Help with shuddering, mech can't figure out.

[lagwagon]

So my 2007 GT 5eat has been having some issues with shuddering. I handed it over to my wife in March so I'm not really sure when they started. I had rebuilt OEM axles installed in March and everything seemed good when I gave it to her.

 

Fast forward to July and I drive the car and feel a shudder/vibration during low rpm acceleration. It gets worse on the next drive so I take it in and replace one axle (torn boot, no grease) with another rebuild OEM from Subaru (no new axles available in Canada anymore). That helps out somewhat and shudder is pretty minor when the car is cold and without any load (wife, kids, stuff etc.)

 

The shudder is slowly getting progressively worse so we flush the trans. No debris came out. Fluid was old/slightly burnt but otherwise clean. Not sure if filter was replaced, I'll need to check the work order. No change to the shudder after the flush and it is still progressing. Two weeks after the flush and it is now shuddering during almost all acceleration and vibrating at the same approximate frequency almost all the time. The "all the time" vibration is still pretty minor but noticeable, much more noticeable when the car is warmed up and loaded with weight. Its still minor when cold and/or when only one person is in the car.

 

In cruise, the transmission shifts fine and the tc locks and unlocks fine. There is no change to the vibration/shudder while it is shifting either in auto or manual mode.

 

In neutral at highway speeds, the vibration is still present (I braked from 110 km/hr to a stop).

 

There is a slight vibration in neutral that has been there since I bought the car (2 years ago). Seems typical of auto trannys to me (nothing extreme).

 

All the suspension was replaced in Feb/March other than the steering rack/outer tie-rods, rear upper links and trailing arm front bushing. Everything drove great after it was aligned, which also came it almost dead on spec, not even high or low in spec. Tires are Nokian Entyre 2 with 7/32 all round and no unusual wear patterns.

 

My regular mechanic doesn't think its the transmission or differentials. They think it might be a bent drive shaft or failing u-joints but based on what I've read, that doesn't seem likely. They are also not very sure if that is actually the problem (they aren't Subaru specialists).

 

Its going into the dealership on Monday to see if they can figure it out. Anything I can check into in the mean time, or any thoughts on what it could be?

[lagwagon]

Update: took it to the dealer and they diagnosed it as front wheels out of balance (more on this further down). They rebalanced the wheels and said the shudder was gone. Two blocks down the road I could tell it wasn’t gone.

 

I took it back and they then diagnosed it as a worn rear axle. They replaced the LR axle and said the shudder was gone. Two blocks down the road I could tell it wasn’t gone.

 

I swapped the wheels out tonight to see if it was a tire problem or possibly bent wheel. With the winter wheels it was actually worse. The kicker was the LF wheel that they said was an ounce out of balance was coated thickly in axle grease and they didn’t think to clean it off before rebalancing the wheel, WTF? There was probably, oh, about an ounce of grease in there! And not evenly coated.

 

Anyways, I did some tight corners, both directions, and got popping, both directions, and some telltale bangs from the center console area, and the shudder is getting worse. I am now pretty sure it’s the drive shaft, and possibly also a CV (RF was rebuilt from a used oem, RR is original AFAIK).

 

Oh yeah, the dealer took the muffler off the hanger and didn’t want to pop it back on for me before I took the car, they said I’d need to leave it with them, again, WTF? I did convince them to come out and pop it back on the hanger, in the parking lot but it was like pulling teeth.

[Max Capacity]

FWIW, I have a post on here, https://legacygt.com/forums/showthread.php/chasing-front-end-shimmy-282490.html

 

 

After replacing a bunch of parts and having two different shops do an alignment.

 

I had a solid steering U joint from a 2008-2014 STI installed. The shimmy is gone, I only have 600 miles with that solid U joint, but so far so good.

[lagwagon]

When you say shimmy you mean the front end feels like it moves side to side?

 

Mine feels more like misfiring would feel when accelerating. When it’s really bad it is almost what I would call bucking, but the engine is still accelerating smoothly. I don’t feel anything through the steering wheel and the wheel doesn’t shake. Car tracks well with no tramlining.

 

It actually has a similar wear pattern on the outside of one brake disk as you had on the inside, on the front left.

