Well, I had SHEP do the diff pin upgrade, always possible something got screwed up with that??

 

I've had the same issue also which started in 4th around 5k rpm, but now is present in 3rd and 5th through the meat of the power curve. I did both lower springs and the Cobb V2 Stage 1 Beta maps at the same time when the issue came up. Without access to tuning, I tried several different maps, even going back to the Stage 1 map that I had origninally, and the issue still persist, so I'm I narrowed it down to suspension and/or drivetrain thinking even my clutch was going.

Well, my clutch did go, which has been replaced with a CM HDSD which is working out wonderfully for 2k miles now, yet the issue is still present. The clutch was installed by the dealer, who did note that the CV joints seem to be making some noise but they found no issues with them. They said that's common of lowered Evo 10s and the only fix is to bring it back to stock.

Too bad I had already bought a RCA kit which is still sitting in my trunk, as I'm still deciding if I should go back to stock or see if the RCA helps.

 

Mine feels like in 4th and 5th maybe change the transmission fluid?

 

Someone smarter than me should post up (Iowa?) but I'm surprised the dealer would indicate abnormal wear on the CV joint with a lowered car. If I recall (as I'm not under the car right now) the CV joints and half shafts are not under additional load with the car lowered and are designed such that the wheel can move independent of the cv's position. You'll have wear on your bushings and tires, of course, but that should be about it.

So, just to follow up,

- any additional noise with the vibration (wheel bearing)
- have you tried swapping wheels or tires just to confirm they aren't related
- I'd be surprised if changing the tranny fluid helps, but it's a good thing to do anyway
- do you feel more vibration through the stick shift or through the seat?
- can you reproduce it on a dyno? Do you have any nearby?

 

Not a wheel bearing.
Swapped wheels/tires and still the same.
Tranny fluid changed.
Neither. Accelerator pedal.
Not going to spend money on a dyno or take the time.

 

I kind of gave up on this thread when I couldn't tell if it was speed-dependent, gear-dependent, or what. In general, when it's truly gear-dependent, you look at the tranny. When it's ground-speed dependent, you quickly rule out the tires/wheels and then you look at the driveline, always starting with the transfer case (on any Mitsu) and working forward, ending with wheel-bearings. If it's engine-speed dependent, you start with the clutch and work backwards.

The one exception to this that I know of is when it might be an engine mount. Those can be weird, as they often depend on load, instead of gear, ground-, or engine-speed.

But first you do some testing to see exactly what factors determine when it happens.

With all that said, on an Evo X it usually turns out to be the stupid transfer case.

 

Hmmm,

[QUOTE=dboz;10500553]Not a wheel bearing. OK, I tend to agree, but did you have these checked?

Swapped wheels/tires and still the same. Good Test

Tranny fluid changed. Figured this wasn't it.

Neither. Accelerator pedal. I never thought this would do anything

Not going to spend money on a dyno or take the time. - Well, this is telling. It must not be that bad....

So, maybe the transfer case, like Iowa says. Did you check your bushings?

 

Just wondering if the OP solved the problem. I'm having the same issue under hard acceleration in 4th gear.

 

i have the same problem since i lowered my car on coilovers. It was only in 4th gear under wot. It wouldnt do it if i redline 3rd and shift into 4th and continue on. It would be if i was just cruising in 4th and then decieded to get on it. I have just a cobb accessport and an exhaust and intake for mods. But i raised the car up a little bit more since when i searched threads a lot of people said that made it go away. And sure enough that pretty much eliminated the problem for me. Its still slightly present but much less noticable then before.