3.73 installation time

Take a guess how long it would take for a shop to put in 3.73 gears into me car.......I hope its not longer than a day...
How will the 1/4 mile time be affected?
I have the money, just time is a factor cause I need my car.

Tanks

Would it be better 3.43 for a daily driver or are 3.73 ok with the 4speed 700R4?

The job should only take a few hours at most. Just bring the car in early and make sure they understand you need it finished that day. If your switching from 2.73 gears to 3.73 that's a big difference. I'd give you almost a full second reduction in quarter mile ET... well 7 or 8 tenths anyway. What does it run now?

The job should only take a few hours at most. Just bring the car in early and make sure they understand you need it finished that day. If your switching from 2.73 gears to 3.73 that's a big difference. I'd give you almost a full second reduction in quarter mile ET... well 7 or 8 tenths anyway. What does it run now?
Never taken it to the track, none really near me, like 3 or 4 hrs away.

Plan on taking it early tommorrow to the rear shop.

Only a few hrs to do it?

Itll boost the 1/4 mile that much?

Expect to pay big bucks tho (up to a few hundred) because it can be a tedious process and needs to be precise. Biiiiiiiig difference though, you be be grinning ear to ear when you take it out after the install.

Expect to pay big bucks tho (up to a few hundred) because it can be a tedious process and needs to be precise. Biiiiiiiig difference though, you be be grinning ear to ear when you take it out after the install.
Yea, got a quote, and can afford it getting it tommorrow if the shop has time,

what 1/4 mile you think?


How come you want 4.10's, do you like the 3.42's or is that stock?

3.08s were stock

Most of my driving is city, and 4.10s not only GREATLY increase acceleration but help city driving... any even with highway the milage won't be hurt too much. And peopel say "oh you'll lose top speed"... it'll still be a good amount over 3 digits and really who needs to go that fast, I'm not trapping near there for a while and I never really go above 70-80 on the highway... so yea.

3.08s were stock

Most of my driving is city, and 4.10s not only GREATLY increase acceleration but help city driving... any even with highway the milage won't be hurt too much. And peopel say "oh you'll lose top speed"... it'll still be a good amount over 3 digits and really who needs to go that fast, I'm not trapping near there for a while and I never really go above 70-80 on the highway... so yea.
What 1/4 mile you think? (in mine with the gears?)
I wonder if itll take my bros stock 5.0 GT.......maybe off the line.....at high speeds.....bye mustang...lol

ummm you like pony in your rear view? get used to it ;)

And I have no idea... ask a 305 guy

ummm you like pony in your rear view? get used to it ;)

And I have no idea... ask a 305 guy
Thanks......one more thing.....would I have to change the speedo, or would the shop change it for me, how off would it be?

you have to change the speedo gears in the tranny tailshaft, there's a write up on that on TGO.

you have to change the speedo gears in the tranny tailshaft, there's a write up on that on TGO.
The shop wont do it?
How off will it be.......cause its in the shop and should be done around 3 California time.

97 couldn't have said it any better. The 4.11's i have now make city driving so goddamn fun. Don't really feel the need to travel at triple digits all the time. You'll feel the difference bag. Do you also have posi? I had 2.73 and the open diff. before i swap in the 94 trans am rear. Big difference!!! I had a big ass grin on my face, the smile was from ear to ear.

I don't know if the shop will do it or not, you have to bring it up to them.

Btw Bag, do you have a tbi or tpi? Forgot what you said you had. Also, do you have headers? If not, you should get some TES's man, for some strange reason they really wake theses cars up, those manifolds suck monkey balls.

Btw Bag, do you have a tbi or tpi? Forgot what you said you had. Also, do you have headers? If not, you should get some TES's man, for some strange reason they really wake theses cars up, those manifolds suck monkey balls.
I have the same year and style car, a 91 r.s camaro tbi, and i got a quote for 3.73 and he said $250 labor and $110 for gears. And another great mod for the tbi is heads and headers. I am going to go to a junk yard and get some tpi heads and have them redone, to rebuild them it is going to be like $210 for both.

