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non over drive rear end ratio poll sort of

8K views 34 replies 21 participants last post by  UBER SS 
#1 ·
Just wondering what gear ratios your running, those of you with out over drive trans., and do you use it for road trips, and or use it on the highway and interstate, how far do you road trip it. just wanting to know what everybody is dealing with lower gears. One more thing are you auto or manuel trans.

I will start it I am using 3:42 with an auto and a slight stall, 2900 rpm at 60, no interstate, but back highways. Turns to many rpms for interstate driving, I like to take trips to florida about 580 miles.
 
#2 ·
Tk, 3:08's are a nice trade off for performance and interstate driving. The 2900 stall is not going to like the steady cruise unless you are above it. What I have found is that 2200 - 2500 is a decent cruising rpm for most cams.
It is tough to have a race car and a highway cruiser all in one.
 
#5 ·
My 1980 came stock with 2.29 gears. That's right, 2.29!

It had the 4.4 liter V8 and automatic. That was an odd combination.

The PO replaced the 4.4 with a 5.0 (305) before I got it. It ran pretty good on the street and loafed on the highway. 2.74 or 3.08 would probably have been better.

Jack
 
#7 ·
3.36's runs about 3200 rpm @ 70, I have a 700 r4 I will install someday, probably after the big block goes in. presently running a th400 with a more or less factory converter.

My vette had 3.70's and spun 3600 rpm on the freeway before the TKO was installed.
 
#8 ·
I'm running the factory 3.08's with the factory Powerglide and I believe the factory converter.


I get surprisingly good mileage on the highway. I usually cruise about 55-60 (yeah, I'm one of those guys), and usually turning around 2500rpms, I'd have to double check... I cruise real low on the streets too.


I read a lot about 3.08's being a perfect "middle ground" between performance and mileage.


I'll be going to a 2004r w/ 3.73 in the rear once my current set-up takes a poo poo.
 
#9 ·
My post it does not read right, I have 3: 42 gears, and a 2200 to 2300 stall converter, and turn around 2900 to 3000 at 60 mph. I like to run on the interstate for road trips, like to Florida for the silver springs show, but with 3:42 gearing, 75 mph is to many rpms for me. I was just wondering what others run, and they deal with it. I am planning on going to 3:08s during the Christmas holiday. Hope it does not kill to much performance, the Camino runs so good with the current gears, would like to try 3:73.
 
#14 ·
Yea mine came with 2:41 also, was great run 80+ on the interstate all day with no problems, but with my new engine, and trans. set up loves the lower gears, except for no traction, I love shocking all of these new "muscle cars" around town with my stock looking Camino, and an old man driving it.
 
#15 ·
new "muscle cars"
Darn straight! I don't care if it's a Camaro - plastic, Styrofoam, and a tasteless design isn't muscle!
 
#18 ·
old worn out, nearly bone stock 307---TKO600 5-pd---3.07 rear

1900 at 80mph----this thing is a freeway flyer (the blue 66 Elky)

The black 59----454HO---old timey TKO II-----3.36 rear-------about 2200 @ 70mph
This is just lugging----the cam in this engine really wants to go faster.
Runs the smoothest at about 80---but fuel mileage really starts to drop after 75.
 
#20 ·
My truck had the stock 2.41 with a TH250c. I swapped to a 3.08. RPMs were a little high on the freeway. I addded a 2004r tranny out of HKd"up 87's truck. With overdrive and the 3.08 I could set a land speed record. The motor was loping along well under 2000 rpm at highway speeds. I had the rearend rebuilt with 3.73 gears and posi. My RPM at 70 mph is now about 2350-2400. My rear tires are 255/60/15 and 27.1" diameter. If I had it to do over I would have gone with a 3.42 ratio which would have been a good compromise of performance and highway legs.
RTT Todd:smileyb:
 
#23 ·
'75 SS el Camino stock with 2.73's and Turbo 350, in process of going to 3.42 with 2004R (GN trans).

'87 SS el Camino stock was 2.73's with Turbo 200, now has 3.73's with 2004R (Monte SS trans).
 
