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Discussion Starter #1
Since installing my Daystar lift, I've noticed a low gear shudder that I can feel through the steering wheel as well as the auto shifter lever. I'm running the Total Chaos UCA's as well by the way. I've had the front end aligned to Nissan specs (had to get the alignment bolts which allow camber/caster adjustment). Anyways, I've never experienced this before in a lifted application but thought I'd check to see if any of you are experiencing this?

Interestingly enough, I found the following on Drivelines Northwest's website.

Low Gear Shudder
Probable Causes:
Secondary couple load reaction at shaft support brg.

Probable Corrections
- Reduce U-Joint's continuous running angles.
- Shim drivetrain components to equalize U-joint angles.
- Check O.E.M. maintenance manual or alignment arrows on slip yoke and male slip shaft for correct yoke phasing.- If 2 piece-3JT driveshafts...Adjust shaft lengths to 50-50 or 40-60 split.
- Reposition shaft support bearing.

I'm thinking of having a longer driveshaft with a double cardan joint installed. Once the Daystar lift was completed, I noticed that while the driveline angles were okay, the drive shaft was pulled out of the slip yoke another 1.25 or so inches from the factory position.

It seems somewhat extreme to have to go to these lengths after only a 1.5-2" lift but being a daily driver, this is going to get very annoying quickly. Any thoughts on this issue from those of you with the Daystar lift?

Thankyou,

Terry
 

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It almost sounds like something is loose.

You should have no vibration with the Daystar lift (shackles in the rear). If you went with AAL then I can see a vibration problem.
 

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Discussion Starter #3
that's the thing, I've checked all bolts and nuts (on the suspension, transmission mount, front differential mount, rear suspension, rear spring pack mounts,etc). All's well! Oh, and I've got the Daystar greasable shackles in the rear.

It seems to happen in low gears (i.e. 1-3) and right around 1500-2500 rpm during light acceleration. I can power past the shudder with medium to hard acceleration though. Interesting! (not in a good way of course)

Another thing I was considering is maybe some of the vibration that would have previously been absorbed by the rubber bushed UCA's is now being transmitted more to the steering box/transmission since installing the polyurethane bushed TC UCA's?
 

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Does the vibration correspond to ROMs or MPH? Meaning, if you are costing down a hill can you still feel it?

When you checked all bolts, did you recheck the ones you took off when doing the lift? When you checked them, did you check the torque, or did you just check to make sure they were tight?
 

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Discussion Starter #5
everything was torqued to Nissan specs. I've got the Nissan Electronic Service Manual for my vehicle.

The "shudder" seems to disappear when I take my foot off the gas. Only seems to happen between 1-3(I'm assuming since I've got an auto tranny) and is right around 1500-2500 RPMs on light to mild acceleration.
 

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I have same lift, tight as all get out, no vibrations. I wonder if it could be that rear Tranny mount in the TSB? The one they say is a clunk? Kinda like something that is suppose to be isolated by rubber is making metal to metal. My 1st thought was same as Muzikmans (Is something loose)
Anyways I just jump in to say I have that lift (Metal spacers) And no problems so may be elsewhere.

Kinda hard to diagnose here, like giving a haircut over the phone. MC
 

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Vibration that occurs only at low rpm tends to be associated with a loose item. Through acceleration there's significantly more sheer force placed on driveline components than when you're at or near cruising speed.

It takes more torque to go from 0-15mph than from 50-65mph.
 

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Discussion Starter #8
I appreciate all y'all's willingness to pipe in on this issue. It blows me away that I'd have an issue with such a "mild" lift. I'll definitely look into the TSB mentioned by USMC xterra. I paid extra attention to the shudder tonight and it is really noticable at 2000rpms at around 30mph. However, when I let off the gas, it goes away once the rpm's hit around 1-2K. On the freeway at 40,50,60+ mph, it's smooth as a baby's butt.

I've checked all bolts & nuts associated with the lift and even the transmission/transfer case mount. One thing I noticed is that the lift caused the slip shaft to come out of the the transfer case an additional 3/4". I'm wondering if there's just not enough shaft inside the TC to prevent a harmonic (as mentioned by the driveline shop I visited today). The other thing I'm wondering is if the Bilsteins that I'm using may be somehow contributing to this as they are the longer ones designed for the 90's Pathfinder. It's really wierd that this is happening cuz the driveline angles are good (confirmed by the shop also). They said there is a slight angle issue with the Ujoint at the transfer case but it wasn't enough that they'd point to it as the culprit. however, they did say that while they don't know the slip shaft length, it's possible that with it out of the transfer case housing like it is, it may be possible that is the source of the shudder/vibration. of course it could be that the drive shaft is not perfectly balanced. I may have them yank it off and test it just to be sure

arrrrggghh!
 

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I think you are barking up the wrong tree. You just have shackles right? There are a ton of people who have shackles and no problems with the drive shaft or the slip yoke.

I have both AAL and Shackles and no problem. I also have the save shocks.
 

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Discussion Starter #10
Rear tranny mount clunk TSB?

MC,

Can you direct me to the TSB dealing with the rear tranny mount? I only found one from 2005 dealing with the front differential.

Thank you,

Terry
 
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