Drop Gears

[TomS]

What are these?! They use them in ASCAR(or whatever is called now) and also in the DTM. In autosport (december 30th) it has a feature about Allan McNish driving the Audi A4 DTM and says how they have a set of internal gear ratios that cannot be changed, so the cars overall gearing is changed by swapping between sets of drop gears. Are there any advantages of this over changing internal ratios other than forcing the teams to all run similar ratios, so a cut down in testing?

[imull]

if its like the drop gears on a mini, there are a set of gears that are crank driven which drop down into the gear box and drive that...

a lot less complex than a gear box and substantially cheaper too I would guess, if I am on the right track.

[StephenRae]

I thought the drop gears were in a housing at the back of the diff, by changing a pair of gears the final drive ratio can be varied .

[1200Datto27]

They can be located anywhere in the drivetrain, and are used to either increase or decrease drivetrain rpm in relation to engine rpm.

[Adam43]

Much in the same way we are changing our 2.88 ratio diff for a 3.54. It is a lot cheaper than changing ratios in the 'box (or a new box).

[StephenRae]

I race a FF1600, we are spoiled by being able to change ratios at will, even with only 4 gears (most of us!) I can only think of Kirkiston where gearing is compromised. You have my sympathies!

[RWC]

Sounds exactly like changing sprocket sizes on a bike
A crude way of spacing out gears or closing up the gaps a little
...or to fine tune revs on the longest straight

It is a compromise between the two usually but better than no adjustment at all