It's suspension walkaround time for our 2008 Ford Focus SES Coupe. And not a moment too soon, because its time with us is fast drawing to a close.
I have mixed feelings on the subject because the chassis of the Focus has always been one of it's strongest selling points. It's always been a sound-handling compact car, and even though its suspension tuning has grown soft over the years, I'd still take one of these over a Toyota Corolla.
As long as I don't have to look at it, that is, as the styling and level of interior trim isn't what I want to see in my driveway. But we're straying off topic. On with the show.
I'm starting with the front brakes today because I simply like this picture. And it doesn't need any arrows because this sliding brake caliper's single piston stands out like a sore thumb.
Zooming out, we can see that the Focus utilizes a MacPherson strut (white) and an L-shaped lower control arm, just like most other front-drive compacts.
Looking from behind, you can see how the stabilzer bar (yellow) loops over the steering rack. Said stab bar connects directly to the strut housing via a long link (white).
There's a lot going here. You may have to scroll up and down a couple of times.
You've heard me talk about why front-drive cars with a transverse-mounted engine and transmission (white) must use a rear-mounted steering rack (black). There's simply no room to do it any other way, as you can see.
You've also heard it said that front-drivers are inherently prone to understeer. It's not simply that the engine is mounted in front of the driver and because of front-biased weight distribution. It's also because the heavy lump that is the engine and transmission assembly sits ahead of the front axle, which makes for a bad polar moment of inertia. That said, this layout still works well for civilian vehicles that aren't raced or otherwise driven on the limit all their lives.
We can see all of this easily because the Focus does not use a "perimeter" front subframe that encircles (or cradles) the engine. Instead, the Focus uses a solid-mounted front subframe (yellow) that extends no further than necessary to locate the lower control arms, a move that offsets some of the front weight bias.
The engine and transmission hang from two large bushings, one on each frame rail inside the fenders, while a torque link (light blue) prevents the engine from rocking overmuch when torque is applied (ie: when you mash the gas).
Finally, we come to the ball joint. This type of riveted attachment is a nod to service because you don't have to replace the entire arm when the ball joint goes bad. Instead, you drill out these three rivets. The replacement ball joint will come with three same-sized bolts for an easy swap. I've done this on my own cars a couple of times, and it's easier than it sounds if you have the tools.
Here's another view of that "torque reaction" mount (yellow).
We can also see that the Focus' transmission uses a jackshaft that makes it possible to use equal-length drive axles to reduce the tendency for torque steer. This isn't actually common in 4-cylinder applications because it costs more money.
At one point Toyota and Hyundai (and most others, to be fair) only used such a set-up in V6 applications on the basis that 4-cylinder engines don't make as much torque and 4-cylinder cars need to be less expensive. Instead, one long axle is used on one side and a shorter one is used on the other--a recipe for torque-steer, but only if you have enough torque.
Not much to see here but 25,000 miles of grime and a coil-over strut.
We're back where we started. If you're changing brake pads, the two black bolts are where you want to start. Need to change rotors? Then the two yellow bolts (yes, there is another one higher up) need to be removed because the entire caliper has to come off to get the rotor off. You'll want to hang the caliper from a zip tie or a coathanger looped through the coils of the spring so you aren't tempted to crack-open a hose fitting (and don't ever crack open a hose fitting).
We'll cover this in a DIY story soon.
The green arrow points to the single bolt that clamps the lower end of the strut to the knuckle. The strut has a little ear that slides into that gap, then the bolt goes through it to keep everything aligned.
Moving on to the rear, we see what Ford calls "control blade" rear suspension. I don't know if they actually invented it or not, but it worked so well on the Focus and the Mazda3 that it began to appear elsewhere after certain companies "benchmarked" the first Focus.
Basically, "control blade" a particular flavor of multilink that uses a tall yet skinny trailing arm (white) that can handle all of the torque loads and define the vertical motion axis on the wheel all by itself. Lateral loads and the camber and toe curves are therefore the sole responsibility of the remaining three lateral links (green, yellow, black). The control blade is thin enough that it can flex a bit to allow the links to swing through their arcs without binding or fiction. It's a very efficient arrangement with a clear separation of duties among the parts.
The lower controls arms are different lengths. As the suspension compresses the forward link shortens more than the rear link as they swing through their respective arcs, and that generates a little extra toe-in as the outside tire compresses under cornering loads. This slight increase in dynamic toe-in is beneficial, because that generates roll-understeer, a desireable stabilizing characteristic.
The longer rear arm has an eccentric cam on the inner pivot to adjust static toe-in on the alignment rack.
The small yellow circles show that the spring works on a 0.67:1 arm ratio, while the stabilzer bar (light blue) is saddled with a fairly inefficient 0.33:1 (or thereabouts) arm ratio. But the packaging is quite compact and efficient this way, so the trade-off is probably worth it.
Here's another view of the same links. It's also easy to see that the rear shock absorber (white) bolts directly to the knuckle for a 1:1 motion ratio. And this makes the shock valving as efficient and precise as it can be, which in turn allows a smaller-diameter shock to be used.
