3 Linked 80 is clattering....? (2 Viewers)

[petwhookie]

Hi mud,

I am going crazy these last few months and thought I'd type up my thoughts and ask the mud folks what they think. This all started after I had my local fabricator friends help me 3 link my 80. Please take a look at my notes below and let me know what you think?


The Truck:

• 4wu 3 link
• Tom's DC front driveshaft
• 37s, 5:29
• Brand new OEM rear drive shaft
• Part time kit + spool + high&low gears
• Front axle was dissembled & assembled by fabricators who did 3 link
• Front caster set to 6.5* degrees

Symptoms:

• Driving 55+ when I'm off throttle there is a loud clatter coming from the truck
• While going 55+, if I slap the truck in neutral & coast it clatters much louder
• Happens in both 4wd & 2wd
• Hubs locked in 2wd - clatters slightly louder
• Hubs locked in 4wd - clatters

Troubleshooting methods:

• No front driveshaft, unlocked hubs … grinding noise
• No front driveshaft, hubs locked… less grinding noise
• No rear driveshaft .. grinding noise

• Discovered front axle was low 1qt in fluid in front diff
  • Filled up 1qt... grinding noise
  • Drained the fluid & found some decent shavings for only <1,000 miles (pics below)
  • Refilled front diff ... grinding noise
• Drained & filled transmission… fluid looked clean

• Thought my T-case was bad and making the grinding noise
  • Installed part time spool with new bearing, old race with original T-case (I messed up here)
    • Drained t-case & full of metal shaving
  • Had Valley Hybrid build me a new & different T-case with PT spoo, high & low gears
    • Installed ... still grinding

• New t case, remove rear shaft… still clatter
• DS wheel bearing loose, tightened .... still clatter
• Confirmed part time hubs work

• Measured pinion angle in rear-
  • T-case 2.1* down
  • Rear diff 2.6* up
  • 14* new on driveshaft
  • New OEM driveshaft
  • Confirmed in-phased

• Used a Chassis ears tool (and I couldn't identify it well)
  • Front diff - clatter matched, loud
  • Transmission - low clatter did not match
  • T-case - clatter matched, louder
  • Rear diff - clatter, matched loudest

• Front diff backlash is fairly loose
  • ~5/8 back lash measured from pinion flange
  • It takes about 1" roation from the hubs to move the front driveshaft

Right now -- what's throwing me off is that the clatter happens with no power the front font via hubs and/or taking off the driveshaft. If I understand correctly the clatter shouldn't happen without power to the front assuming the problem is my front diff gears.

Lastly, when I had my fabricator put my front axle together. I did not have my part time spool installed yet and only had the part time hubs installed. He stated that he had parked my truck on a slope and it moved while he was outside of the truck. I'm somewhat thinking this could of somehow hurt some part of drivetrain??

Thank you as always, Mud

 

[petwhookie]

hold

First time draining the front diff fluid after I got truck back. I assume the standing metal shaving is from the wire wheel brush when my axle was being built.

Rear pinion angle

 

[scottryana]

Front pinion bearing

 

[petwhookie]

Front pinion bearing

I'm thinking it's because they reused the pinion washer. I vaguely remember though I used the hard washers instead of the crush washers.

But will the clatter still happen if it's only in 2wd?

 

[BILT4ME]

A few pics of the side view of the driveline would help.

How much lift are you talking about here? Just having a 3 link without referencing the amount of lift over stock gives us no reference point.

My first thought is U-joints binding because that typically happens under deceleration because there is "intermittent load" and the drive line changes angel between the diff and TC in a bad direction during decel. Also, if your rear stock DS is too short for the lift you now have, you may be at the length limit of the yoke and the yoke is wagging on the end of the DS. Your rear diff will rotate down during decel and may exacerbate the binding.

Are your axles aligned left to right properly? The mounting flanges have not only a vertical orientation, but a third axis orientation as well, as they are not perfectly aligned in the center of the truck, but they SHOULD be parallel.

 

[baldilocks]

How long after 3 link install did this begin? Or, how long after the last major modification did this begin happening? I agree that the front third member is suspect if only because of the metal particles that drained from it.

Are all suspension joints good to go?

