The Elusive Power Sliding Door Mechanism

Update 5 April 2010: Question answered!

From day one since I put my interest on Honda Freed I searched high and low for a mechanical rundown for its power sliding door. It’s an important thing for me because I live in a place where 10 cm standing water is a common sight on the streets. On rainy season that amount of water can reach 30 cm deep even. So it’s important for me to know the working of the power sliding door to take any precautionary measure when going through a flooded street.

I waited for Freed to go international outside of Japan before asking around and even now almost 2 years later I still didn’t get a definitive explanation about how a power sliding door works. So I decided to take matter personally and wrestle around the internet and found some patents describing how a power sliding door works.

Power sliding doors are surprisingly complex. Based on two patents that I found regarding power sliding door mechanism, they all work on a system of pulleys and cables. Here’s a quote from Magna as an assignee on its sliding door mechanism patent:

Power operation of the sliding door between the open and closed positions has become a popular feature. Cables are commonly employed to pull the door open and closed due to a required long and curve-linear travel path of the door. Cables are driven by spooling drums of large size to store the required cable lengths. It would be desirable to employ a compact linear drive mechanism to operate a sliding door using cables but without cable drums to reduce size, weight, and complexity.

And here’s another power sliding door patent from Hi-Lex Corporation as an assignee:

According to the invention, an electric motor assembly is mounted on the door and includes a drum driven by the motor, and a cable system driven by the drum includes cable runs adapted to be anchored to spaced points on the body structure. The cable system is operative in response to energization of the motor to move the door assembly between open and closed positions.

Read more: http://www.patentstorm.us/patents/6553719/description.html

Seeing that these patents refer to a pulley system, it’s not too out there to suspect that Honda employs a similar system. However, no information regarding where the motor or the mechanism is located on the car. If a cable system is used then the answer would be that the mechanism is situated smack dead in the middle of the guide rail, which is very preferable for me. That means if I wade through high standing water, I won’t have to worry about the sliding door mechanism got submerged and damaged. However, upon closer inspection, every time I open Freed’s power sliding door, I can hear an electric motor spinning from the bottom of the car. If the sliding door mechanism is situated around the floor of the car… Then it’s going to be a problem for me.

Finally, I’ve conclude that Freed’s sliding door mechanism is indeed using a cable and pulley system. I’ve always look below the sliding door tracks and never pay attention to the sliding door rail. The thing is, logic told me that the most complex system will be its major moving force. So the bottom side of the sliding door has the most complex mechanism visually. However, it turns out that it’s just a swiveling door hinge and power window conduit cable. So much for careful observation… The cable system that pulls the power sliding door can be seen clearly when the door is fully opened.

Such a small thing to pull the weight of the door

For those having concern about the power sliding door system failing, whereby you can’t open the door… Fear not, as the Freed power sliding door system can be deactivated, making it basically a regular sliding door. The downside of having the system turned off however is the added weight of the system when opened/closed manually. Opening/sliding the doors with the system turned off yield a much heavier door compared to non power sliding door trim. Given, because now you have the added resistance of the motors and the pulley system.

With its power sliding door system and anti-pinch safety measure, Freed’s power sliding door system alone is already a big selling factor. Hope you enjoy yours.

Freed Against The World (Paper comparison against its local rivals)

Freed is unique, more so that it actually is a smaller scale premium people mover like its big cousins, Honda Elysion and Toyota Alphard. It’s front wheel drive system and almost box shape size means it delivers the best of space inside the cabin. The car might be classified as just another compact minivan, just like Suzuki APV, Daihatsu Granmax/Luxio, Toyota Avanza, and Nissan Grand Livina before it. But the overall stance of the car gives it a slight edge in term of perception and overall riding impression.

This blog entry will tell a tale of the tape, a technical background for Freed and its competitors. It’s not a comparison per se, just the facts about all the cars given the relevant specification data. It is comparable, but in the end it’s up to you to decide what is best… Hey, I’m not being paid to write this.

  • Freed direct competition (Size): Suzuki APV, Daihatsu Luxio, Toyota Avanza, and Nissan Grand Livina.

A short list of things that is going to be compared:

  1. Size
  2. Drivetrain
  3. Engine
  4. Suspension
  5. Trim

1. It’s not the size but how you use it

Size is off course the first thing that first came to mind on most people buying a car. Because we humans rely on first impression to an extent, and visuals are the first sensory tools we use to judge something. However size is not everything, as you can see in this comparison.

