Anyone else ever sat down and thought about the benefits of more gears?



I work in the diesel truck trade. Alot of you might not realize that trucks have plenty of gears. This is because the diesel powerband is a narrow 1200 rpm to 1900 rpm (estimated generically in the transport industry).



The transmission has 5 forward gears (low, 1, 2, 3, 4). Internally, it has a ratio splitter on another shaft assembly that is actuated pneumatically to engage, at which point, the truck has another 5 forward gears, all at higher speed ratios than the previous five. Which altogether is 10 speeds.



Some are equipped with a split differential, another pneumatically actuated rear end that has two ratios. This means the truck has 20 speeds (low is hardly considered a speed since the reduction is so slow, so they are just called 18 speeds).



Recently for a special heavy haul application, we took an 18 speed highway truck and added another splitter box between the transmission and split diffs for extra reduction. Bringing our truck to a whopping 36 speeds. WOT in low gear, low diff range, and low splitter range yielded a speed no faster than a man could walk. Of course, the amount of torque it was producing just to get going, it would pull just about anything with that kind of reduction. The more I looked into it, the more I noticed the other companies in extreme heavy haul actually neccessitate use of splitter boxes, split differentials, and 18 speed transmissions. The technology in heavy haul driveline alone is staggering (see Premay - Transport Architects). Few pictures in there of extreme heavy haul.



Remeber, the diesel powerband is very low, and they are designed for hauling weight. This techonology can be applied to race cars. I've read about this over and over and seldom do I see it make it's way to racing.



Many have had the pleasure of driving a 6 speed sports car over a 5 speed. Some have been around for the days of the 4 speed. What's the difference? Well the more gears you have, the more your car "hangs out" in the powerband.



Imagine 7, 8, or 9 speeds? Imagine your peak horsepower and torque band being applied to your wheels more often? Imagine losing that laggy area of your shift (although some of you don't really recognise it with high horsepower).



What if applying maximum power to the wheels was your neccessity?



Just food for thought I guess.. I recommend anyone who can get their feet wet in driveline technology just to jump right in. Some of the creations out there are just as technologically advanced as the motor that turns the input shaft.

yeah when ever im on the highway i always wish i have 6th gear but thats just for gas mileage. but definatly wouldnt mind having a longer pwer band. good post

1200 to 1900 isn't all that narrow, in comparison. Multiply by five and you have 6000 to 9500, wider than many performance rotary powerbands.



Regardless, more, closer gears is nice to have, but more gears also means a transmission that is either larger, heavier, and with more rotational inertia, or weaker. Or both. Plus, with an H-gate, reasearch has shown that beyond seven gears, it can be easy to get lost in the gate.



Peugeot concentrated on giving their WRC engines a wider powerband so that they could run a four speed transmission instead of a six speed. Bear in mind that they have electronically aided sequential transmissions, so "getting lost" is not a problem. They must have seen some significant advantage in having fewer gears to go that route.

I definitely agree with what you're saying - I just got an old golf gti which has the closest ratio box I've ever seen in a car - top speed is probably around 120mph bouncing off the limiter, but the other thing it does is it means you don't have to rev out of the powerband to land in it again! It makes the car an absolute joy to drive (apart from motorways maybe https://www.nopistons.com/forums/pub... ).

Does it have the VWMotorsports transmission in it? Those are nice. 2.4 First, 1.05ish 5th, well spaced in between, perfect for a well built lump.

Well, I'm not entirely sure about how to go about a little project like this or where to begin really.



Just wanted to stimulate some minds..



The trucks still use H-gates, but there is an air switch for the pneumatic actuation of the splitter. Air switch on the shifter itself. The beauty part is it is done on the fly. It's all in knowing how to drive it. For example, picture your 5 speed knob. Replace 1,2,3,4,5,R, with: R,Low,1-5,2-6,3-7,4-8. Lets row through all the way up to 8th. 1 accelerate to top revs, shift to 2 accelerate, shift 3 accelerate, shift 4 acc-flipswitch-elerate, sh*click*ift 5 accelerate, shift 6 accelerate, shift 7 accelerate, shift 8 accelerate. The pneumatics are part engaged during 4th gear with no damage to anything. The second you pull it out of 4th, the split fully engages long before you even go to stick your shifter from 4 back in to "would-be-1-but-now-is-5"



All you have to do is at some point during your acceleration motion in 4th is flip the pneumatic switch, and you have nothing else to worry about. You can clearly see what gear range you are in by the position of the switch. Sure you could get lost, but truckers are doing this across north america every day. I'm sure any one of us could figure it out.



http://www.roadranger.com/ecm/groups...per13image.jpg



Notice the lever where your index and middle finger would be? It's a simple up down switch.



