How do YOU downshift?
01-14-2011, 07:08 AM
#31
The only time I've heard of that was from Vin Diesel in The Fast and The Furious
. "Granny Shiftin, not double clutching like ya should. Now me and the mad scientist gotta rip apart the block and replace the piston rings that you fried." Classic. Hopefully no one would take anything but entertainment value from that movie. I have to hand it to semi-truck drivers though for their need to double clutch upshifts since their rpms drop quickly between shifts due to their cargo loads. Unless you upshift like a grandma whose never driven stick before, double clutching an upshift does nothing since engine and transmission speeds are already up due to acceleration. Are you Vin Diesel?
01-14-2011, 07:15 AM
#32
Do you even realize what that grinding sound you hear when you do something stupid with your transmission? Hint: it's not the gears in the transmission.
01-14-2011, 11:41 AM
#33
It's funny? I don't see how you'd think it was funny. Before the days of synchromesh gearboxes, truck drivers would have to double clutch every upshift they made. Of course we don't have to do that today, but if you happen to drive a car with weak or worn synchros, you can easily get by just fine by double clutching on the upshift. That's a fact.
Yeah, I'm Vin Diesel. Got a problem with that? What's really funny is that you think double clutching is only needed due to 'cargo loads'. Now that's funny. Truck drivers used to double clutch because they had to, regardless of the load they were pulling. That's a fact.
Yeah, I'm Vin Diesel. Got a problem with that? What's really funny is that you think double clutching is only needed due to 'cargo loads'. Now that's funny. Truck drivers used to double clutch because they had to, regardless of the load they were pulling. That's a fact.
01-14-2011, 11:43 AM
#34
Gears NEVER clash in a modern manual gearbox. That's because all the gears are always in constant mesh. It's impossible for the gears to grind unless you have one or more broken gears. And if that's the case, you're screwed anyway.
Do you even realize what that grinding sound you hear when you do something stupid with your transmission? Hint: it's not the gears in the transmission.
Do you even realize what that grinding sound you hear when you do something stupid with your transmission? Hint: it's not the gears in the transmission.
01-14-2011, 12:35 PM
#35
Registered User
Gears NEVER clash in a modern manual gearbox. That's because all the gears are always in constant mesh. It's impossible for the gears to grind unless you have one or more broken gears. And if that's the case, you're screwed anyway.
Do you even realize what that grinding sound you hear when you do something stupid with your transmission? Hint: it's not the gears in the transmission.
Do you even realize what that grinding sound you hear when you do something stupid with your transmission? Hint: it's not the gears in the transmission.
So yes, when you drive your 6MT and you grind the gears, that IS your gears begging for mercy.
01-14-2011, 01:01 PM
#36
Wrong. Synchronized transmissions are NOT constant mesh. Only unsynchronized transmissions like those on big rigs and motorcycles (and some racing "dog boxes") are. That's the job of the synchros on a synchronized manual transmission, to synchronize the gears so they don't clash. A constant mesh transmission doesn't need a clutch to up or downshift, the only time I ever double-clutched a big rig (I drive those things on a daily basis) was when I took the CDL DMV road test. Since then I never use the clutch until I come to a complete stop.
So yes, when you drive your 6MT and you grind the gears, that IS your gears begging for mercy.
So yes, when you drive your 6MT and you grind the gears, that IS your gears begging for mercy.
I've rebuilt countless T5 transmissions (used extensively on 5.0L Mustangs, as well as other vehicles) and trust me when I say the gears are in constant mesh. If you need me to post pictures, I will.
Last edited by MSCA; 01-14-2011 at 01:30 PM.
01-14-2011, 01:04 PM
#37
First of all, I was talking about the old, big trucks, not a 1970 Chevy. LOL. Back in the days of crash box transmission (you might have to look that up if you're not familiar with the term), the only way to shift WITHOUT making some nasty sounds was to double clutch. Synchronizers have not been around as long as manual transmissions.
Last edited by MSCA; 01-14-2011 at 01:30 PM.
01-14-2011, 01:06 PM
#38
01-14-2011, 01:08 PM
#39
Registered User
You need to do some research. You're 100% wrong. Our gearboxes are constant mesh, as are just about every MODERN gearbox on every manual trans car. The job of the synchro is to match up SHAFT speeds, not gears. Yes, the gears are attached to the shafts, but they are alread in constant mesh. Don't take my word for it, look it up yourself if you don't believe me.
I've rebuilt countless T5 transmissions (used extensively on 5.0L Mustangs, as well as other vehicles) and trust me when I say the gears are in constant mesh. If you need me to post pictures, I will.
I've rebuilt countless T5 transmissions (used extensively on 5.0L Mustangs, as well as other vehicles) and trust me when I say the gears are in constant mesh. If you need me to post pictures, I will.
Back on topic: I think the original topic was concerning the interesting behavior of an Automatic transmission and engine rpms? Was it AT or MT Mr. OP?
Darn it this is the wrong thread! Ignore the on topic foobar.
Last edited by Coprolite; 01-14-2011 at 01:15 PM. Reason: realized which thread I was posting to...
01-14-2011, 01:13 PM
#40
I'm interested in learning about this. If they are always in mesh, but they are rotating at different speeds, wouldn't they have to be out of mesh somewhere along the way. What is the definition of mesh? To me it means aligned with each other, like being in phase. Does anyone have a good link for this?
Back on topic: I think the original topic was concerning the interesting behavior of an Automatic transmission and engine rpms? Was it AT or MT Mr. OP?
Back on topic: I think the original topic was concerning the interesting behavior of an Automatic transmission and engine rpms? Was it AT or MT Mr. OP?
YouTube - How Manual Transmission Works
01-14-2011, 01:16 PM
#42
Registered User
This might help you visualize it. Notice that all the gears are constantly in mesh.
YouTube - How Manual Transmission Works
YouTube - How Manual Transmission Works
01-14-2011, 01:17 PM
#43
01-14-2011, 01:21 PM
#44
Here's a nice picture of a modern constant-mesh manual transmission. If you can visualize it, all the gear sets are meshed and never separate. You can clearly see the groove where the shift fork sit on the synchronizer collar. This is what moves back and forth when you moved the shift lever and the dog clutches help spin up to match shaft speeds.
01-14-2011, 01:29 PM
#45
Guys typically turn off electronic nannies at the track because they usually don't hep return the best possible lap times or track speeds. As an example, who wants to race (road course or drag strip) with traction control on? Not me...it will just slow me down as it cuts power if a wheel slips. That's what I meant when I said that someone who buys a G37 because it's a grand touring car will generally appreciate driver aids. And people who are racing (or like to drive like they're racing) will generally like to turn off the driver aids and make the car perform to the best of their own ability. Just my opinion....