 

[petwhookie]

The 3 link is about a 4” lift. The traditional measurement of lift (axle to fender) doesn’t work as I’ve cut the front fenders. Rear lift is 4” heavy slee springs with 30mm spacer. Rear bumper, drawers, spare tire etc. I estimate a 4" lift.
@BILT4ME

For the noise, it’s been there ever since I got the truck back from my fab guys. I thought it was my front driveshaft which opted me to get a Tomwood's DC front driveshaft and go part time. The noise is still there.
Also, all my bushings are good and have been replaced within the last two years. My rear sway bar bushing near the frame are bad.
@baldilocks

 

[petwhookie]

Here is a pic of the diff fluid after draining. I thought it was dark for such low miles. I do blame myself for letting it low about 1qt.. maybe <1500 miles

 

[Delta VS]

The 3 link is about a 4” lift. The traditional measurement of lift (axle to fender) doesn’t work as I’ve cut the front fenders. Rear lift is 4” heavy slee springs with 30mm spacer. Rear bumper, drawers, spare tire etc. I estimate a 4" lift.
@BILT4ME

For the noise, it’s been there ever since I got the truck back from my fab guys. I thought it was my front driveshaft which opted me to get a Tomwood's DC front driveshaft and go part time. The noise is still there.
Also, all my bushings are good and have been replaced within the last two years. My rear sway bar bushing near the frame are bad.
@baldilocks

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are panhard attachment points still stock? if so, use method in post one here to determine lift: Compiling/comparing lift and caster data - https://forum.ih8mud.com/threads/compiling-comparing-lift-and-caster-data.1099600/

 

[BILT4ME]

The 3 link is about a 4” lift. The traditional measurement of lift (axle to fender) doesn’t work as I’ve cut the front fenders. Rear lift is 4” heavy slee springs with 30mm spacer. Rear bumper, drawers, spare tire etc. I estimate a 4" lift.
@BILT4ME

For the noise, it’s been there ever since I got the truck back from my fab guys. I thought it was my front driveshaft which opted me to get a Tomwood's DC front driveshaft and go part time. The noise is still there.
Also, all my bushings are good and have been replaced within the last two years. My rear sway bar bushing near the frame are bad.
@baldilocks

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Your rear DS appears to be off a spline or two from being correctly in phase. Angle is steep but I think ok. The splines being off could cause the noise.


Your front DS appears to be at full stretch on the yoke and you're going to get yoke wobble at that stretch. It appears that pic was taken with the tires on the ground. In other words, your DS is too short.
The angle of the front pinion to the DS should be near parallel. All angle should be taken up by the double cardan joint at the TC.
The full stretch is likely the cause of the noise at decel.

Also, make sure you lube all 5 zerks on that DC shaft at every oil change. 3K -5K miles

 

[thatcabledude]

Front pinion bearing

How?

 

[thatcabledude]

How long does what you’re calling “clatter” last after you let off the throttle? Go away away after a second or two? You are pretty much describing the exact issue I have had ever since I went to 4 of lift. (65k miles ago) Our pinion angles are about the same too. You’ve done all the same things I have to try and fix it too. ( I even rebuilt my transmission lol) Only thing left I guess is a DC rear shaft. Before that I’m going to try and point the pinion up more just to see what it does.

It’s been a long time since I did it, but IIRC, I didn’t have the sound when testing in FWD only.

I hope you figure it out

 

[baldilocks]

@petwhookie I run Slee 4” heavy progressives in the rear with no additional spacer and the hub to fender measurement shows well over 5” of lift with the dual swing out Labs bumper, spare tire, rear mounted compressor, spare drive shaft and tie rod clamped to inside of the bumper and the Labs wheel well mounted cargo baskets inside as well as two front runner boxes packed with get out of jail and go home parts that are not exactly light. No back seats and no drawers. I can add three full Jerry cans on the rear basket and more crap and tools than anyone needs in the cargo area and still have 4” lift.

I suspect your rear lift to be over 6” unless your drawers are loaded with lead. Those springs have a rate in the neighborhood of 400lbs/inch.

Since this clanging and banging began with the 3 link install, I’d be revisiting their work, all rod ends and the rear drive line.

I followed a guy on the Sierra Trek run once who’s 80 was on Slee 4” with spacers and even though his rig was loaded down with “stuff” it was still taller than mine and he had a lot of problems along the way that I didn’t have. My advice would be to ditch the spacers and go from there to dialing in the rear driveline.

Do you know the condition of your engine and trans isolators? Are there rubber bushings at the frame or is it, what looks like Johnny Joints at the axle, also at the frame end of your links ? Are all suspension bolts smoked down tightly?

 

[petwhookie]

Thanks everyone for the feedback so far. Tonight I had the chance to pull the front driveshaft off just try it again with my freshly rebuilt t-case. And.... it still made the clatter noise.

@Delta VS
The panhard in the rear is still 'stockish'. I have your 3" panhard bracket which is probably a little too small for my current lift.

@BILT4ME
The rear driveshaft is in-phase. I made sure of it the few times I took it on and off. I guess the photos made it look out of phase. Oddly, when I took the rear driveshaft off and drove in FWD... it still made the noise... so I'm concluding it may not be the rear DS.
You did make a good call out on the front driveshaft being too short. I am addressing that very shortly BUT... when I took the front driveshaft off. It still made noise. UGH!

