TypeRD
Senior Member
Interesting info I found online to the question: Is it bad to skip gears in a manual transmission?
“From an ex-manual transmission engineer - it depends…
If you are upshifting it won’t hurt the transmission at all. (OK, maybe infinitesimally but not enough to matter over the next 500,000 or so miles.) However, you may get to a gear that’s too high for the speed you are going and either stall the engine or not have any power to accelerate. You’ll figure that one out very quickly so it probably won’t be an issue more than once.
Downshifting is another story. Downshifting is always harder on the synchronizers. (For anyone not aware, synchronizers are the things that make for smooth shifting.) Why? Because during an UPshift you need to slow down the clutch disc that is already trying to slow down whereas a DOWNshift is doing the opposite - it’s trying to speed up the clutch disc that wants to slow down. If you are downshifting at a relatively high speed for the gear you are shifting into, it can be *very* hard on the synchronizers. Of course, doing this a few times won’t be an issue. Do it on a regular basis and your sychronizers won’t last long.
Some possibilities …
- Shifting into 1st gear 0 miles per hour - no synchro wear at all.
- Shifting into 1st gear just before coming to a complete stop (probably less than 5 miles per hour in most cars) - no significant synchro wear. (I do this at most stops.)
- Shifting into 1st gear at a speed that will give you 4,000 RPM in 1st gear - not really a good idea due to increased synchro wear but it won’t damage anything right away.
- Shifting into any gear at a speed that would result in more than maximum engine RPM if you let the clutch out - much harder on the synchro (and requires a lot more force on the shift lever) AND likely to remove the clutch friction material due to excessive centrifugal force. (If you know someone who says their engine was so strong that they pulled the friction material off the clutch disc when they popped the clutch in a racing start, they are wrong. The facing material can’t be removed that way unless it has already been damaged - such as by downshifting too soon to a low gear and spinning it off. I could go into more detail but it gets complicated. Just trust me.)
- Double clutching into a lower gear - If done properly, no damage at all because the clutch disc will be slowing down as you shift into the lower gear. I.e., the clutch and synchros think you are upshifting as you go into the lower gear.
Bottom line…
The harder you need to push on the shift lever or the more time it takes to complete the shift when downshifting, the more damage you are doing to the synchronizers.
Note also that a slow upshift can be almost as bad. If you take too long, the clutch disc will slow down so much that the synchros will need to speed it back up! So when you upshift, just do it. It’s designed to work that way. Don’t power shift; just do it. I’ve seen people try to be easy on their synchros by doing a step-by-step upshift (go to neutral, move the lever sideways, go into the next gear in 3 separate steps) and that’s almost as hard on the synchros as a downshift.”
“From an ex-manual transmission engineer - it depends…
If you are upshifting it won’t hurt the transmission at all. (OK, maybe infinitesimally but not enough to matter over the next 500,000 or so miles.) However, you may get to a gear that’s too high for the speed you are going and either stall the engine or not have any power to accelerate. You’ll figure that one out very quickly so it probably won’t be an issue more than once.
Downshifting is another story. Downshifting is always harder on the synchronizers. (For anyone not aware, synchronizers are the things that make for smooth shifting.) Why? Because during an UPshift you need to slow down the clutch disc that is already trying to slow down whereas a DOWNshift is doing the opposite - it’s trying to speed up the clutch disc that wants to slow down. If you are downshifting at a relatively high speed for the gear you are shifting into, it can be *very* hard on the synchronizers. Of course, doing this a few times won’t be an issue. Do it on a regular basis and your sychronizers won’t last long.
Some possibilities …
- Shifting into 1st gear 0 miles per hour - no synchro wear at all.
- Shifting into 1st gear just before coming to a complete stop (probably less than 5 miles per hour in most cars) - no significant synchro wear. (I do this at most stops.)
- Shifting into 1st gear at a speed that will give you 4,000 RPM in 1st gear - not really a good idea due to increased synchro wear but it won’t damage anything right away.
- Shifting into any gear at a speed that would result in more than maximum engine RPM if you let the clutch out - much harder on the synchro (and requires a lot more force on the shift lever) AND likely to remove the clutch friction material due to excessive centrifugal force. (If you know someone who says their engine was so strong that they pulled the friction material off the clutch disc when they popped the clutch in a racing start, they are wrong. The facing material can’t be removed that way unless it has already been damaged - such as by downshifting too soon to a low gear and spinning it off. I could go into more detail but it gets complicated. Just trust me.)
- Double clutching into a lower gear - If done properly, no damage at all because the clutch disc will be slowing down as you shift into the lower gear. I.e., the clutch and synchros think you are upshifting as you go into the lower gear.
Bottom line…
The harder you need to push on the shift lever or the more time it takes to complete the shift when downshifting, the more damage you are doing to the synchronizers.
Note also that a slow upshift can be almost as bad. If you take too long, the clutch disc will slow down so much that the synchros will need to speed it back up! So when you upshift, just do it. It’s designed to work that way. Don’t power shift; just do it. I’ve seen people try to be easy on their synchros by doing a step-by-step upshift (go to neutral, move the lever sideways, go into the next gear in 3 separate steps) and that’s almost as hard on the synchros as a downshift.”
Sponsored
