1g AWD Driveshaft Vibration can't solve

[danl]

I am posting this for a friend who has been trying to fix this issue for over a year. I will provide cliffnotes at the end if you don't want to read through the whole next paragraph.

The story starts with a 1990 GSX 5 speed that had no vibration problems. We then put a DSS 3.5" driveshaft in the car and it was fine. Then the first track day he snapped the cross shaft on the stock rear section that you reuse with the DSS shaft. It beat around in the car real good as the tires spun and the broken driveshaft was wacking the subframe pretty good. So then we put a used rear section in the car and it had a horrible vibration at 30-40mph and did not go away with speed. I then let him borrow a complete OEM driveshaft from my 91 AWD 5 speed that was under construction. The car ran fine, cut some 1.4 sixtey foots and no vibration. I then needed my driveshaft back so he sent his DSS shaft to a local driveshaft shop to be rebalanced as we assumed it was somehow damaged. It was rebalanced, returned, and put on the car with an unknown condition rear section. The whole assembly vibrated. Another rear section of unknown condition was put on, the whole assembly vibrates. He has tried 3 different TX cases even though the one was fine with my driveshaft on the car. With the car on jackstands in the air he can not see the driveshaft vibrating anywhere. We are at wits end on this one as he is putting a THIRD rear section in the car now. I'm going to start putting these driveshafts on my car to see if the problem follows his car or if it is indeed the driveshafts. I do not believe the problem is the tx case, any part of the actual driveshaft, or the rear end. What else could cause this problem? The carrier bearings are filled on these shafts.


CN: 1g AWD broke driveshaft and can't seem to piece together a driveshaft that won't vibrate. Have tried multiple driveshafts and tx cases.

Here is a picture of the driveshaft assembly so we are all on the same page.

 

[Colt4G63 also]

This might not be much help, but I just filled my support bearings, and I have a vibration now too. I just ordered new bearings, and I'm hoping that absorbs the vibration as well or better than the worn cracked ones before I filled them with urethane.

If my problem persists, I'm sending the whole assembly to Powertrain Industries based out of California because they can balance the whole thing as one unit. The weight on the front of the rear section is also working on the rear of the middle section, and in part affecting the whole shaft, so mixing and matching is really not the right way to do it.

EDIT: Another thing to note is the alignment of the shaft pieces. The C/V joint section can be bolted up in six different directions, but only one is right.

 

[danl]

Thanks for the reply. I'm not ruling out that both rear sections have bad carrier bearings that is causing the misalignment and vibration issue. He is putting a third rear section in. Also it was my understanding that the driveshaft shafts are balanced individually by mitsubishi.

 

[Colt4G63 also]

Thanks for the reply. I'm not ruling out that both rear sections have bad carrier bearings that is causing the misalignment and vibration issue. He is putting a third rear section in. Also it was my understanding that the driveshaft shafts are balanced individually by mitsubishi.

I don't have any first hand information on how Mitsubishi Balances them, but I brought my driveshaft to a local shop last week, and their shop balances the parts as a whole. The tech there felt that it was the only right way to do it. Some shops will balance two pieces, and the other piece seperately, but only because the machine they are using doesn't accomodate two support bearings.

 

[talondave]

Check the yoke on the DSS drive shaft! I had the same problem with my HD DSS drive shaft... One good launch and then it would vibrate like crazy, the yoke twisted and bent a little! Will the drive shaft yoke slide all the way into the tcase?

 

[danl]

Check the yoke on the DSS drive shaft! I had the same problem with my HD DSS drive shaft... One good launch and then it would vibrate like crazy, the yoke twisted and bent a little! Will the drive shaft yoke slide all the way into the tcase?

He had to beat it off from what I recall. However even with a stock 2 piece front it still vibrates.

 

[talondave]

He had to beat it off from what I recall. However even with a stock 2 piece front it still vibrates.

You said it didn't vibrate with you're stock drive shaft! Have him look down the yoke for twisted splines! I bet that yoke needs replaced.

 

[Colt4G63 also]

I bought three of those repair kits just for the u-joints. If it turns out you need a yoke let me know.

 

[danl]

The yolk on the DSS shaft (which is the only one to get stuck in the TX case) is a modified unit, the stock yolk won't work. I'm going to try to put some of these driveshaft parts on my personal GSX to see if the issue follows the car. I'm still baffled that my driveshaft worked fine on his car, so we are going to go the other way and try drive shafts from his car that vibrate on my car.

Also rear diff fluid came out clean on his car and the input pinion on the rear diff has no play. The one rear axle has 1/16" of up/down movement but that is fairly normal from what I recall.