The knuckle is quite interesting, because it's formed from the same thin flat piece of steel that makes up the "control blade" itself. It's all one piece, in fact, and it's quite a nice piece of work. Because it's so thin, it's probably as light as any forged aluminum knuckle would have been.
Here's another view of the blade and the thin cross-section that prevents it from fighting with the links as they swing through their arcs. The main pivot bushing and its two mounting bolts are just barely visible in the dim shadows.
Here's another clever detail: The rear subframe mounting bolts are centered smack-dab in the middle of the springs. Not only is this a clean design, it means the springs act in-line with the frame rail beyond, and that means this subframe doesn't have to deal with off-center loads.
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Tucked away in a corner is the bump stop, which is made of rubber. The witness mark above shows where it makes contact, and the span between gives you some idea of how much suspension travel this design provides. It's actually a bit more than that, because the pivot sits outboard of the bump stop, and the bump stop itself will compress 40% or so.
That's about it. To sum up, the Focus is an inexpensive car, but that's not to say someone (more like several someones) didn't put a lot of thought into the suspension. It's too bad the body that sits atop it all hasn't been given the same attention.
I don't know about you, but I've always been someone who would rather have a nimble compact car than something larger, and that hasn't changed as my career has progressed.
But I want my small car to be well-appointed inside, with a higher grade of materials and a longer options list than this Focus. That's exactly the kind of Focus that Ford sells in Europe, and I'm holding out hope that we don't get short-changed when they finally bring that Focus over here in a couple of years.
I'm crossing my fingers.
Dan Edmunds, Director of Vehicle Testing @ 25,059 miles
7driver says:
10:33 PM, 07/29/09
Great job again, Dan. The front suspension is about as mundane as can be. I've seen pretty much the same thing a bazillion times on FWD cars. However, the rear is quite inspired for a cheap compact.
saxdogg says:
10:34 PM, 07/29/09
Nice job on these...
dalaw says:
12:25 AM, 07/30/09
That oil filter looks like piece of cake to remove with minimal drip.
hondacura4 says:
01:36 AM, 07/30/09
Edmunds, whats the next compact LT vehicle? Mazda3 sedan perhaps?
bodyblue says:
06:50 AM, 07/30/09
Great post Dan. As you know building cars is a trade-off. It seems the Focus has the money well spent even if you dont think so. If Ford brought over the Euro-spec Focus it would cost more than a Fusion and what sense would that be? All in all the Focus is a well built and designed and INEXPENSIVE small car and that matters a lot these days. Like it or not it has been a huge godsend to Ford.....it had a good product that sold for a low price in large quantities at a time when Ford most needed it. Chrysler would be on its knees begging for such a product to sell. For the money it is almost impossible to beat.
joefrompa says:
07:03 AM, 07/30/09
Dan,
I think the new Mazda 3 is basically Ford's premium compact version for the states. I'm dying to test out the new mazdaspeed 3 when it comes out. I've sworn off FWD cars for the future, but that might make me come back.
Great review overall, and I'm impressed with several of the thoughtful details. The ball joint rivets I would've never guessed....who knew that DRILLING OUT fasteners was part of a planned replacement part, lol.
The only thing I don't like is the exposed oil filter. It's great for keeping the oil cool (and therefore engine longevity) and for oil change jobs, but it's such a sensitive part to be so exposed. Not that I expect this on a lower-priced vehicle, but my Subaru Legacy GT has a great solution.
The plastic undersiding that controls under-car air flow has a access panel with 3 pop-it screws and the label "oil filter" on it. You pop the 3 screws out, rotate the access door around the 4th pivot point, and then access the oil filter easily (and you can use a big, red, plastic cup to un-screw it and catch all the drip-off).
Protects the oil filter, manages air flow, and looks good doing it.
Joe
foxtrot685 says:
07:44 AM, 07/30/09
@ bodyblue, the world focus was supposed to be built here in the states i thought. they would all ride on the same platform but be built in or close to the countries they are sold. like we would build our focus here in the states, europe would build theirs in germany, asia would build theirs in china but it would still be the same car worldwide. if this is the case, it will help keep costs down. and with the fiesta coming soon, those who will think the focus is a bit too pricey (im thinking a base msrp of $15k-$17k) the fiesta will be the entry level car. the reason the focus is inexpensive now is because it is the entry level car, so it has to be inexpensive. the trade off for this is you have to keep the cost to build down... hence the lower quality plastics. if they brought the euro focus over now and it had a starting price of $17,000 no one would even look at it because theyd say "oh, thats too much money for a ford product" and ford knows this. i believe this is why they are introducing the fiesta first and then the world focus
sylvia says:
08:06 AM, 07/30/09
Thank you for the coverage - very interesting!
msdaisy says:
08:08 AM, 07/30/09
"This type of riveted attachment is a nod to service because you don't have to replace the entire arm when the ball joint goes bad."
