Parallelism: pinching and opening

Parallelism, everyone knows from afar or close. So let's take a closer look at this setting here, as well as the implications of a neutral, positive, or negative angle (pinched or open).

Here is such a parallelism in the hair! The wheels are almost * perfectly parallel to each other. This is a desirable target when you are going to do concurrency with your mechanic or tire supplier.

*: because you want a slightly more open angle (opening) for traction (most cars) and a more closed angle (pinch) for movement (usually sports cars and handsome Germans).

Open corner (OPEN)

When the angle negativewe call it "overture“. A logical word, since when viewed from the front it seems that the wheels are opening in front of us. The diagram will help you better understand this concept. Logically, the fact that the wheels are no longer aligned will affect the car's behavior as well as tire wear. Wear that will be both faster and uneven (wear towards inside the tire, which can be guessed by observing the picture).

As for the consequences for behavior, we will deal with oversteer : A car that tends to roll (the rear wants to drive forward due to some kind of lean effect) when cornering (the opposite of understeer, which would send you straight out of the corner).

Closed corner (PINCH)

When the angle positivewe call it "pinch“. As with the open corner, wear will be faster and more uneven, but this time the wear will be visible on the sidewalls. external tires.

At the car level, this causes understeer : a car that pulls straight if you turn too fast, backsteer (do a search on the website for a more detailed definition if you do not understand this concept).

How did it go wrong?

You know very well that you need to regularly check its parallelism to keep your tires, as well as some parts of your chassis. But how is it that the corner can move over time? It's easy, with every trip to sidewalk, the shock anecdotally breaks the angle. The problem is that after passing 300 sidewalks, the angle has seriously changed… Of course, the sidewalk is just one example, any other bumps should be taken into account.

Additionally, worn out ball joints cause game : the angle is then no longer fixed ...

Concurrency cost

If from a distance it doesn't seem very expensive, as it is an adjustment and you should know that you will still have to pay between 60 and 100 euros in the garage. So avoid the sidewalks!

All comments and reactions

Dernier comment posted:

frbonvin225 (Date: 2021, 10:16:17)

My 95 Nissan Sunny is pulling to the right despite the wheel offset.

I believe the right wheel toe was not done correctly. Onmedit is that it is a backlash in the rack. but I don’t believe it, considering that this is the minimum neutral rudder offset of 2 centimeters,

What do you think ? thanks

Il I. 1 reaction (s) to this comment:

• Ray Kurgaru BEST PARTICIPANT (2021-10-17 13:35:42): Привет,

  not being a mechanic, I think there is 2cm of play in the steering wheel, so the column is pretty abnormal.

  I have had ANY play in the steering wheel of any of my cars in 50 years, except for a very old 1981 Renault Trafic without a DA, which I did not know the mileage of (and rather in a "close to Ohio" condition like Isabelle Ajani sang in 1983).

  Ã ?? Please note that it did not affect the vehicle along the axis of the vehicle, it did not pull to the right or left, just a very slight delay effect when turning the steering wheel is evident.

  As for the anecdote, "my mechanic" was packed with grease to "soften" the game a little, and without any worries went to the TO.

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