I have the same year and style car, a 91 r.s camaro tbi, and i got a quote for 3.73 and he said $250 labor and $110 for gears. And another great mod for the tbi is heads and headers. I am going to go to a junk yard and get some tpi heads and have them redone, to rebuild them it is going to be like $210 for both.
It should be more than that.....but thats just my opinion.
Anyways, got em in......very sweet. Has anyone noticed with the stock 2.73 when you put a muffler on it, you lose some low end torque.....well I did and it was very noticeable. My car would shift down too low....out of the torque range and it would take a few valuable seconds to get to the range. With the 3.73's though, its like you press the gas pedal down less to about half way down and you stay right in the torque range its sweet. I actually did my first wheel spin with em from a stop, with the 2.73's it was almost impossible. The only downside is I dont have the money at this point to change the speedo and its way WAY off. Doing 65, the speedo says like 100/ 105, dont know exactely....lol. The guy said to multiply something by three and subtract to figure it out but I forgot what he said, if anyone knows let me know..........

It should be more than that.....but thats just my opinion.
Anyways, got em in......very sweet. Has anyone noticed with the stock 2.73 when you put a muffler on it, you lose some low end torque.....well I did and it was very noticeable. My car would shift down too low....out of the torque range and it would take a few valuable seconds to get to the range. With the 3.73's though, its like you press the gas pedal down less to about half way down and you stay right in the torque range its sweet. I actually did my first wheel spin with em from a stop, with the 2.73's it was almost impossible. The only downside is I dont have the money at this point to change the speedo and its way WAY off. Doing 65, the speedo says like 100/ 105, dont know exactely....lol. The guy said to multiply something by three and subtract to figure it out but I forgot what he said, if anyone knows let me know..........
Great, i will have to get the spedo fixed, how much does it cost?

That's awesome bag. Whats your next move? You got headers yet?

That's awesome bag. Whats your next move? You got headers yet?
I dont know how much the speedo is but its ok for now, Im figuring it out the more I drive, and those signs on the streets that tell your speed really help, everytime I see a cop I freak and try to go pretty slow....lol

My next move......probably a new torque converter, but not for a while.
No headers yet......debating because I want to spend most for performance, and I dont see enough reason to spend money on em.....yet

tq verter is a good choice!

yup......eventually.

I'm going with 3200

Does that seem a little high.........
Me, probably 2000 something.......

Oh wait, yours can get higher RPM's right, whats your redline?

uhh, header will prolly be one of the most performance beneficial things to do.

Headers on the l03 help out a lot. But if you can't afford to have you car out of commission for at least a full day than you probably want to look for a shop to put them on if you can find one that will do it. Mine took about three days of off and on work, but I had just about no idea what I was doing either.

What kind of headers......I was thinking some Flowtech.......if I were to get them and how much would the labor be?

Bag, Geno is right. They are one of the most beneficial mods you can do for our cars. They wake the hell out of them. When i installed mine (it was out of comish for the weekend, 1st time install, but pretty easy), there was a major difference in performance and economy. 0-60 was much quicker, throttle response is excellent, mgas mileage increased, i can even get sideways with the 305 when i punch from a dig (due to the 4.11 and posi, thank god!!) I went with edelbrock tes ceramic coat $500! Spent my whole paycheck on them, but i assume that any header will vastly improve and give you the grin you want. Our stock exhaust manifolds are very, very restrictive.

If you don't like the sight of rusted metal in your engine bay get ceramic coated headers. Mine had the paint on them any they were rusted all over in a couple weeks. It's worth the extra money.

I think the speed sensor for the 3rd gens was mechanical - on the 4th gens you had to modify the computer. From 2.73 to 3.73 the changes in speedo will be quite a lot - not so much at lower speeds but its a ratio so the faster you go the more out of whack it will get.

I did a similar swap about two years ago - on the street I can say the car woke up and then some... I was always getting killed being stuck in the wrong gear (A4) but now it was insane the amount of torque it made. Shredding tires all through first and then screaming into second for like 4 seconds...

On the track though "I" personally didn't get to see that much of a difference. My best with the 2.93's I had (yes not 2.73's) was 13.8 @ 101 mph - that was a hot summer day on BFG G-Force. A few years later when I tired out the 3.73's it was a cold and damp Oct. day on much harder Firestone Firehawk tires... best time was 13.7 @ 102 Mph, with lots of violent wheel hop down the line and the car getting slightly sideways shifting in second. I know it could have done better had the conditions been better but it wouldn't have been that better... half a second maybe.



ANyhow, changing gears is indeed a very complicated job. If done right there should be NO gear whine... they should install them with special paint on the gears, drive it around , take them out so see the wear pattern on the gears, then shim the gears within the differential accordingly.

