Driveline vibrations, round II

[aston]

Jeez Goodimes, the only thing I can suggest is to find another 03TJ and compare side-by-side.

How about those frame straightening shops - I wonder if they have a book of vehicle datums.

OTOH it would seem reasonable that the crank is parallel to the centerline of the vehicle and it sounds like it isn't.

good luck

[Bachman]

Damn Dude!!!

[TDS SD]

Vibrations

If you feel the frame is not straight why not take it to a frame shop? They will tell you if it is and tell you what you can do about it. There is also the possibility the rear mount under the tranny/transfer case needs to be moved one way or the other. My holes were enlongated on the skid plate at one time and I had to weld some thick washers to get the mount back in its proper place. This help my problem. Hope you find a cure as it is very fustrating spending money on a fix and getting nowhere.
George

[goodtimes]

The reason for not taking it to a frame shop is simply a lack of time, and I don't feel the frame is the problem. There are other issues that need to be resolved before investing time and money in the frame.

That said....I got the drivetrain straitened out. The t'case output shaft is now offset to the passenger side the same 3/4" that the rear pinion is. This was a large pain in the butt...mainly due to the stupid high humidity we have right now. It made cutting/grinding/welding/rolling around under the jeep rather miserable....which is probably why it took me so long to get it done.

Unfortunately, this did not solve the problem 100%. The vibration doesn't start as soon as it did before. In fact, at 65mph, things are very tolerable. At 75mph though, it has once again gone to s#!t. Not nearly as bad as before, but still there. With the adaptor ring running true to the t'case output shaft (after some modification), I still get .010" of runout measured at the splined half of the slip joint. Tom Woods has finally agreed to take care of any problems they can find with the driveshaft, so it is in a crate on the back of a UPS truck somewhere. We'll see.....

[TDS SD]

Vibrations

I have talked with him at least half a dozen times over the past 2 years trying to straiten this out. I am ready to send the shaft back to him and tell him where to shove it.

You have been fighting this problem for quite some time. Did this problem show up after a lift?

[Bachman]

I know this may not help but I put a 4" kit on a 05 Rubicon, the owner went with the CV shaft and the yoke that replaces the stock balancer and flange on the T-case. We omitted the t-case drop set the pinion angle at 1 degree down, thus far after about a month no vibes. Maybe Pfeiffer has it, I would hate to throw more money on the fire but your time, effort, and frustration are worth something...:dunno:

[goodtimes]

The problem began as soon as I installed the lift and driveshaft (done at the same time).

The CV is running pretty close to 17 degrees (the CV joint operating angle, not the rear pinion angle). That is well within the capability of the joint. Eliminating the flange and balance ring and installing a traditional yolk will only reduce the operating angle of the CV joint by approximately 2 degrees. Since I am only at 17 degrees to begin with, it doesn't make sense ($$$) to change to a different design.

The design of this driveshaft/adaptor is not in question. Hundreds of people are using it with no problems. The issue is with the manufacture of this particular driveshaft and adaptor. It is a whole lot cheaper for me to send it back to them ($21 for UPS), than it is to buy a different driveshaft whos design doesn't have any advantages for my application.

Once the known problems are taken care of, then I can proceed with looking at the other "possible" problems (frame, etc) if the problem persists. But the known problems must be addressed first.

[RAT]

Wtf???

This is the case with both driveshafts installed, or just the rear. With the rear shaft out (now in "front wheel drive"), the vibration is non existant, up to 75mph (don't drive much faster than that). This has been the case since the day I installed the lift and CV driveshaft ~10,000 miles and 2 years ago. Vibration has slowly gotton worse.

I don't see anywhere in you posts where you have checked the alignment of the rear axle. As I read this, you installed the lift and drive shafts and thats when the vibration started. There is a possibility that the control arms are not adjusted correctly side to side (measured from center to center of front and rear axles on both sides of Jeep). This must be done with the Jeep on the ground to get the suspension's true geometry. Since the lift was installed, the front axle might not be true either, so the alternative is to pick a point on the frame, somewhere you can get a clear and true reference point, then measure from the centerline of axles to this point and compare readings front to rear, and on both sides.
If the rear axle is out of alignment, which is very common when new suspension/lifts are installed, the pinion angle, relative to the centerline of the vehicle and the drive shaft (side to side) will cause vibration in the drive line. The fact that you say this vibration is non-existant with the rear drive shaft removed may mean this is part of the problem. I'm not convinced the drive shaft measurements you took are all that drastic. Not great, but not horrible either. If the rear axle is out of alignment as I described, and it's bad enough, the vehicle will squat or swerve when you get on and off the gas at freeway speeds, as anybody whos' torn out a control arm mount will testify to, but it doesn't have to be that bad to cause vibration.
If you don't think you can make these measurements accurately, take the jeep to an alignment shop. These are the same measurements used to check 4 wheel alignment; they'll be able to get the data you need.

I know you've been getting a lot of ideas and suggestions, and after all the time you have spent on this it's got to be damn frustrating. Sure hope you get this fingered out...
Rat

[goodtimes]

The rear pinion is offset to the passenger side right at 3/4". Same as the output shaft of the t'case...just like they are supposed to be (and like mentioned in my earlier posts). The measurements I took from the driveshaft (see earlier post) were bad enough that the manufacturer of the driveshaft feels it is a problem. He knows alot more about what is acceptable and what isn't (with regards to the driveshaft) than I do....so I'll take his word for it now that he admitted it was a problem.

It really is a PIA, mainly because it has proven to be an atypical problem. All the usual suspects check out OK. It is the off the wall stuff I keep finding and fixing only to find out that it really wasn't the main problem. It will eventually be figured out. Hopefully sooner rather than later.

[goodtimes]

Tom Woods recieved my driveshaft on Tuesday. They cut/re-welded the tube, replaced the u-joints (despite them saying there was nothing wrong with them), balanced it and shipped it back to me with a new adaptor. It arrived Friday via UPS. Total time I was without it was one week (friday afternoon to friday afternoon).

The new adaptor was a much tighter fit than the old one, particularly on the driveshaft side of it. The pilot measured .003" runout (old one measured .008). With the driveshaft installed, the stub (splined end of the slip joint) measured .004" runout (previously was .010").

Up to 70 mph the jeep is remarkably smooth (keep in mind that I haven't driven it without a vibration for years). It's no caddy.....but MUCH better than before. At ~70 it picks up a vibration (go figure), by 75mph it is bad enough to vibrate the rear view mirror.....which it would do at ~55 - 60mph prior to sending the driveshaft out for repair. It is much better.

Of course, I must have left something loose, as I picked up a new rattle underneath...so the test drive was cut short....

In short, things are improving.