[Max Capacity]

Feels like the tires are out of balance. That speed of 68-70mph is where a out of balance tire normally shows itself.

 

 

What your talking sounds like the engine is surging say between 2300-3000 rpm ? that's a common issue.

 

It can be fixed.

[lagwagon]

No, its all the way through the rev range from about 1500 rpm and up. If I am holding speed consistently on the highway (no major hills) there is a vibration (which could be wheel balance) but not the major shuddering that happens during acceleration.

 

I have read some threads on the surging issue but didn't see a consistent resolution, plugs, injectors, coils, fuel pump, tgv issues etc. Do you have a link to a good thread with something conclusive?

[Max Capacity]

Sorry, no I don't.

 

Look around some of the threads, there's a newer member I think warlock that seems to be good with reading data logs.

 

Do you have a Cobb AP ? or some way to data log ?

 

https://legacygt.com/forums/showthread.php/accessport-vs-tactrix-283697.html

 

check out post 15

there

[chato]

I've had a couple surging issues over the years, its usually a bad front O2 sensor giving variable fuel/air information to the ECU. There's also something about aftermarket speed sensors in the wheels that can cause it in cruise control.

[lagwagon]

Sorry, no I don't.

 

Look around some of the threads, there's a newer member I think warlock that seems to be good with reading data logs.

 

Do you have a Cobb AP ? or some way to data log ?

 

https://legacygt.com/forums/showthread.php/accessport-vs-tactrix-283697.html

 

check out post 15

there

 

Thanks for the help guys. I have a V2 AP on my 2005 but nothing on my 2007. I do have an ok scanner (Innova brand, about 18 years old now but still works, used it when tuning my old turbo neon).

 

My mechanic has done a few test drives and logged data while it is shuddering and said nothing appears wrong from the data.

 

I can log with my scan tool, but only one parameter at a time plots on the graph and I would need to find my rs232 cable and adapter and see if I can get it to run on a USB 3.0 port. I do have an older computer to connect to the AP but it is pretty flaky and I haven't run that adapter on it either. It won't display the logged data on the scan tool screen. I also haven't had any luck downloading logged data from the AP (may be a problem with the AP itself).

[lagwagon]

Quick update: had the dirty wheel rebalanced after cleaning, rotated the tires, set pressure. No changes.

 

Plugged in the innova 3130 and it obviously doesn’t display the same data as an AP. It looks like it only displays O2 voltage and no AF learning. It shows some sort of stft and ltft which I can only assume are af correction 1 and 3 but the values don’t match up with what I would expect to see. Front O2 I s varying from about 2.6 to about 2.75 V at idle. Haven’t had a chance to drive it see what’s happening. I can do that today when I drop it off to have the prop shaft inspected.

 

The vibration is worst from 1800 to 2300 rpm (spikes at 2300), then settles down and continues throughout the rev range. I’m thinking it might be a combination of old O2 sensor, trans mount and prop shaft and possibly the rebooted cv.

[lagwagon]

Driveshaft specialist has balanced the shaft, it wasn’t bent but was out of balance, and has ordered new u joints. Sounds like all the bearing caps were locked up pretty good. He’ll need to rebalance after the u joints are replaced.

 

Hopefully I get the car back tomorrow and everything is running smoothly.

[Max Capacity]

I'm surprised you didn't feel the vibration under your right elbow if you rested it on the center console when driving.

 

That's how I knew my center carrier bearing was going bad.

 

Let us know if he was able to replace the U joints in the OEM shaft. They say they are not replaceable.

[lagwagon]

I mentioned that in my second post that I did hear a tell tale loud bang when doing tight corners (I was actually doing u-turns around a boulevard to get that to happen), but I can't actually reach the arm rest when I'm driving or maybe I would've felt it sooner.

 

The driveshaft specialist said he thinks the driveshaft doesn't have enough angle in the joints to stop it from binding up. Maybe it is a combination of motor mounts and rear diff mount being old that did it.

 

This car only has 192,000 kms (120,000 miles). Not unheard of for them to go this early but doesn't seem the norm.

