GraniteCrystal build thread

[wayoflife]

So, you got all the skids that might make the noise you're hearing but you're still hearing it? Exactly what is it that you're hearing?

 

[GraniteCrystal]

When does the noise occur? Also, if needed I have a set of chassis ears you can borrow.

So, you got all the skids that might make the noise you're hearing but you're still hearing it? Exactly what is it that you're hearing?

Noise started around the time of new gears, new driveshaft, and 37s. That all happened with a couple days. At first I thought gears maybe just needed to break in, smooth things out. Did diff oil change at 750 miles and all looked good. Oil was green with a little shine to it. Sound didn't go away.

I'd describe it has a low drone/hum when the engine is between 3-3.5k RPM, regardless of gear. There's also a distinct vibration you feel through the floor.

The driveshaft wasn't fully greased before it went in, so that had some play in it and ruined my pinion seal which is now leaking/sweating. Driveshaft is out getting rebuilt. Will put in new seal when it gets back.

So, so far we've pulled the front driveshaft and the skid plates. The sound/vibration is less but still there. As noted earlier, diff temps are 124F and 150F so not thinking it's anything internal to the diff.

 

[wayoflife]

Noise started around the time of new gears, new driveshaft, and 37s. That all happened with a couple days. At first I thought gears maybe just needed to break in, smooth things out. Did diff oil change at 750 miles and all looked good. Oil was green with a little shine to it. Sound didn't go away.

I'd describe it has a low drone/hum when the engine is between 3-3.5k RPM, regardless of gear. There's also a distinct vibration you feel through the floor.

The driveshaft wasn't fully greased before it went in, so that had some play in it and ruined my pinion seal which is now leaking/sweating. Driveshaft is out getting rebuilt. Will put in new seal when it gets back.

So, so far we've pulled the front driveshaft and the skid plates. The sound/vibration is less but still there. As noted earlier, diff temps are 124F and 150F so not thinking it's anything internal to the diff.

Okay, so what you're hearing only happens when you're moving and doing about 3-3.5K RPM? The sound is not speed related? Also, does the sound/vibration oscillate or is it constant? Did you try pulling the rear shaft and running in FWD to see if that made a difference?

 

[GraniteCrystal]

Okay, so what you're hearing only happens when you're moving and doing about 3-3.5K RPM? The sound is not speed related? Also, does the sound/vibration oscillate or is it constant? Did you try pulling the rear shaft and running in FWD to see if that made a difference?

Correct. I put it in neutral with E-brake, revved it, didn't feel/hear it.

Not speed related. As soon as it downshifts below 3k RPM, it stops

I'd say it's pretty constant but maybe a very small oscillation to it. Not a big one though.

Haven't pulled rear driveshaft yet. You think that's next step?

 

[wayoflife]

Correct. I put it in neutral with E-brake, revved it, didn't feel/hear it.

Not speed related. As soon as it downshifts below 3k RPM, it stops

I'd say it's pretty constant but maybe a very small oscillation to it. Not a big one though.

Haven't pulled rear driveshaft yet. You think that's next step?

How do you get it to down shift in neutral?

No point in pulling the rear shaft if you don't need to be moving to create this noise.

 

[WJCO]

Does it change with accel or decel? If it does, it is for certain a power train noise as the change in load is what changes the tone of the noise. Took me a good 10 hours to figure out mine with my new locker making noise. It's a PITA diaging these things.

 

[GraniteCrystal]

How do you get it to down shift in neutral?

No point in pulling the rear shaft if you don't need to be moving to create this noise.

Sorry, that was confusing. Two scenarios: 1) sitting in neutral, no sound/vibration. 2) driving down highway, accelerating, it stop when it shifts to next gear and goes below 3k RPM (i.e. not speed related).

Does it change with accel or decel? If it does, it is for certain a power train noise as the change in load is what changes the tone of the noise. Took me a good 10 hours to figure out mine with my new locker making noise. It's a PITA diaging these things.

Change as in different between accelerate and decelerate? I think it's there in either case. Anything between 3-3.5k RPM.

 

[wayoflife]

Okay, if you're sure it's not speed or movement related and strictly a sound created by RPM, you need to be looking at your engine and not your drive train.

 

[GraniteCrystal]

Okay, if you're sure it's not speed or movement related and strictly a sound created by RPM, you need to be looking at your engine and not your drive train.

Great. The one part that's a black box to me. Tips on where to start? Again, started happening around the time I changed gears, driveshaft, and tires. Maybe reprogramming shift points changed the engine in such a way to make a new noise? Maybe just some loose insulation somewhere that's vibrating with new acoustics?