Of course it has since been gone over again, and they have another range splitter (on most trucks generally) at your thumb position. So those models have one at your finger and one at your thumb.



It really doesn't take too long to get to know how to work the range splitters. I learned flawlessly just driving them in and out of the shop. Of course I was using a low diff range so shifting to 5th was still yeilding a small MPH.

You're thinking of doing this on a car? I'd love to see it! I can't think of how you'd retro fit something like that to a car gearbox - you'd have to have a kind of seperate reduction gearbox somewhere along the line?



A problem you get with some bike engines for kitcars is that the output rotates far too fast to use with a standard ratio diff - so what I've seen done once or twice is they fit a car gearbox backwards in between the bike's gearbox and the propshaft! Not really a solution if you ask me, not sure that a gearbox would like being run backwards and that's a lot of extra pointless weight - but the idea of having ~30 gears is cool - would make setting the car up for different circuits pretty easy!



Heretic - no vw motorsport box, it's still a daily driver - but at the same time I'd be surprised if 5th wasn't pretty close to 1.00

Well not 30 gears.. Just utilizing some of the driveline technology for a little more versatility on a road car.



I was thinking more of a small splitter box with a 1:1 ratio and a smaller ratio, and being able to shift between splits on the fly.



Considering most of our cars have independent rear suspension, calculating driveline angles is way easier if you were to incorperate a splitter between the trans and diff.



I was thinking along the lines of having a simulated split differential with the box. And being able to change on the fly could prodouce something like rowing 1-5, shifting the split back to 1:1 from low range and reusing 4th and 5th gears again. Of course the math comes into play as to finding out which gears are virtually doubled with the split. 4-Low and 3-High might be pretty close to the same ratio with the splitter box massaging the output speed.



That or just using low range 1-5 in city/short courses (depending on your application) and 1:1 range 1-5 during highway/broad courses, maybe using a 3.9 final drive diff rather than my stock 4.1.



A simple two gear splitter box that can handle the output power of a 13B has potential to be pretty compact.

Why not dabble more in advancing the CVT? Of course that probably wouldn't be good for hauling loads, but for a sports car, it could have great benefits. Engineer the engine to operate best at a single rpm, and let the CVT do the ratio-choosing.

Just go to Quaife and buy their range-change gearbox. Available with steel or aluminum maincase, synchromesh or dog ring.





http://www.quaife.co.uk/Ford-Rocket-Comple...-alloy-maincase



If you don't mind a PDF, you can see the ratios and a better image

http://www.quaifeamerica.com/downloads/14-26.pdf here on page number 15.



Picture a nice racing 4-speed, with a gear-splitter activated by rotating the shift knob 90 degrees.

Cool!

Wow surprised I didn't see this earlier. Here's a neat setup that replaces the tailshaft assembly of popular transmissions. Electromagnetic actuation.



http://www.gearvendors.com/images/install1.jpg



Didn't realize this was an option to add-on to a factory box. Apparently 4 speed hot rodders have been into this for a while..



http://www.gearvendors.com/installation.html

That 's based on a type e gearbox, I'm not sure one of those could handle the power of a 13b unless quaife have beefed it up a bit.



EDIT: the rocket box I mean.

i was about to chime in; the triumphs of the late 50's and early 60's came with the option of an overdrive like that. the racers used to wire it up so that they could use it in 2nd 3rd and 4th, think like having a 3rd and a half gear... 4th... 4th and a half....



so its been done and it works, http://www.tjwakeman.net/TR/Net_racing.htm

Ahh yes, there is a TR6 at our local autocross that has that. I was wondering aloud how he could shift so quickly, then someone explained it to me.

very interesting read

now as much i'm into engine bulding, i gotta admit, i know as good as nothing about trannies. But i'd like to throw some food for thoughts in:



i had an old volvo 740 stationwagon. However, it had a 940 engine including transmission.

Now the tansmission was like this: Gears 1 to 4 had H-pattern, as million other cars.

But the 5th gear was activated with a switch. You had a switch on the center of the shiftknob. Depress clutch, press the button, and clutch in. Bam, 5th gear.

The transmission consisted of three intersections: the bellhousing, the transmissioncase with the 4 gears AND an additional "box" bolted to the transmissioncase. The propellershaft goes into that "box". A cable was routed from the 5th gear-switch to this box. When the 5th gear got activated, a big electromagnet got supplied with power. you get the idea.

btw, when we had to sell the car, it had over 300.000 kilometers on the clock, and that special 5th gear worked flawlessly.

Your overall drive speed is determined by how many RPM the shaft is spinning.



