shuttering on acceleration only

[charm]

2000 OBW 165k miles auto tranny

 

Shuttering, shaking, more of a vibration really. It only happens when accelerating and not when holding a steady speed or slowing down. It sorta feels like I have a tire severely out of balance or a flat.

 

Power seems fine, according to the speedo, it's accelerating normally. I can't tell by feel or sound because of the shaking.

 

It does feel like it's idling a little low, but it does that when it's cold outside.

 

I (still) have a P0420 code which like has something to do with the giant dent in the bottom of the front cat. Not sure it's related since I don't have a power problem, but thought I'd mention it.

 

The rear struts are new, the fronts are likely stock.

 

The engine doesn't seem to jump like I have a broken motor mount.

 

Any other ideas?

[GeneralDisorder]

The most likely cause is bad inner axle joints (known as "Double-Offset Joints") on the front axles. They can shake violently when badly worn or when lacking lubrication. If any of your axle boots are torn (especially the inner's) then it would be a good idea to just replace both axles. Shaking like that usually means they aren't worth regreasing/rebooting. They aren't real expensive - I get the EMPI axles for $65 each. Takes about 30 minutes per side if you don't run into a lot of rusted parts.

 

GD

[charm]

I just found a post describing this and, like you said, axles it is.

 

Obviously, I could do this for less money if I did it myself. I seem to recall that most folks strongly suggest using a Subaru axle. Is there another option? Does EMPI offer as good a quality? Are they easy to get locally or would I have buy online?

 

If I do it myself I'll do both fronts. If I take it to the mechanic I'll have him figure out which one is bad and just replace that.

 

How many miles can I drive the car like this? I've got about 180 on it now and would like to do about another 200 before I Tuesday when I have my appointment at Smart Service.

[charm]

Do I have this right?

 

To remove the axle, both sides:

 

-remove the top camber bolt (after marking it) and lossen the bottom one.

-remove the pin from the tranny side of the axle

-the axle comes right out

 

Is that it? It sounds like it'll take longer to get the axles and put the car on jack stands then it will to replace the axles.

[GeneralDisorder]

You missed the part about removing the axle nut - it's a 32mm and it greatly helps to have an impact gun. They have a punch-down ring on them so the ring has to be punched back out of the way before the nut will come off.

 

I don't take the camber bolts loose - I take the ball-joint clamp bolt loose and remove the top of the ball joint from the knuckle - but there's no rust here so I can get away with that. If you have a lot of rust you probably are better off marking the camber bolts.

 

Otherwise you have the basic idea, yeah. They sometimes rust into the splines in the hub and it takes a drift punch and a big hammer to get them out but that's probably only 1 out of 10 that I find that way (again - little rust here so YMMV).

 

GD

[GeneralDisorder]

The shaking can cause other damage - most notably it has been thought to cause premature failure of the speedometer drive gear inside the transmission - they are plastic. It's also not good on the engine or tranny mounts but those are easier to fix.

 

I doubt that 200 miles will cause any appreciable damage though.

 

The EMPI axles should be availible from any aftermarket VW parts dealer - or online. No - they aren't as good as geniune Subaru axles, but they are 1/4 the price. I have had good luck with them and I'm pretty hard on them.

 

GD

[charm]

So I'm already to run out and buy, or order a new axle. Was even considering two. I put the car up on some ramps to identify which axle is toast and all of the boots are intact. One is a little cracked, but not severely enough to make my car feel like it has a flat tire when accelerating.

 

Based on this thread and what I've read elsewhere, it seems like it's an axle...but how do you identify which one?

 

My hightech diagnostic device, the buttmeter, is telling me it's the right front, but eyes can't confirm or deny that.

 

Do I just replace both fronts and cross my fingers?

[corvette6698512]

On my XT6, when the axles got worn out and cause the vibration, i could grab the axle, and the splined part of the cv and twist them in opposite directions and they would twist maybe 1/8". You can really feel the slop when they are off the car. Good luck.

[idosubaru]

Sort of stinks to not know for sure. There's other possibilities, axles are the highest probability. I've had the vibration cause a speedo driven gear to destruct...but it was vibrating VERY bad thanks to the awesome coal dust or whatever that extremely abrasive stuff is they throw on the snow here in the mountains. that stuff is terrible.

 

If one has ever been replaced before, that's the one that's causing problems.

 

One time I was faced with the same scenario. My plan was to replace both at some point (since the previous owner had put new aftermarkets in and of course they vibrated so i didn't want either one in there). But only one was necessary at that time. I replaced the one I thought was causing the vibrations and I got it right. Had I gotten it wrong I would have just replaced the other one too, but I didn't have to do that for awhile later.