*in Milimeters/metric

When looking at the dimension specification of the car, we need to be careful not to be deceived by numbers alone, external size is never anything. Take for example; front and rear bumpers, they too account for the car’s overall length, but does it contribute to the car’s interior space? Definitely not. The same goes to the width and height of the car. Sometimes, manufacturers also input body claddings and roof rack to the car’s dimension, creating a sense of a bigger car on paper at least.

What we really need to take into consideration really, is the width, height and the wheelbase of the car. Width and height usually will not be that much different even with the extra body cladding and roof rack, and wheelbase indicates the space between the wheels, the space where most people sits in. After all, most people bought minivans to move people around not just cargos, so it’s important to have long wheelbase.

Judging by the numbers, the Freed has a slight advantage here. Honda Freed is the widest (only by a hair compared to Nissan though) off the bunch, offers relatively high ceiling that makes seating inside the car relatively “roomy” (applicable to APV & Luxio too) and for having the longer wheelbase for that extra leg room. As such the Freed offers the best theoretical passenger comfort compared to the others. On the cargo side, Nissan Grand Livina is clearly the car of choice for its extra length. Thankfully, Grand Livina extra length is not just a long bumper, and combined with the fact that the third row seat can be folded flat, offers good cargo space. The Freed, Avanza, Luxio and APV Arena all offers flat floor cargo space and better vertical space, but for practicality, people seldom stacks their cargo, they just throw whatever they bring into the cargo bay and scoot.

2. Which wheel drives the car again?

2.1.Proper chariot has its horse in the front

Before we talk about the car’s engine, let’s talk about their drivetrain first because for some this is the most important matter when purchasing a car. Drivetrain is the sum of all things mechanical in a car; it is the sum of all things that finally moves the car, or in lament term, which wheels drives the car. Now in this comparo, we have two distinct drivetrains, the front wheel drive and the rear wheel drive.

Honda Freed and Nissan Grand Livina are both a front engine front wheel (FF) drive cars. This type of drivetrain is preferable when building a passenger car. Thanks to front wheel drive car engines, transmission and axle are all contained in the engine bay, the space between the dashboard and to the rear trunk is maximized for the driver and the passengers. Also, for not having a rear axle, rear passengers can enjoy a quieter drive as they cannot hear the axle spinning like on rear wheel drive cars.

On a side note, FF cars also have better fuel economy from comparable cars. Some has cited that there are inertial forces in play on rear wheel drive cars because of the long axle. However this notion is unproven. What has been proven though is that yes rear wheel drive cars usually have slightly worse fuel consumption, but not because of the axle inertial force, but more because rear wheel drive system is heavier than a similar setup on a front wheel drive system, thus more energy (more fuel burned) is needed to move the system.

All seems perfect, except for one thing. FF cars driving wheel is of course, on the front and given most car shape, when it is fully loaded with passengers and cargo, the car tilts rearwards, reducing front grip in some extreme situation. However, do not be worried, thanks to uncle Newton, car engineers knows this “seesaw” phenomenon. That’s why through suspension engineering, most FF cars are designed to “ignore” the extreme weight on the back of the car. The body of the car might seemed to tilt rearwards when fully loaded, but the whole body of the car also pressed the front suspension through calculated weight distribution.

On a side note, I remember strongly some “interested party” tried to discredit Nissan Grand Livina when it was launched in Indonesia with strong positive acceptance. There’s pictures floating around the internet and one youtube video depicting Nissan Grand Livina incapability to climb steep grades compared to the competitors (all are rear wheel drives). Still though, the picture and video is valid but there are telltale signs that it was staged. It can be seen clearly on one picture that depicts Nissan Grand Livina loosing traction while going up on a ramp, shows that the rear suspension is awfully compressed, a sign that the car is loaded with something heavy in the rear.

One simple solution… Just distribute the passenger weight evenly; heavy people sit upfront while lighter people seats in the third row. Gravity will do the rest and keep the nose of the car planted to the ground and feeds steady traction to the front wheel.

Other report indicating that front wheel drive cars inability to climb steep grades sometimes border the unintelligent and just demands a little bit of consideration. Most cars are designed with specific purpose in mind; you just can’t have it all. FF cars are designed for comfort and you just cannot take it on a 20 degree slope hill climbing track… Something that we Indonesians encounter frequently outside the capital.

2.2.Im’a going to push you to the top

Then we have the rear wheel drive system, the go to drive system for sports cars and heavy haulers like trucks. On paper, the rear wheel drive system is a blessing. Because the driving wheel is the rear, you can just load the car with everything you wanted and the car will never lose its grip… so to speak… More weight equals to more traction as more weight is pressing down the driving wheel. Sure the car still tilts rearward, but climbing up fully loaded, rear wheel drive cars are king of the hill (unless you have bald tires or slippery road).