Ive read in several places that a 3.73 gear is too much for a tpi motor because of its rpm limitations and breathing capabilities. A 3.42 gear or something close to that was found to be the best performing gear. What do you guys think? It makes sense to me.

Can everyone please explain the gear ratios to me real quik, if its geared low, you will get a higher top speed but it will accelerate faster, if its geared high you will get a lower topspeed but it will accelerate slower? Is this correct?
What is a good gear ratio to go for for a 305 tb1, what is it geared at currently? Its all stock just the way i got it havent changed anything like that yet, what is a good in the middle one to shoot for, a pretty good acceleration but not loseing that much topspeed?

I heard that aswell 92. I kinda believe it too. The 4.11's are definitely fun in the lower rpm range, but when you get higher, where tpi starts running outta breath, it gets ugly. Fun on the streets though, high way, nooooo!!

Ive read in several places that a 3.73 gear is too much for a tpi motor because of its rpm limitations and breathing capabilities. A 3.42 gear or something close to that was found to be the best performing gear. What do you guys think? It makes sense to me.

A gear swap on it's own is good, but to rid these problems, add a bigger cam (nothing crazy now, mild street cam is ok), matched stall speed converter to cam, and a trans kit, headers if not already done, and problems solved.

Ny 305 tpi being an '85 was blessed form the factory with a larger cam than the rest. With the aboved mentioned, frist time my brother in law who has a 350 GTA, sweared up and down there was no way in hell it's a 305 under the hood. Hopefull this spring we'll get a track time in between the 2. His is mechanically stock, jsut a tuned ECM & chip.

That is if I can bring mine back from the dead :(

some gears work better with auto and manuals...like you can get a higher gear ratio with a manual because of the extra gear and with autos i dont think i would go bigger than 3.73 ive been told many times that 3.42 is pretty much the best choice all around...i have them in my car and love them....it didnt take too much away from my top

Hey wright, if i can bring mine back, you sure as hell can bring yours back. I've been pondering about something. When I go to school, and i get some major knowledge about the insides of the motors and forced induction, i think i may turbo the 305. It'll be original and fun indeed. I wonder if it's been done. Forged the insides (good luck find the stuff i guess) some turbo(s) and have fun. I'm thinking about, atleast it'll be my original motor (here i go rambling on again....)

Has been done. Ive seen bored stroked 305 with twin turbos. Not technically seen but online or in an article.....I really wish I could remember where I read this stuff.....

And about the speedo gears. It depends on if you have a mechanical speedo or not. I think its 90 - 92 thirdgen camaros have electronic speedometers. I think the firebirds got it a few years earlier than the camaros.

eh, too many parts in turbos that can and will go wrong. I will have a supercharger, if the sub frame will withstand it.

As far as just getting runing goes it's just pissing me off right now, fix one problem, it creates 5 more. Now it's starting to look like the weirdest ICM failure I've ever dealt with, but there are other issues with the distibuter (like replacing it) that have to dealt with first. Going to a swap meet this weekend and will hopefully bag one for cheap and be running 9correclty that is) Sunday night.

Dont ya wish you could just rip it all out and replace everything with fresh and new parts all at one time?

fuck those are wimpy gears, im gonna run 5.13's in my 12 bolt.. hehehehe

fuck those are wimpy gears, im gonna run 5.13's in my 12 bolt.. hehehehe

well, holy hell son, why don't you just put some tank treads on that there 12 bolt? :lol:

Dont ya wish you could just rip it all out and replace everything with fresh and new parts all at one time?

If I didn't have a garage already packed with slumbering cars, I would, believe me.

Can everyone please explain the gear ratios to me real quik, if its geared low, you will get a higher top speed but it will accelerate faster, if its geared high you will get a lower topspeed but it will accelerate slower? Is this correct?

