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Speed differences for low and high gears

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
And if you're looking for maximum speed in each gear, most don't rev their Broncos to the max very often, if at all. So won't have that info.
And that would vary by transmission type anyway.

Or are you looking more for crawling speed, shifting speed, or cruising speed numbers?
Those will also vary greatly by differential gear ratios. What do you have? 3.50's or 4.11's or 4.56's? Or something non-factory?

Paul
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
What speed differences do you show for

Low 1
High 1

Low 2
High 2

Low 3
High 3


Are you looking for MPHs in Low 1 / 2 / 3 & Hi 1 / 2 / 3

If yes, what gears, tire size and at what RPM?


DJs74
 
OP
OP
7

70sbudget

Jr. Member
Joined
Jun 1, 2017
Messages
92
Sure, shift mph per each gear will do. Regardless of trans, gear ratio and tire size and the wide variations those will bring, what are your shift mph (obviously approximately) per each gear.
 

DirtDonk

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Bronco Guru
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Messages
47,345
Sorry budget. I'm just not getting how this can help you unless you specify and compare other characteristics of the individual Broncos. The only thing that will remain consistently comparable is engine rpm.
Then again... I'm probably overthinking it and you're just curious what others do?
Do you have a tach?

If still going for MPH only, and looking for recommendations on how to drive yours, I'm not sure you should say "regardless of gearing and tire size" for your question. Since that's exactly what dictates the MPH at whatever rpm someone likes to shift at. And add the different manual transmissions in use today, and you have even more variables.

Otherwise it makes no sense, since whatever we tell you means nothing unless you have the same gearing and transmission and tire size. As well as weight of the vehicle, modifications to suspension and overall ride height, etc.
To that we can add engine modifications of course.
A stock 3speed first gear with 4.56 diffs and 28" tires is going to shift at 8 mph or so. The same guy with 3.50's and 35's is going to be speeding along at 20 or more when he shifts out of first.
So better tell those answering with speeds to add that info to their responses.
At least for me, I use rpm (sound, feel, tachometer) and not speed, to get shift points on any drive.

So in my case I'm not going to be any help (sorry again:( ). 'Cause whether around town in traffic, or off-road in the rocky terrain I frequented, it varied every shift practically! Sometimes I stayed in 4-wheel low for three days on the trail without ever shifting out of first!
But for RPM, I generally liked shifting at 2500-3000 rpm most of the time.
What speed that is going to be for you would only work if you have the same 4.11 gears and 32" tires I had. And whether it works for you or not might depend on if you have a stock engine or modified, stock chassis or modified, or are carrying a load or empty.
Sorry I can't remember what speeds those rpm levels equated to exactly. Too much variation.
Then again, maybe I can half-guess just to give a starting point.

Good luck getting any consensus or reasonable recommendations though, unless everyone specifies what gear ratio, tire size and transmission they're running.
It's what you want and feel comfortable with. These things are kind of road-pigs anyway. If you've got the stock 3-speed manual gearbox, all the ratios are wrong almost all the time for what's needed.
I would rev it to 4-grand trying to get into traffic, or 2500 cruising along.

And when in low-range? I couldn't tell you if I've ever even looked at the speedometer when in low! After all, in low you're always on a trail of some kind. Never on the street unless in very special circumstances.
Anyway, I'm the one over-thinking it here. Maybe all you want is to see what others do, rather than are looking for what you should be doing. With all the people here, there's bound to be a few that watch their speedos all the time.

So I'll play after all.
Driving isn't as simple as it used to be around here, but even in the good old days of less traffic, I probably shifted:
From first to second at anywhere from 10mph to 20mph.
From second to third I probably shifted anywhere from 25mph to 45mph.
In low range? No data. Never looked.


Good luck.

Paul
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
Sure, shift mph per each gear will do. Regardless of trans, gear ratio and tire size and the wide variations those will bring, what are your shift mph (obviously approximately) per each gear.

Here is a link from Advance Adapters
http://www.advanceadapters.com/calc_form.php

Choose your transmission and transfer case (Bronco D20 is last one) from the drop down menu.
Choose C4 for A/T and T150 for the manual 3 speed. I looked up the Bronco 3 speed ratio and found 2.99:1 for 1st, 1.75:1 for 2nd and 1:1 for 3rd of course - so the "T150" ratios match (I'm not sure what the T150 is exactly but I don't think it matters, the ratio is what you are after)

Next, input your gear ratio, tire size and what specific RPM you are looking for a MPH, click "calculate" and review the information generated at the right. You'll see your calculated MPH for low and high range at the same time.


DJs74
 

Nothing Special

Sr. Member
Joined
Nov 25, 2016
Messages
804
....A stock 3speed first gear with 4.56 diffs and 28" tires is going to shift at 8 mph or so. The same guy with 3.50's and 35's is going to be speeding along at 20 or more when he shifts out of first....

And driving style and performance needs weigh in as well. I have a 5 speed with overdrive in my Bronco, but I'm often shifting into 4th (same as a 3 speed's 3rd) by 20 mph (4.10 gears and 33" tires). I don't get very good acceleration doing that, but most of the time I don't need very good acceleration.

Like Paul said, you really need to just develop a feel / ear for it. If the acceleration rate is dropping and the noise is getting too high before the shift, you are shifting too late. If the power goes flat after a shift, then you shifted too early. And if both happen, well then welcome to the world of 3 speed transmissions!


As far as shift points in low range, that's even more pointless to discuss. Even with my overdrive 5 speed I will start in 5th gear at times (of course I also have a 4.3:1 low range transfer case). But generally in low range you are just changing gears to get the speed that feels right for the trail.
 

Nothing Special

Sr. Member
Joined
Nov 25, 2016
Messages
804
This made me literally lol. It's 100% true, 2nd is always wound out grab 3rd and bog.

Not as bad as a Model A! There's a somewhat steep hill on my way to work. Not mountain-steep, but pretty steep for central Minnesota. There's a stop sign at the bottom of the hill so you're always starting up it from a dead stop. When I drove my 1929 Model A to work I'd wind it out in first, try to force the non-synchro trans into 2nd as quick as I could and I'd be going too slow to pull 2nd by the time I let out the clutch. After about 3 tries I gave up and just chugged all the way up in 1st.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
If you think the Model A is bad with the 3-speed, a Model T only has two forward gears. First is 3:1 and high 1:1 Think of driving a 3-speed and only using first and third gears. Model T is on my list of cars I need to own sometime in my life. I'm going through my big block phase right now.
 

metal1

Full Member
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May 2, 2016
Messages
259
Loc.
hidesert ,socal
my other 1/2 was taught how to drive a stick by the delivery co she drives for and she was told to hold each gear till it quit making power then shift .her first time in my truck I thought she was going to blow it up
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
If you think the Model A is bad with the 3-speed, a Model T only has two forward gears. First is 3:1 and high 1:1 Think of driving a 3-speed and only using first and third gears. Model T is on my list of cars I need to own sometime in my life. I'm going through my big block phase right now.

I have known quite a few old guys go through the small blocks, then stroked or built small blocks, then big blocks, then Model T's....

There is something about that transition,

Jim
Dan
Wayne
My Uncle Kevin

Just a few of the old timers I have watched make this transition through the years...
Funny...gotta be something to it...
 

DirtDonk

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Nov 3, 2003
Messages
47,345
It's like the thrill of a 300 Win Mag, only to shoot some 22's and remember just how much they make you grin.

Paul
 
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