So what’s not to like on rear wheel drive cars? It’s their inefficient space eating setup that’s what, and the noise. Rear wheel drive cars need an engine, transmission, driveshaft and a rear axle. Unlike front wheel drive cars where all of that mechanical parts are located in the engine bay, common rear wheel drive mechanical parts extends from the engine bay to the rear of the car through the cabin. People sitting on the third row are going to hear the axle spinning in the same rhythm of the engine; couple that with skimpy sound deadening, it’s going to make one noisy ride.

Luckily, Toyota Avanza, Daihatsu Luxio, and Suzuki APV Arena designers/engineers put interior space for passenger as the first priority and thus you won’t find the regular “bulge” that usually ran through the front dashboard to back, literally slicing car interior half and half on rear wheel drive cars. But they can’t just defy law of physics and designs… That driveshaft needs space, and what Toyota, Daihatsu and Suzuki engineers did? They raised the floor of the car.

Raised floor gave Toyota Avanza, Daihatsu Luxio and Suzuki APV Arena ace cards to fight evenly with the front wheelies. For one, the raised floor means flat floor in the interior of the car. This raised floors also gave the cars tall ground clearance, great for undulating and pothole ridden roads. However, tall ground clearance also has its drawback, and mainly in the driving dynamics department. Tall car + tall ground clearance = wobbly driving. It’s plain physics, you take a sharp turn, and you’re going to feel the whole car felt like it’s going to turnover on itself. Inertia came to mind, but this is a very extreme example, and joe dad is not going drive fast and furious on these things anyway.

On a side note, APV Arena and Daihatsu Luxio have their engines smack dead under the front seats. It makes the car having a good deal of space because less space is used from the total length of the car for engine. However, because the engine is inside the cabin (so to speak), you’re going to hear the engine more noticeably than cars with proper engine placement. Sound proofing only involves firewall, sound proofing material, the seat and literally your posterior, while front engine cars have firewall, sound proofing material, glass, and metals between your leg and the engine.

The other problem having the engine under your seat means that the seating height is fixed. Sure you can slide the seats front and back, and the back support still reclines, but you can’t adjust seat heights. Having the engine under your seat also means the seating position is raised somewhat.

So how the numbers stack up? The Freed tall cabin and low floor (thanks FF) makes for a very good and comfortable people mover but Toyota Avanza is definitely the go to car for a good hauler (passenger and cargo).

3. A strong heart and a stronger brain

When we talk about cars, we never talk about just the size of the car and the drivetrain, we also talk about the power and how that power is used. Old engines are bad jokes compared to modern engines. Back then, a 100 horsepower engine comes only from big thirsty engines, now look where we are now. All the cars here are mostly 1.5 liters in size, and all but one have more than 100 horsepower. One special engine here is Grand Livina’s 1.8L engine. As the biggest it produces the highest power and torque rating, so for fairness, the engine will not be compared here. The same goes to Avanza 1.3L for being the smallest.

One engine that stands out from the rest of the pack is the 1.5L i-VTEC engine powering the Freed; With 118ps, it is the most powerful engine in its class. However, I have to be objective here and as such, I cannot just mention Freed engine as the most powerful without any catch. Freed 1.5L engine is the most powerful, but with some slight sacrifice.

Horsepower is the result of engine torque times engine rotation or torque x RPM = horsepower(ps/hp/kw/dk/etc). Freed large power comes from a high revving marginally low torque engine. Take for example, Nissan Grand Livina 1.5L engine; it is not the most powerful, but its maximum torque of 148 Nm came out at a lower point of 4400 RPM compared to Freed’s 146 Nm at 4800 RPM. The result is the same though, Freed’s engine still deliver the hardest kick but the driver needs to punch the gas pedal more, resulting in more noise from the engine. Some might call Honda high revving engine characteristic as a weakness, but as a matter of fact, it is Honda trademark high points. Honda engines can spin at high revolutions because they can and willing. Enthusiasts like Honda engines because of that specific characteristic.

For any engine there is the accompanying transmission, and here where the Freed once again distanced itself with the rest of the pack. The Freed comes standard with a 5 speed automatic gearbox, and one of the more feature packed automatic gearbox available in the market. The 5 speed alone gave a huge advantage for the car as the wheel can spins at higher speed than the engine, increasing fuel efficiency at constant speed, not to mention it’s unique because all other cars in the comparo only have 4 speed automatic box.