A lower gear has a numerically higher number; a 3.73 is lower than a 3.42, and will give better off the line acceleration. A higher gear is usually better for highway fuel mileage and may allow a higher top speed, but not always. There are other considerations. Like engine power, tire diameter and overdrive transmissions. A larger diameter tire will give the same effect as raising your rear gear ratio. If you put larger tires on, and don't change your rear gear ratio, you just made your car slower. (acceleration wise, assuming good traction)

With overdrive transmissions being common nowadays, I have seen many cars that have as high, or even higher, top speeds when in 3rd (auto) or 4th (manual) than when in overdrive. Why? Because their final drive ratio was so high that the engine couldn't pull enough rpm's in overdrive to out run the lower gear. In this case switching to a lower gear would give better acceleration and the maximum top speed could then be achieved in overdrive. I remember a new Pontiac Formula (in the 80's?) that would only shift into overdrive if you didn't have your foot to the floor. You could hold it down for minutes on end and it would stay in third around 4500 rpm's and 120 something MPH. On other cars I can tell just by doing tachometer math. In overdrive my stock Jeep (5 speed manual) does around 65-70 mph at 2000 rpm's. So at 4000 rpm's I'd be going 130-140 mph right? Nope. The engine could never pull this. It would probably have a higher top speed in fourth.

Quote: <HR SIZE=1>Originally Posted by 92zcamaroperson
Ive read in several places that a 3.73 gear is too much for a tpi motor because of its rpm limitations and breathing capabilities. A 3.42 gear or something close to that was found to be the best performing gear. What do you guys think? It makes sense to me. <HR SIZE=1>

I would think that as long as your motor can't exceed its redline in top gear (overdrive) when held at WOT, then the rear gear is not too low, unless you want to cruise at 120 plus mph for extended periods. You'd have to do the math to see if this is the case with the 3.73.

That sucks wright, hope all goes well for ya man. I wish i could just buy all new parts at one time. Damn, i wish....
Btw 92z, i just went over to thirdgen.org, it been done and there are some pretty impressive results too. People used all junkyard parts and push upwards to 400hp. Not bad at all. Just what i'm looking for and i love my 305 to death.

3.73's put the l98 motor too high in its powerband to be effective while at cruizing speeds and highways speeds. From a dead stop it will throw you in your seat very quick. If we were talking about an lt1 or ls1 engine then that changes things. They breath much more up high than a tpi does. A stock one anyways.


And a lot of the thirdgen cars(cant give you specifically which ones did and didnt) wont allow you to shift into overdrive. My car wont unless you back off a little. But really im not sure if its good for your trans to have full throttle on it when in overdrive. So ive heard. Yet another thing which I have no idea where I read it but Im sure I did. lol

Yes indeed does it throw you in your seat. I love it!! I wish there were a way to make the tpi breathe better up top like an LT1 or LS1. Is it possible?

AlmostStock
Thanks for all the time im sure it took to explain that but im still confused as hell!
Let me state what im thinking... a small gear usualy has large numbers... like 3.75, and a larger gear would be smaller in numbers, like a 3.42, basicly switched around.
What exactly do those numbers stand for though?
Also, this is the only part that i understand, the whole number switching (Man i hope i understand that right.. or i dont understand anything! lol)
When you change your tires, if you go with larger tires, you need a small gear, basicly to compinsate, correct? That makes sence, i hope i got that right or else im really messed up
What do the 3rd gen autos usualy come stock with?

Us 3rd gen autos usually come with 2.73 stock.

depends on the model. rs models had the 2.73's. Irocs and z28 models have different gears. Mines an auto and comes stock with 3.23's.

DuesEx:

what it means is how many times dose the driveshaft (pinion) have to spin to make one revolution of the ring gear that drives the wheel. Torque is what gets you moving, not horsepower. The larger the gear ratio, the more torque that is applied..

AlmostStock
Thanks for all the time im sure it took to explain that but im still confused as hell!
Let me state what im thinking... a small gear usualy has large numbers... like 3.75, and a larger gear would be smaller in numbers, like a 3.42, basicly switched around.
What exactly do those numbers stand for though?
It is the amount of teeth on the ring gear divided by the amount of teeth on the pinion gear.

Also, this is the only part that i understand, the whole number switching (Man i hope i understand that right.. or i dont understand anything! lol)
When you change your tires, if you go with larger tires, you need a small gear, basicly to compinsate, correct? That makes sence, i hope i got that right or else im really messed up

If by smaller gear you mean lower, then Yes. Wrightz28's explanation is another way to state it.

92z, did you install those subframes yourself. Bolted in or weld? How's the car feel now? I wanna get some connectors, but i need some that will not interfer with the edelbrock tes y-pipe. Is that why you have a custom y-pipe. (Sorry for going off topic) 4.11's rule!!!

