removing 5 lbs of ring gear weight....friction free?

[jackchan]

a friend of mine has removed 5 lbs of weight from the back of his ring gear(thru machineing). The ring gear is from an 8.8 Ford Mustang rearend.This particular car is drag raced in a class where hp is limitied by rules to around between 280rwhp up to around 320rwhp. How much effect would this weight removal have on a #3200 car spinning at up to 6100 rpm?
thanks
Jack

[graham bahr]

here in the UK a ring gear is attached to the flywheel so i guess your referring to the crownwheel in the differential, dont know that maths on this one, but it wont provide any more power, but will reduce the inertia in the drive train, not sure how much by though, lightening flywheels and engine internals gives good results as the effect of the removed mass is multiplied by the gear ratios throught the transmission, so the biggest gains are found in the lower gears once in top it doesn't make nearly as much difference, even though the you then still have to feed it through the final drive,

in this case you have lightened the final drive the end of the line as far as gearing the transmissions concerned, so i wouldn't expect much gain, although as they say every little helps and if nothing else you now have a lighter rear end

[Al Weyman]

It might explode as well!!!!

[jackchan]

Thanks for the info graham bahr. You are correct it is the differential ring gear (or as you call is crownwheel). And the idea is to reduce the inertia in the driveline. Since our drag race class only runs mid 12 second passes in the 1/4 mile, every bit of advantage is an advantage assuming we are getting the most from our combo's to start with. One of our little tricks we use is a custom set of wheels called "Bogarts" they are extremely light and are as much as 22 lbs lighter than other aluminum wheels. Again this is lowering inertia...therefore its only reduceing a loss in horsepower not creating it.

titanium valve components such as retainers, locks, springs are another way these guys in my class were having an advantage, but the rules changed drasticly this year and will not allow the lightened ringgear nor the lightened valve components.
Also the flywheels they used last year were aluminum along with aluminum clutch presure plates. Which have also been banned from the class.
the class last year was running high 11.40's...........but this year with all the additional rule changes will slip back to the mid to low 12 second range. Still I search for every little advantage I can get!

thanks
Jack

It might explode as well!!!!

[Lukin]

You might lose the effeciency of the differential in lower gears.

The same loads going through but with a lower mass crownwheel it might deflect more, robbing you of torque.

I heard a normal road car diff has a variance in 4% effeciency from first to last gear due to the higher torque deforming the gears more in lower gears.

[jackchan]

they just banned the lightweight ring gear in our class, just last night...as our final rules came out.
thanks for all the good info guys
Jack