There are other features on Freed’s gearbox but most are insignificant on daily driving, however, the most important feature is the Grade Logic Control (GLC). The GLC enables the Freed to ascend and descend climbs with the right gear. Conventional automatic gearbox occasionally downshifts when car is climbing a grading surface, but most often than not, the gear just don’t know what is going on and just holds the gear. If the gear held is a lower gear, then it’s fine, the engine can spins at higher revolution and push the car forward. But when it’s a higher gear that is held, the car would just slows down going uphill and the transmission would just suddenly shifts to lower gear and jerks the car. It’s not that bad, but it’s going to disrupt the comfort of the passenger.

Now that we have talked about the engine and the transmission, let’s put the engine number where it counts… The power to weight ratio. No matter how powerful your engine is, if the weight of the car is just too heavy, it’s going to affect the performance directly. The ASEAN built Freed doesn’t have specific weight, but going through Singapore Honda website and Japan Honda website, the Freed weighs in at a hefty 1330 KG of weight (dry), quite heavy for a 1.5L engine to pull. But let’s put the numbers where it counts here.

By dividing the dry weight of the cars with their respective horsepower, we get power to weight ratio, how much weight per horsepower the engine have to move:

The Freed although came in at the heaviest still manages a good power to weight ratio, slightly bettering the Grand Livina. The APV Arena and Daihatsu Luxio (assumed same with APV because it shares same drivetrain setup) scores slightly worse because of their respective weight and low power engine. The best power to weight ratio award off course goes Toyota Avanza… Kind of a shocker really, never knew the Avanza could weigh that light, even the old Fit/Jazz weighs in at 1100 KG. Some suspect Toyota Avanza thin plating is to blame/praise for its lightness. Some blame it because the body plate can be dented with just a push, and some praise it because it gave the engine smaller mass to move and hence fuel efficiency. Half empty or half full, you decide for yourself.

With the numbers above, Freed garners a technical excellence for having a strong engine and an advanced automatic gearbox. But if those numbers are summed up, Freed theoretical performance is just above average, good but not the best. Toyota Avanza crazy light chassis makes for a spirited drive ever that much easier.

4. Sure footing for a comfy ride

Engine and transmission alone are not the hallmark of a good car. Specially for a people mover, the suspension plays a pivotal role and can be a deal breaker for some. However there are no special characteristics between the cars that garner special mention. Freed’s McPherson Strut and Torsion beam setup is the same with Nissan, and Toyota Avanza, Daihatsu Luxio and Suzuki APV arena shares the same McPherson Strut and rigid axle + shock absorber setup. The crazier thing is that… All of these cars suspension setup are similar to each other in real world behavior. The torsion beam on the Freed and Grand Livina behaves the same like a rigid axle because the rear wheels are connected through a torsion beam.

For how comfortable the ride is, it’s hard to tell. I am only a person without many experience tests driving a car (well outside Honda). But I can tell you that the Freed suspension setting feels a bit softer than second generation Honda Jazz but still on the firm side. Over uneven roads, I can feel the damper is working hard resulting in short “gliding” feeling on bumps. I can also feel more body rolling feeling compared to second generation Jazz, but it’s probably because of the extra height. Overall, it’s very much usual Honda suspension tuning, firm but assuring with a softer touch.

5. That extra special thing

We finally came to the final criteria, that extra special thing about the cars that makes people wants to buy it. Here’s a list of things on table format what each cars offered in terms of that unnecessary but “glad to have it” things:

When talking about nice to have things, Freed came out on top with the standard ABS, captain seat and optional power sliding door and airbags. However, people criticize the lack of rear air conditioner system on the car, especially for those who live near the equator like Indonesian, Singaporean and Malaysian. Thankfully, ASEAN spec Honda Freed all came with the captain seat as standard, thus the front air conditioner system is deemed enough to deliver cool air through the vacant alley way of the car.

6. That hard decision (conclusion)

6.1.The price factor

Finally it’s over. This is the part where I chime in with my opinion using all the data above. So do we have a clear winner after seeing all the category above? The Freed came out on top for prioritizing creature comfort with its front wheel drive system, tall roof, the advanced engine transmission combo and available amenities like the power sliding door, but is it enough? Because we haven’t talk about price yet.

On a side note, the trim level in this comparison are chosen to reflect Freed highest level trim, so it’s only limited to 1.5L engine and automatic transmission, therefore Avanza 1.3L and Grand Livina 1.8L trim line are excluded.

