I have 3.50's in my 9" that resides in my turbo Ls chevelle but I run a turbo 400 with a 4l80 in future maybe some day. If you are breaking traction with a 3.07 rear than a lower ratio will make it worst. Look at your suspension?

 

Yeah, my rear suspension is the pits. Hadn't thought of that.
As for the 4l80 and TH400, they're both identical (4l80 has OD) and they're higher geared than the 700r4 and 4l60e. So is that the reason you need the lowered geared r/e?
I do like the Positraction, but I do feel some chatter when making a turn, and now I'm wondering if they used the proper Delco lubricant for the Posi.
Bob

 

Bob I was going to put a 496 bad boy in my car but when I was over 8k in parts only I decided to stop. I was going to have a 496 with Brodix Big Brodies and a 1050 dominator for the street..Lol. I could go with a 3.20 gear due to the turbo but its not bad cruising and still having some get up and go power. I did a bunch to the 5.3 this year and im expecting in the high 600 hp rwhp. I just put a TRZ 4 link in the back of her for more traction to the M/T 275 SS radials. I would do a better suspension..world of difference

 

Bob: I believe your rear axle ratio (3.07) is ideal considering an overdrive ratio of 0.7; that coupled up with 2.15 75/15 should give you about 1694 rpm @ 65 mph.

I think that tranny has a first gear of 3.06; 3.06 x 3.07= 9.39 should give you great performance off the line.

Let's get some more opinions.

Plug these numbers into this calculator to check your approximate RPM's:

http://www.crawlpedia.com/rpm_gear_calculator.htm

Ken 57bowtie-trifive

 

Yeah Ken, it does have some pop in first gear. I do need beefier shocks in back (I have coil overs in front). It purrs at 65-70mph, but I'm still babying it as it has loads of new stuff. Gas mileage is not good so far, but it's probably due to jack rabbit starts,
I like the the Sanderson headers but coupled with Dynomax 14" Super Turbos, it does attract attention when I punch it. Worries me I might attract the wrong attention.
Bob

 

I think it's the perfect 'all around' ratio for the combination, and is what I'm using in my '57 Nomad with LS1 and 4L60...

 

Glad to hear that Bama. My Nomad will have a '94 350tbi converted over to a holley 650, hotter Voodoo cam and Sanderson Headers. The tranny is a 700r4, which is like a non electric 4l60e. I believe the rear end is a 3.35 in the Nomad so I'm thinking both the Olds and the Nomad will have equal power to the wheels...but then again, I'm only guessing.
Bob

 

I have a 2006 LS 5.3 with a 4L60e tranny in my '49 Olds 98 convertible. Only changes was the addition of Sanderson 2.5" headers and cold air induction.
It's a torquie little bugger and it makes the Olds wanna get up and go. I had the rear end rebuilt without asking what it was, so today I decided to find out what it is I have.
The rear end gear ratio is 3.07 with Positraction. The previous owner had 14's in the back so it kept breaking traction even at 30mph if I punched it. I put on some 15's this morning and it improved traction.
I just ordered a set of American Classic 215 75 R15's.
Is all this a good combination for a daily driver with an occasional show of acceleration?
Bob

the problem you have is not a gear problem, it is a tire and suspension problem. a stock 5.3l with a tune will put over 300hp to the rear wheels. your 3.07 gear is perfect for you intended use. your car is probably light in the back too. the major deficiency I see is you have nowhere near wide enough tire and poor working rear suspension, My 68 firebird has 225-60 in the back with posi and stock 5.3 and it blazes the tires pretty easy. you need at least a 245 wide tire of a soft compound type and some good springs and shocks

 

