Gearbox changes in F1

[andyps]

With the penalty given for replacing a gearbox before its allotted number of races I was trying to understand what constitutes a gearbox change. I know it used to be the case that gear ratios would be regularly changed for different circuits but am not sure if this is still allowed with the 4 race rule. The technical regs - http://www.formula1.com/inside_f1/rules_and_regula... - say about seals but are not clear on changing ratios. If a set of cogs is changed does that not constitute a gearbox change?

I may be missing the obvious here but would be grateful if someone could clarify.

[TheArchitect]

iirc they change ratios each race but must set them on the friday/thursday for the weekend. I am in no way an expert though.

[andyps]

The implication from the full technical regs is that they are allowed a certain number of different ratios to use over the year, and I think you are right that they choose a set of ratios for the race weekend, but if the internals can be changed what constitutes a new gearbox which prompts a grid penalty?

[TheArchitect]

I've tried searching because I remember a similar question been asked before, I think you can change the ratios, a few seals and that's about it. Maybe try asking on F1 technical as they're usually a bit more clued up on this stuff.

[LocoBlade]

They can change ratios but obviously you've got other parts that cant be changed such as input/output shafts and bearings etc that the ratios all run on, all the selector forks and probably electronic actuators etc that make the changes, plus the casing which is load bearing on the outside (for suspension etc) as well as internally for support of the gearbox driveline.