What rear gear ratio are you guys running in your in your cars. I still want good performance but would like better mileage. Right now I have a 4.11 gear and get about 10 mpg out if a 350 with a mild cam. Car runs great but tachs about 2700-3000 rpm at 60mph. Was thinking about using a rear gear in the 3.08 range. What do ya'll think
Best Gear Ratio
- Thread starter trhccd
- Start date
HDWRENCH
Member
I have an 8" rear in my T with 2:73's. Although this and 3:08's are great for mileage, how do these ratios work in town? Will the trans hold first or second @ 45mph, or shift into Drive (3rd) ?...Just asking as I'm still building the car and thought about using 3:55's with a torque converter in the 2500 to 3000 rmp range to eliminate creep at a stop light..
My one car has a 383 with a 700r4 and a 3.73 rear and 26" tires. Has too big of a cam and gets about 12-14 mpg. Also has a 2500 converter in it and because of the big cam you can't hardly use the lock up on the converter.
The other car has the blower with a 4.10 Dana 60 and 31" tires, 3500 stall, manual shift turbo 400 and get about 4 mpg, but hey its a hot rod.
The other car has the blower with a 4.10 Dana 60 and 31" tires, 3500 stall, manual shift turbo 400 and get about 4 mpg, but hey its a hot rod.
donsrods
Member
I mentioned this on another thread. I have 3:00 gears with a 30 inch tire, 350/350 combo in my T. Coming back from Billetproof last week at 60-65 I am just off idle, and used just over 4 gallons for one 120 mile leg. Sounds like BS, but I swear that is what I got. Up till then I had been getting 20+ mpg, and it was creeping up as the engine started to seat. The almost 30 mpg floored me.
I have no plans to change gear ratios...........or ANYTHING!!! :lol::lol:
:lol:
Don
I have no plans to change gear ratios...........or ANYTHING!!! :lol::lol:
:lol:Don
TRoadster
New Member
Hey trhccd, Have you swapped out your rear gear yet? I was reading through some of the older posts and saw this one. One thing about going from a 4.11 to a taller gear, like a 3.08... I believe that will effect your stall on your torque converter. I'm not an expert on automatic transmissions, always owned a manual, but I think your stall speed may drop. Something to look into.
LumenAl
Member
trhccd said:
that 4:11 is sweet off the line! I took mine out... put in 3.35 positraction... was trying to find a 3.08 but no one had one in stock... run 29 inch tires get 10 mpg...
Dang high compression motor eats premium too!) But to answer your question... you;ll give up some of that power off the line, but you'll still be plenty fast... Only have one question... what size tires you running?
donsrods
Member
As I mentioned in my earlier post, I have 3:00 gears with a 30 inch tire, and mine pulls fine and sips fuel going down the road. It is fine for me. My Son Don is currently running an 8 inch Ford rear with 2:79 gears because we just needed to get it on the road. While we have his motor pulled out we are going to replace them with probably 3:80 gears because his 302 was built for dragracing and has a cam that doesn't come in until about 3000 rpms, so he can't get into his power band. We figure with the 30 inch tires he is running the 3:80's should be about right.
My other Son Dan is running a 455 Olds in his '29 roadster pickup and a 9 inch Ford rear. He is getting ready to order his pumpkin and is kicking around 3:50 or 3:89 gears. His motor has a bunch of torque, but a radical cam, plus he is running very tall (32 inch) rear tires, so we still have some calculating to do.
I am running 3:90 gears in my '27 in a 9 inch rear and with 30 inch tires, and with the stick transmission it was just about right. A friend had the same setup but 4:10 gears and he was always lagging behind on the highway because he was turning too many r's.
With the current fuel prices I bet we start seeing lots more cars with higher gears and more overdrive transmissions.
Don
My other Son Dan is running a 455 Olds in his '29 roadster pickup and a 9 inch Ford rear. He is getting ready to order his pumpkin and is kicking around 3:50 or 3:89 gears. His motor has a bunch of torque, but a radical cam, plus he is running very tall (32 inch) rear tires, so we still have some calculating to do.
I am running 3:90 gears in my '27 in a 9 inch rear and with 30 inch tires, and with the stick transmission it was just about right. A friend had the same setup but 4:10 gears and he was always lagging behind on the highway because he was turning too many r's.
With the current fuel prices I bet we start seeing lots more cars with higher gears and more overdrive transmissions.
Don
cdan
Member
I'm running 350/350 with 30in rear wheels. At 2000rpm i'm only doing 50mph.... currently running 355 gears in an 8in ford re.........i need taller gears for better fwy speeds. Thinking maybe 3:00 ?I mentioned this on another thread. I have 3:00 gears with a 30 inch tire, 350/350 combo in my T. Coming back from Billetproof last week at 60-65 I am just off idle, and used just over 4 gallons for one 120 mile leg. Sounds like BS, but I swear that is what I got. Up till then I had been getting 20+ mpg, and it was creeping up as the engine started to seat. The almost 30 mpg floored me.
I have no plans to change gear ratios...........or ANYTHING!!! :lol::lol:
Don
benT
Active Member
Hmm- I have 30" tall tires as well, but running 3.73's. I don't find it an issue on the highway- probably in the 2500 range if I had to guess. Don't have a tach, but get about 17 mpg on road trips. As I put more miles on around town, I prefer the shorter gear.
If you are set on different gears, 3.23 or 3.27's have worked well for me in the past- good compromise for street/hwy.
If you are set on different gears, 3.23 or 3.27's have worked well for me in the past- good compromise for street/hwy.
cdan
Member
maybe a little off the subject but.....i'm getting a pulsing vibration at 2000rpm, I can feel it under my butt, maybe 1sec off 1sec on, jacked it up, took the wheels off, still get it, took drums off, still get it...took the driveshaft off had it checked......all is ok. Thought maybe it was trans but shops i've talked to say not really anything in the trans that would cause that at a particular rpm. I've heard if the harmonic bal slipped it might cause it................any ideas?
On the first post, google an rpm chart, that utilizes tire and gear size. I would think you would want to be about 2000 rpm at cruise speed. You pick your cruise speed.
On the last post, rotate your driveshaft on the pinion flange 90* at a time or 180* if you have a u joint. Be sensitive to any changes, ie improvements or worsening. If you do not get it all out rotate the trans end of the drive shaft on the output shaft at 90* per try. Be sure to maintain the best setting on the rear. Might be better to do the front first. Second possible area of concern will be your pinion angle and or drive shaft angle out of the trans. Run out on a ring gear, carrier bearings and axle bearings can come into play. Hope this helps.
On the last post, rotate your driveshaft on the pinion flange 90* at a time or 180* if you have a u joint. Be sensitive to any changes, ie improvements or worsening. If you do not get it all out rotate the trans end of the drive shaft on the output shaft at 90* per try. Be sure to maintain the best setting on the rear. Might be better to do the front first. Second possible area of concern will be your pinion angle and or drive shaft angle out of the trans. Run out on a ring gear, carrier bearings and axle bearings can come into play. Hope this helps.
EX JUNK
Moderator
Getting back to the subject of Best Gears To Run, I have a 350 Turbo with an Eaton 4.10 posi unit and I'm running 285/70x15 tires which are 31" tall. At 3000 RPM I'm doing just under 60 MPH (58.6 to be exact). That may seem a bit high but it sure is a lot of fun in city traffic where the biggest part of my driving is done.
Jim
Jim
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