Undercover: Subcompact Vehicle Upgrades — A Reduction in 'Class Size' -

Undercover: Subcompact Vehicle Upgrades — A Reduction in ‘Class Size’

Over the next decade, it would appear that we will see a shift to smaller, lighter and more fuel-efficient vehicles, much like we experienced in the 1970s.

figure 1Back in the late 1970s, I went to work for a VW/Audi repair shop in Bellevue, WA. Within a year, I had pretty much replaced my entire fleet of personal cars with VW products of various types.

One of the first cars I purchased was an early Rabbit with the carbureted, 1.5L engine.

I got it cheap because the car didn’t run well, but after updating and sorting out the carb, the car was so much fun to drive that I started buying, fixing and selling them on a regular basis.

My favorites were still the air-cooled cars, but for daily commuting, in any weather, the water-cooled cars were more comfortable.

What made that early A1 Rabbit, and its competitors like the Civic, Tercel (1980), GLC and Subaru DL, so much fun to drive was the lightweight (right at a ton) FWD and a free-revving small engine that made power-to-weight ratios a performance standard.toyota’s yaris and its cousins — the scion xa, xb and xd seen here, offer the sub-compact market segment undercar performance modification opportunities.

Compared to the cars provided by American manufacturers, these cars felt like you “put them on,” instead of just sitting in them.

Like those early VWs, today’s Toyota Yaris (see Photo 1) and its sister vehicles, the Scion xA, xB and xD are tiny, lightweight vehicles.

And, with more than 100 horsepower, they, too, can be fun to drive. Performance, though might be stretching things a bit — or is it?

The models I listed above were all entry-level cars that didn’t really inspire performance driving, but after a little research I found that all were used in some form of at least amateur racing with some success. figure 2

The Yaris is used for racing in several types of motor sports (see Photo 2), but mostly in other parts of the world.

When I checked in with my friend, Charles Damewood at Z Sport (www.zsport.com), he said he didn’t know of any modified cars in our Seattle area.

After searching through websites and online forums, it is obvious that there is a following for these cars, just not so much in the U.S.

Small cars sell much better in just about every other country. That could all change as more and more sub-compact models are exported to the U.S. from Europe and Asia.

figure 3Asian models that are available here are the Honda Fit, Chevy Aveo (Daewoo built), Nissan Versa, Ford Fiesta and the Hyundai/Kia Rio/Accent.

Most of these cars come with both larger and smaller engines in other countries, and most are available with diesel power in other countries.

I feel that diesel may catch on again in the U.S., once we see the price of fuel rise and fuel economy becomes a larger issue. Turbocharged gas and diesel versions of the Yaris have been available in other markets, as well.

From the Front …

One of the things I especially liked about my first Rabbit was its simplicity. Strut-type suspension had been around for a while by then, but the strut suspension on the Rabbit was about as plain as it can get. figure 4

The Yaris is just as, if not more, simple than that car.

The front strut (see Photo 3) is nothing more than a coil-over shock, as the steering arm and lower control arms are connected at the separate bearing carrier.

Removal is a simple process of separating the strut from the bearing housing, disconnecting the link armfrom the strut housing (see Photo 4) and removing the upper mount from the body.

Everything else is standard practice as far as compressing the spring in a strut fixture and removing the shaft nut from the bearing plate.

Since these cars are so light, replacement of the upper mount will not usually be necessary. Although, if an inspection reveals any cracking of the rubber however, replace it.

Make sure the plate moves freely after reassembling the strut assembly and reinstall in reverse order. Note: When ordering parts, the struts are different side to side, so you will need to order a set, or individual struts for each side.

figure 5The difference is the shape of the spring plate and mount for the sway bar link.

There is very limited factory adjustment provided for alignment, other than toe adjustment at the tie rods.

Aftermarket camber bolts are available to allow for additional camber adjustment, but except for performance tweaking, if the alignment cannot be brought into spec, look for signs of body damage, subframe mount problems or other factors that would cause the alignment to change.

The front wheel bearings are standard, press-in duplex roller bearings. Be aware that the bearing is different, depending on whether the car has ABS or not.

