Should Chevy Join The Chain Gang?

[MonaroSS]

Should Chevy Join The Chain Gang?



Op-Ed by MonaroSS
GMI Contributor - 24 Oct 2009

As can be seen above, one of the oldest forms of sending power from an automobile's engine to the wheels is the Chain Drive. And today superbikes, sportbikes and racing motorcycles still use Chain Drives instead of the shaft drive because it is lighter and drains less energy.

Now we all know that we enthusiasts want RWD vehicles for their fun dynamic qualities and the accountants want FWD vehicles for their improved fuel efficiencies. And we have debated whether FWD is more fuel-efficient than RWD, but we do know this, that one of the energy consumers is turning power through 180 degrees via the pinion and ring gear in the rear differential. And if you have an AWD transverse engined car then you also lose power with a second pinion and ring gear at the front diff where the rear drive shaft takes off power for the rear wheels. That is why most AWD vehicles revert to FWD when cruising, so as to cut those power losses from the drive train to the rear. The other thing that the accountants have on their side is the economies of scale due to most small/medium vehicles today being transverse FWD, which means the component sets and the build costs are lower than RWD.

So here is my thought. What if you took a car like the Chevy Cruze and left it with it’s transverse engine/gearbox layout (for economy of scale) but you deleted the front diff and FWD drive shafts out to the front wheels? What if instead you replaced that front diff with a sprocket from which a Chain Drive took power back via a modern chain to a rear diff which had it’s ring gear replaced by a sprocket?

What you have is a RWD vehicle that does not lose power through trying to turn it 180 degrees a couple of times, and is as energy efficient as a FWD drive train. And which uses cheaper FWD engine/gearbox sets. The other thing you get is that now the front wheels are not driven so you get to push the front wheels further forward in the Cruze for less overhang and better weight distribution. Just as GM did with the Camaro platform, where they left the engine/gearbox of the Commodore/G8 where they were but lengthened the front frame and moved the wheels forward.

So I hear you ask, if this is so advantageous then why don’t carmakers already do it? Well in fact in a way they already have. Below (see pic) GM’s first FWD cars had Chain Drives, also many transverse gearboxes in recent times and today still use Chain Drives. They just don’t use ones as long as I’m suggesting.

Above - GM Chain Drive on Eldorado/Toronado. Below - GM Chain Drive on V6 Fiero

One downside of chains over shaft drive is lubrication and dirt and chain tensioning maintenance. So unlike motorbike chains these Chain Drives would need to be fully enclosed by a plastic chain cover box with oil scavenging and have an automatic chain tensioner. The other downside is more noise. That Fiero Chain Drive in the pic above is about the size of the chain that would be used on Cruze, it’s just that the chain would be extended over 10 feet instead of 1-2 feet. But it’s not the length of chain that makes the noise, it’s where the chain engages the sprockets that generates the sound. So a long Chain Drive on a Cruze would create no more noise than the short Chain Drive on the Fiero. If it were a problem though, mainly perhaps producing droning on freeways, then one solution would be to put microphones at each sprocket and use active sound suppression via the car's own sound system emitting the same sound from the microphones, but 180 degrees out of phase as developed by Lotus Engineering, which cancels the noise out.

But I don’t think sound will be an issue. Just as Camaro can be built on the same line as G8, so too Chain RWD Cruze would be built on the same lines as FWD Cruze and sold as a cheap non-executive RWD GT sports sedan (something that does not exist today). Buyers wanting quiet cruising would buy FWD Cruze and those wanting the RWD Cruze GT would be more interested in a louder sporting sound from the exhaust and don't mind some mechanical sounds.