[lagwagon]

Re: u-joints - they can be replaced but you need to source joints with snap rings inboard of the bearing caps since the yokes don't have a snap ring groove. Mrsubaru1387 has a video on it. The center bearing, I'm not sure about that.

[lagwagon]

Well, drive shaft is in, straight, balanced, new u-joints and it didn't fix anything.

 

This is now getting into the range of repair costs that are unreasonable given the market value of the car. I guess this is why subi bois are always asking "part-out?" on any sale post. Car can't realistically be sold for more than a few grand like this, which is about the value of all the new parts its had put on in the last two years.

 

I think I might try a new O2 sensor, even though the current (A) readings look ok based on the response curve I found on nasioc, and a Perrin steering lock down. If those don't help then its either getting traded in or I'm swapping all the body panels and as much interior as possible into the 2005. Maybe even the engine. Unfortunately, I can't do much work myself so I'm leaning toward trade in.

 

Also, the new axle seal the subi dealer installed when replacing the rear axle is leaking so I'll have a pooched rear diff soon as well if they can't get me in right away.

[Max Capacity]

Sorry to hear that.

 

I would think a bad O2 would give a CEL.

 

Is there a way to check out the torque converter ?

[lagwagon]

Other than a stall speed test, I'm not sure. I'd have to reread that section of the FSM.

 

EDIT: Looks like stall speed test is all I can do without any DTCs.

Edited September 4, 2020 by lagwagon

[Max Capacity]

"In cruise, the transmission shifts fine and the tc locks and unlocks fine. There is no change to the vibration/shudder while it is shifting either in auto or manual mode.

 

In neutral at highway speeds, the vibration is still present (I braked from 110 km/hr to a stop).

 

There is a slight vibration in neutral that has been there since I bought the car (2 years ago). Seems typical of auto trannys to me (nothing extreme)."

 

"Anyways, I did some tight corners, both directions, and got popping, both directions, and some telltale bangs from the center console area, and the shudder is getting worse. I am now pretty sure it’s the drive shaft, and possibly also a CV (RF was rebuilt from a used oem, RR is original AFAIK)."

 

Would this lead to a bad CV axle or something in the center diff ?

 

It that reman axle, a life time warranty ?

 

Years back with my 5mt, I noticed clicking sound when taking off from a stop sign from the left front. Stopped by my trusted mechanic and as i mentioned the clicking sound, he say's "when taking off from a stop sign". They replaced the left axle for free, they had found that some of the new after markets CV axles were too long.

 

I had no other indication of a issue.

[chato]

 

I would think a bad O2 would give a CEL.

 

I’ve never had a bad O2 trip a CEL

[lagwagon]

"In cruise, the transmission shifts fine and the tc locks and unlocks fine. There is no change to the vibration/shudder while it is shifting either in auto or manual mode.

 

In neutral at highway speeds, the vibration is still present (I braked from 110 km/hr to a stop).

 

There is a slight vibration in neutral that has been there since I bought the car (2 years ago). Seems typical of auto trannys to me (nothing extreme)."

 

"Anyways, I did some tight corners, both directions, and got popping, both directions, and some telltale bangs from the center console area, and the shudder is getting worse. I am now pretty sure it’s the drive shaft, and possibly also a CV (RF was rebuilt from a used oem, RR is original AFAIK)."

 

Would this lead to a bad CV axle or something in the center diff ?

 

It that reman axle, a life time warranty ?

 

Years back with my 5mt, I noticed clicking sound when taking off from a stop sign from the left front. Stopped by my trusted mechanic and as i mentioned the clicking sound, he say's "when taking off from a stop sign". They replaced the left axle for free, they had found that some of the new after markets CV axles were too long.

 

I had no other indication of a issue.

 

The LF and LR axles are from the dealership so I assume they have some sort of warranty, probably 1 year. The RF was rebooted so no warranty really.

 

I have been thinking it could be the bearings in the center diff carrier, but only because I know people have had issues with them at higher horsepower, not because I know what it would feel like. There are still no noises during normal driving, which I think would generally be a strong indicator of the location of the problem. I don’t have the skills, tools or time to tackle something like the bearings myself and it doesn’t make sense to put the money into it that a shop would charge.

