few questions with bucking, vibrating, belt length, etc.

[n0sympathy]

I've been chasing some issues with my subaru and a few of these just have me stuck. I've tried searching and I am not coming up with anything that seems the same. 

 

Have an 02 legacy L Auto that I use for winter driving with 160K miles and I got it with about 135K miles. within the past year I've replaced ball joints, front/rear bearings, brakes, tires, front half shafts, and maybe some engine pieces I'll list below where they belong. 

 

Car when driving forward from coasting feels like the rear shudders hard. Only for a second then drives fine. Shifts a little rough but not any worse than any other auto car I've had or driven built around the same time, just seems to be when giving gas from a coast. 

 

Paired with that, the car vibrates at a stop while in D, R, 1,2,3. Not in N or P. Gets worse on cold days and feels less intense on warm days. With moving from 40 degree to single digit days, has been a real roller coaster of an experience. I've had someone sit in the car with it in D and me looking at the engine, don't really see it vibrating all over the place, trans when pushed and pulled on doesn't really have any noticeable play. Feeling disappears the moment I release the brakes. Pull my foot off the pedal fast as I can and the vibration immediately goes away. Feel like I ruled out the engine mounts or trans mount, but I am still open to replacing those. 

 

Would the two be related? I've ran through a few ideas of what to change, but would love an opinion. I would think if it was the convertor I'd have more issues than just vibrating while stopped. 

 

Last is the power steering/alternator belt. I replaced my alternator and my belt a while back because the car kept dying and it proved to be the alternator, but replaced the battery too because I wasn't sure how long it'd been with the car. I have the adjustment as high as it goes, with the bolt to hold the alternator adjustment in place so, actually, they were rubbing slightly. Didn't realize this but belt looks ok minus the one rib being a little shaved, but the belt has way more play than it should(read like a half inch or so and I have nearly 2 inches), and appears to be slipping. Notice issues like, headlights dim when I hit the button for the power windows, air fan speed increases when I rev the engine and other small odd things. Car also has trouble turning over some days. Complains something fierce but still does. haven't measured but not sure the alternator is charging the battery enough due to the belt slip. 

 

Anyway, I took the belt off, adjusted the alternator back where it was, and took a string and wrapped it around all 3 pulleys and it measured almost exactly 35 inches. Which is the ID size belt recommended for the car. So if the max adjustment where I am rubbing the belt is also the length of the belt, well of course I am having trouble. I was trying to find a shorter belt, like a 33-34" belt which would work perfect but couldn't find anything. Maybe the alternator is wrong? It looked identical to the one I pulled out. Just at a loss on this one. Adjust the belt any tighter is going to have the belt rub that bolt end hard and that is obviously bad. Only other thought is to adjust that bolt past the belt up higher, but it'd have to go up a full inch and that is probably too much. I know the stock alternator and belt were slightly below this adjustment point, so I really think it might be the design of the alternator. I was in a hard spot and got one from autozone. Worked great when the alternator and belt were brand new and tight. lol. 

 

 

[porcupine73]

Paired with that, the car vibrates at a stop while in D, R, 1,2,3. Not in N or P.

What kind/brand/source of half shafts did you use on the front? What you describe has been associated strongly with many aftermarket axles, especially those from chain parts stores.

 

The rear shudder brainstorming a few things are possibly the propeller/drive shaft, sometimes the u joint gets flaky, though then I think it's more of a whomp whomp almost all the time up at cruising speeds and feels like it's under the driver seat moreso than just on/off the throttle.

 

Not sure on the belt. Any parts store should be able to look up the correct belt for that year/model, but if the alternator really is slightly different then maybe it needs a shorter belt.

[Fairtax4me]

The shudder/jump from the back of the car is probably the Subaru jerk. When these cars get a lot of miles on them the parts of the drivetrain wear and the excess play in the transmission gears, axles, and differential, creates a pretty large amount of slack in the drivetrain. When you transition from coasting to accelerating all of that slack has to be taken up before the wheels start to push again. The more wear on the vaeious parts of the drivetrain, the more slack there is, and the worse the jerk is.