So why create a RWD Cruze GT on Delta II when GM is going to be making a dedicated compact RWD platform on Alpha? The answer is price. A RWD Cruze GT would be very much cheaper than anything built on Alpha simply due to economies of scale. Delta II already has an AWD version that has the rear diff, rear drive axles and suspension. Yes it may need beefing up with parts bin bits from EPII’s AWD rear set-up, given all the drive power goes to the rear wheels. But even if you put the 2.0 DI Turbo with 300hp in the RWD Cruze GT you don’t need to strengthen the body like you would if it were mounted in-line. A powerful in-line engine applies a lot of twist to the body but a transverse powerful engine only applies it to it’s immediate engine mounting system and the rear diff/suspension mountings.

Even as out of the box as this concept may sound, the engineering changes would be less than what it takes to make a Camaro Coupe a Camaro Convertible. From a marketing point of view the RWD Cruze GT, and a Monza GT Coupe version of it (with the same front and rear ‘face’ of the bread and butter FWD Cruze sedans) would bring some serious ‘cool factor’ to small Chevy’s. Especially as they could be raced in the fastest growing motor sport of Drifting, which is very popular with younger buyers.

Chevy Cruze GT
- CLICK TO ENLARGE -


Chevy Monza GT
- CLICK TO ENLARGE -




The chain runs in an air, water and oil-tight industrial grade plastic box connecting between the gearbox and diff.
The front sprocket is sealed off from the gearbox oil but the chain shares the diff oil
and is auto-tensioned electro-hydraulically for low maintenance and noise.

Well that is my commentary on how GM could use a Chain Drive if they wanted to create some cheap but exciting compact RWD sports sedans and coupes. What do you think?

[crm2019]

that monza looks freaking awesome.

[A Bum In A Bus]

I love it.

[mkaake]

I've got to be honest - I didn't make it all the way through your post, but I have a few thoughts...

a) chains in FWD transmissions are common... until GM brought out the 6 speed FWD transmission, all of their transverse trannies had chains. When the 6 speed was introduced, they moved away from chains to gears.

b) In general, gears are stronger than chains. For the torque you're talking about transmitting, hardened gears are the way to go...

c) Chains stretch over time, and have more mechanical points of failure. With a chain long enough to stretch to the rear area of a car, you're talking about many points of potential failure.

d) Chains cost more than gears... especially, again, chains long enough to reach the rear of the car.

e) Chain drives still have mechanical losses, tied to the quality and tolerances in manufacturing. I wouldn't expect to see any major improvements by using a chain drive vs. a traditional 'gear drive', especially at the tolerances that make economic sense in mass manufacturing.

Chains have their places, and they're still in use in your car - but these days, they're mostly regulated to turning cams underneath your front cover...

[rueben44]

Yes that coupe looks killer.....if it had quad coupe like doors then it would be out of this world. Also I like your drive train idea it doesn't seem like a bad idea on the surface. I have no technical knowledge so I can't go any further than that.

[PocoToro]

Quick thought............(no time spent on it)
Why not reconfigure some gears in a front wheel drive unit (turn the drive unit around) and stuff it all in the trunk ?? You should even be able to save the rear seats by having the engine behind the rear wheels. And name it Corvair

[jetstar63]

I''m not a fan of chain drive for vehicles with more than two wheels as it's not as strong, reliable, has higher maintenance, more noise and not as asthetically pleasing as shaft drive, (lacks symmetry).
How much power loss are we talking about? I have heard it before that the power transfer must be turned 90 degrees and thus takes more effort to drive, but ring and pinions work simmilar to a spur gear arrangement only that the ring gear is driven on the side as opposed to being driven on the end with helical teeth.
Using electric motors to drive the rear wheels gives designers more freedom to buid it into the drive system without the power losses and this seems to be the future drive system.

[MonaroSS]

Originally Posted by mkaake

I've got to be honest - I didn't make it all the way through your post, but I have a few thoughts...

a) chains in FWD transmissions are common... until GM brought out the 6 speed FWD transmission, all of their transverse trannies had chains. When the 6 speed was introduced, they moved away from chains to gears.

b) In general, gears are stronger than chains. For the torque you're talking about transmitting, hardened gears are the way to go...

