Technical Documents

How A Gearbox Synchro Works

When you start to engage (any) gear the synchro ring and hub create friction as they begin to mesh as they are both spinning at different speeds.

Once they match they engage with the dog teeth onto the drive gear.
(That’s why a dog box is faster to change gears, it has no synchros to wait for!)

If you force it (esp. 1st as this gear is designed to be slow) you generate heat and basically make the synchro assembly work harder and hence wear faster.


If you want to grab 1st gear FAST, (or any LOWER gear) you can choose to double clutch….and to clear this up, its as follows:

  • clutch in to select neutral
  • clutch out (in neutral) blip the throttle (this spins up the gearbox (input) shafts to match the faster speed of the (output) gear you will be selecting)
  • clutch in, select gear. (if you have blipped the throttle the “right” amount the gear will select almost instantly as you do’t have to wait for the synchros to do anything)
  • clutch out and MATCH the engine Rpm with the road speed (normally higher RPM) if you do’t do this you will effectively have to slip the clutch until the engine and gearbox speed match….

Remember there aint no point blipping the throttle if you do’t have the clutch OUT.

Leave a Reply

Your email address will not be published.

No products in the cart.