The ABS sensor should always be removed before any work is done on the hub or bearing to prevent damage to the sensor. figure 6

The bearing assembly can be replaced with an on-car bearing press or the bearing carrier can be removed and the bearing replaced with a shop press. Removal of the bearing housing, however, will require rechecking the alignment, unless you are very thorough about marking the housing and strut relationship before disassembly.

The front sway bar is mounted behind the steering rack, (see Photo 5) between the front subframe and the body, so even replacing the bushings is labor intensive. The sway bar links are equipped with tie rod ends on both ends, so unless they are bent or the boots are damaged, they will probably last for the life of the car.

In researching this article, I did find an interesting TSB from Toyota dealing with the relationship between tires and alignment problems. If you come across any car with a lead, pull or control problem that isn’t readily apparent, this might be a good article to look up and add to your knowledge base. figure 7

The TSB is #TSB-0391-08 and is titled Repair Manual Supplement, Vehicle pulling to One Side, dated December 24, 2008.

… To the Rear
The rear suspension is even more basic than the front (see Photo 6). The rear springs and shocks are separate units, supporting a beam-type axle that acts as the trailing arms. Some models included a sway bar that doesn’t exist on the base model.

The rear shocks are just double-acting dampers and are identical side to side. The shocks are also the limiter for the movement of the rear axle, so care should be taken to support the axle when the shocks are removed.

The springs can be removed by disconnecting the shocks and carefully lowering the axle. Make sure to get the insulators reinstalled properly when the springs are reinstalled.

Rear-wheel bearings are the modular, hub/bearing-type bolted to the trailing arms as a unit. Like the front wheel bearings, these units are different for cars with or without ABS. As noted earlier, any repairs on the bearing or hub should begin with disconnecting or removing the ABS sensor to prevent damage.Figure 8

Taking a Brake
Nothing out of the ordinary here, either. Front disc brakes (see Photo 7) with vented rotors and rear drum brakes are fully adequate for these cars. ABS, stability control and what Toyota refers to as Electronic Brake-force Distribution (EBD, a load-sensing brake proportioning system) are on some models.

Before ordering any parts for these cars, you will need to know which system they use. The rear brakes are self-adjusting either when the car is braking in reverse, or when the parking brake is used. Whenever the rear drums are removed, the adjusters should be checked for free movement.

Even at 100K miles, this Yaris still has acceptable lining remaining (see Photo 8).

Online Performance
From the amount of parts available from a number of suppliers, these cars can be modified to just about any level from mild to wild.

Spring upgrades are available from popular manufacturers such as Ksport (www.ksport.com), Tein (www.tein.com) and Eibach (www.eibach.com), as well as many others.

Strut upgrades are available, including completely adjustable coil-over units for setting up the car for improved handling and lowering the car. Tire Rack (www.tirerack.com) is a good place to check for suspension kits, along with tire and wheel packages.

Sway bars are available in many different diameters, for both the front and rear to tighten up the suspension and reduce body roll caused by the relatively soft stock suspension.

There also are big brake kits available from several vendors, but the prevailing opinion among drivers who use these cars for autocross is — big brakes are probably not required for this type of use, simply because the car is so light. I have to agree (having autocrossed my A1 Rabbits) that braking is not a big problem with light, well-handling cars.

A supercharger kit from Blitz (www.blitzpowerusa.com) should provide enough added spunk to make a standard Yaris into a little screamer.

Final Notes
Throughout the 1970s, a fundamental change took place in the U.S. as we encountered fuel shortages, insurance increases based on horsepower and the total lack of cars that were available from the American car companies, putting the import vehicle/repair market on the map.

Over the next decade, it would appear that a lot of the same dynamics are going to force a shift back to smaller, lighter and more fuel-efficient vehicles. That’s OK for some people, but there are still those who will want to modify and improve their grocery getters.

The little Toyota Yaris and its cousins from Scion may be a little early for the market, but with the latest models and the availability of modification parts, they will be around for a while.
I think I might just go out and get one for myself, and play around a little.

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