 

Vibration in park is usually due to poor quality aftermarket front axles. Sounds weird, but there's quite a bit of info about that problem floating around here and on other Subaru forums. Better quality axles are the fix for that.

 

Alternator. There's a number on the belt. Something like 5PK895

The first number (5) is the number of ribs, the last 3 or 4 numbers are the length of the belt in millimeters. (Another example could be a 6PK1450, 6 ribs wide, 1450mm length)

I've had the same problem you have both in getting belts that are too short and too long. Parts store listings are not always correct, and there are variances between engines that require a different length belt from model year to model year.

Too short and you can't get the belt on the pulleys at all, too long and there isn't enough adjustment to properly tighten the belt. Look at the belt you have, and go to the parts store and ask for a belt 5-10mm shorter. Say yours is a 895, you could ask for an 890 or 885. Most stores carry those lengths in stock because those are common belt sizes for many Japanese and Asian vehicles.

 

The dimming lights is kind of a common trait of these cars. At idle the alternator isn't able to create full charge. When your sitting at idle, fan on, lights on, brake lights, radio on, that's when the electrical parts of the car are placing the highest demand on the battey and alternator, and the alternator is just barely able to keep up. The difference between idle charge voltage, and full charge voltage at about 1500rpm is only maybe 1volt, but one volt is more then enough for you to notice a brightening of lights and the uptick in fan speed when that charge voltage picks up. It doesn't necessarily mean there's anything wrong with the alternator, it's just a characteristic of how alternators work.

 

Some things you should check to make sure your electrical system is able to operate at its best.

Make sure the battery terminals are clean and tight.

Make sure the ground cable is clean and tight at the block. Make sure the body ground wire is clean and tight.

Make sure the main charge lead from the alternator is clean and tight at the alternator, and on the bottom of the main fuse panel.

 

If you can see green in the very ends of any of the cables where they are exposed at the terminals, there's a good chance that corrosion has spread far down into the cable underneath the insulation, and that will lower the current capacity of the cables. That means they can't supply enough current to satisfy the demands of your electrical system.

[ccrinc]

Torque converter. 

 

They are known to wear out much faster than the old ones did.  In fact, we recommend that anyone doing an engine replacement who has an automatic also replace/rebuild their torque converter.  

This would also explain why you have no issues in neutral or park because the converter is not engaged.

 

Emily

[n0sympathy]

What kind/brand/source of half shafts did you use on the front? What you describe has been associated strongly with many aftermarket axles, especially those from chain parts stores.

 

The rear shudder brainstorming a few things are possibly the propeller/drive shaft, sometimes the u joint gets flaky, though then I think it's more of a whomp whomp almost all the time up at cruising speeds and feels like it's under the driver seat moreso than just on/off the throttle.

 

Not sure on the belt. Any parts store should be able to look up the correct belt for that year/model, but if the alternator really is slightly different then maybe it needs a shorter belt.

 

I used what I read was an excellent replacement, Cardone. I should have been more clear on that, I replaced them only a few weeks back, I've had the car for two years and the vibrating was happening with the OEM axles since then. Not sure if they are original or not. It feels like the vibrating comes from the back honestly. I am using the looked up belt size, went to subaru themselves and 3 big brand auto stores. All list the same size belt.

 

The shudder/jump from the back of the car is probably the Subaru jerk. When these cars get a lot of miles on them the parts of the drivetrain wear and the excess play in the transmission gears, axles, and differential, creates a pretty large amount of slack in the drivetrain. When you transition from coasting to accelerating all of that slack has to be taken up before the wheels start to push again. The more wear on the vaeious parts of the drivetrain, the more slack there is, and the worse the jerk is.

