The Difference between Synchronized and Unsynchronized Gearing in Manual Transmissions

By Mister Transmission

There’s a good reason why large commercial vehicles, motorcycles, and race cars still employ an unsynchronized gearbox

For stick-shift adherents, there is no greater joy than driving a car with a manual transmission. But what’s behind the mechanics of changing gears? And from a driver’s perspective, how does manual transmission synchronized gearing compare to manual transmission unsynchronized gearing?

Most modern urban vehicles fitted with manual transmissions likely feature a synchronized gearbox also referred to as a synchro-mesh gearbox. This device keeps the gears in mesh and rotating, or they can be locked to the shaft. In other words, when you change gears, you’re locking different gears to the transmission’s input or output shaft, thereby allowing you to increase your vehicle’s speed or slow it down. The manual transmission’s synchronized gearbox is what helps you smoothly lock gears into place.

It was a remarkable evolution in manual transmissions because the synchronizer did away with the need for motorists to perform double-clutching – releasing and re-engaging the clutch twice whenever changing gears – a requirement to operate a vehicle with a manual transmission unsynchronized gearbox.

Why the Manual Transmission Unsynchronized Gearbox Still Matters

A manual transmission unsynchronized gearbox is an older design (possibly the earliest design of a manual transmission) that required a lot of effort and skill on the driver’s part. It included a sliding-mesh gearbox, and the driver would need to carefully time when to shift gears to ensure the gears were rotating at the same speed, which was no easy feat. Do it improperly, and you’ll hear grinding and other noises.

However, the unsynchronized gearbox continues to exist. You will often find them installed in transmissions for large commercial vehicles such as heavy trucks and farming machinery, as well as in motorcycles and high-calibre race cars. Why? For two reasons: synchronized manual transmissions are more prone to breakdowns, and shifting gears on a synchro-mesh gearbox is slower than the unsynchronized version.

Are you experiencing a problem with your vehicle’s manual or automatic transmission or have questions about transmissions? Visit the Mister Transmission location nearest you and get the expert help and information you need.

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Albert Wilton
Good and friendly and reliable people and they work hard to get your vehicle doneService: Transmission
Date: July 25, 2021
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Christy McMurray
Thank you, Mister Transmission! After taking my vehicle to the dealership where I bought it, and paying $150 for them to tell me what I already told them was wrong, the Dealer gave me a quote of $6,500 to replace my 9 year old transmission with a factory rebuilt one, because it couldn't be fixed or rebuilt by them. Thankfully I called Mister Transmission and Chris knew exactly what the issue was, how to fix it, and it only cost me $385 for everything and it was fixed in a day. I am so grateful that Chris and Dawn run an honest operation and provide genuinely great service. Thanks again!
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Cambridge Mister Transmission was awesome....
Sarah MacArthur
Cambridge Mister Transmission was awesome. We ended up having a small issue but they still took the time to show me where on my vehicle the problems were and fully explain the possible issues. They were prompt in getting back to me the following day and I had my vehicle back in no time. Chris and Nick were amazing and the office is so clean and pleasant. Great customer service!
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Great service , friendly and very knowledgeable.Excellent work
Date: July 23, 2021
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Mazda 3 AT light came...
Chris Elmquist
Mazda 3 AT light came on one with some bad noises and clunking. Dealer said need a new transmission for only $4400. Took it to this and a quick check they determined it needed new TCM which is very common on the mazdas. They took care of it and even did a bunch of extra work fixing a wiring harness all for the cost of the TCM . cannot say enough about how we were treated by Chris and Dawn. Would recommend them. FIRST CLASS!!!!!
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Ely Bolivar
Workers are very nice and explain thing clearly. Also they have an option to finance your repairs.
Date: July 22, 2021
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Colleen H
They assessed the problem quickly, quoted a good price, provided fast service, in a no-pressure, friendly manner. I've been telling everybodyService: Transmission
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Kieran Massicotte
I took my differentials down to get rebuilt and Steve was very professional and the total was 200 bucks cheaper than the quoted price and there was a few things during the whole process that didn’t go as planned as I had brought all the bearings parts and some bearings were the wrong ones and I had brought 4.88s to put in end they would not work and before continuing with anything Steve would call and double check to let you know what needs to be done and get the ok from me first before they would continue overall amazing place Steve and the guys were awesome and the work was done perfect and the diffs have never been more smooth highly recommend.
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Thank you Kyle and the Mr. Transmission team for very professional and friendly customer service and repair. I definitelly recommend their services.Service: Transmission
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