Rear axle ratios ???????

Pete · Post by **Pete** » Fri Jan 18, 08 9:14 pm

I go for Red line at the Traps.

You do need to be able to make the HP to reach the red line by the end of the track.

Dave's brilliant speadsheet can help you out here, but with 32" balloons I guess you are looking at 4.56:1 gears; maybe even 4.88:1's. do the maths!!!

Kev · Post by **Kev** » Fri Jan 18, 08 9:51 pm

What gears have you got?

Kev · Post by **Kev** » Sat Jan 19, 08 11:30 am

AllKiller · Post by **AllKiller** » Sat Jan 19, 08 1:03 pm

5.13's ......i have in my garage

Pete · Post by **Pete** » Sat Jan 19, 08 1:07 pm

AllKiller wrote:5.13's ......i have in my garage

Depends on splines?

AllKiller · Post by **AllKiller** » Sat Jan 19, 08 4:14 pm

489 type

SteveCase · Post by **SteveCase** » Wed Jan 30, 08 7:18 am

Steve, l done that too. Bought some 5.13's then decided to go with 4.56's, funny thing is, i'm sure l hit the rev limiter last time out before the line!

Anonymous · Post by **Anonymous** » Wed Jan 30, 08 8:08 am

Novice question again - sorry.

So, are you guys ALWAYS aiming to be on the redline at the finish? What happens if you hit it before, do you back off and have a rethink?

Apart from gearing, isnt whether or not you hit the red line at the end of the strip very dependent on whether you change into top at the right time????

Is fidling with gearing in the box ever considered, or just not worth the gain?

andyrob · Post by **andyrob** » Wed Jan 30, 08 8:51 am

clivey ,gearing is nearly as important as hp, as you want to make the most out of your hp by being almost on the limiter as you go through the trap

Anonymous · Post by **Anonymous** » Wed Jan 30, 08 9:05 am

Would you (or could you) ever change the gear ratios in the gearbox to give it longer legs. (you may have guessed, I'm a spectator

) Trying to work out whether one cancels the other out.

Dave-R · Post by **Dave-R** » Wed Jan 30, 08 9:30 am

Short legs = low gears = good sprinter.

Long legs = high gears = distance runner.

The point of gearing is to keep the engine at the rpms where it is making the most power.

Because power is dependant on rpm it forms a curve on a graph. The idea is to make as much AVERAGE HP between the start of the gear you are in and the point at which you shift gear. This is why you normally shift to the next gear past the point of peak power.

Dave-R · Post by **Dave-R** » Wed Jan 30, 08 9:33 am

Also the more gears you use the shorter the rpm gap between shifts so the higher the average HP on the same engine.

You want to aim for top rpm in top gear at the finish line. That way you have used all the power of the engine.

Kev · Post by **Kev** » Wed Jan 30, 08 9:39 am

Often wondered why so many people use a 2 speed Powerslide and others use 4 or 5 speed Lencos. Surely the more gears the better to keep in that powerband. But I suppose the convertor in a 'Slide will keep it all in the pb. There are low gear ratio sets for the torqueFlite boxes, that giv a lower 1st gear ratio and a slightly lower ratio in 2nd and stock ration in 3rd. The Taxi has one (courtesy of DaveBishop's RangeRover.) That's one of the reasons for the Taxi's 60ft times and wheels up action. Paul Worrow had one in his '73 Charger and that lifted the wheels. Not a light car!!)