Toyota 4x4 how to replace front wheel unit bearings

Posted by Mark Hawley on Apr 23rd 2017

Toyota 4x4 front wheel bearing replacement Prado 120 & 150

For: FJ Cruiser 07-14, 4Runner 03-18, Tacoma 05-18, Lexus GX470 03-09, Lexus GX460 10-18

Time too replace: With the proper tools can be done in about 45min to 1hr per side. 

The Toyota Unit Bearing assembly:

Toyota uses basically the same front unit bearing in the front of the entire line up of 4x4's that are built off the Prado 120 and 150 line up.  The front bearings are meant to be a sealed combined "Unit" with the front wheel hub spindle pressed into them with a lip seal between the two primary parts.   Commonly referred to as "Unit Bearings".    The Toyota Unit Bearings have a 4 bolt flange built into them that has 4 captured bolts that bolt the unit to the front spindle.  The front spindle is what the upper and lower control arms bolt to.   The other key component of the Toyota 4x4 unit bearings is located on the backside of the inner bearing, the ABS sensor ring.   The ABS sensor ring is a black magnetic ring permanently atached to the inner bearing.   The ABS ring spins with the bearing and is what the ABS pick up gains the reading of the wheel movement.   This ring has an A then B signal that the pick up reads this allows very accurate readings as well as telling the computer if the wheel is spinning in reverse.  We need to use care when handling the unit bearings as the ABS sensor ring is always exposed when the bearings are off the truck.  (Note do not set Unit Bearings on the direct ground with the sensor ring facing down.  Also use caution with metal dust from grinding etc. as the ring is magnetic.)  The unit bearings are not right and left spacific, so one will fit either side.  

ABS Sensor ring location:


Running over-sized tires combined with hard use off road lead to the bearings to ware.   You can check for ware by lifting the truck off the ground and pulling the top and bottom of the tire feeling and looking for play at the hub.  The other sign of them going bad is the dreaded growl from one side when you turn. 

Toyota wheel bearing replacement is rather straight forward. You have two options for doing the job:

 1st is to buy pre-assembled unit bearings.   These are new bearings, seal and 4 bolts with a new wheel hub spindle already pressed into the wheel bearings.  This is a direct just swap out the unit bearing and cost about $100 more per side. Local auto parts stores AND Toyota do not typically stock the unit bearings as built assemblies.   However you can find them on line pre-assembled with both Chinese bearings or the typical Toyota OEM "KOYO" bearings. 

2nd option is to buy the bearing and seal, then press out the stock wheel hub spindle and press it into the new bearings. This option you can find a large range of bearings in both local auto parts and over the Toyota parts counter.   For the Lexus GX trucks, its the same bearing used on the same model year 4Runner so just get them from Toyota vrs. the extra "Lexus" part charge. 

This is a step by step going with the 2nd option where you just transfer the wheel hub spindle vrs. spending the extra $$ buying new ones.   There really is no need to buy new hub's if your existing ones are in good shape. 

Step 1.

With the wheal off and the truck safely in the air,  follow the ABS sensor wire to the pick up bolted to the spindle.  You do not need to un-clip the wire from the sensor, just use an Allen wrench and remove the single bolt holding the sensor in.  With the single bolt removed you just pull the sensor out of the spindle, it has an o ring on it so it takes a little effort.   Once its out, put a plastic bag over it and zip tie it closed to keep it clean and safe.   Un-clip the ABS wire from the plastic clips so the wire can be safely moved off the front spindle assembly.  NOTE: the #1 failure when doing any front end work is to pull on the ABS wire.  The outer jacket will stay intact however the inner wire can be pulled and severed.  The ABS system will go into limp mode and the ABS light will come on.   Its very easy to remove the sensor and wire from the front.  Take the time to do so to save yourself the head ache of an ABS failure.  (experience talking here!) 

ABS sensor being removed from front spindle assembly.   For clarity we show the ABS wire un-cliped, however you do not have to unclip it to remove the sensor. 

Step 2. 

Remove the black hub can cover off the center of the hub.  Remove the cotter pin and hub nut lock cover.  Using a 35MM socket remove the large hub nut.  If doing this w/o and impact wrench have a helper apply the brakes to lock the hub from turning.   You can brake the nut free with a 1/2" beaker bar and some good force.  (Its torqued on to 174' lbs so takes some effort)  With the hub nut loose spin it almost off but leave it on the threads of the CV shaft.   The CV shaft is locked into the wheel hub flange by splines.   You need to brake the splines free so the CV shaft can be left in place when you remove the unit bearing.   Use a dead blow mallet OR a block of wood to protect the nut and end of the CV shaft and 2lb hammer to strike the end of the CV/nut.   This will brake free the splines and the CV should move freely inward and outward, but still in the hub.  Take the hub nut all the way off and set aside. 

Step 3.

Remove the brake caliper. Unbolt the two bolts on the back that hold the caliper to the front spindle. Use a wire/zip ties/bungee cord to hold the caliper up out of the way w/o stressing the brake hose. Remove the disk brake and set aside, its just loose on the wheel studs at this point. 

Step 4.

Using a box end wrench unbolt the 4 bolts behind the wheel flange.   These are the bolts that hold the unit bearing on the front spindle, the bolts will not come off the assembly at this point, but once backed completely off the unit bearing assembly can be removed and set aside. 

Unit Bearing Assembly off the truck. NOTE: The assembly is sat on the wheel studs and NOT the ABS ring. 

Step 5. 

The brake backing plate/cover will be lose as its just bolted between the unit bearing and the front spindle.  Remove the cover and set to the side. 

Removing the brake backing plate:

Step 6. 

Put a large bearing separator (the OTC brand 6" fits perfectly)  between the hub flange and the bearing. 

Bearing separator:

Bearing separator bolted on between bearing and hub flange ready for pressing:

Step 7.

Using a shop press, press out the wheel hub spindle from the bearing.   Make sure you use the appropriate size Toyota front wheel bearing tool (we are using a large socket) only pushing on the wheel hub spindle.   Tip: Put a card board box below your press as the wheel hub will fall free of the press, the box will catch it and keep it from being damaged. 

Unit bearing w/separator in shop press ready to be pressed out:

Step 8.

The hub spindle is now free! 

Wheel flange hub spindle:

Step 9.

Install the lip seal that goes between the bearing and the hub spindle on the new bearing.   Use a block of wood to distribute the impact to install with out damaging the new seal. 

Lip seal between the hub spindle and the bearings, Toyota part number shown:

Wood block used to distribute impacts installing seal:

Step 10.

Install all 4 of the mounting bolts.  (dont forget this step!  Once its pressed together you can NOT install them and will have to pull the hub spindle off again) 

Install the 4 flange mounting bolts:

Step 11.

Locate an appropriate sized press tool (big socket here) to support the bearing correctly. 

Sized press to support the bearing, note not touching the ABS ring:

Step 12.

Put the bearing assembly in the shop press, confirming the lower press tool (large socket) is supporting the inner bearing correctly and NOT on the ABS ring.  Confirm all 4 bolts are in place.  Put the hub spindle on top and press the assembly together. 

Pressing the bearings and hub spindle together:

Step 13. ;

Finished new Unit Bearing Assembly:

Step 14. 

Install the new unit bearing assembly in reverse order of steps 5 to 1. 


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