 

[talondave]

I went through this 5 times last year with my DSS drive shaft, kept twisting the yoke, and then it would vibrate like crazy! Put a stock drive shaft on and all would be good! Drive shaft shop replaced my yoke everytime, and also had them make the driveshaft longer, cause I didn't think the yoke slid far enough into the tcase... Hell my DSS drive shaft only slid into the tcase 2"...I would also have to beat my DSS drive shaft off!

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[danl]

That is not normal dave. His isn't nearly that bad but its still out 1/4" or maybe 3/8" more than what a stock yolk goes into the tcase. He is so frustrated that he just dropped off parts at my place and over memorial day weekend I will see if I can assemble a good driveshaft for him on my car. I still have things I want to try like putting the U joints in "phase" and adjusting the driveshaft "levelness" if that makes any sense. I'll also inspect the U joints for wear, tear, and other trauma, but these parts are off of stock parts cars (automatic cars) that say little if no abuse. We are not using anything that was ever at a drag strip when trying to put together a good 3 piece stock shaft.

 

[Colt4G63 also]

If that yoke doesn't slide on and off effortlessly it might be part if not all of the problem. If it's twisted, it could throw off the balance, or cause u-joint binding due to misaligned ears (for lack of a better term), or even bottom out the C/V joint section when the engine torques forward and back.

I have a driveshaft from a friends clean (un-messed around with) 90 GSX, and the u-joints are phased like this:

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[danl]

Yeah, I think the problem may be he doesn't have the lobro bolted together such that the U joints are phased correctly. Even if they are phased correctly, they may have to go 180 degrees out. So realistically, 1 out of 6 possible ways to put it together and I'm betting his was always wrong.

This is a good article that I think has the solution to our problem.

jeepgarage.free.fr/OWN/drive%20shaft%20alignment.pdf

 

[talondave]

Well, If you're ever In Maryland, you can pick up the drive shaft I took out of my car last year... Its not the best looking thing, but it drives smooth and doesn't vibrate... Hope you guys figure this out, and good luck!

 

[Colt4G63 also]

I figured mine out today! I pulled the shaft right out of the car to check everything out, and I discovered my front yoke was a little twisted. I put on my spare, and made sure all the u-joints were working smoothly, but that didn't really affect anything, the vibration was still there.

Then I rotated my lobro joint 180, but that made it worse. I rotated my front section 180, and that also made it worse.

Here's where it gets creative: With the car still on the lift, I removed all the wheels in order to minimize other vibrations, and bolted the rotors onto the hubs. I wrapped a piece of paper around the shaft (up front where it was shortened), put a large washer on top of that, and then wrapped tape over the washer. The paper prevents the tape from sticking so the washer could be rotated incrementally.

I ran the drivetrain at various speeds between 30 an 65 mph, and had a friend rotate the washer 180, then 90, then 180 again, then setteled about 25 degrees or so from one of those spots. Then I added a smaller weight on top of that, then tried adding the smaller weight opposite that. I determined the smaller weights only made things worse, but the big washer was a definite improvement.

Then I did the same thing at the rear of the front shaft with a smaller washer, but that was just making things worse. Then I tried the small washer at the back of the center shaft in various positions, and found the sweet spot.

Even with my urethane filled center bearings, the car drives incredibly smooth at any speed now. I almost wish I hadn't ordered the new center bearings. I removed the paper barrier, and taped the two washers on with duct tape, and then covered that in aluminum tape to protect it from the exhaust heat. I made sure to wrap it in the right direction so the tape won't unravel while driving.

If this thing still feels as great by the time my new center bearings arrive, as it does now, I'll just weld those on and skip the expense of sending my driveshaft to the opposite end of the continent for balancing.

I'm just in awe that it worked out so well, and the car hasn't been this smooth since it was FWD.

Danl: Let us know how that one works out, I'm still curious to find out if you find something bent, binding, out of phase, or if it just needs to be balanced to sync up the DSS piece to your OEM piece.

Ps. Wow you're right, that is a good article.

 

[danl]

In the article you can see that they used worm clamps and rotated those to find the imbalance. We are not using the DSS until we get a stock driveshaft working. Everybody should read that article if they have any driveshaft (high frequency) related vibration problems.

 

[Limegrntaln]

I'm having a driveshaft vibe problem also. This is the stock shaft. I went ahead and replaced the carrier bearings this past weekend and I also changed out the front yoke with the recall kit. My car is a 2G though. The front bearing still vibes and I can feel a vibe on the highway, but it's real subtle. Deceleration is worse than acceleration. It's my DD right now, so I can't afford to have the shaft removed and mailed out. I live in California so I need to find a place local that can do it the same day.