3.73's put the l98 motor too high in its powerband to be effective while at cruizing speeds and highways speeds.
I had an '84 Trans am 5.0 HO 5 speed that I bought brand new. It came from the factory with a 3.73 gear. I never had problems being "too high in the powerband" on the highway. It seemed just right to me. The motors you're talking about make even more power than mine did. Some guys without OD are running 3.73's and even lower. That's too low for long distance cruising in my opinion. It just depends on what you want.

depends on the model. rs models had the 2.73's. Irocs and z28 models have different gears. Mines an auto and comes stock with 3.23's.

The T5 rs came with a 3.08 open rear.

I wish there were a way to make the tpi breathe better up top like an LT1 or LS1. Is it possible?

Heads... get aftermarket ones or port your stock ones and throw in bigger valves.

A bigger cam with a longer intake duration will also help, but the real power lies in the heads...



When you change your tires, if you go with larger tires, you need a small gear, basicly to compinsate, correct? That makes sence, i hope i got that right or else im really messed up

Changing gears has little to do with what size wheels you should use… I mean, chancing either your wheel diameter or gear ratio will distort your speedometer accuracy, but other than that I don’t see why it’s a cause for concern. Are you guys talking about trying to balance out the speedometer’s accuracy by using larger diameter wheels/tires with shorter gears or something??

Going with a smaller sized wheel will make your car go faster… ex. Say for arguments sake that a 19” rim with /35 sidewall tires measures 30” in diameter, and suppose it takes 2 feet for the wheel to roll before it makes one full turn. If you put on 15” rim with /50 sidewall that measures just 24” in diameter, it will take less distance (say a foot & a half) for that wheel & tire to make one full turn. That’s why you see drag racers running these tiny (and thin) little bicycle wheels up front and drag slicks with on small rims in the back.

Some goes with using shorter gears – shorter gears allow your engine to accelerate faster and produce peak power sooner… if max HP in a TBI is @ 3500 RPM (I don’t know) your engine is going to be able to accelerate up to that point quicker with a 3.73 than it would with a 2.73. You are literally multiplying your torque. However I didn’t know that a gear swap would affect a TBI motor in the high RPM’s that much.


If I had the choice again (and I will in a few years) I don’t think I would have sprung for the 3.73… I think I would have been happier with a 3.42 because I loved cruising on the highway. Now the car runs at over 3000 RPM @ 140ish kph (that’s like 87mph). Mind you I love how ridiculously fun it is shredding the tires from stoplight to stoplight. I think the 3.42’s would have given me the best of both worlds…

BTW – if you’re swapping out 2.73’s and plan on keeping your 2 series carrier you will have to buy specific gears meant for a 2 series otherwise you’ll need to get a 3 series carrier to house the shorter gears (numerically higher). I’m pretty sure that Strange makes 3.73’s for a 2 series.

Changing gears has little to do with what size wheels you should use… I mean, chancing either your wheel diameter or gear ratio will distort your speedometer accuracy, but other than that I don’t see why it’s a cause for concern. Are you guys talking about trying to balance out the speedometer’s accuracy by using larger diameter wheels/tires with shorter gears or something??Like you pointed out, everything else being equal, a larger tire will roll farther for each engine revolution. Therefore changing tire size will net the same results as changing your gears. The engine rpm at any given mph (actual mph, not what the speedometer says) will be effected. Taller tire = higher gear. Shorter tire = lower gear. If you do the math, it is possible to balance out a larger tire with a lower gear and end up with the same effective ratio. Your speedometer would be correct, and assuming no traction issues between the two tires, the car would be just as quick and have the same top speed.

If you ever drove a truck were the owner put monster tires on it without changing the gears you will notice this big time. The vehicle becomes a slug and OD becomes practically useless unless your rolling down a hill at 80 mph. Granted if the tire is only slightly taller the difference will be slight, but it is still there nonetheless. Does this mean you HAVE to change your gears if you change your tires? No. It all depends on what you want.

Oh and :bigthumb: on going after the cylinder heads for more power.

Yup, 3.73's are great on mine.......from a stop I can hammer it and make it sqeel. On the freeway, cant go as fast (top speed), and def. no freeway racing. It has great power all around now though
The rpm's at around 2500 going im guessing around 70. Its fun.
I keep looking for races..(mustangs) to see how itll do, but none around. It sucks when you cant test her out.
The only issue I have to get used to with mine is now the rear end wistles/ wines at certain RPM's. Its normal, but wonder how it sounds outside the car,,,,lol.


How much for labor in a header installation?

too much, do it yourself

too much, do it yourself
Its easier for me to just get it done somewhere........