Topic: grind noise in 4WD

[xnoahx]

Hey all! I'm trying narrow down a noise I'm getting in 4wd. Truck is an 87 4runner with SAS and stock 22re, manual trans. When I'm in 4 low or high and going more than 5-10 mph I start getting a steady grinding noise that will get worse with more speed. It will make the noise if the hubs are locked or free. I pulled the front drive shaft and the noise goes away. I have drained the oil in my t-case and front diff and didn't find any chunks of metal in either one. I put the front of jack stands and with the hubs locked I can spin the tires freely with my hands and nothing feels like it binding up. I'm just trying to see if anyone with much more experience than I have can maybe point me in the right direction before I pull and disassemble my t-case or 3rd member. Thanks in advance for any help.

UPDATE with further testing, I have the noise in 2wd with the front hubs locked and the driveshaft installed. If I remove the front driveshaft the noise stops with the hubs locked and unlocked. Im going to replace my ujoints to have that eliminated as a potential problem.   

[YooperYota]

Check for play in the transfer case front output flange and the front pinion flange. If it still does it when the driveshaft is removed it could be the weight of the shaft hanging on the flanges causing the bearings in them to grind if they're going bad. Or it could be that when you're applying torque through the driveshaft the birfields are grinding if they're on their way out. Does the noise get worse when turning?

[xnoahx [OP]]

I'll have to do some testing tonight to see about the turning and the play in the flanges.

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[fireitup]

Have you put any suspension lift on your truck?  If the angle that the front driveshaft makes between the output of the TC and the Front Diff is too steep that can cause issues.  I am currently dealing with this on my 82.  Not sure if the 87's have the same setup though...

 

[xnoahx [OP]]

With further testing, I have the noise in 2wd with the front hubs locked and the driveshaft installed. If I remove the front driveshaft the noise stops with the hubs locked and unlocked. Im going to replace my ujoints to have that eliminated as a potential problem.

[Toybrota]

Might be the driveshaft. I had a problem similar to yours, but worse. Mine would bind up, the Double Cardan was bad. The Double C is a PAIN to replace, take it to a shop. Got mine done for $180

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[ArloMyles]

Check out 4crawler.com It has lots of drivetrain angle info. My 85 4runner does the same thing. I have a u joint on either side of the front drive shaft and after the lift the angles are all off. Vibrates really bad in 4 wheel drive. Going to order a new one from highangle driveline in Paradise.

[xnoahx [OP]]

I figured out the problem, the yahoo that a bought my truck from had 4.30 gears in the front and 4.10 gears in the rear.