 

But doing one at a time will at least rule out which is good and which is bad and you might end up only needing to replace one. You can save the good one for later or sell it to someone who needs it.

 

Or you can buy one axle - replace the passengers side. If that isn't right install the previous axle that you removed into the drivers side, so you still only need to buy one axle. I recommend replacing the inner boot...or both boots if they look dry at all while you have it out.

[charm]

I even have a set of boots from my Imp that never got installed. I like the idea of going with my gut and then swapping the other one if I'm wrong.

 

Assuming I get it right, is it worth rebuilding myself so that I have a spare when the next one goes? Or do the severe vibrations I'm getting mean that it's permenantly done?

[idosubaru]

Or do the severe vibrations I'm getting mean that it's permenantly done?

everyone on here is going to say you can't do that and don't do it. i doubt anyone will say what i'm about to but since i have experience (in the last two months) i'll say this. i can't wait to hear all the responses to this!

 

i've actually done it. that set i ran for 4,000 miles to colorado and back - up to 10,000 feet off road mountain passes - vibrating like crazy - towing a thousand+ pounds of trailer, 4 wheeler, and gear. so bad i had to pull over a few times to stuff with grease and slow down immediately....gas pedal placement made all the difference in vibration severity.....that same set i rebooted and they're smooth as a whistle right now in my daily driver lifted XT6 - drove it this morning. perfect ride. they were originally an MWE set i bought years ago that have been on a couple XT6's since then.

 

i sort of did it as a test to see what would happen because every time i stuffed a bunch of grease up in there the vibration would go away. so i thought maybe they'd be fine with new grease/boots.

 

i think it's okay to give it a whirl personally, the metal expands due to heat and all the tolerances and balance is off - but install new grease and it won't do that, surely that's what happened in my case.

 

it might be that they don't last but something tells me they'll be okay. mine is even lifted and they're at a stout angle and being stressed - the new axles that came on the car couldn't take that angle. yours not being lifted, should be even more forgiving.

 

So - all that to say, I think there's a high chance of that axle being fine if you reboot it.

Edited December 14, 2009 by grossgary

[johnceggleston]

So - all that to say, I think there's a high chance of that axle being fine if you reboot it.

 

gary, where do you buy your boots?

 

used axles are 30$ and boot kits, inner and outer, from advance auto are ~30$. plus the mess to do the work.

 

for 75$, plus shipping ($15 ?) i can get one from MWE. used with new boots is cheaper, but will it last as long as re-man?

 

 

just wondering.

[GeneralDisorder]

If the boots are intact then I would open them up - might just be that the grease has gone sour. Clean the joints out, regrease and reboot - they will probably work - slim chance they won't but the boots are cheap.

 

GD

[charm]

If I had known it was THAT easy to swap an axle I would have never paid to have had it done!

 

The pin was kind of a pain, but not too bad. Otherwise the hardest part of the job was jacking up the car and putting it on jack stands (not hard).

 

I do have 1 question that may necessitate pulling everything back apart. How much and where should I have lubed everything I was putting back together? I used the only grease I had, the grease that Subaru sold me when I bought the CV boots. I put some grease on all the splines. Should I have used gobbs? Gobbs and some are accurate and technical measurement terms, btw.

 

I'm now gonna pull apart the old axle and reboot it.

[GeneralDisorder]

I usually just coat the splines (hub and transmission) in anti-seize. Grease works as well. Just a thin coat is fine.

 

Glad you got it fixed and it wasn't as bad as you thought. That's often the case - people are more scared of doing something new than anything. Most jobs on Subaru's are far easier than other makes.

 

GD

[GreenSub]

Glad to see this post. I just got back from a trip to Baja with sporadic vibrations during acceleration and a bit on deceleration. I'm hoping I've got the same issue. Pulled the front right axle since it seemed to have a bit of slop when I pulled on the tire. Now I've got it out and there isn't anything super noticeable.

 

I've got the symptoms, but what are the signs?

 

What should I be looking for that would indicate what and where the damage is?

 

Any thoughts on this are appreciated.

[Qman]

While axles do generally act this way have you checked the trans fluid level. Auto trans dip stick is located on the drivers side. I had a shutter on my wife's Outback and thought it was an axle. Found it to be a little over half a quart low. Topped it off and the shutter went away. Not saying it isn't your axles but it won't hurt to check fluid levels will it?