Is the reverse gear stronger than first gear?
Posted by Ammar_aamir20@reddit | askcarguys | View on Reddit | 59 comments
Just came across a video of a dumper aiding another low bed truck stuck on a hill pushing him up in reverse and someone mentioned reverse gear has more power than first. How true is that? Also does manual reverse gear has more power than an automatic, im sorry if its a dumb question idk how it works.
Fancy_Specific_5283@reddit
Y,che b. Gbr FG B
Davohk@reddit
Aside from gear ratio, almost all reverse gear are straight-cut gears which also translate to more direct transfer of power vs helical cut gears. Hence, the whiny noise in reverse. Fun fact, the whiny noise in race cars are due to straight cut gears
Cheapsilverware@reddit
Everyone is failing to mention the fact that traditionally reverse is a straight cut gear in manual transmission. Not helical, no synchros. Makes for a noisier, beefier gear.That's why they whine in reverse.
Ammar_aamir20@reddit (OP)
Thats good knowledge,thanks
cshmn@reddit
So in a heavy truck, low gear and the lowest reverse gear (there are often more than one reverse gear) are usually about the same. Near infinite power at walking speed.
In a car or pickup truck, usually reverse is the same ratio as 2nd gear. This means that reverse actually has less power but a higher top speed than 1st (depends on the transmission.)
imothers@reddit
Any time I have ever looked, reverse is lower (numerically larger) than first gear, never mind second gear. So you get the most torque multiplication and best pushing power in reverse.
bigloser42@reddit
Every car I’ve owned reverse has been between 1st and 2nd in terms of the gear ratio. It’s always going to vary car by car.
itsjakerobb@reddit
That’s interesting. In every car I’ve ever owned, reverse has been lower than first.
Epidurality@reddit
Which cars? I've never experienced this for any manual, auto, or dct I've driven.
itsjakerobb@reddit
Mostly GM stuff. Just looked up and found that one (‘99 Silverado 2500 w/ 4L80E) is as you said — between first and second.
Epidurality@reddit
I know a few people who have mentioned this: it feels slower in reverse but mostly because people don't go above a couple thousand rpm in reverse. Whereas first is more regularly "rung out" higher up so feels like it can go faster. The actual ratios are almost always geared for lower speed in first than reverse for passenger vehicles.
itsjakerobb@reddit
In addition to the Silverado, I also checked the rest of my current vehicles: 2002 Camaro (T56): reverse is lower (2.90 vs 2.66) 1987 Grand National (200-4R): first is lower (2.74 vs 2.07) 2005 Liberty (545RFE): they’re the same! 3.00:1 2018 Regal TourX (AW F8 F45): first is lower (5.52 vs 4.22)
Not going to bother looking up the dozen or so cars I don’t own anymore, but I learned something today! 🙂
Worth noting that there are three different gearsets found in the T56, and in the other two, first is lower than reverse).
Epidurality@reddit
T56 is a 6 speed isn't it? Must be a hella tall first gear for whatever reason, or a surprisingly short rear. Odd, but I also learned something! Be interesting to know why a manufacturer would do it one way or the other, or what the reasoning is for such a tall first.
Admiral_peck@reddit
90's camaro t56 got a very low first and a very long axle gear, extremely wide gear ratios.
T56 has 3 different 1st gears, 2 different 2nd gears, the same 3rd and 4th, 2 different 5ths, and 2 different 6ths available. First ranges from like a 3.27 to a 2.66, 6th ranges from .67 to .5
itsjakerobb@reddit
Yes, six speed. In stock form, first is good for 51mph, and 2nd gets to 77. Some have theorized that these ratios were selected so that you could get to 60 without shifting to third and while in the meatiest part of the powerband, in order to optimize for 0-60 specs, which were a big selling point for these cars.
1-5 are pretty evenly spaced. With that same setup, fifth gear was capable of 186 (power limited though; fastest I ever went was 162). Sixth was a big drop though. I could also cruise at 1000rpm in 6th at 45mph, or 2000rpm at 90. Just loafing along! 29mpg on the highway.
I swapped the stock 3.42 rear gears out for 4.10s, and now I can “only” get to 46 and 68. If you do the math and notice that it doesn’t check out, that’s because I also built the engine, which allowed me to raise the rev limiter from 6200 to 6600. It’s not fully tuned yet, so I can’t say how much quicker it is, but it sure feels and sounds amazing. 😁
itsjakerobb@reddit
This — but first gear is often physically larger and more robust than reverse. Capable of delivering more torque by the numbers, but maybe don’t count on the gear surviving the task.
Vendii32@reddit
How does this work in a CVT transmission? I’ve always wondered since it technically has one gear does that mean reverse is basically the same as drive?
WizeAdz@reddit
s/power/torque/
power=torque*rpm
The engine provides a specific torque, rpm, and power. The gearbox matches the engines’s output to whatever it is driver needs the car to do.
itsjakerobb@reddit
Not sure how many car guys are going to understand your sed expression. 😉
substitute-bot@reddit
So in a heavy truck, low gear going forward and the lowest reverse gear (there are often more than one reverse gear) are usually about the same. Near infinite torque at walking speed.
In a car or pickup truck, usually reverse is the same ratio as 2nd gear. This means that reverse actually has less torque but a higher top speed than 1st (depends on the transmission, there are many variations.)
^^This ^^was ^^posted ^^by ^^a ^^bot. ^^Source
Total-Composer2261@reddit
Not even close to infinite power at any speed.