I have a 2006 LS 5.3 with a 4L60e tranny in my '49 Olds 98 convertible. Only changes was the addition of Sanderson 2.5" headers and cold air induction.
It's a torquie little bugger and it makes the Olds wanna get up and go. I had the rear end rebuilt without asking what it was, so today I decided to find out what it is I have.
The rear end gear ratio is 3.07 with Positraction. The previous owner had 14's in the back so it kept breaking traction even at 30mph if I punched it. I put on some 15's this morning and it improved traction.
I just ordered a set of American Classic 215 75 R15's.
Is all this a good combination for a daily driver with an occasional show of acceleration?
Bob

the problem you have is not a gear problem, it is a tire and suspension problem. a stock 5.3l with a tune will put over 300hp to the rear wheels. your 3.07 gear is perfect for you intended use. your car is probably light in the back too. the major deficiency I see is you have nowhere near wide enough tire and poor working rear suspension, My 68 firebird has 225-60 in the back with posi and stock 5.3 and it blazes the tires pretty easy. you need at least a 245 wide tire of a soft compound type and some good springs and shocks

I’ve also got an esthetics problem. My Olds is designed for fender skirts. Won’t look right without them, so I’m limited in the size tire I can use in the back.
I bought the American Classic radials from a distributor that specializes in sale to those that want to maintain some of the original look. They recommended this size tire. These tires will have 2.5” white sidewalls. I want to use my original hubcaps.
Bob

 

It won’t look as “purdy”.
5.3L engine cover panels will be painted same color as body will give it some bling.
Bob

 

to make horsepower and torque, its all about airflow. the 350 tbi engine has absolutely the poorest flowing heads of any small block made after 1970. they just suck. the 5.3ls head flows almost double. no amount of cam, intake, carb, and header can make up for that, period. if you had an aftermarket set of heads that matched the ls airflow or a little better you might have a chance at making more than the 5.3l. also with a correct choice in accessories and relocation of coils etc. the ls can look way better than that small block. also with a mild cam and header swap you could easily pick up another 75 hp out of the ls engine and have all the driveability of a grandmas car. I am done with big and small blocks in my cars for this reason alone. when my 383 sbc dies I will put a 408 ls in it and never look back.

 

Your in San Franscico right? The 3.07 would suck on hills in first and second gear. I would run 3.55 or even 3.73. 3.55 would be best all around. If you were in flat land 3.08 is great for mpg.

With that size tire if you mash it then it will break lose with out a good size sticky tire. Just have to learn the fine line of what the car will do.

 

Nope, I live in the south bay or "technically" known as Silicon Valley. Our only change in elevation are the divots in our golf courses or in our ever increasing pot holes. We're about 35 or 40 miles south of SF.
But in my opinion, driving the short but steep hills of San Francisco, this car would seldom reach 3rd gear. With the 4L60e, 1st gear ratio is 3.06, and 2nd is a milder 1.62. So with the help of 1st gear and a 3.07 rear end with Positraction, I feel the 5.3 will push this Olds up a 45 degree hill without much problem.
My concern was whether I needed to go to a high 2's to keep from chirping the tires, but with the suggestions I've received, I need to look at a firmer rear end. This makes me happy because I like the 3.07, but I probably wouldn't mind a 3.35 or 3.55 if I was 20 or 30 years younger.
I wanna be able to cruise up and down the California coast in this convertible at 1600rpm to 1800rpm (Miles ??)
Bob

 

the 5.3l will be happier at 2-2200 rpm on the hwy. mileage will still be good.

 

You're talking mid 70's to low 80's. My Chev with the 327 and 3sp O/D purrs at 2200rpm/70mph so cruising at 75 in the Olds at 2 grand should be easy, but I worry about the unexpected on long trips. My normal time to Reno is about four hours but when I go to HAN I usually lay over in Sacramento if I'm driving one of my classics.
Bob

 

Run a 3.50 to 3.73 gear...

 

Save it for the next brave soul. I'll stick with the 3.07...for now.

 

Its not so much rpm as aerodynamics. Your can run then 16-1800 in later model vetts as they do, but they are way better aero wise than a box 50’s car. So keep it 2k at 70 IMO for best drivability with a 4 speedo auto.

