: Q. for anyone who knows re: FWD N* - Why Transverse?



JimHare
07-20-04, 02:33 PM
Well, the title kinda says it all..just wondered why it was decided to turn the N* sideways. Is it because a transverse V8 is easier to adopt to FWD?

That's the only reason I can think of, it just seems that you lose a fair amount of energy when you turn that driveshaft this way 'n' that to get power to the wheels...

I suppose in the new RWD models it's twisted back the right way???

:hmm:

RLLOVETT
07-20-04, 03:13 PM
Fits in better that way--more room for passenger compartment on shorter wheelbase...having always opposed FWD cars on principle I have to say my Eldorado is excellent in snow and ice. I still prefer being pushed by my car rather than pulled plus the serviceability of RWD is superior but it's like saying you like fins on cars...

JohnnyO
07-21-04, 10:10 AM
:coolgleam Transverse mounting in a FWD car takes up less space. Also the transmission design may be simpler then but I couldn't say for sure. The old-school Toronados and Eldorados were FWD with a front-to-rear mounted engine, but that was back in the bigger-is-better days when nobody cared about weight or fuel efficiency.

elwesso
07-21-04, 05:18 PM
The definitely do increase interior space..... They can really cram a LOT in the enigne bay (mechanics nightmare), and there are less parts... Instead of having a rearend, the final drive is in the tranny (making it a transaxle)...

RLLOVETT
07-21-04, 08:24 PM
On the contrary--the transaxle is MUCH more complex than the transmission/differential setup of yesteryear. But the advantage is in manufacturing cuz they can set that engine/transaxle up and drop it in in one fell swoop and be done. A nightmare ESPECIALLY for DIYers...

brougham
07-29-04, 06:24 PM
Intrepids and LHSs and other front wheel drive Chryslers like that all have their engines mounted the normal way. Just thought I'd throw that in :)

RLLOVETT
07-29-04, 06:55 PM
Interesting, cuz I assumed ALL the FWD cars had the transversely mounted engines...

JimHare
07-30-04, 03:03 PM
If there's no need for a driveshaft back to rear wheels, why does my Deville still have that hump running down the middle of the passenger compartment? Is it just there for the console box and rear seat ventilation vent to sit on?

I guess if you think about it, you can come up with all sorts of interesting observations. I've had several 4 cylinder FWD cars, and they were, to the best of my recollection, all transverse mounted - a 76 Honda Accord, an 81 Chrysler Laser (Turbo), and an 85 Isuzu Impulse, also turbo. The last two had their engines cocked way off kilter as well, to keep the t/charger mechanisms lower. I may be wrong about the Accord engine, can't really remember.

I assume the N* in the new RWD configurations is bolted in the "regular" way?

Mikethegreeat
07-30-04, 07:23 PM
that hump in your FWD deville is to house the Exhaust pipe..cat etc...i asked the same question a few years back...and finally found out when i put my car on a lift ... ;)

RLLOVETT
07-30-04, 07:27 PM
The concept of 'unibody' or monocoque frame construction goes hand in hand w/ the FWD: the body IS the frame (unlike the traditional 'body on frame' construction, with a ladder-like frame). So that hump down the middle is there to add strength to the body, which is the frame. My 94 Eldo was apart recently for HGs (head gaskets) and it was amazing to see the cradle in which the engine lives dropped completely out, leaving only the painted body (no frame rails) and rear suspension...kind of ironic that we lost the drive shaft but still have to have that hump robbing the interior of legroom. I will add that in the dinosaur days of FWD (early Eldo, Toronado) the hump was pretty minimal.

JimHare
08-03-04, 11:53 AM
Yep - confirms my thoughts, esp. w/regard to the unibody - adding a nice "bend" in the floorpan probably adds strength and reduces diagonal twisting. Thx guys....

Anthony Cipriano
08-03-04, 03:12 PM
You could write a book on the advantages/disadvantages of transverse vs. longitundinal engine mounting, FWD vs. RWD, transaxles vs. rear axles and driveshafts, etcetera.

About the only statement one can positively make concerning the various arrangements is that there is no single "best" powertrain arrangement for all applications. There are so many factors that must be taken into account for the vehicles in question that there's just no single one way of doing it that fits all applications.

Generally speaking, with passenger cars, front wheel drive is nice because it concentrates all the powertrain in the front of the vehicle. This provides pluses for packaging, driveability (traction) in inclement weather, assembly, cost, mass, etcetera. Since the structure of the vehicle that is supporting the heavy bits (the engine, transmission, driveline) with the FWD arrangement is all at the front the rear of the car doesn't have to have the heavy structure and mounting assemblies associated with the loads of RWD. This allows the vehicle to be made lighter - and lighter equals fuel economy. Mounting the engine sideways parrallel to the transmission and driveshafts eliminates the right angle gear drive necessitating a hypoid style gear set that has high frictional losses - more fuel economy gain.

To the vast majority of drivers any "handling" advantage of RWD in a passenger car is mostly in their heads. The FWD cars are unquestionably better in rain, snow and ice and are inherently more stable in slippery conditions as wheel spin manifests itself as relatively benign understeer rather than sudden oversteer as with RWD. Otherwise, on dry pavement 90% of drivers in 90% of driving conditions cannot tell the difference between FWD and RWD. Admittedly you will never see a FWD F1 car but that's not a passenger car on real roads in the real world.

Since trucks have frames out of necessity to carry heavy loads (on occasion) the issue of the structural savings with FWD is negated. Similarily, when trucks are loaded or have trailers attached, the traction advantages of FWD dissappear quickly and become a detriment - unless you get the rear wheels on the algae on a boat ramp. Then the FWD car is still pretty competitive at pulling the boat out of the lake. Not likely that you will see many FWD utility vehicles with transverse engines because of this.

There are many other examples but the point is that there's no single "best" way of mounting the powertrain. Each specific vehicle has use and performance requirements that dictate which drive train arrangement to utilize for best utility. Regardless, there are compromises in each way so each vehicle just has the compromises biased in it's favor to do the best job.

One minor point that does apply to transverse and longitundinal mounting of the engine for FWD. As mentioned there are FWD cars with both setups. Since the transverse arrangement does take up considerable space between the front wheels it has the net impact of limiting the turn angle of the front wheels which will eventually dictate the slow speed maneuverability of the vehicle ie. the turning radius. This is important to city drivers and for parking and maneuvering in tight places. Transverse FWD cars typically cannot turn as sharp as longitundinal FWD or RWD cars - all other things being equal. This feature also eventually limits how wide a tire can be mounted on the front wheels, too. For a good comparison, a GMC Envoy will turn much sharper than a Deville due to the different driveline arrangements even though both take up about the same space in the garage. With the inline 6 engine (narrow) and RWD the Envoy has a much tighter turning radius even though it is perceived to be more "truck like" than the car.

None of these things are absolute positives are negatives making one "best" or "worst". Just different characteristics illustrating different ends of the compromise that is built into every vehicle.