Langeb75

I have an 86 4runner in great shape, no rust and only 94,000 miles on her. Two weeks ago the saga started. Driving on the highway I heard a nasty grinding noise in the rear end at speeds of 70 miles per hour. It was very intermittent and it didn't matter if I was going over bumps or on the flattest part of the highway. I put new u-Joints in the drive shaft, no dice. I took my third member out and took it to the guy who put the 4.88's in to get his opinion and he went through them while I watched and everything looked great. I have no play in my bearings. I tightened up all my U-Bolts on my suspension, no dice. It only happens on the highway. Now today as I was on the highway I got some new noises that sound like my tires going flat almost with a nasty thumping noise which is also intermittent. I can drive 20 miles with nothing, truck sounds and drives great then grinding or thumping. I have no power differences when this happens as I continue to cruise at 70 - 75 miles per hour. I have been frustrated for two weeks and want the piece of mind that I can fix something and be on my merry way. I wish something would just break so I know what it is. No signs of anything. PLEASE HELP yotatech gods.

BigBluePile

iTrader: (3)

First off, I hate you and your super clean 94K miles 4Runner.



Second, I'm jealous.


Third, does the sound just "happen" or does it get worse when you accelerating or deceleration? Have you looked over your drum brakes?

Langeb75

Thanks for your reply BigBluePile. It just happens, I can't get it to happen it will just do it when it feels like it and when it does it is noticeable. I have tried accelerating, decelerating, changing lanes, hitting bumps. I did take my drums off and looks to see if there were any broken springs or anything out of the ordinary and everything looks great. The pads are getting down there but I would say they still have 1/8th of an inch left. Parking park works great.

BigBluePile

iTrader: (3)

Does it actually SOUND like it's coming out of the rear end? Or could it be a sound possibly from the transfer case area?

Langeb75

Trust me Big Blue Pile it is coming from the rear end. I have my console out right now as I am redoing it and could tell if it was coming underneath me. It is coming from way back Tell me what to do PLEASE be my savior.

BigBluePile

iTrader: (3)

Hmmmmmm, do you have somebody that can go with you and take a good sound video?

BigBluePile

iTrader: (3)

Either that or swap out the axle...

waskillywabbit

iTrader: (-1)

Replaced U-joints.

Rear diff examine.

Checked brakes.

Nothing left in the rear axle but seals/bearings to make racket.

Or your rear output bearing on your tcase.

Langeb75

BigBluePile that is a great idea. I think I will rig up my camera underneath my truck to shoot video of the rear end. Can I send it to you via email somehow so you can see it?

Langeb75

waskillywabbit but if it was my bearings wouldn't I be able to move my brake hubs up and down left or right or wouldn't there be a continuous whining of some sort?

Matt16

Hold on, you've got a 4" lift, that is very possibly high enough to make the angles in the driveline steep enough to need a high-angle driveshaft. Try loading the truck up with a couple hundred pounds and see if it goes away. If the extra weight (and resulting lower suspension) helps, then pull a leaf out of the pack and relax the torsion bars to match.

Langeb75

Matt16 the leaf springs from Skyjacker came with a angled piece of steel built in to compensate the drive shaft angle in the rear. The drive shaft is straight into the 3rd member in the rear and that is where the fun is.

BigBluePile

iTrader: (3)

Idk, I'd still check out the transfer case like Wabbit mentioned.

Langeb75

How do I check out the transfer case and what am I looking for?

BigBluePile

iTrader: (3)

Look at the out flange where the driveshaft bolts to. See if there is excessive play. You might have to tighten it up.

Langeb75

BigBluePile I did that this morning and its solid at the transfer case. I taped my camera to the underside to take a video and after I got the camera out it only stayed on for 4 minutes and it acted up at 8 minutes. It was really cool watching the video though. I will try again.

Langeb75

Hey guys this may sound crazy but I just put a new muffler on it and I haven't heard the binding sound in 65 miles. Heading to get a new yellow lab tomorrow, 6 weeks old, 230 mile round trip so I will keep my fingers crossed. I will let you know when I get home.

redhawk427

musta been the muffler bearing

Langeb75

I was thinkin the quarter knuckle thermal bearing. I pray this stinkin muffler was my culprit. I am skeptical because it sounded like a serious binding. We will see.

02Runner.phxaz

i had the same problem and replacing the bearing fixed it