I've been talking some guys at one of the car boards I'm a member. Theres a thread thats been going for a few days now and they just cant seem to grasp the difference between transmission gears and rear end gears. Absolutely ridiculous! It's got me sooo frustrated I feel like shooting something.
Some people just don't get it...
- Thread starter 5LiterMustang
- Start date
Front wheel drive transaxles still have rear end gears and tranny gears, the only difference is that they are contained in the same housing.
I personally don't think it's hard to understand. The rear end gears effect the final drive ratio as do the tranny. But when someone says they've got "gears" 99.99 percent of thetime they are talking about 3.73 or 4.10s etc which are rear end gears. I went over it in fairly good detail and they just couldn't grasp the concept of how gears will get a stock 5.0 mustang out of the power band when you start revving much past 60. They help tremendously to 60mph and a fair amount to 80 but from a roll geared cars get spanked a lot of the time simply because the gears do not complement the mods they've done to their car.
You might do better to refer to rear end gears as a differential. It is less confusing, particularly in the context of front wheel and all wheel drive vehicles.
If your posts on other boards are similar to your last one here, I can see why they get confused.
By a "geared car" I take it you mean a car with a lower final drive ratio ?(higher numerically)
A Mustang with final drive ratios in the range you mention, 3.73 to 4.10, is hardly going to be out of its powerband at 60mph.
If you have 2 identical cars, with the only difference being the differential gearing, the lower geared car is going to almost always out-accelerate a higher geared car, until the lower-geared car's engine rpms reach a level where torque falls off dramatically. I would guess that's somewhere between 100-120 mph if the car is a stock 5 liter Mustang.
As far as rolling starts, it's possible that at a certain speed the higher-geared car would be at a more optimal rpm in a certain gear, but the same thing would be true at different speeds for the lower geared car.
edit- just wanted to add that the lower-geared car will require the driver to shift gears at lower speeds, so depending on the speed reached at the end of the competition the lower-geared car may have had to shift gears more. If the person is competent at shifting gears this shouldn't make a whole lot of difference.
If your posts on other boards are similar to your last one here, I can see why they get confused.
By a "geared car" I take it you mean a car with a lower final drive ratio ?(higher numerically)
A Mustang with final drive ratios in the range you mention, 3.73 to 4.10, is hardly going to be out of its powerband at 60mph.
If you have 2 identical cars, with the only difference being the differential gearing, the lower geared car is going to almost always out-accelerate a higher geared car, until the lower-geared car's engine rpms reach a level where torque falls off dramatically. I would guess that's somewhere between 100-120 mph if the car is a stock 5 liter Mustang.
As far as rolling starts, it's possible that at a certain speed the higher-geared car would be at a more optimal rpm in a certain gear, but the same thing would be true at different speeds for the lower geared car.
edit- just wanted to add that the lower-geared car will require the driver to shift gears at lower speeds, so depending on the speed reached at the end of the competition the lower-geared car may have had to shift gears more. If the person is competent at shifting gears this shouldn't make a whole lot of difference.
Originally posted by: Dead Parrot Sketch
You might do better to refer to rear end gears as a differential. It is less confusing, particularly in the context of front wheel and all wheel drive vehicles.
If your posts on other boards are similar to your last one here, I can see why they get confused.
By a "geared car" I take it you mean a car with a lower final drive ratio ?(higher numerically)
A Mustang with final drive ratios in the range you mention, 3.73 to 4.10, is hardly going to be out of its powerband at 60mph.
If you have 2 identical cars, with the only difference being the differential gearing, the lower geared car is going to almost always out-accelerate a higher geared car, until the lower-geared car's engine rpms reach a level where torque falls off dramatically. I would guess that's somewhere between 100-120 mph if the car is a stock 5 liter Mustang.
As far as rolling starts, it's possible that at a certain speed the higher-geared car would be at a more optimal rpm in a certain gear, but the same thing would be true at different speeds for the lower geared car.
edit- just wanted to add that the lower-geared car will require the driver to shift gears at lower speeds, so depending on the speed reached at the end of the competition the lower-geared car may have had to shift gears more. If the person is competent at shifting gears this shouldn't make a whole lot of difference.
We are ONLY talking about rwd cars on the other board. Yes you're right on gear shifting too...here's the deal. A stock 5.0 motor makes peak horsepower at 4200 rpm and is pretty good till 5000 after that it hits the floor. The power falls off very rapidly after 5000 rpm. With a 5 speed car on the shift from 2nd to 3rd assuming you shift at redline the rpms fall off to 4000 which means the car only runs 200 rpm with power gaining and after 1000 it starts to fall off by the time 5500 rolls around you're not making much power so you either a. shift again or continue the the current gear. When you shift down to 4th if you shift at redline then you're already above the powerband if you shift at 5500 you're at about 4000rpm once again only 200rpm while power is building....the point is gears really only help you below 80. From 60-80 there isn't much of a difference if there's one at all. From a roll a stock geared mustang will pull slightly at 60 and then get walked by a stang with stock gears. Assuming you're running 4.10s (which was the gear ratio discussed in the thread at the other board). With 3.73s it'd still be a good race but eventually 90+ the stocker would start to pull pretty good. It all has to do with the power band unless you've seen a dyno graph it's probably hard for you to understand what I'm saying. Plus I suck at wording things.
I shift my car at 5200 w/ 3.73s in it. Like you said, the car makes crappy power above 5000. If you keep pushing the car above 5000, you're not really accelerating very fast, and you're wasting time. The car pulls better from 3500-4000 than it does from 5000-5500, so you're better off running the car up to 5000 and shifting it back to 3500 than you are running it up to 5500 and shifting back to 4000.
*All numbers are approximated, the gearing between 3 and 4 is brobably not exacly a 1500 RPM difference at whatever speed you're going at 5000rpm in third (about 80).
*All numbers are approximated, the gearing between 3 and 4 is brobably not exacly a 1500 RPM difference at whatever speed you're going at 5000rpm in third (about 80).
5litermustang,
I understand what you're saying. In your scenario of a race that starts at 60mph it's certainly possible for the higher-geared differential car to have better ratios to keep the car in the powerband. The higher the speed the race starts at the more likely this is to be true.
One factor which I'm sure you already know is that the final drive ratio in any certain gear is the transmission gear ratio times the differential gear ratio.
So the 3.73 gear car in 3rd gear might actually have a lower final drive ratio than the 4.10 gear car in 4th gear.
Additionally, if the aerodynamics are good enough, the 3.73 car would have a better top end speed than a 4.10 car.
Tire diameter also affects final drive ratio, smaller diameter having the same effect has a lower differential gear.(higher numerical, as always)
I'm sure you know a lot more about the specifics of Mustangs than I do, I'm just talking about general applications.
I understand what you're saying. In your scenario of a race that starts at 60mph it's certainly possible for the higher-geared differential car to have better ratios to keep the car in the powerband. The higher the speed the race starts at the more likely this is to be true.
One factor which I'm sure you already know is that the final drive ratio in any certain gear is the transmission gear ratio times the differential gear ratio.
So the 3.73 gear car in 3rd gear might actually have a lower final drive ratio than the 4.10 gear car in 4th gear.
Additionally, if the aerodynamics are good enough, the 3.73 car would have a better top end speed than a 4.10 car.
Tire diameter also affects final drive ratio, smaller diameter having the same effect has a lower differential gear.(higher numerical, as always)
I'm sure you know a lot more about the specifics of Mustangs than I do, I'm just talking about general applications.
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