Vibration Under Load!

[DSM_ThuNDeR]

I'm apologizing ahead, sorry for my punctuation. Anyway I'm going to try to be as descriptive as I can be. It's been a VERY long time that I have not been able to take my 2g awd ANYWHERE. I Installed a new motor just last year(spun rod bearings) and the motor seems REALLY healthy. The vibration problem was there before I spun my rod bearings. In the process of taking out my motor I took oviously the tranmission down too. Checked the driveshaft for anything odd(carrier bearings, u-joints, all 4 wheel bearings and CV axels). I also checked my inner and outer tie rods. I even got the wheels aligned and that did not help one bit. Everything lookes fine to me! The vibration problem got worst and worst overtime. It seems to me that the more you drive it the vibration starts to escalade more and more. I only feel it sometimes between 2500-3500 and eventually sometimes fades off.

For example's:
If I been driving the car about 9 mins, the vibration is really bad, and I shift onto a lower gear, the vibration minimizes.

Suppose I'm going about 30mph and I'm having vibration, I let off the gas and it STOPS! So I continue going about 30mph step on the clutch and rev(to see if my mounts are causing this) and the vibration stops no matter where I rev it to.

If the the driveshaft is out of balance could this be as well? The vibration is def felt in the rear. I really want this car to move safely with no issues. What things can I look for? What kind of vibration problem does this sound like? PLEASE HELP! I don't know if I want to pay 80 bucks the hour to someone that might not be able to fix it.

 

[DSM_ThuNDeR]

I've searched and search but found nothing close to mine, all of the other vibrating problems I've found are going at high speeds like in the highway.

 

[94awdcoupe]

sound like recent AWD car here local.

had welded center diff in trans and a tire wearing much faster than the other three. in an AWD car all tires need to be very close to same diameter. with welded diff they need to be exact or the tires fight each other just driving in straight line, resulting in driveshaft shutter. most problematic under power. coasting it was not noticeable.

 

[DSM_ThuNDeR]

I changed my transmission, and the same thing is actually going on. A mitsubishi dealer tech told me to replace my old one because the center diff was bad. As you can see, he just made me waste money.

 

[lazyazzdaddy]

sounds like it could be your transfer case to me.

 

[twicks69]

Check your front axles again, and your halfshaft bracket bolts. The problems you are facing sound like a toast front axle, or a front driver-side axle that is not fully installed into the halfshaft, or a halfshaft bracket bolt issue.

 

[DSM_ThuNDeR]

sounds like it could be your transfer case to me.

Changed that as well too, just in case. Still have the same problem.

 

[DSM_ThuNDeR]

Check your front axles again, and your halfshaft bracket bolts. The problems you are facing sound like a toast front axle, or a front driver-side axle that is not fully installed into the halfshaft, or a halfshaft bracket bolt issue.

both halfshaft bracket bolts are on tight. When I took the transmission I checked both axels for play and found nothing.(I SHOOK THE HELL OUT OF THEM)
I also checked the rear axels for play when I put in my 7bolt and this time when I took down my transmission as well.

Could UNBALANCED wheels cause this problem?
I was email chattin' with one of the near by dsm shop's and the owner(sean @ full function effect) asked me if the wheels have ever been balanced. Since I got the car, that has not been done. What can I do to find out If these wheels are UNBALANCED? I heard about putting the car in gear while all fours are in the air, and if I don't feel vibration, that might be my problem

Any ideas??? I am determined to fix this problem with your guys help!

 

[Cesar]

does the vibration increase with road speed?

420 POSTS!!!

 

[DSM_ThuNDeR]

After 20mph+ is when the vibration starts to happen. Vibration is only felt between 2500 to 3500 r.p.m.s and eventually fades off after 3500 rpms. Tomorrow I will have the car on all four wheels again and I will come back with any findings.

 

[rush2252]

IF you have a SAFE WAY to suspend all four wheels in the air get the car off the ground. This is best performed on a lift. Start the car and have a friend engage it into driving gear. Using either a mechanics steth or a long handled screwdriver check the rear diff and wheel bearings. You should hear a grinding noise if you have a bearing going out. My rear wheel bearing was shot and it had no slack. The AWD are a pain to change but it got rid of my vibration and noise issues.


Good Luck

 

[twicks69]

Yes, unbalanced wheels/tires could easily cause this problem.

Go get your wheels/tires balanced. It is cheap.

Also, when the car is on jack stands, inspect the drive shaft carrier bearings for excessive wear or damage.

 

[gorf]

Just for clarification..
You have vibration between 2500 rpm and 3500 rpm - is it the same rpm range in all gears completely independent of your speed?
If that is the case you pretty much have eliminated everything from the tranny to the ground.

Must be something in your engine at that rpm range.
Do you feel it if you are out of gear and just rev the engine to 3000?

Get your tires balanced anyway.

 

[94awdcoupe]

Just for clarification..
You have vibration between 2500 rpm and 3500 rpm - is it the same rpm range in all gears completely independent of your speed?
If that is the case you pretty much have eliminated everything from the tranny to the ground.

Must be something in your engine at that rpm range.
Do you feel it if you are out of gear and just rev the engine to 3000?

Get your tires balanced anyway.

balance shaft timed incorrectly would cause this.

would have said that right off the bat , but he did state drive train vibration not engine vibration.

 

[DSM_ThuNDeR]

Just for clarification..
You have vibration between 2500 rpm and 3500 rpm - is it the same rpm range in all gears completely independent of your speed?
If that is the case you pretty much have eliminated everything from the tranny to the ground.

Must be something in your engine at that rpm range.
Do you feel it if you are out of gear and just rev the engine to 3000?

Get your tires balanced anyway.

As stated in my first post, the vibration does not happen when the car is neutral and I rev thay high, or when the car is rolling and I press the clutch pedal in and rev that high either. I'm going to have to put the car with all four wheels in the air. Then take them off to rule out the "unbalanced wheels" to see if the vibration still continues. I'm new to an awd suspension, how much play exactly do the carrier bearings have to have in order to determine that they need a replacement? Thankx for the replys guys.

 

[gorf]

As stated in my first post, the vibration does not happen when the car is neutral and I rev thay high

Sorry went back and read it again. Only under load and you think it is coming from the rear. already been mentioned - ujoints or carrier bearings.

When I did my awd conversion, I checked my ujoints, they all moved and had no excessive play - so I used them. Shortly afterward I picked up a vibration. Mine turned out to be that one ujoint was "stiff". It didn't move real freely so caused vibration, replaced it and vibration gone..

Get all 4 wheels in the air and spinning, look at the drive shaft, if it is out of balance you will see it. Look at all four wheels if one rim is slightly bent, it will be obvious. If one wheel is out of balance you will see it bouncing. Get a stethascope or long socket extention and go around to every bearing and listen, you will eventually find where it is coming from.
Please report back - this sounds like a good problem.

 

[DSM_ThuNDeR]

Thanks for the the help. Sean at full function was right! I got my wheels balanced and fixed the problem!