So...does Ford plan for that part to go bad?
joefrompa says:
08:17 AM, 07/30/09
They go bad on almost everycar, especially in the snow belt. Just too much exposure to movement + wet + salt + snow + temperature fluctuations.
Some go bad sooner, some later. But yes, it's a replacement part.
roadburner says:
08:23 AM, 07/30/09
"I've sworn off FWD cars for the future, but that might make me come back."
It would be nice if if the new MS3 had the Revo Knuckle system like the Focus RS. Car, EVO, and Performance Car all love the RS. My MS3 is almost certainly my first and last FWD car, but I may consider the new Focus RS if Ford doesn't soften it up to suit the mediocre tastes of many US vehicle operators.
As for oil filters, the only setup that is better than Subaru's is a cartridge filter mounted under the hood.
joefrompa says:
08:52 AM, 07/30/09
Yeah, I had the catridge filter too....that was pretty sweet. I've heard that many owners of e39 BMWs will just drain the oil via a vacuum pump through the oil fill hole and swap out the catridge filter. No jacking, no fuss, no mess.
I'm so torn with all the wonderful options out there...
roadburner says:
09:03 AM, 07/30/09
"I've heard that many owners of e39 BMWs will just drain the oil via a vacuum pump through the oil fill hole and swap out the cartridge filter. No jacking, no fuss, no mess."
That's exactly what I did on my wife's old 528i. Her X3 sits high enough that I can reach the drain plug without jacking it up.
actualsize says:
09:17 AM, 07/30/09
@bodyblue: I understand you point, but I also agree with foxtrot. Ford's current Focus strategy forces those who want a high-content compact car (like me an a LOT of west-coast folks) to look elsewhere.
And that leads them to Japan and Europe, because those companies' home markets have had high fuel prices and narrow roads forever. Consequently their compact cars are not conceived as an entry-level concilation prize for those who can't afford something larger. People with money actually choose compacts in those markets (and to a certain extent the west coast) because they fit their lifestyle and the physical driving (and parking) environment.
And as the new higher CAFE regulations kick in, Ford and others are going to have to sell a lot more small cars. The appeal factor (level of interior trim, high-tech options) has to go way up from where it is today to pull that off. Hopefully the new Fiesta/Focus strategy that Foxtrot touches on plays out that way.
bodyblue says:
09:48 AM, 07/30/09
@actual.....
I agree with both you and foxtrot...but my point is that the Focus has been exactly the right product for Ford at the right time. It will have to change as the market improves of course, but when the new model came out many of those in the car media did not think much of it. But the sales numbers and the reliablity of the platform cannot be argued with.
kingkhalas says:
10:20 AM, 07/30/09
This car has a lot of rust.
bc1960 says:
10:21 AM, 07/30/09
The "American" Focus was the European "premium" Focus when it was introduced, and it didn't sell very well, especially compared to the cost of offering all the different body styles. Since reducing the line to two styles that compete directly with the Cobalt, it has been relatively more successful. It's behind the times compared to what Europe gets--but I think Edmund's test shows it's still competent compared to most of its domestic, Japanese, and Korean competition, except the very newest, and that frequently happens when vehicles at the end of their lifespan are compared to ones just introduced.
I wouldn't buy this car, you wouldn't buy this car--but enough people are buying it, and style points for producing "better" cars the market rejects don't earn you profits. Ford may get lucky with timing by introducing the next Focus when the economy is improving, fuel prices are much higher in real terms than they were in 1999, and more people are willing to consider a small car with more premium features.
actualsize says:
11:56 AM, 07/30/09
@kingkhalas: Well, the unpainted front knuckle, made of iron, certainly has some, as does the ball joint and the drive axles. But, unlike the challenger, the painted parts seem to have a sturdy coat of paint with no rust spots peeking through.
greenpony says:
02:41 AM, 07/31/09
Why not bring a more well appointed Focus to the line by making it a Mercury, like the Escort/Tracer line?
naimmecheng says:
10:42 AM, 08/ 3/09
Very informative article. Ford will be lunching the all new World Focus in the next couple of years. There will only be one focus sold in all markets including North America. I would like to see the suspension set up on the AWD Ford Fusion.
wjtinatl says:
10:53 AM, 08/12/09
Nice work on the photo's and descriptions. Although I find the current Focus to have very uninspired exterior and interior styling, I can attest that they a very sturdy little cars. I have an '03 SVT 3dr that is great driving as well as the cheapest car to own that I've ever had. At 70k miles, it has had nothing but oil changes and air filters. Original brakes, etc. Total maintenance over 5 years and 70k, $480, $1920 if you include 3 new sets of Dunlops! Tires don't last much past 20k, but I can put some blame on an enthusiastic driving style. And zero repairs outside of a new fuse for the gauge cluster when some careless handling of jumper cables resulted in a power surge. Would have been great if Ford had continued the SVT version of the Focus, but they never did sell very well and seem to be a pretty well-kept secret. Sure hope the next generation Focus is as reliable and efficient as this one, while upping the drive and comfort experience just a bit.