Synchromesh Gearboxes Suck. Racers Use THIS Instead

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If you have watched any form of professional motorsport you will have seen drivers shifting through gears at lightning speed often without even lifting their foot off the throttle. How?
Andre runs us through what a synchromesh gearbox is and why it cannot shift as fast as a dog engagement gearbox. As well as shift speeds of 30 to 80 milliseconds depending on the setup, a dog box can also be set up to sequentially shift through the gears by either manual or pneumatic actuation, and sometimes even both options are on hand via paddle shifts and a strain gauge fitted shift lever.
If this video looks familiar to you that is because it is from RaceCraft, a company we merged into HPA back in 2020 and the content is too good to not post up on this channel 😎
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TIME STAMPS:
0:00 - High-end Motorsport
0:10 - 'Conventional' Gearbox: Syncromesh
1:09 - Faster Way: Dog Gears
1:53 - Shifting Speed
2:14 - No Clutch!
2:38 - H Pattern OR Sequential
2:58 - Sequential Gearbox Setup
3:28 - Free Stuff
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TAGS:
#highperformanceacademy #dogbox #gearbox #gearshift #dogengagement #sequential #learntotune #enginebuilding101 #dontletthesmokeout #wiring101 #dieseltuning #datanerd #gofasterwithdata #racecraft #learndriveoptimise #motorsport #buildtunedrive

[@hpa101]

🦸‍♂ Building a fast car? Get $400 OFF the all inclusive VIP online course package deal: hpcdmy.co/vipy68 ⚡ Kickstart your EFI Tuning knowledge. Get 50% OFF your first online course: hpcdmy.co/offery68 TIME STAMPS: 0:00 - High-end Motorsport 0:10 - 'Conventional' Gearbox: Syncromesh 1:09 - Faster Way: Dog Gears 1:53 - Shifting Speed 2:14 - No Clutch! 2:38 - H Pattern OR Sequential 2:58 - Sequential Gearbox Setup 3:28 - Free Stuff

[@ATomRileyA]

Great video explaining things. I used to have a car with a CAT engagement gearbox so it would only go into the right gear when it felt like it and sometimes it was taking a nap and would not respond. DOG's are better and tend to be better at following instructions :)

[@JohnKickboxing]

Hey, anyone here can tell me the reason no car manufacturer opts for this type of gearbox and integrates it with engine like the bike engine. so that the structure of engine suppresses the noise made by the dog gears.

[@quentagonthornton49]

@@JohnKickboxingFirst of all, integrating the transmission with the engine will have no effect on noise. To drown out the dog engagement sound, the engine will have to be made much louder, via intake, exhaust, engine mounts, etc, and while I along with most other enthusiasts wouldn't care, in reality, us enthusiasts are an extremely small proportion of car buyers. The other significant issue with a dog engagement transmission is the greatly reduced wear life. For fast shifting, yet good wear life, and even low noise, there is already an option on the market: the dual clutch transmission. Yes, it's heavier than a manual, and has less driver engagement, but it shifts faster than any dog engagement manual and can be tuned to always shift perfectly, unlike a human, so it is the optimal choice for performance. Dual clutch transmissions can also handle much more power with stock clutches than a manual.

[@MightyTubbyTuba]

I always wondered but never actually looked it up, thank you for the short informative video!

[@MichaelFarrell-no2zw]

Great video! I've never 100% understood how dogs work, got it straight away here.

[@JETZcorp]

Dogboxes makeva lot of sense to me, because it's how basically all motorcycles work. Synchros are still mysterious to me.

[@233kosta]

Synchros are super simple - the synchro is a cone on cone fit (causing it to smoothly jam into the main gear). It has the same set of dogs on it that the gear does, so then the shift fork pushes the collar into it, it syncs up to the collar. Then it slides into the cone of the intended gear, which is the momentary "stop" you feel, where friction syncs up the gear to collar or collar to gear. Then the force on the dogs eases amd the collar can slide in. If you bash it in and there's no time for the cones to engage (or if you overpower the friction that's preventing the collar from sliding past the synchro ring), you will grind the dogs on the gear against the collar. Not exactly what you want in that situation 🤔

[@solo2r]

Dream transaxle there!

[@noahwhite7848]

Another excellent video guys! Thank you for all your hard work!!

[@enoswhitaker7967]

Same as a motorcycle transmission shifter forks and gears.

[@aaronhausken3226]

1 down 5 up

[@toddxhiggins]

Another excellent video!

[@chippyjohn1]

I would love to see an in depth video of the Hollinger factory. Not a lot about them on the internet.

[@PreludeDude]

Thank you for this video and clear vision into dogboxes! I'd like to ask what gear selector is preferred for a transmission like this, for street and track driving since it will be a actuated off a switch?

