Dat260 Posted September 15, 2002 Share Posted September 15, 2002 Hi everybody. This is my first time posting after browsing this site for over year and let me say, this site rules. My first question is, can anybody confirm me that a ratio of, let say 3.90:1, means that the pinion flange or driveshaft turns 1 time for 3.9 tire revolutions or it is the other way around? The logic for me would be that you would want less driveshaft revolutions for more tire revolutions. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 15, 2002 Share Posted September 15, 2002 The pinion gear turns once and the ring gear turns .2564. Smaller gear turning bigger gear means less turns for bigger gear (gear reduction). It also means greater torque multiplication, which a reciprocating engine needs. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted September 15, 2002 Share Posted September 15, 2002 3.90:1 means the driveshaft turns 3.9 revolutions for 1 tire revolution. Johns answer was exactly perfect, but maybe this is a little clearer. No offence, John. And welcome to the forums Dat260! Quote Link to comment Share on other sites More sharing options...
Dat260 Posted September 16, 2002 Author Share Posted September 16, 2002 Thank You for clearing up my confusion guys and I am glad to be a member. I have read so many post from you guys, I feel like I know some of you . Dan, are you eventually going to paint your car? John how did you get the decimal number from 3.90? and please be obtuse . Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted September 16, 2002 Share Posted September 16, 2002 It's in paint (and body) jail now. But the judge threw the book at it. Could be there a while. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 16, 2002 Share Posted September 16, 2002 Obtuse is my middle name.. Quote Link to comment Share on other sites More sharing options...
Guest greimann Posted September 16, 2002 Share Posted September 16, 2002 If I may jump in here. I worked with DAT260 over on Zcar.com, and since things are slow around here... BTW DAT260, good for you in cross checking information. It is always good to get a second opinion! Gear ratios are calculated very simply by dividing the number of teeth on the driven gear, by the teeth on the drive gear. In the case of a automotive rear end, if the ring gear (driven) has 39 teeth, and the pinion (drive) has 10 teeth, 39/10 = 3.9. If you were to look at it from the other way, 10/39 = .2564. In the case of a pulley system that has no teeth, you use the diameters instead. Here is an animated gif I found that is kind of simple, but gives you a visual: http://www.howstuffworks.com/differential3.htm Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted September 16, 2002 Share Posted September 16, 2002 Originally posted by johnc:Obtuse is my middle name.. Better to be Obtuse than Acute; being Acute will get you your own padded room w/a special white coat that has extra long sleeves. Kevin, (Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
Dat260 Posted September 16, 2002 Author Share Posted September 16, 2002 Hi Greimman. Thanks for the link. You know that ratio question bothered me since last time I posted on Zcar and I had to go back & reply to the same guy to correct my answer. Thanks for not getting offended Quote Link to comment Share on other sites More sharing options...
johnc Posted September 16, 2002 Share Posted September 16, 2002 My wife says I'm acute. Or she did many years ago... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted September 17, 2002 Share Posted September 17, 2002 I had an infection that was acute once.. Regards, Lone Quote Link to comment Share on other sites More sharing options...
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