#24 ·
How are you measuring speed? Your speedo is set for your gear; changing tire size won't change what it reads. That said, with a 26" tall tire, 3000rpm is 90 with a 2.41 rear. It's 65 with 3.55s. If you had 2.41s, 3 grand would be 85 to 100 depending on tire height. (235/60/15 and 225/70/14 are about 26").
I bet your gears have been swapped.
Patrick
 
#25 · (Edited)
I checked my stock speedo with my GPS, they matched each other up to about 55 mph , then up to 85 only off 1 to 3 mph at 85( GPS 88)then I took the GPS up to 105 mph , of course my speedo stopped at 85 . So the speedo is very close & I get 14-18 mpg sooo the tach must have been off . But I would still like to have O/D .I do a lot of shows all over the state . But I don't want converter lock up , I have totally de computerized & de smogged the car. So could I run a O/D tranny without a lock up converter ?? and I am running 225s .Oops I think I answered someone elses post ...
 
#27 ·
3:31 Posi with T400. 396 turns about 3000 RPM at 65. Engine seems to be at it's best above 2800 RPM.
I don't understand why people are hesitant to drive at freeway speeds with ratios above 3:23. These engines were designed to run their best at higher RPMs.
My GTO had 3:55s with a Dearborn 3 speed. It would run all day long at 75-80 and still get 13-14 mpg.
With the price of gas these days there's no excuse not to open it up!
 
#28 · (Edited)
I am running a th400 stock converter 454 and 3.36 gears. I was running a 2.56 gear and the car ran all day on the freeway down around 2200 rpm at 65
The car originally had a small block with 350 tranny. That's why it had such high gears origonally. After I put in the 454 and th400 the car would launch ok but when it hit second it sort of bogged down. Thats why I went to the 3.36 gears. The car really feels much better leaving a stop sign and runs about 2800 2900 at 65 or so and according to my gps the speedo is off to the slower side by about 5 mph. Long story but I am putting together a posi rear and thinking about a 3.73 gear. I think I read somewhere that the 454, th400s came with 3.73 gears. Is that correct. I guess it could have been ordered with several ratios but 3.73 was the factory gear. Right,wrong I don't know for sure. Im not on the highway much. Would 3.73 be too low?
 
#29 ·
I'm told by the older guys that 273s came stock on the old Th400 big block cars. If you run 373s behind a big block at highway speed you will probably be waiting for the boom sound. Doug213xrj, you said you ran 3.23s behind a 3 speed auto. How did you like that set up ?
 
#30 ·
I went and put 3:08 gears in my Camino this past week. I like the highway feel and drivability of the 3:08s. The 3:42s felt good around town, but could not use the torque motor made because it wound out real fast, plus traction was a very big problem. So I will be using the 3:08s till I get more money to get my Currie rear end, and OD installed. :secret:
 
#31 ·
Wow a long list.. bear with me
4.56 gears PG trans 147mph @ 7200rpm (loose converter {31" slick}
4.30 gears TH400 122MPH @ 6050pm {33" slick}
3.73 gears 700R4 76mph @ 2550rpm in OD) 3500 in 1:1) {27.5" tire}
5.43 gears TH350 116mph @ 6225rpm {33.5" slick}
3.43 gear NV4500 75mph @ 2450rpm {26"ish tire}

The point is nothing makes sense until you put tire diameter with it. A small change in tire diameter makes a significant change in highway RPM

i.e. 75mph,, 3.43 gear

26" tire = 3324rpm
27" tire = 3200rpm
28" tire = 3087rpm
29" tire = 2980rpm

We raised the car 1-1/2" with a 3" diameter increase and knocked off 350rpm @ 75mph. The difference between 2900 and 3300 will be HUGE in effect on effeciency,,, and on your nerves.

Not really the answer.... just saying
 
#32 ·
Darned fine post Marv (as always)

I hear people say the speedo is set for your gear and tires dont matter all the time, and few realise what a big difference tires can make not only for the speed rating but obviously the odometer as well

You gotta know your rolling diameter if you are going to get it right
 
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