What is a dual clutch transmission?
Updated 11 Oct 2019
You’ve heard the term around high-performance vehicles, typically turbocharged compact cars and luxury vehicles: dual-clutch transmission, or DCT.
It’s clearly meant to be a positive talking point for these vehicles.
But what is a dual-clutch transmission and how does it work?
Are they better than a conventional automatic transmission, and are they expensive to fix?
We’ve got your back. Here are the basics about a DCT gearbox.
HOW A DUAL CLUTCH TRANSMISSION WORKS
The purpose behind a dual clutch transmission is to enable your car to shift faster.
That gives you better acceleration and performance, and that’s something we all want, isn’t it?
A single clutch system can only operate so fast on an automatic transmission.
But what if your car had the next gear ready to go, whether it needs to shift up or down? A DCT transmission does just that.
A dual clutch transmission centres around a two-piece transmission shaft. It simply can’t work without it.
Even-numbered gears operate on one part of the shaft while odd-numbered gears are on the second part. Each section of the shaft has its own clutch.
No matter what gear you’re in, the next gear up and down is ready and waiting thanks to the second clutch.
For example, if you’re in third gear currently with clutch number 2, both second and fourth gear are standing by with clutch 1.
“How is a DCT faster?”, you might ask. Think about it compared to a single clutch system.
A single clutch has to disengage its current gear and change to the next gear up or down.
A DCT cuts the time to shift in half or less because the gear is ready to go – one clutch just needs to release and the other engage.
(BMW X2 M35i with a DCT)
IS A DCT BETTER THAN A CONVENTIONAL TRANSMISSION?
There’s a purpose for every type of transmission.
For some drivers, a manual transmission is irreplaceable for the connection between driver and car.
For others, the added performance a DCT presents isn’t important.
Rather, a comfortable, soft shift is preferred so a conventional automatic transmission will do just fine.
For performance-centric vehicles, though, there’s hardly an argument that stands up against DCTs.
They can shift faster than you can manually or with any automatic transmission, and they’re quite strong.
WHAT DOES IT COST TO FIX A DCT TRANSMISSION?
The good news is that DCT transmissions are known to be very durable.
You don’t hear many instances of a dual clutch transmission needing to be repaired.
The reason that’s such good news is that it’s very expensive to repair a DCT.
In fact, most DCT transmissions aren’t serviceable.
That means that, unlike conventional automatic transmissions, you can’t rebuild a DCT. A new unit needs to be purchased and installed.
Should you require a replacement DCT transmission, expect a repair bill of $4,000 or more.
However, you can keep repairs at bay through routine maintenance.
Ensure you change the fluid in your DCT transmission at or before its recommended interval to make it last as long as possible.
Should you need to replace your DCT transmission, be sure to get quotes from multiple high quality, local mechanics on AutoGuru.
Search, compare and book it all online, it’s that easy!
Jason is a Canadian automotive content writer with a background in the auto service industry, but he’s been hooked on cars and mechanics since childhood.
One of his first cars was an ’80 Mazda RX-7 that’s sorely missed to this day. A ’68 Ford Torino GT, a ’66 Ford Country Squire Woodie station wagon, and a ’96 Suzuki GSX-R 750 have spent time in his fleet of cars, bikes, and trucks over the past two decades.
Jason’s pride and joy is under construction – a turbocharged ’88 Mazda RX-7 convertible. Also on his resume is CASCAR official certification.