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
 

Photo
- - - - -

general fwd question


  • Please log in to reply
3 replies to this topic

#1 johnc

johnc

    New User

  • Members
  • PipPip
  • 25 posts
  • poconos/Philly

Posted 26 February 2009 - 10:37 AM

Hope you experts won't mind a generic question [91 Tercel 207K, 4sp]:

Mechanic warned me to fix a front wheel bearing at inspection in Nov., so I stopped using the car until I could clear an indoor space to do it [Pocono winter]. Now that I'm ready, we've both forgotten which wheel it was!
To find out, I lifted each wheel separately but felt no 12-6 o'clock play. He had warned me sometimes you can't tell that way, and thought his diagnosos had been made after running the car on the lift. So next I put the front end on blocks and drove the wheels in 2nd gear, I think. Very localized, continuous noise immediately showed pass. side was the one to replace!
Strange thing [for me] was, however, that after about a minute, maybe less, as the engine speed dropped [engine was initially cold, so warming up a bit?] the driver's side wheel slowed and stopped altogether, while the pass. [bad] one continued to spin seemingly quite fast. I could rotate the driver's side wheel by hand, even spin it a bit, i.e., little resistance, but it soon came to rest again.

PLease can someone explain to me what's happening here?

#2 RallyKeith

RallyKeith

    Got Subaru(s)?

  • Members
  • 1,486 posts
  • Reading, Pa

Posted 26 February 2009 - 10:45 AM

It's just the physics of an standard open differential. It only truely puts power the wheel with the least resistance. For what ever reason there is less resistance in the passangers wheel transmission path than the drivers. If you were to go and try to stop the passangers wheel you would easily get it to stop and the drivers wheel would start spinning. It's a matter of how "tight" all the components are, including the wheel axles shafts, bearings, and brakes. Bad bearings are usually loose and would would imagine that with no load on them should appear to spin more freely.

Hope this helps somewhat.

Keith

#3 grossgary

grossgary

    Elite Master of the Subaru

  • Members
  • 20,065 posts
  • WV

Posted 26 February 2009 - 12:14 PM

FWD = one wheel drive
and 4WD really only = 2WD

unless their are limited slip type systems involved that's the way it works as he just mentioned.

#4 CNY_Dave

CNY_Dave

    03 LL Bean H6

  • Members
  • 1,448 posts
  • Near Cortland NY

Posted 26 February 2009 - 04:11 PM

FWD = one wheel drive
and 4WD really only = 2WD

unless their are limited slip type systems involved that's the way it works as he just mentioned.


A 4wd-auto/awd-auto trick- if you hold the brakes on, apply throttle, and quickly take your foot off the brakes, then quickly take your foot off the gas and stomp back on the brakes, you get a brief moment of gen-u-ine four wheel drive. You get back on the brakes quick to keep that inch of progress you just made.

Essentially, the torque that it takes to drive the 'free' wheel up to speed (especially since when you lock one wheel of a differential the free wheel spins faster) is also applied to the wheel with traction, for that brief moment before the free wheel spins up.

Progress can often be made, but will be somewhat slow. This works really well if you are in a spot where rocking it will help, and you get a bigger gain each time you switch direction.


Dave




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users