The Freed off course have the most expensive price tag here in this comparison; at 258,5 million Rupiah, the Freed literally towers over the competition in term of price. Even the second most expensive car in this comparison is Nissan Grand Livina at 188,5 million Rupiah, a 70 million Rupiah cooler. The rest of the pack mirrors Grand Livina price. Suzuki APV Luxury is priced at 185,5 million Rupiah. Daihatsu Luxio at even cooler 171,8 million Rupiah and Toyota Avanza (not surprisingly) comes with the most affordable price at 171 million Rupiah.

I might be biased towards Honda, but personally I feels that the Freed is priced just about right, with very slight tendency of being overpriced. Simply because the price increase is justifiable. Let’s compare Freed extra price with its nearest competitor (price wise), the Grand Livina: The Freed comes with a high revving powerful engine and advanced 5 speed automatic box, those alone might worth a 20 million in mechanical upgrade and assembly. The airbags costs around 10 million, and finally the power sliding door would cost up to 20 million by itself. Still, that’s only 50 million Rupiah advantage over the rest, perhaps the extra 20 million Rupiah is for Honda brand and the design of the car, which arguably stands above the competitors.

Why Honda put a premium price for the Freed is already stated at the beginning of this blog entry, and that’s Honda is emulating the bigger premium people mover like Alphard/Vellfire/Elysion. Freed is undoubtedly “the real real” (that’s two real) mini Alphard/Vellfire/Elysion. Freed’s captain seats and seating position is similar with its bigger cousins, meaning that getting in and out of the car is like going up or down a staircase. This means that if you have fancy suits or dress like a wedding gown/dress with fancy nancy skirt you can just get up from the seat and steps down without worrying much of that skirt will get too jumbled and tied somewhere. In a low slung sedan, the limited space and somewhat low seats makes the occupant need to grab the top handle to get out of the car (try doing that while holding wedding dress with fancy nancy skirt). This is why wedding services are upgrading their rental wedding fleet with Alphards, well, even premium taxi providers are preferring it over Mercedes C & E. This mini premium people mover notion is applicable to APV Arena and Daihatsu Luxio too. However, that engine inside the cabin just diminish the notion of mini premium people mover over the Freed.

Looks are subjective, but if I have to rate all the cars here, I would choose Freed at the top. The side panel lines and the front fascia is unique without bordering weird and excessive. Grand Livina is a close second, the front fascia is okay but the rest of the body design is vanilla plain. APV Arena are close third, the tall design works out okay, and the APV has a nice bulldog look to it. Fourth would be Avanza, looked utilitarian, simple but too simple and in the latter year models, too much accessories. The last would be Daihatsu Luxio, okay front fascia but very boxy looking.

On a side note, Honda Freed and Daihatsu Luxio comes with a sliding door which is both practical and comfortable. Sliding doors allows people to enter from any direction because there any doors obstructing the path. This means people can get in and out on tight parking space with ease, a very convenient method of entry/exit. However, sliding doors needs more effort to close/open. With conventional hinge door, you just need to “push” the door, with sliding doors, you need to “pull” the door which involves slightly more effort. That’s why Honda came with power sliding door for the Freed.

6.2.The best things in life is the freedom to choose

Coming down to it, choosing between Freed, Grand Livina, Avanza, Luxio and APV Arena is a matter of personal preference, needs and emotional decision:

  • If you need a driver car, Nissan Grand Livina is the best pick of all; although the car has relatively high ground clearance, Grand Livina doesn’t have the extra height compared to the cars compared here. Body roll theoretically will be minimal, and if you got 209 million Rupiah, you can get the 1.8L engine good for burning rubber and tire on the highway. Just remember to distribute weight evenly.
  • If you need an all rounder, Toyota Avanza is the best choice bar none, its light body exemplify great power to weight ratio and rear wheel drive is great for hauling cargo. Thin plating are non problem if you don’t mean to ram cars in front of you.
  • If you’re low on budget, Daihatsu Luxio is a great car to have. Captain seat, rear aircon and rear wheel drive makes the car a good all rounder on budget. That and if you don’t mind seating above an engine.
  • If you want presence, Suzuki APV Arena Luxury comes with loads of it. The Luxury trim line comes with a 17” rims, and the bulldog design is both macho and ooze a little bling.
  • If you want engineering excellence and comfort, Honda Freed is a great choice. Power sliding door makes you looked important on any shopping complex lobby, the captain seat is comfortable, and the overall design is subjectively the best. Just make sure you appreciate its high revving engine nature.

Update: 1st May 2010: Sugar coats

Source:

Daihatsu Luxio Specification

Toyota Avanza Specification

Suzuki APV Specification

Honda Freed Specification

Nissan Grand Livina Specification