Rear Ends-Parasitic loss comparisons

[Rcktscientist]

Has anyone done research and has actual data of parasitic loss comparison between a Winters Quick Change, Ford 9 inch and Ford 8 inch?

Also, does anyone know if anyone has/makes a coupler for the 8 inch, 25 spline pinion?

[1leg]

For stock rear ends the general rule is the GM 10 and 12 bolt rears have the least amount of loss. I do not know what they compare to a quick change.

[kiwi belly tank]

I'm sure there's somebody that can tell us all the mathematical mumbo jumbo on parasitic loss in a quick change but in my logical brain I see two extra bearings on the lower shaft, two small spur gears normally run in overdrive ratios to get an appropriate calculated high ratio from a low ratio ring & pinion. That's a lot of power sucking crap right there that you don't have with a desirable ring & pinion ratio for your targeted speed.
It takes less power to turn a big tire than it does to turn a big gear but if that tire is out in the air then at some point there will be a tire size to gear ratio tradeoff for best results.
Once you get to a certain speed with 1 to 1 in the trans, the highest ring & pinion ratio available to you & the tallest tire, you will have to look at some sort of overdrive but that choice should come last.
In my long pile of parts I have the highest factory ratio 10 bolt 2.14 gears (2.136 actual) then 55% overdrives in front of each pinion.
  Sid. 

[SPARKY]

GM rears are at least in rounded numbers 4% less drag than a 9"  due to the increased surface of their hypoid tooth contact ( has to do with where the center of the pinion is in relation to the center of the ring gear.

A Ford 8" is derived from a GM 12 bolt and is built by what is now American Axle but use to be GMs axle division.

   in round numbers the quick change is in round numbers  for the reason Sid said  has 1 to 2 % more drag than the Ford 9"  The execption is the old QC that were built with Bevel ring gear and pinions.

[desotoman]

Sparky, I found an old post you did on this subject over 10 years ago and thought it might help Rick out.

Tom G.

https://www.landracing.com/forum/index.php?topic=14676.msg266920#msg266920

OR

7.5   2.14 2.28 2.56 2.73 2.92 3.08/ 3.08 3.23 3.42 3.73
8.5   2.41 2.56 2.73
10-12  8/78 (almost the same as Fords 8.  2.28 2.42 2.56 2.73 2.92 3.08

"The driving efficiency of an automotive hypoid gear is 92%-96%. Unfortunately the spiral bevel gear can not replace a hypoid gear in an automotive drive axle because it can not transmit as much of torque as a hypoid gear."

old Ford bevel gears are in the 98% range

GM axels are the 96%-95%  range the 7.5 being more efficient

Ford 9"  is in the 92%-91%

Virtually the only company still making car and light truck axels in the USA is American Axels--  spun of GM back in the 80-90s---the reason they are still around---better mileage in this day of mandated fuel economy because they are more EFFICIENT
? Last Edit: December 18, 2014, 01:39:14 PM by SPARKY ?

Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

We are going to explore the racing N words NITROUS & NITRO!

[SPARKY]

Thanks Tom  I sure am not able to recall the finer points any more :lol:

[desotoman]

Thanks Tom  I sure am not able to recall the finer points any more :lol:

Sparky, I understand exactly what you are saying.  Your welcome.

Tom G.