1:1 ratio means the differential input is spinning at 9500 on a powerhouse rotary, and 1900 on a slugging diesel. So while you're going much faster than multi-lane highway speed (upwards of 100 mph? 9500 in 4th gear), imagine how fast that same car would go in 4th while only spinning 1900 RPM. 45 mph? Roughly?



I meant to point that out earlier to help show why trucks need more gears, but I left it out.

It's all about the powerband. Scaling up or down just helps to illustrate that a 1200 to 1900rpm powerband represents a roughly 60% increase in speed. That's actually pretty good.



Of course, it has been proven time and time again that a proper close ratio gearbox will benefit any engine, even stock low-performance street engines. It's one of the simplest ways to improve a car's acceleration, albeit oftentimes an expensive one.



I'm sure the truckers are not overly concerned with the quickest 20-60 times, but they would be concerned with getting the optimal fuel economy under all conditions, which makes it good to have a wide variety of gears to choose from so they can get their BSFC down. Even shaving a tenth of a MPG makes an enormous difference when you do well into the six figures per year and your clients are beating you up for the last penny per mile in shipping rates.

And you're right. When you get 4 mpg, a slight increase is a huge difference. We have trucks in our fleet with 1,200,000 kms. 1999 model units. So mathematically very tiny increments in savings dictate thousands saved per year.



I was just trying to give some backround behind purpose for so many gears. Smaller trucks using diesel engines using common final drive ratios in differentials needed more gears to achieve highway speeds.



It's tough to work between economy, power and speed.



Now the differentials have splits for healthy balance between gears for economy, power, and speed (although some may not realize).



Older trucks have a big difference in speed between pulling 50,000 lbs and running empty. That's not fun especially, when empty, the truck takes five minutes to get between 80 kmph and 100 kmph. Right now we have new trucks in our fleet that you can hardly tell between empty and 100,000 lbs. And, barely slower than common low power econoboxes hitting the on-ramp (if, you can grab your gears fast enough that is).



Half of the fuel economy and performance improvements on large trucks has been with driveline modifications (over the years).



That said, both our posts point to a common conclusion. Driveline design dictates power, economy, and speed, just as much as the motor does. A strong motor design can be tweaked with additional focus on what puts the power to the pavement, and that was the purpose for shedding light on those who might not have ever thought about doing anything different to their driveline after building up their supermotor.

Keep in mind you will be wasting A LOT of potential acceleration time just shifting gears. Formula 1 only uses 7 gears, even though they are computer shifted FAR faster than you can by hand.



Unless you are no-lift-shift-ing https://www.nopistons.com/forums/pub...#>/biggrin.gif you will find you are spending an awful lot of time with your foot off the gas and it won't matter that you are staying in the powerband.



I'm not a truck driver, but I don't think too many of them hit all 18 gears on the way down the on-ramp.

It takes, what, a quarter second to shift?



You have a good point, but for production, wide ratio (1st lower than 2.5:1) gearboxes, we are on the side of the curve where the gears are too far apart, unless you have some great turbo technology permitting a very wide/bottom-heavy powerband. And, at that point, you'd still be better off retuning to make it top-heavy and get more/closer ratios, assuming for example that you're not forced to draw through a 32mm restrictor causing your 2-liter turbo engine to run out of steam at about 5000-5500rpm.

ive been driving around the rx8, its got nice gear spacing.....

With the amount of money you would spend doubling your gear ratios (and adding weight to your car) you could build that better turbo system, and have a car that you would enjoy driving.



When Yamaha first brought out the R6, it had a 15,500 RPM redline, with the power peak at only 12,500 RPM. I believe that is so you weren't force to shift gears in the middle of a corner.



Too many gears would make it difficult to A) find that right gear for each corner and B) finish that corner without hitting the rev limiter. You can't shift when you are turning, so driving in and out of a corner would be badly affecting by having too many gears.

thats whats nice about the rotary too, it doesnt mind too much being revved a little high

One of the loonies I work with drove his first RX-7, an early carbureted model. He was surprised at how the engine didn't have any definite peaks or slumps in the power delivery, just a smooth puuush from idle on up to the end of the tach.



I told him that if the car wasn't stone stock with the restrictive pellet-bed converter and the all too common siezed fan clutch, it would feel the same but a lot more puuuush but the lack of fan noise would be more than made up for with exhaust noise.



Most of the engines we build or tune are of the kind where there's nothing, nothing, nothing, and then some little elf in the camshaft pulls the lanyard and, as JPIII once said, the irresistable force slips off of the immovable object and pushes on you instead. These are the reason why GM used to install four-speeds with only a 55% speed difference between low and high.