loyaleflush Posted October 3, 2004 Share Posted October 3, 2004 Hello all, I'm new to the board, and just wanted to get some input on a 4WD problem I am having. Basically, It doesn't always seem to go in to 4WD when I press the button. In addition when it does engage, there is a significant braking effect. This doesn't seem like increased engine braking, but actual hold me still on a incline braking. From previos posts, I have checked for vac leaks and there dont seem to be any. The tires are all the same diameter, but the rears are slightly wider ( used tires put on by the prev. owner to pass inspection.). Also, I don't want to hurt anything by driving on pavement in 4WD if there are any problems. So Could some body clarify what the "do's and don'ts" of when and how to use 4WD on a Sub? Thanks ! Quote Link to comment Share on other sites More sharing options...
Skip Posted October 3, 2004 Share Posted October 3, 2004 4wd sometimes takes a few revolutions of the wheels to engage and can be engaged evan if the light on the dash is not illuminated. Sure sounds like you have tires that are not exactly the same rolling circumference. (read slightly different diameters) They should be all the same size AND manufacturer. Do not use 4wd on any surface that has enough traction to prevent tire slippage. The front and rear wheels are essentially locked together when in 4wd. They do not travel the same distance when rounding curves, so one set must slip to prevent tranfer case binding. I have an article I wrote on trouble shooting and repair of the Subaru push button 4wd system. I can email it to you if you email me and request it. (click on my name and select "send email") Welcome to THE board and hope this helps some. Quote Link to comment Share on other sites More sharing options...
WoodsWagon Posted October 4, 2004 Share Posted October 4, 2004 Its crucial that the tires are the same size. Even varied inflation will cause binding. The only other thing than tires would be if the previous owner had swapped a 3.7:1 differential in the back. Quote Link to comment Share on other sites More sharing options...
loyaleflush Posted October 4, 2004 Author Share Posted October 4, 2004 Thanks for all the info ! One question, what is the tolerance for tire size variance? Would a 1/8" variance in circumference cause problems or does it need to be more significant? Quote Link to comment Share on other sites More sharing options...
92_loyale_dan Posted August 1, 2005 Share Posted August 1, 2005 hey there, just wondering if you got that "braking" issue figured out. i just took off one of my CV shafts and ran it for a bit to see if it was making the sound I was hearing, it wasnt, so I put it back on and when I did, my 4wd did what yours did. It was like someone was putting on the brakes and it did not want to disengage and once it finally did it was quite a clunk. Anyhow, just wondering if you ever got it diagnosed, fixed and how much did it cost....yikes?! thanks in advance Dan Hello all, I'm new to the board, and just wanted to get some input on a 4WD problem I am having. Basically, It doesn't always seem to go in to 4WD when I press the button. In addition when it does engage, there is a significant braking effect. This doesn't seem like increased engine braking, but actual hold me still on a incline braking. From previos posts, I have checked for vac leaks and there dont seem to be any. The tires are all the same diameter, but the rears are slightly wider ( used tires put on by the prev. owner to pass inspection.). Also, I don't want to hurt anything by driving on pavement in 4WD if there are any problems. So Could some body clarify what the "do's and don'ts" of when and how to use 4WD on a Sub? Thanks ! Quote Link to comment Share on other sites More sharing options...
TROGDOR! Posted August 1, 2005 Share Posted August 1, 2005 Dan - Something is binding up in your 4WD system. Either you have a tire at a different diameter than the others or your differentials or mismatched. Note- this could be ANY of the tires, by no means the same wheel or even the same side of the car where you removed the axle shaft. Say for example your left front tire is worn more than the others, causing a discrepancy. You remove, say, the left rear axle shaft. Surprise, the problem goes away! Why does this happen? Assuming your car doesn't have a rear LSD- when in 4WD, both differentials ALWAYS turn at the same speed- this means ONE wheel in the front must be turning at the same speed as ONE wheel in the rear. This means that if you're in 4WD, with all wheels on the ground, and you have a mismatch- you'll either get binding (resistance in the differential is less than the resistance of the tires against the ground) or wheel hop (resistance in the diff is greater than the resistance of the tires, forcing them to hop to keep up with the change in ratio). Removing ANY of the axle shafts will allow you to have an axle stub spinning freely. This free-spinning axle stub will spin at the same speed as whatever tire is currently mismatched, making the car run smoothly again- no matter which tire is off and which axle you remove! Does that make any sense? In a nutshell- check your tires, and precisely. Quote Link to comment Share on other sites More sharing options...
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