What Is the Difference between Constant and Sliding Mesh in a Manual Transmission?

By Mister Transmission

Driving a stick? Get to know more about the gearbox that powers your car or truck

The history of manual transmissions and their evolution is fascinating. For instance, at one time, your car’s manual transmission included either a sliding-mesh gearbox or a constant-mesh gearbox.

A manual transmission sliding mesh is typically found in older vehicles. It is, in fact, one of oldest types of gearbox. To shift between different speeds using a sliding-mesh gearbox, the gears on the main shaft are shifted right or left for meshing them with the appropriate gears on the counter shaft (this is where the phrase ‘shifting gears’ comes from).

The problem with a sliding-mesh gearbox is when changing gears, the speeds of the input and output shafts must be matched first. Otherwise, the sliding dog teeth of the meshing gearwheels do not align, and they “crash” into one another. That is why this type of gearbox is alternatively referred to as a ‘crash box’.

A manual transmission constant mesh, meanwhile, is commonplace in newer manual transmissions – notably those in large trucks and farm vehicles. All of the gears mesh together simultaneously and at all times. In other words, the gears rotate freely on the main shaft, and the gear ratios are selected by clutches that connect them to shafts to power your vehicle.

Why a Constant-Mesh Gearbox Is Your Better Option

A sliding-mesh gearbox may be mechanically efficient, but the noise it generates when changing gears, and the difficulty that was involved when changing gears left much to be desired.

In comparison, the advantages of a constant-mesh gearbox include:

  • The gears used in a manual transmission constant mesh are helical and double helical and are quieter during operation
  • Because the gears in a constant-mesh gearbox are in constantly meshing, it’s less likely to damage the gear teeth, and there’s typically less wear on the gears
  • If a driver makes a “bad” change in gears, any damage that may occur will be limited to the dog clutch

The Synchro-Mesh Gearbox Comes to the Fore

For stick-shift enthusiasts, though a manual transmission constant mesh was an improvement over the sliding-mesh gearbox, drivers still required tremendous skill to operate them. That gave way to the synchro-mesh gearbox, a unit that has many similarities to its constant-mesh predecessor since the gears are always engaged. The exception is the inclusion of a cone clutch that sits between the dog clutch and gears. That means motorists no longer have to trouble themselves with the necessity of double declutching as they would using a constant-mesh gearbox.

 

Are you experiencing transmission troubles or have questions about your vehicle’s transmission? Visit the Mister Transmission location nearest you and get the expert help you need.

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David Thompson
After a catastrophic failure of the CVT in my 2013 Subaru Outback I was glad to find such Professionals. Chris, Janna and the Technicians went above and beyond to get my vehicle back in service. Due to Covid-19 restrictions I had to send the Outback to Moncton on a flat deck. All the time it was there I was kept up to date on their every move and diagnoses. From the first Phone Call until I picked it up there was no doubt "This was the right place". Thanks again Mister Transmission !!!
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Very profesional and effortable pricing
Date: April 19, 2021
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Andrew was fantastic and provided...
Henry Martin
Andrew was fantastic and provided great insight on the actual issues with my vehicle. He was very informative and educated on what needs to be done on my vehicle. I highly recommend Andrew and Mister Transmission!!
Date: April 19, 2021
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Stafford was very polite and...
Marco Allen
Stafford was very polite and professional through our exchange, the service we received was outstanding, the car has never run better.10/10
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Stafford and Crew were completely...
Richard Kelly
Stafford and Crew were completely professional during my repair. Calling regularly with updates. Work completed on time and at the initial quoted rate.Strongly recommend Mr. Transmission.
Date: April 18, 2021
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These days, among all the...
Tony D
These days, among all the horror stories you hear about auto shops who either don't know what they're doing or flat out make things worse (and charge mightily either way), it's easy to overlook the real gems who deliver over and above. This shop came highly recommended to me by my son's auto shop class teacher - this on top of the numerous and overall excellent Google reviews. I had transmission shifting problems with an old Dodge pickup truck with which they were initially unfamiliar, and not only did they take on the challenge, research possible causes, and effect what appeared to be logical repairs (at a *very* reasonable price, I might add), when those repairs turned out not to be the root cause of the problem they took it upon themselves to further track down and fix the problem without additional charge (drawing upon their networks of other contacts in the industry to do so). All in a timely manner, keeping well-appraised of their progress every step of the way. As a small business owner myself, I can say that you simply can not expect better service than this. If I could give more than 5 stars I would. Although this is my first experience with them, I will not go anywhere else in the future for transmission work on any vehicle I own.
Date: April 17, 2021
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Daniel Connolly
They brought our Honda back to life within hours for the best price in town! Awesome service, excellent staff!
Date: April 17, 2021
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Mister Transmission saved us! We...
Natasha Mohammed
Mister Transmission saved us! We had a sudden car issue and were taken care of by Raman. He quickly let us know how to get our vehicle to the shop and was very transparent about the process. He was up front with all costs beforehand and was very responsive, putting us immediately at ease. The fix was completed quickly and even before the estimated time given! We were super pleased with his professionalism, knowledge and workmanship. Car issues suck, but this was an excellent, pain free, no hassle, process. Highly recommend!Thank you Raman & Mister Transmission team!
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The owner went above and...
Lillian Mason
The owner went above and beyond to fix my car. So much so he called one of his employees back after they were closed to check another issue for me that was unrelated to my original issue. Amazing is all I can say
Date: April 16, 2021
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Paul was the gentleman who...
Michael James
Paul was the gentleman who was taking care of my appointment. He was very informative with the issues I was having with my transmission. He was honest in giving his opinion on what course of repair I should use to fix my issue. His customer service and personability were exemplar. The repair was done in a timely manner and he even did some cleaning of the engine bay of my car without mentioning it. For any transmission or drive system repairs I wouldn't recommend any shop other than this one.
Date: April 15, 2021
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