Jump to content

Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse

- - - - -

What's my revs?

  • Please log in to reply
3 replies to this topic

#1 jono


    Reader and writer

  • Members
  • 1,688 posts
  • Southern Hemisphere - AUS

Posted 19 September 2017 - 07:40 AM

If in my five speed part time 4wd box from ea82 I don't know gear ratios figure all the same for3.7:1 diff ratio.

If I reach 80 kph in second gear on 175.70.13 tyres nearly new tread....am I really doing the near 8000 rpm my tacho tells me?

#2 DaveT


    Subaru Nut

  • Members
  • 3,627 posts
  • Colchester

Posted 19 September 2017 - 10:22 AM

Something wrong here. Ea82 red line is at 6000? Mine won't go faster than that anyway, they just stop increasing rpm.

#3 robm


    Subaru Nut

  • Members
  • 933 posts
  • Terrace, B.C.

Posted 19 September 2017 - 11:30 AM

According to Wikipedia, second gear is 1.95:1.  At 3.7: 1 final drive, total ratio from the engine to wheels is 7.215:1


175/70-R13 tires are supposed to be about 1807 mm around.


80 km/h is 1333.3 m/minute


So I get 1333.3/1.807*7.215 = 5324 RPM.  Not 8000.


If it is a 3.9:1 final drive, then the RPM is 5612 RPM.  That is a bit closer to a redline marked at 6000 RPM.  Could the tach read 7% high?  If so, this may be what you are seeing. 

#4 jono


    Reader and writer

  • Members
  • 1,688 posts
  • Southern Hemisphere - AUS

Posted 19 September 2017 - 05:28 PM

Thanks for the smart work. It is suspected tacho is way out and useless. Something to take up with the company. I do have somewhere my ea82 tacho in a box I should hook up and compare. If I find tachi is out it is just a waste of space time and money.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users