View Full Version : Gear Ratios?
Reaper948
04-17-2003, 11:47 PM
Normally i think id know a lot about cars....But tonight i was pretty stumped and angry cuz i was.....
Gear Ratio....whats it mean?
"THe ferrari has such an awesome gear ratio"
what the hell does that mean too?!.........
:help:
RF Overlord
04-18-2003, 06:46 AM
Gear ratio refers to the number of teeth on one gear versus the number of teeth on the other, or more basically, the number of turns it takes one gear to make the other one turn once.
Example: the popular 4.10 rear gears...the ring gear has 41 teeth and the pinion has 10... the 3.55 that comes stock with the car uses a ring gear with 39 teeth and a pinion with 11...
As far as the Ferrari with "such an awesome gear ratio", that's a poorly worded statement taken out of context, so it could mean a lot of things...transmission gears, final drive ratio, ?????
cyclone03
04-18-2003, 07:29 AM
Another way to look at is,think of gear ratio as leverage.
If you had a lever 4 ft long you would apply more force than you could with a lever only 3.5 ft long.
A 4.10:1 gear ratio puts about 1200 lb/ft of torque to the axles assuming a 1:1 gear from the trans.Add in the first gear ratio in the trans and that number climbs to almost 3500lb/ft of torque!
Gear ratio= Leverage
Reaper948
04-18-2003, 08:05 AM
When you shift up, are you shifting to a larger gear with more teeth? or a lower gear with less teeth.....
RF Overlord
04-18-2003, 08:14 AM
reap:
It's not actually that simple...a transmission, manual or automatic, has multiple gears that may be engaged for a given forward "gear" or "speed" (1st, 2nd, OD, etc), so the ratio being referred to is the ratio of the number of turns of the input shaft to the number of turns of the output shaft...the actual number of teeth on any given gear is not important in this context, since there are more than 2 gears involved.
martyo
04-18-2003, 08:17 AM
They are ratios. It relates to how many turns of the input side (the engine) gives you a turn on the output side (the wheels). This can be accomplished with in a number of different ways (gear combinations).
cyclone03
04-18-2003, 12:09 PM
when you shift from 1st to 2nd you shift to a higher ratio/lower numericaly.:i.e first gear 3.00:1,2nd gear 2.0:1,3rd gear 1.0:1.
(note above example does not reflect actual gear ratios of any transmission I know of.)
Now how many gears are involved depends on what transmission your talking about.The old Ford toploader used 4 gears for first gear.Power came in the input,went to the forward gear on the countershaft,then out the aft gear on the countershaft,then to first gear on the output shaft then off to the driveshaft and rear end.
Automatics I have no idea what happens from the input to output shafts.But it's kinda the same too............
Forth gear in the old toploader used zero gears,shift to forth and the input and output are connected directly together.
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