[@Runmeerkat]

Is it common for the selector ring to pop out when you go from full to 0 load?

[@GroovesAndLands]

No. The torque reversal that occurs between coast and drive only lasts a split second. The gear will rotate about 20º in relation to the dogring, and then the gear/dogring will be locked together again. If you are pulling on the gearstick during the transition between coast and drive, you can snatch the dogring away from the gear - but you kinda have to try to make it happen. It's the same with a synched transmission - I'm sure you've ever noticed you can pull the trans out of gear during a transition between coast and drive - but again, you must do it on purpose. That said, there are highly specialized drag racing gear boxes that have the raked face on the engagement dogs for keeping the gear and dogring locked together while under load - but the back side of the engagement dog is ramped to specifically push the dogring away - unselecting the gear. In these transmissions, each dogring is dedicated to a single gear, unlike the transmission shown in this video where each dogring serves two gears. Anyway, the point of the specialized drag racing dogbox is so you can select the next higher gear WITHOUT having taking the previous gear out of engagement. As the shaft speed increases on account of the higher gear being selected, the previous gear overruns the dogring, the dogring hits the ramp, and gets kicked out of gear. The obvious advantage being a shorter overall amount of time for the shift. Disadvantage being you can't engine brake at all. Hope that explanation helped.

[@gordowg1wg145]

If that's a issue you're having, it usually means the bearings are worn and allowing the helical gear to physically pull it out of engagement, the bearings are moving in the housing/on the shaft for ditto, and/ or the indent spring is damaged or broken. With some front wheel drive vehicles, broken engine mounts can allow the engine-transmission assembly to move enough to pull it out of gear. In either internal or external cases, you will probably see excess gear lever movement.

[@Runmeerkat]

Damn guys thanks those are great answers.

[@denimpantz]

You know, it always interested me how drivers in NASCAR shifted the H pattern without the clutch. Now I know why.

[@spdcrzy]

And now you also know why NASCAR gearboxes are INSANELY overbuilt lol.

[@denimpantz]

@@spdcrzy That’s just race cars in general lmao

[@spdcrzy]

@@denimpantz not really. NASCAR gearboxes deal with WAY more torque output than most race cars ever do. 700 lb-ft of constant torque at WOT for hours at a time isn't something you find in ANY other discipline of motorsport. Add to that the fact that there were no paddle shifters until very recently, and those gearboxes take an absolute beating.

[@stevemcilroy.62]

Might sound like a stupid question, but can chipped teeth on dog gears be repaired, or are the gear kits knackery after that point?

[@Marko-hr4rj]

You have a regular manual gearbox without Synchromesh. The so-called non-synchronized manual gearbox that was used in the 70s in f1

[@MadsKongsved]

You don’t need an ECU controlled torque cut, a lift of the throttle pedal should suffice.

[@dataminetk]

true, but that could cause a loss of boost (on a turbo engine) so will be slower than a momentary ignition cut.

[@MadsKongsved]

@@dataminetk correct. But for a manual dog box it provides for the possibility to drive or race like a two pedal car. In our Danish DTC car we had a G-force 4-speed dog box, and our driver left foot braked and drove like a two pedal car, and only used the clutch pedal for setting off.

[@paradiselost9946]

if the free valve had been a thing, the idea of simply opening the exhaust earlier would maintain boost and give torque cut... ignition cut? what, all that nice fuel going out the exhaust cold and unburnt? may as well light it up and keep the turbo toasty. almost has me tempted to stuff around with the decomp lever on my diesel... now, if it were cam operated to only act on the power/exhaust strokes...

[@spdcrzy]

No, but it's a LOT nicer (and more repeatable) as well as less harsh on the drivetrain.

[@redcrafterlppa303]

​@@paradiselost9946I may be wrong but isn't ignition cutting used to keep the turbo running? Letting the unburned fuel ignite in the hot headers and turbo resulting in flames coming out the exhaust and and the boost staying high

[@claymore806]

You don't need to use the clutch when you upshifting but you have to use it when downshiftibg

[@redcrafterlppa303]

Not necessarily. You can rev match a dogbox as well. You just rev in neutral instead of clutch down.

[@smokestrong1000]

what about straight cut syncromesh gears? I heard they're not as noisy

[@yummyhershey5902]

The straight cut is what makes them noisy. Synchro or dog engagement won't affect the noise because they only lock together once.

[@crossbreedperformance]

Which is faster Sequential or DCT?

[@hpa101]

In a tiny nutshell, sequential dog box/'manual'. Lighter & more efficient power delivery too. Trade off is NVH & more maintenance - Taz

[@LukAS-yp1bj]

they should remove the synchros from sport manual cars