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M1009 4" lift driveline vibration troubleshoot/new driveline components

WARWAG

Active member
First and foremost. Anytime you install a lift you should change out the U-Joints. They are cheap insurance and are pretty easy to install. Get the best ones for your application. IF you still have a vibration I would shim the rear axle. If one of those dont fix your problem then Im out of guesses. And all of these replies are guesses. Some more educated than others but still guessing since all we can see is what you type. I bet one of these guys could ride in the truck and tell you right off what it is. Good Luck and tell us what you find along with some PICTURES!
 

nudewheeler

New member
41
1
0
Location
Tucson, AZ
Howdy Folks -

Figured I would post a quick follow up to this thread. I see it's grown a bit since my last reply, some additional questions have been asked and a PM popped into my inbox.

I am traveling for the next few months so M1009 is on the backburner. Then other financial priorities have put the M1009 back on schedule sometime in 2013.

Follow ups:
No tire/wheel changes during the lift. I don't believe changing wheel/tire size would affect driveline angles which are the source of my vibrations.

I changed both U joints on the rear driveshaft during my first troubleshooting session. No avail.

I purchased 2, 4, and 6° shims for my next troubleshooting session. I worked with my buddy, took some measurements, and threw the 6° shims in kicking the pinion down in attempt to make the pinion and t-case output parallel (that's the goal of playing the shim game). Got the pinion pointed 2° under the t-case output so that under power the axle can rotate up slightly and hopefully be in parallel with the t-case output. DO you own reading on this theory and come to your own conclusion. I feel under normal driving conditions at speeds that may induce driveshaft wiggles, pointing the pinion anywhere from 0-1.5° under tcase output is kosh. Again, not the topic of discussion, many threads about where to point pinions.

6° shims with my pinion 2° under was disaster. Huge vibrations. 4° and 2° shims lessened vibrations, but still worse than no shims. Tried pointing pinion up for shiggles, no improvements. Crappy day.

Lowered the t-case by flipping the position of the 1" spacers that on top of the frame lip. I played the shim game again and came up with something that is driveable but still wiggles. I can't recall what shims I have there. I'd take a peek but again I'm traveling and won't be back for while.

By lowering the t-case I now have an 09 with a pregnant belly. Not cool for breakover angle but at least I can drive it. I did measure angles at both Ujoints on the driveshaft and each Ujoint is bending around 22°. From my understanding this is a lot for Ujoints, period. I may get a couple thousand miles out of them if this was my final setup. However, I've been gather some parts...:D

Over the past few months I've gathered some parts and here is my plan. Yes I know, expressing dreams or setups that aren't finished doesn't really accomplish anything but this driveline issue basically prompted this entire surgery plan.

Picked up a 14 bolt for the rear, a D60 for the front, an NP205 as half of my 241/205 doubler. By using an NP205, you have a fixed yoke on the Tcase. This increases the X distance from the tcase output to the pinion which decrease the angles at both U joints on the driveshaft. However, by throwing in another Tcase inline, I will do the opposite, shortening the already short distance and increase Ujoint angles. There is really only one solution for the rear driveshaft in this setup and that is getting a double-cardon 3 Ujount drive shaft and rotating the rear axle so the pinion is parallel with the driveshaft (rear most driveshaft angle is 0°).

When the 09 is complete, the above configuration will hopefully eilliminate rear driveline angles. Costly, but should be able to conquer terrain and go down the street without worries.

Another alternative on the semi-cheap is to swap out the NP208 for something else like a 203 or a 205 that has a fixed yoke and get a double-cardon driveshaft. 4xshaft for a custom job, or pull something large from a junkyard and DIY.

The blazer has a short wheelbase and its driveline components are rather close together. When you start mucking with things, affects ripple larger, faster then in longer wheelbase vehicles.

Some Ideas:
  • Lower t-case
  • New rear Ujoints
  • play the shim game
  • fixed yoke t-case + double cardon driveshaft

Basically if you're on the cheap, play the shim game until you're satisfied.

Hope this makes sense. Haha, I'm actually recovering some a nasty stomach bug at a hospital in Singapore. I did proof this reply once and it flowed for the most part.

Hope this helps.
 

WARWAG

Active member
When I asked if you had changed out to larger tire combo I wasnt implying that it would change your pinion angle. Just going to larger tire combo like the Wrangler (old style hummer tire) would see you hard pressed to get those tires balanced if at all possible. They suck as far as in the balance department and thus gives you some serious vibrations at any speed. OK SO ITS NOT THAT.

I would take all of the shims out from your Tcase and bring it back to the stock position. Shim your rear axle 5 degrees.
 

fstfrdy

New member
78
1
0
Location
crosby,nd
Threw the 2.5* in first with the large part of the wedge facing the front of the vehicle to kick the pinion down towards the ground in attempts to match the plane of the pinion and t-case output shaft
the large area goes to the rear . you want to reduce the angle not increase. i worked in a suspension shop installing lift and lowering kits and saw this regularly. most likely its worse under under acceleration is because that you are close to right on until you hit the gas and the torque puts a twist in the rear(lift springs are always softer than factory) and puts the shaft farther out of angle and binds the joints.
 

dirtroadoutlaw

New member
17
0
0
Location
Florence, MS
As a reference, u-joints in a single-cardan setup, like that, should be within two degrees of each other. Spicer's tech manual says a maximum of three degrees but that would be too much IMO. The closer, the better as to achieve the most longevity from your joints and the smoothest operation. Exceeding that 2 degree threshold creates a harmonic chatter within the joints that even the best grease cannot absorb causing premature and irregular wear.
 
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