Critical-Border-6845@reddit
Well enough to twist driveshafts and blow u-joints apart
Total-Composer2261@reddit
That's more like it
clintj1975@reddit
I just looked up my Tundra. Reverse is only a few percent higher than first (3.52 vs 3.22). Second is 2.04
irtimirtim@reddit
3.52 vs 3.22 is a higher number but lower gearing. In other words the lower gear is “more powerful”.
clintj1975@reddit
Right. Reverse is 3.22 in my truck
ZenZen_Car@reddit
I think it is but people will think reverse is less powerful because most cars have a reverse limiter.
midri@reddit
Reverse gear is often a higher ratio than first, which does technically give it more torque.
Senappi@reddit
A fun fact is that Mercedes-Benz used to have models with two different gear ratios for reverse. This was linked to if winter mode was selected for the gearbox or not
jeepsies@reddit
Neat
69_maciek_69@reddit
It is? I don't think so. Both my cars had reverse with gear ratio close to second gear. Although they were both auto
kingkamikaze69@reddit
Best comment on the thread
Ammar_aamir20@reddit (OP)
That makes sense, thanks
Hersbird@reddit
Is the reverse gear stronger? No and the differential gears aren't designed and adjusted for high loads on the "coast" side of the gears either. You might get more torque multiplication from the ratios, some are lower in reverse than 1st, some aren't. But a really heavy or stuck recovery will be more likely to break something done in reverse vs 1st.
I used to do snow and ice recoveries all the time in reverse. It's easier to line up and see what's going on, but there is very little traction to break anything. If something is buried to the frame in mud, I'm doing it in a forward gear.
Electronic-Youth-286@reddit
Nissan CVTs had/still have a reverser gear. I never tried it out but it would mean that you'd be able to drive at the same speed forward as you could backward.
Ammar_aamir20@reddit (OP)
Interesting
No-World2849@reddit
Rever
WhiteBeltKilla@reddit
Fun fact, Ford recommends you put the manual transmission into reverse when lifting the car
ScaryfatkidGT@reddit
Could be a lower gear… shouldn’t be on a dump truck tho, on a car maybe, but on heavy duty stuff that has lots of low gears it usually wouldn’t be.
Ziazan@reddit
Depends on the car.
Check the gear ratios of that transmission.
ken120@reddit
Also cheaper to repair the box then the engine if gets bent out of shape.
Rocket_Monkey_302@reddit
It is common (but not universal) for reverse to be a higher ratio (on passenger vehicles anyhow), more torque multiplication but lower output RPM per the input RPM.
The power output is based off power input, torque and speed (RPM) are exchanged by changing the gear ratio.
The strength or power you're referring to is torque and ultimately tractive effort.
Ammar_aamir20@reddit (OP)
Right so the reverse gears lower than the first and in exchange of speed it produces greater torque than the first. So that means if a cars struggling to go uphill reversing it would make it easier due to the torque provided by the reverse gear
vilius_m_lt@reddit
Reverse gears are also usually straight cut while forward gears are helical (cut at an angle). Straight cut gears are stronger but make a whining noise. This is only true for manual transmissions
Rocket_Monkey_302@reddit
Agreed, stronger, as in not breaking, and this may indeed be the actual reason why a heavy-duty vehicle operator is pulling in reverse.
Rocket_Monkey_302@reddit
Yes, provided that a lack of traction (like wheel spin) or some other problem was not the reason it was struggling.
AlaskaGreenTDI@reddit
Maybe the dumper was in reverse because of the gear ratio, but it’s also possible it was because of weight distribution and being on the hill.
Ammar_aamir20@reddit (OP)
Wouldn’t the weight be dragging it down regardless of it facing up or down
AlaskaGreenTDI@reddit
Yes, of course, but I don’t mean gravity taking the whole truck down the hill. If the dump truck is loaded, it could be far more stable backing up the hill than pointing forward up the hill.
Ammar_aamir20@reddit (OP)
Makes sense
1PistnRng2RuleThmAll@reddit
Something more important to consider is the rear diff is often stronger, and some diffs are weaker when driven in reverse.
The difference between 1st and reverse is often negligible at best.
Fish_Dick@reddit
The problem with a heavy load in reverse is the risk of blowing out the axle gears. They're not as strong running backwards.
Ammar_aamir20@reddit (OP)
I love reddit so much raw knowledge not from computer bots but from actual humans with differing opinions
ProfessionalScale747@reddit
Most of the time reverse is a taller gear than first but it depends on what you drive
Rattlingplates@reddit
Naw that shits snaps
Ammar_aamir20@reddit (OP)
Cool thanks for the information im gonna educate myself on different types of transmissions to learn more. Big trucks always fascinated me so much with their complex transmissions its time i learn more about these machines
WizeAdz@reddit
Hybrids and EVs are also interesting from a gearbox-engineering perspective.
eCVTs are super-simple mechanically, but super-smart in the thinking behind it.
Most EVs don’t have shiftable gearboxes because they don’t need one - they usually have just a reduction gear. The reasons for that engineering-decision are fascinating!
PckMan@reddit
The gear ratio for reverse is usually shorter than 1st, as in it provides more torque at the expense of less speed, which makes sense because you're probably not planning on cruising in reverse. Specific gear ratios for each type of car and gearbox vary.
superbotnik@reddit
You can look up the ratios for a specific transmission