Hey guys,

I am racking my brain and cannot figure out what is wrong with my 87 4runner.

Here is the problem...as I am driving down the road I hear a slow "turning or grinding" type noise. The faster I go the faster the noise gets.

The best way I can explain it is if you had a flat spot on your tire and as your tire turns you hear a "thump" noise. However, it almost sounds like a slower grinding or turning noise.

I hope that is enough info to help figure this out?

Any and all suggestions are appreciated.

thank you....

 

Do you feel vibrations along with the thumping noise? I had a (seemingly) similar problem with my 88 that turned out to be 2 things: #1-my rear driveshaft was out of balance/the u-joints needed to be replaced and #2-the pinion on my differential was loose - probably due to the unbalanced driveshaft.

I'd suggest getting under there and wiggling things around. Your pinion should be tight - there shouldn't be much movement under there. If it moves up and down then you definitely need to either replace your u-joints and/or the flange on your differential. If you disconnect the driveshaft from the diff you can check the pinion individually.

Hope that helps a little.

 

Sounds exactly what I'm going through. I brought mine to two shops, both said an axle bearing is going out due to a bent axle shaft. Might be something to check..

 

Thanks guys...I will look into both.

 

Ok...I checked the drive shaft and it is secure but now I am worried about the axle bearings.

Question...are the axle bearings hard to replace and are they expensive?

Thank you...

 

i have the same noise in my 89 yoter r/e. a man put in new axle seals and bearings and i replaced my pinion seal while i was at it. he was the one to tighten the 32 MM nut to hold the yoke to the rear end to " make sure the pre- load on the pinion bearing was correct". my question is if my u joints are still okay and if turns out my pinion bearing is loose how tight is to tight with that 32MM nut?

 

I use about 90 ft.lbs. on mine:
- http://www.4crawler.com/4x4/CheapTri...ionSeal/8.html