 

It really is a shame since the exterior and interior of the car are probably the cleanest you’ll find for a 4th gen GT wagon at this point, and it has thousands of dollars of new parts on it.

[lagwagon]

Update: o2 sensor swap seems to have gotten rid of 90% of the vibrations. There is a clicking on left turns now, probably the rebooted used axle. Now the vibration feels like a minor wheel balance issue but with the clicking joint and leaking rear diff (thanks dealership!) it could be the axle and/or the diff.

 

I also noticed one of the front sway bar bushings is ripped and it looks like the bar might actually be able to hit the crossing member through the crack. Might tackle that this week before the car goes back to Subaru for them to fix their mistake on the axle seal.

[lagwagon]

Update: Pulled the winter tires out of storage and checked the tread wear. Note these are not the same winter tires I used to check for wheel balance problems. Here are the numbers (converted from mm, hence the funny values):

 

LF: 7.5-8.2/32 (random)

LR: 7.5-8.2/32 (random)

RF: 5.7-7/32 (inside to outside i.e. feathered, can see this visually)

RR: 6.3-8.2/32 (inside to outside, can't see this visually)

 

This is a largest difference of 2.5/32 but an average difference of only 1.6/32. I should probably check the center depth on all four to see what that looks like.

 

Circumferences are all the same within the accuracy that I can measure them (metal tape measure wrapped around the tire tread center).

 

When I checked these in the fall their wear looked normal, and alignment was done shortly after the tire swap so I'm not sure what went wrong. Tire wear on the all seasons is still normal and we do way more driving on the all seasons that the winters. I wasn't aware of any vibration until well after the all seasons were installed so I didn't look at the winter tires (already stored away for the summer).

 

I am guessing that something might've been damaged due to the differences in tire sizes but from what I've read, the 5EAT is the most forgiving on differences since the transfer clutch is designed to be constantly slipping and the front differential is open.

 

The part I still don't understand is that neither Subaru nor my regular mechanic think it's anything to do with the transmission.

[boxkita]

check all your bushings, you'll likely have one that's failed. the big one on the lca fails in a way that's hard to see without a light. I didn't see it until I pulled the lca. ymmv.

 

check the cv boots? the axle grease had to come from somewhere?

 

take the tires down to a tire shop and ask them to swap tires on wheels? have them check each wheel for straightness? tires can spin on the wheel which changes the balance of the wheel

[lagwagon]

check all your bushings, you'll likely have one that's failed. the big one on the lca fails in a way that's hard to see without a light. I didn't see it until I pulled the lca. ymmv.

 

check the cv boots? the axle grease had to come from somewhere?

 

take the tires down to a tire shop and ask them to swap tires on wheels? have them check each wheel for straightness? tires can spin on the wheel which changes the balance of the wheel

 

The grease was from a split boot and that axle had to be replaced.

 

Front control arms have 30,000 kms on them (Mevotech aluminum ones) but I have heard of some people having early failure of the ball joint, not sure on the bushings. In the rear, both front and rear trailing arm bushings are original as far as I know (I know the rear is technically the rear lower outer control arm bushing...) and the upper control arms are original as far as I know. The other three bushings were replaced along with the new lower arms in March or April.

 

The tie rods are original as far as I know and they’ve been checked numerous times but the toe-wear pattern on the one tire has me wondering. What about bushings in the rear cross member/diff mounts or steering rack? Could any of those cause vibrations?

 

I have wondered about a bent wheel, which is why I swapped wheels, to no relief. My summer wheels were powder coated which could’ve damaged the structure if they got too hot, and the finish is really slippery so a slipping tire is possible. I should mark the tires to check.

 

As of now, the vibration only occurs at idle in gear (very mild) and during acceleration, not braking or cornering (unless also accelerating). Mild acceleration doesn’t result in much vibration and manual shifting to keep above 2000rpm helps slightly, but maybe that’s a placebo.

 

Thanks for the ideas, I do really appreciate it. It’s much nicer than hearing sorry, we don’t know what it is.

[boxkita]

vibration at idle in gear? was that an original problem? the car is not moving?

 

check the transmission? last fluid change? filter change? Does it have any codes?