Well if what you say is correct then GM FWD cars that used the 3.8 V6 and even the Impala V8 used chains and they all put out more torque than we are talking about with Cruze. And remember those 7-8 liter V8's in the FWD Cadillac’s ran through chains too, and they were not shy on torque.

Originally Posted by mkaake

c) Chains stretch over time, and have more mechanical points of failure. With a chain long enough to stretch to the rear area of a car, you're talking about many points of potential failure.

It is true that a chain is only as strong as it's weakest link, but how often do you hear of those GM transmissions failing due to a broken chain? As to stretching, an idler sprocket with a hydraulic auto tensioner can take up several inches of stretch and that would take a lifetime to happen.

Originally Posted by mkaake

d) Chains cost more than gears... especially, again, chains long enough to reach the rear of the car.

Perhaps so, but this is a trade off to get better mpg and efficiency. It seems that all new technology to get better mpg has a cost to it. But on a relative basis to the price of a car we are not talking huge sums.

Originally Posted by mkaake

e) Chain drives still have mechanical losses, tied to the quality and tolerances in manufacturing. I wouldn't expect to see any major improvements by using a chain drive vs. a traditional 'gear drive', especially at the tolerances that make economic sense in mass manufacturing.

Chains have their places, and they're still in use in your car - but these days, they're mostly regulated to turning cams underneath your front cover...

All the losses occur as the chain wraps around the sprockets. There is virtually no loss in the straight sections of chain, no matter how long they are. So a 10-foot chain would have the same loss as a 2-foot chain. And it is a fact that chains are more efficient than shaft drives.

[MonaroSS]

Originally Posted by jetstar63

I’m not a fan of chain drive for vehicles with more than two wheels as it's not as strong, reliable, has higher maintenance, more noise and not as aesthetically pleasing as shaft drive, (lacks symmetry).
How much power loss are we talking about? I have heard it before that the power transfer must be turned 90 degrees and thus takes more effort to drive, but ring and pinions work similar to a spur gear arrangement only that the ring gear is driven on the side as opposed to being driven on the end with helical teeth.
Using electric motors to drive the rear wheels gives designers more freedom to build it into the drive system without the power losses and this seems to be the future drive system.

You won't be able to see it so it's symmetry won't matter. Given it is fully enclosed and auto lubed and tensioned it will have virtually no maintenance.

Each ring and pinion has losses about 1 mpg, so a RWD is 1mpg worse than a FWD and an AWD is 2mpg worse than a FWD, as a rule of thumb.

Electric motors may be the future but as a transmission of power they save on mechanical losses but lose more on heat losses.

[ARCANGEL]

your ideas are intriguing and as always your chops outstanding!

[rsbaker]

Gosh that looks amazing! Whether or not the Engine/Tranny configuration was changed or not, A coupe with those proportions would certainly be a worthy successor to the Cavalier Z24 and Cobalt SS. A Monza Coupe and a Turbo Monza GT seem so obvious they'd be crazy not to do it. I'm still amazed to see what a difference racking the windshield back a few degrees makes on the entire look of the car. It has a dramatic affect making the hood look longer and lower. It actually makes the car look more refined and expensive You should definitely E-mail that photo to as many people at GM as possible!

Here is the Original lest we forget: 1977 Monza Spyder 2+2

[GM-Joe]

The Monza looks sweet!

[Hitman1970]

I will take that Monza as my commuter car in a few years, please. Fantastic job, Monaro SS. Again. Why aren't you a GM designer right now?

[Smaart Aas Saabr]

There are major cost, reliability, performance and packaging issues inherent to this kind of design. I don't see how it could be cheaper or more practical than just putting a prop shaft. Especially if the Cruze comes in an AWD model

[Edaw 0]

That Monza looks awesome!

Originally Posted by rsbaker

You should definitely E-mail that photo to as many people at GM as possible!

and multiple times


a day.