 

I don't have any problem with that Bo. I use a GPS Speedometer ap and I like keeping my 265 and 327 Chevies at a steady 68-70mph but I have pushed 'em to 90+ with plenty of pedal left. The 265 has a 700R4, and the 327 Chevy has the original 3sp with OD.
Even my '42 flathead Merc runs nice at 60-65mph without OD.
My '49 Olds coupe sounds noisy at 55-60mph with the BIG SIX and 4sp Hydro so I haven't used it on long drives yet.
Mileage on these cars runs from 12mpg to 17mpg.
The '68 Toyota six Land Cruiser will not be a long distance driver, but it sounds OK at 50mph.
The '55 Nomad of course has a boosted up 350 with a 700R4, and the Olds has the 5.3L with the 4L60E. Both of these will be long distance drivers. No trailer queens in my garage.
Gas mileage is not as much a concern as range is.
My wife's new Lexus RX350L has a range of over 400 miles, and the F150 Lariat Diesel I just ordered has a range of almost 600 miles. This with a 26 gallon tank.
Bob

 

Gas milage is a big concern, as it effects range greatly. Big dofference in 15 mog vs 20mpg range wise. 375 miles bs 500 miles using say 25gal as exampe.

I would keep the 3.08 gear make sire posi is good and enjoy.

 

Of course gas mileage and range go hand in hand Bo. What I meant is the price of gas is more important to me than gas consumption, and the less I have to go out of my way to "fill up" the better I like it.
Also, I've been waiting almost two years for the F150 diesel. not so much for the economy but for the durability. I currently have a 2001 F150 4X4 Off Road with the large Triton motor. The truck has been very well maintained and is in excellent condition, but even though it has a trailer towing package, I am constantly replacing brake pads or resurfacing rotors. It is also beginning to use up oil in between 5000 mile oil changes.
I understand the diesel has excellent towing capabilities, and I like the new trailer towing options such as power mirrors and down hill braking by automatically locking out the three higher gears of it's ten speed tranny. I also have a selection of rear end gear ratios. One of the favorites is a 3.31. or a lower 3.55.
Bob

 

Of course gas mileage and range go hand in hand Bo. What I meant is the price of gas is more important to me than gas consumption, and the less I have to go out of my way to "fill up" the better I like it.

I agree I use an app on my phone called "Gas Buddy" shows gas prices close to you filtered by cheapest and distance even shows on a map.

Also, I've been waiting almost two years for the F150 diesel. not so much for the economy but for the durability. I currently have a 2001 F150 4X4 Off Road with the large Triton motor. The truck has been very well maintained and is in excellent condition, but even though it has a trailer towing package, I am constantly replacing brake pads or resurfacing rotors. It is also beginning to use up oil in between 5000 mile oil changes.
I understand the diesel has excellent towing capabilities, and I like the new trailer towing options such as power mirrors and down hill braking by automatically locking out the three higher gears of it's ten speed tranny. I also have a selection of rear end gear ratios. One of the favorites is a 3.31. or a lower 3.55.
Bob

I been waiting on a 1/2 ton diesel. Not real affordable up front and would take forever to pay back the diesel option price in increased MPG, but the range is nice not having to fill up so much. If your towing a lot make sure you have a trailer with brakes and they work correctly this will save your tow rigs brakes wear. The 3.0L is more for economy to get CAFE MPG ratings up it towing its on par with the ecoboost and V8's though.

I am looking at the new 2019 Silverado 1500 with the 3.0 diesel in them may wait till 2020 after they work bugs out.

 

Sounds like you’ve done your homework Bo. The diesel going into the F150 this year has been proven on the F250.
Yes I want a well equipped trailer with a good winch and surge brakes.
Bob

 

Sounds like you’ve done your homework Bo. The diesel going into the F150 this year has been proven on the F250.

This is incorrect,the 3.0L used in the F150 for 18 is Jaugur/Land Rover sourced and build in the UK. It is NOT the 6.7L V8 used in the superdutys. Ford did make some minor improvements to for use in the F150 to improve power and durability.

Yes I want a well equipped trailer with a good winch and surge brakes.
Bob

I would not use surge brakes. You F-150 should come with a build in electric brake controller from Ford. WAY better you can set the braking action for loaded or unloaded (this is what helps saves tow rig brakes) and manual actuate the brakes say if you get sway. Also e-brake parts are simpler and cheaper to maintain. Also you want brakes on each axle too.

 

suspension

I agree its more you suspension and tire size than your gear. Are you running stock suspension ? Rear leaf springs? if so invest in some Cal-Tracs for the rear it will keep you pulling straight and keep you from wrapping your leaf springs.