EDIT: needs to me something heavy enough to cause vibrations on the floor, so probably not some loose heat shield/insulation

 

[Speedy_RCW]

I've had a vibe ever since re-gear as well. I've tried everything imaginable but it's still slightly there. Where I left it was I installed a vibration dampener on the T-case, like the older JK's used, and played with rear pinion angle until I got it as close to gone as I could. My theory is it's a resonance happening between drivetrain and differential frequencies. Not saying this is your case as many people have solved their vibe problems. Just sharing my experience. Hope you get it figured out.


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[wayoflife]

Great. The one part that's a black box to me. Tips on where to start? Again, started happening around the time I changed gears, driveshaft, and tires. Maybe reprogramming shift points changed the engine in such a way to make a new noise? Maybe just some loose insulation somewhere that's vibrating with new acoustics?

EDIT: needs to me something heavy enough to cause vibrations on the floor, so probably not some loose heat shield/insulation

Everything you're saying sounds like a driveline vibration to me but if you're insisting it's not a speed or movement related issue, it's hard for me to say for sure where to start looking without experiencing it myself.

I've had a vibe ever since re-gear as well. I've tried everything imaginable but it's still slightly there. Where I left it was I installed a vibration dampener on the T-case, like the older JK's used, and played with rear pinion angle until I got it as close to gone as I could. My theory is it's a resonance happening between drivetrain and differential frequencies. Not saying this is your case as many people have solved their vibe problems. Just sharing my experience. Hope you get it figured out.

There's a thought. I did always find it strange how some JK's come with t-case that have a dampener and some don't. On the 4 JK's I've owned, I've had both. I'd have to wonder if there's something to it assuming this isn't a driveline issue.

 

[GraniteCrystal]

Everything you're saying sounds like a driveline vibration to me but if you're insisting it's not a speed or movement related issue, it's hard for me to say for sure where to start looking without experiencing it myself.



There's a thought. I did always find it strange how some JK's come with t-case that have a dampener and some don't. On the 4 JK's I've owned, I've had both. I'd have to wonder if there's something to it assuming this isn't a driveline issue.

I've had a vibe ever since re-gear as well. I've tried everything imaginable but it's still slightly there. Where I left it was I installed a vibration dampener on the T-case, like the older JK's used, and played with rear pinion angle until I got it as close to gone as I could. My theory is it's a resonance happening between drivetrain and differential frequencies. Not saying this is your case as many people have solved their vibe problems. Just sharing my experience. Hope you get it figured out.


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Either of you have a pic of what I'm looking for on t case dampener?

 

[Speedy_RCW]

Either of you have a pic of what I'm looking for on t case dampener?

Here ya go.



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[wayoflife]

Either of you have a pic of what I'm looking for on t case dampener?

If you have it, you can't miss it. It'll be a big donut like think bolted to the back of your t-case. MOST t-cases will not have it.

 

[Speedy_RCW]

There's a thought. I did always find it strange how some JK's come with t-case that have a dampener and some don't. On the 4 JK's I've owned, I've had both. I'd have to wonder if there's something to it assuming this isn't a driveline issue.

Yea, I'm not sure what the deal is. Doesn't seem to be year or transmission specific or anything. Figured I'd give it a shot since it was only like $70. Definitely deadened the felt vibration.


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[wayoflife]

Here's a pic - it's the rusty round thing attached to the t-case.

 

[GraniteCrystal]

If you have it, you can't miss it. It'll be a big donut like think bolted to the back of your t-case. MOST t-cases will not have it.

Here ya go.
View attachment 254771


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Thanks guys.

Eddie, to clarify. I'm sure it IS movement related. Maybe not explaining well. It only happens between 3k-3.5k RPM while moving down the road. There is now sound when sitting in neutral revving the engine.

It's just independent of speed.

 

[wayoflife]

Thanks guys.

Eddie, to clarify. I'm sure it IS movement related. Maybe not explaining well. It only happens between 3k-3.5k RPM while moving down the road. There is now sound when sitting in neutral revving the engine.

It's just independent of speed.

So, you're saying that no matter what speed you're going, so long as you're doing 3-3.5k RPM, you hear/feel it? If you're climbing up a steep hill at say 30 MPH but running 3-3.5k RPM, you'll hear/feel the vibration just as much as you would cruising at 75+ MPH running the same RPM?

 

[GraniteCrystal]

So, you're saying that no matter what speed you're going, so long as you're doing 3-3.5k RPM, you hear/feel it? If you're climbing up a steep hill at say 30 MPH but running 3-3.5k RPM, you'll hear/feel the vibration just as much as you would cruising at 75+ MPH running the same RPM?

Yes.......

 

[JeepFan]

Maybe the exhaust is grounding out on the cross member?