@thatcabledude
It pretty much clatters off throttle anytime I'm going over 55+. When I throw it in neutral, it clatters the loudest. And it doesn't go away until I put a little bit of pressure on the throttle again. As of right now when I drive on the highway, I keep my foot on the gas and brake at the same time to avoid the clatter noise.

@baldilocks
Good call out on the lift height. I went with the spacers so I didn't rub in the rear but I should probably lower the rear. I need to cut the rear fenders to fit the Nitto 37s.
In regards to engine & transmission rubber mounts, they are fresh. I would say less than 2 years old. All my bushings should be good to go as they have been replaced back in 2021. Johnny joints are upfront for the 3link and they should be snug. I did a good ol' nut & bolt after the Rubithon this year.

Ultimately, I'm lost. With the rear DS off... clatter. With the front DS off.. clatter. It's leading be to think thats its not my DS. I asked Brian from 4wu and he suggested my T-case might be rubbing against something. I might have to look around and see how the 3 link mounts touch my sliders/armor underneath. OR.... maybe it's the front axle? but it shouldn't make noise when the front DS is off.

Please feel free to chime in and/or challenge my thinking. Thanks all! I appreciate it.

 

[Delta VS]

Thanks everyone for the feedback so far. Tonight I had the chance to pull the front driveshaft off just try it again with my freshly rebuilt t-case. And.... it still made the clatter noise.

@Delta VS
The panhard in the rear is still 'stockish'. I have your 3" panhard bracket which is probably a little too small for my current lift.

@BILT4ME
The rear driveshaft is in-phase. I made sure of it the few times I took it on and off. I guess the photos made it look out of phase. Oddly, when I took the rear driveshaft off and drove in FWD... it still made the noise... so I'm concluding it may not be the rear DS.
You did make a good call out on the front driveshaft being too short. I am addressing that very shortly BUT... when I took the front driveshaft off. It still made noise. UGH!

@thatcabledude
It pretty much clatters off throttle anytime I'm going over 55+. When I throw it in neutral, it clatters the loudest. And it doesn't go away until I put a little bit of pressure on the throttle again. As of right now when I drive on the highway, I keep my foot on the gas and brake at the same time to avoid the clatter noise.

@baldilocks
Good call out on the lift height. I went with the spacers so I didn't rub in the rear but I should probably lower the rear. I need to cut the rear fenders to fit the Nitto 37s.
In regards to engine & transmission rubber mounts, they are fresh. I would say less than 2 years old. All my bushings should be good to go as they have been replaced back in 2021. Johnny joints are upfront for the 3link and they should be snug. I did a good ol' nut & bolt after the Rubithon this year.

Ultimately, I'm lost. With the rear DS off... clatter. With the front DS off.. clatter. It's leading be to think thats its not my DS. I asked Brian from 4wu and he suggested my T-case might be rubbing against something. I might have to look around and see how the 3 link mounts touch my sliders/armor underneath. OR.... maybe it's the front axle? but it shouldn't make noise when the front DS is off.

Please feel free to chime in and/or challenge my thinking. Thanks all! I appreciate it.

Measuring the difference in panhard bolts is simply a way to figure out how much lift you actually have since you were questioning previous method.

Does it still make noise if you take both drivelines out?

 

[petwhookie]

Measuring the difference in panhard bolts is simply a way to figure out how much lift you actually have since you were questioning previous method.

Does it still make noise if you take both drivelines out?

The rear panhard is 41.5”

Both driveshafts? Great tip

I laid under the truck for about 20 minutes and poked around. Per 4wu Brian, it might be the transfer case armor. Couldn’t find much. Argh

 

[YMT]

Since you've eliminated the drive shafts, and your bushings and joints "should be snug", make sure everything is to torque. Also check underneath for any broken exhaust and frame brackets (look for any hairline cracks). Rattling exhaust can sound like a clatter. Mine when I bought it had an exhaust rattle that changed with the rpm.

 

[Delta VS]

The rear panhard is 41.5”

Both driveshafts? Great tip

I laid under the truck for about 20 minutes and poked around. Per 4wu Brian, it might be the transfer case armor. Couldn’t find much. Argh

Willwillwill. look at first post of link again. Length of panhard is not what you’re after.

 

[petwhookie]

Here’s a video for reference, front DS off and I’m throwing the truck in neutral. Clater

 

[petwhookie]

Here’s another video when I first got the truck back from fabricators. This old set up had OEM front driveshaft, no part time, OME heavy springs in rear (all of things I changed)