt worth it.....the process in setting up gears is too time consuming for something so small of a leap as 3.73 to 4.10.

 

I agree. When I put my 3:73's behind my 700R4 and LG-4 305, the same thing happened. I was at that point in need of a set of headers, intake, slight stall torque converter, cam, and exhaust system bad. It sure did perk the car up though. I was in the proccess of installing my 355 so it didn't matter. But if you are not planning any further mods to your Tbi I would go with the 3:42.

 

I went from 2.73's to 3.73's and love it. I am running a 700R4 with a carbed L98. Its a great sotp difference. If you not worried about gas milage and plan on modding you car in the future then go 3.73's.

 

gears were the LAST thing i did, mainly due to the fact that i knew *I* had to install them, and peopl ekept going on and on about how hard it was.....which it turns out, they werent that hard to do at all......tedious maybe, but not what i consider hard.

id definatly suggest headers , intake, carb swap, cam.... after the gears are done.......the 2.73s are prolly actually making more power now than the 3.73s will due to the fact that the 2.73 will keep you in your power range for a longer period....

if you go 3.73s start planning ahead and start doing upper rpm mods thatll let you make power beyond 4 k rpm...... carb is good for that......

 

i make power to like 5500 rpm almost wat a stock lt1 maro does.i want awesome out of the whole response but good top speed and crusing abilitys like right now i go 80 mph at 2100 rpms 100 mph under 3000 rpms

 

well, like i said...whatever gear ratio you have, at 70 mph...in drive...itll be EXACTLY that on the rpms...

Ratio | Rpm
2.73 ....2730
3.23 ....3230
3.42.....3420
3.73.....3730


i run 3.73's, i like them.....they like me....good team.

it wont KILL your top speed, but itll definatly know off about 15 mph from your absolute top speed. But....if you havent added a chip to your car yet, itll only go 114 mph regardless to what you do.

it feels better to launch off the line insanely hard than it does going 140 mph. its much SAFER racing off the line vrs on the highway.......i do not condone people being stupid and going in exces of 115 on the highway, NOT that they cant control their cars, its that moronws seeing you go 115+ tend to do the deer in headlights thing and FREEZE or turn TOWARDS you.....

im voting 3.73, you will be happy with them.....drive up to SC and hop in my car.....show ya what they launch like.

 

If you don't have a place do the the gear install yet, then don't buy the install kit, and give Super Street in Homestead a call. I did my gears with them. It was $250 labor to do ring and pinion, posi, and new axle bearings. I didn't need an install kit. I did however use a solid crush sleeve. Car was done in four hours on the dot, and I don't have any gear whine at all. I was pretty impressed with them.

By the way, I know you mentioned that you didn't have any plans to change engines. Do you plan to stay with tbi, or do something different down the road? Keep your future plans in mind because ideally you want your gearing matched to your cam. If you are leaving your car as is, I would go with 3.42. But thats just my opinion.

 

nothing *wrong* with keeping the 305...i pulled 330 hp out of mine with barely over 600 invested, all parts that will bolt right up to my 383 .....just keep that in mind.....MOST of what you get for your 305 can fit on a 350....i still strongly at LEAST getting headers, open air element if you dont have one already.....those give the best seat of the pants gains other than gears....

 

Hey--did your 330 hp mods to your 305 fit under the stock hood?

 

Yup. no super charger, no blower, no nitrous, completly naturally aspirated

 

StaticVertigo, I wasn't implying that there is anything wrong with keeping a 305. I was just saying that he should consider his gearing with whatever changes he would like to make in the future (if any).

As far as bolting all your 305 stuff up to the 383, I am curious as to what parts you are referring to specifically. You can bolt pretty much anything off a SBC to another size SBC, but that doesn't mean its a good idea. Things should be planned out so they work together. You can slide in a 240 degree cam, AFR 210s, and a single plane manifold on a 305. If you want a daily driver, you just shot yourself in the leg.

 

heh i just ment most everything will *work* not work BEST but itll work.....i.e4. you *can* use your 58 cc heads ona 383.....doesnt make as much power....at all.....but for the time being it would work.....just not Well. as far as intake, cam, ignition, headers carb, all can be interchanged and be fairly decent on both engines

 

yes staying with the 305 tbi just swaping to better heads sometime soon. the guys who built my tranny told me it dont matter wat power my motor makes or to how much i can rev it.when it comes to gears put wat u want he said just remember the higher more take off less top speed.and these guys are a pro drag team locally so i dont think they will lie or not know wat they are talking about so i think i will go with 3.73 seens when i put my heads i will be making like 235 rwhp,also my will run some nitrous a 75 shot

 

Whats the name of the shop that built your tranny? There is a generation of hot rodders that grew up with the mentality that the steeper the gears, the better. Thats not true. I know quite a few people that have been into cars for over 20 years. One of which has an 800 hp mercury with a big block ford parked in his driveway, and hes pretty ignorant

Its not about how much power your motor makes or how high you will rev it. Its about your powerband. Think about it for a second. If you get a set of gears that will keep you out of your powerband, you WILL go slower. If you pick out a gear ratio that will keep you in your power band longer, you gain on your 1/4 time.

Take my car. I had a stock L03 with a 6 speed and stock 2.73 gears. Car felt like a cow off the line, as well as at speed. Didn't have any power anywhere. When I put in my 3.73s, it made a world of difference on the street, especially of the line. Felt better all around while driving it on the city. Would you believe I lost about a full second in my 1/4 time with the 3.73s? I'm not the first person this happens to.

Why did I put the 3.73s? Because I was planning on an engine swap, and didn't want to do gears twice. I'm still overgeared for a TPI setup even though I have a 218/228 cam at .050. Why didn't I go with 3.42s then? Because I'll eventually go with an aftermarket intake like a StealthRam or something similar.

Do what you want, but I suggest you read up a little more on this before you decide.

 

so then 3.42 it is i guess

 

OK--some simple stuff: 92blue, what's the advantage of a solid crush sleeve?
StaticVertigo: what intake setup were you running on your 330 hp 305 that fit under the stock hood? I have a '78 350 4-bolt out in the barn I'd like to build for this car, planning on a 2000-5500 rpm range with 3.23's. Usually I'd run a Weiand Stealth with a 650 Holley but I don't think it'll fit under the hood of this car.
35 years ago we did believe in low gears--my brother bought a '69 Z28 new with an M22 rock crusher and we put an 11/1 427 in it with 4.11's, then 4.56's, then 4.88's before it finally blew up. Meanwhile, he got to work at 45 mph on the freeway. That poor DZ302 was turning about 9000 rpm through the lights before we put in the big block--we learned many expensive lessons about small block valve trains.

 

This is not accurate information my friend. I have the stock 3.23 gear in my car and at 70mph, I am only turning about 2200rpm.

Edit* Sorry, I misread what you said and didn't realize that you said "in drive". One question though...why the hell would you be in drive doing 70mph unless you are drag racing?

 

wel if u wanna waist gas then go ahead

 

what do you mean by waste gas?

 

You aren't taking into account tire radius.

Try this...

https://www.thirdgen.org/newdesign/t...ulations.shtml