 

Vibration in park is usually due to poor quality aftermarket front axles. Sounds weird, but there's quite a bit of info about that problem floating around here and on other Subaru forums. Better quality axles are the fix for that.

 

Alternator. There's a number on the belt. Something like 5PK895

The first number (5) is the number of ribs, the last 3 or 4 numbers are the length of the belt in millimeters. (Another example could be a 6PK1450, 6 ribs wide, 1450mm length)

I've had the same problem you have both in getting belts that are too short and too long. Parts store listings are not always correct, and there are variances between engines that require a different length belt from model year to model year.

Too short and you can't get the belt on the pulleys at all, too long and there isn't enough adjustment to properly tighten the belt. Look at the belt you have, and go to the parts store and ask for a belt 5-10mm shorter. Say yours is a 895, you could ask for an 890 or 885. Most stores carry those lengths in stock because those are common belt sizes for many Japanese and Asian vehicles.

 

The dimming lights is kind of a common trait of these cars. At idle the alternator isn't able to create full charge. When your sitting at idle, fan on, lights on, brake lights, radio on, that's when the electrical parts of the car are placing the highest demand on the battey and alternator, and the alternator is just barely able to keep up. The difference between idle charge voltage, and full charge voltage at about 1500rpm is only maybe 1volt, but one volt is more then enough for you to notice a brightening of lights and the uptick in fan speed when that charge voltage picks up. It doesn't necessarily mean there's anything wrong with the alternator, it's just a characteristic of how alternators work.

 

Some things you should check to make sure your electrical system is able to operate at its best.

Make sure the battery terminals are clean and tight.

Make sure the ground cable is clean and tight at the block. Make sure the body ground wire is clean and tight.

Make sure the main charge lead from the alternator is clean and tight at the alternator, and on the bottom of the main fuse panel.

 

If you can see green in the very ends of any of the cables where they are exposed at the terminals, there's a good chance that corrosion has spread far down into the cable underneath the insulation, and that will lower the current capacity of the cables. That means they can't supply enough current to satisfy the demands of your electrical system.

I can live with the play then, that isn't a big deal, just was mentioning everything. I didn't think there would be that much play, but I am definitely not overly familiar with AWD cars that way. Mostly had RWD solid axle cars.

 

The new axles are Cardone and are just a few weeks old, the stock subaru axles were on there as mentioned above before this, so it's been doing it with both. I can see the logic behind it, but why would the amount of vibration change dependant on the weather? It is really bad in single digit weather and like during the summer, it is there but not worth even mentioning.

 

I have the correct lengh belt as mentioned above by subaru, 3 big chain stores, etc. Is a 35" ID belt. Which the ID is exactly 35" at max adjustment. I didn't think to even bother going and asking for a shorter belt because I didn't think any of the auto places would be smart enough to figure that out. I am going to do that tonight and see if they can give me a shorter one. I know I can get a 34" ID belt on the pullies. Just wondered why the stock size belts don't fit, has me completely puzzled. I am just going to assume the alternator is offset wrong.

 

As for the diming lights and stuff, it actually wasn't nearly this bad, before, but I really think it is the belt slip. The belt is definitely slipping, and it is having a hard time keeping the battery charged. I have the terminals cleaned and coated in dialectric grease, they are picture perfect and same with the other cables you mentioned. Definitely belt slip.

 

Torque converter. 

 

They are known to wear out much faster than the old ones did.  In fact, we recommend that anyone doing an engine replacement who has an automatic also replace/rebuild their torque converter.  

This would also explain why you have no issues in neutral or park because the converter is not engaged.

 

Emily

 

Well, as stated above, would tempeture changes affect the torque convertor? It really is a very light vibration you hardly notice on 90* summer days and is a full blast vibrating bed type feeling on single digit days.

 

 

I thank you so far everyone, just trying to clarify further. I wrote the original post last night while tired, so seems I missed some stuff.