This article was first published in 2007.
Ever thought of what’s on the end of your car’s
gear lever? Yep, duh, a gear knob. But here’s a different question: ever
considered how the mass of that gear knob affects your gear-change? Nope? Well,
here’s why you should care.
The gear knob is mounted on the end of a lever,
with the pivot point way down near the bottom. That means that compared to the
other end of the lever, the gear knob moves both far and relatively fast when
you change gear.
And it’s the ‘fast’ bit which is the key. The
heavier that the gear knob is, the more kinetic energy it has once it’s moving.
And the higher the kinetic energy, the easier it is to overcome notchy gears. In
other words, the fast-moving gear knob actually helps you change gear! Of
course, the downside is that the heavier the gear knob, the more force that
needs to be applied to get it moving. But in the overall scheme of things, that
greater force is no big deal. In fact, a heavy gear knob is likely to feel
chunkier and more robust and also slide home easier.
A better gear change just by changing the gear
knob? Sounds like garbage doesn’t it? But it ain’t.
This story came about because I was wandering a
wrecking yard, looking for a suitable gear knob with which to upgrade the
standard knob in my Honda Insight. I wasn’t particularly after a huge upgrade in
appearance; nope, what I wanted was an improvement in size. The Honda’s standard
gear knob is simply a bit small for my hand.
The first gear knob I found that had (a) the right
shift pattern marked on it, (b) the right thread and (c) the right height, was
from a big Hyundai people mover. That probably would have been sufficient, but I
kept on browsing anyway. And that’s when I made a startling discovery – some
factory gear knobs are very heavy! A Suzuki Swift (current model) knob is f-a-r
heavier than the Hyundai knob; a Suzuki Liana knob heavier again. And it wasn’t
just chance: the heavy gear knobs were clearly designed to be heavy. In fact,
some felt like solid steel encased in grained plastic...
So I bought four different factory knobs at AUD$10
Back home I weighed each knob.
Sorry about the ‘unknown’ and question mark but I
collected, put back and swapped so many gear knobs it became rather confusing
which cars they were from!
Think about the mass of the heaviest knob – that’s
over half a kilogram swinging on the end of the gear lever!
It obviously makes things easier if you select
gear knobs with the same thread as standard. Note that in some cases, a plastic
collar is inserted into the gear knob and it’s this collar that screws onto the
shaft. (Without the collar, the hole in the gear knob is way too big.)
Only one of the knobs needed an adaptor (the
lighter of the two Suzuki knobs – maybe I forget to get the insert) and so I
simply removed the standard knob and replaced it with the heaviest.
An immediate 93 per cent increase in mass...
Fifteen seconds later, the test drive could be
begin – a modification doesn’t get much simpler than that!
The change in shift feel was immediately
noticeable. It wasn’t as great as swapping from a poor gearbox oil to a really
good one (although the difference that makes varies from gearbox to gearbox) but
the heavier knob gave a clear improvement. Notchiness in the gearbox was reduced
and the gearbox had a slightly beefier feel. Together with the larger gear knob
that better matches my hand, the overall effect was clearly better.
Yep, the mod worked...
We’d suggest the first step is to unscrew your
gear knob and weigh it. If it’s light, take it along to a wrecking yard and find
one that’s swappable but weighs a heap more. And of course, the lighter the
gearbox, the more we’d expect the improvement to be – there’s no point adding a
few hundred grams to the knob on a Kenwood truck and expecting the shift to
suddenly be sweet...
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