How to: Replace CX7 Rear Wheel Hub and ABS Speed Sensor

[ahabion]

How to: Replace CX7 Rear Wheel Hub and ABS Speed Sensor (FWD, see differences in AWD further below)

Typical Cause: Bad Wheel Bearing

Symptoms: While driving you may hear a humming sound coming from the rear of your vehicle. If you listen closely, you will be able to distinguish which side it is coming from. While slowing down to a stop, you may also hear a very slight grinding as well (not the regular sound of the brake’s low squeak).

If you remove the rear wheel, turning the wheel hub (grab one of the studs and rotate the assembly) you may hear metal on metal grinding. You’ll be listening for a low grinding noise, making sure it is not the brake pad’s higher scraping noise on the brake disc.

Mazda is already aware of the situation and has put a service bulletin out back in 2008. (see attached pdf)

Difficulty: Moderate (appx. 1-4 hours)

Tools:

• 17 mm socket
• 12 / (or was it 14?) mm socket
• 10 mm socket
• T55 Torque (6 point star) bit - ~$6.50 from Advance Auto
• Large 4 head Philips screw driver
• All-purpose grease (not entirely necessary)
• PB Blaster or something to help remove screws/bolts
• Soft rubber hammer/mallet
• C-clamp

Parts

• Rear Hub (same for both left and right) Mazda Part # GS1-D26-15X-A -- $155 ea from Advance, $282 ea from Mazda dealership
• ABS Speed Sensor
  • Right (passenger) Side Mazda Part # EG23-43-71YC -- $65 from Mazda dealership
  • Left (drive) Side Mazda Part # EG23-43-72YC -- $65 from Mazda dealership

Procedure

1. Disconnect the negative battery cable connection (I didn’t do this but it’s good practice. No CEL after I was done either, so no need to reset windows and radio stations)
2. Chuck the front wheels and jack up the car and get a jack stand underneath. You should never ever only trust a jack to maintain the weight and balance of the car while you are under it.
3. Get the wheel off of the accused bad hub
4. Remove the screws using your Philips screw driver. You may want to spray some PB Blaster or thread unlocking agent and let it sit for a minute or two before you try to remove them. They’re stuck in there pretty good and are prone to stripping so work patiently. I have an impact wrench, so I just attached my bit to the hammer and pushed in on a low setting. If you have someone helping you, have them press on the brake from within the cabin, this will allow you to try to break the screws loose without the wheel hub turning on you… you’ll know what I mean.
5. Using your 17mm socket, remove the 2 bolts holding the brake caliper assembly and pull it off the brake disc. I tied mine up to the rear spring so as to not let it hang from the brake hose.
6. Using the rubber mallet, hammer the back side of the disc brake gently. One or two times to jar it loose. The CX has a dual braking system in the rear, using both disc brakes and an inner drum to aid in braking. The shoes inside the drum are applying pressure to the outer wall of the disc brake, so trying to simply pull it off by hand may be difficult.
7. Remove the brake disc and put it to the side
8. Inspect the inner brake shoes for any abnormal wear while you’re in there, also looking on the inside of the disc to see if you have any deep scoring from the contact with the shoes. Replace if necessary.
9. You should be able to see the threads protruding from the other side, within the inside of the hub assembly. The rest of the work will need to be done from underneath the car and on the other side of the hub.
10. Remove the 10 mm bolt holding the ABS speed sensor to the hub
11. Holding onto the wire, pull out the plastic retaining fasteners (it should be ok if you break them because the new ABS speed sensor should come with new fasteners)
12. The wire will lead into the cabin of the car, the connection is underneath the rear seat. Once you’ve loosened all the connects and the weather seal on the ABS speed sensor, open the door to the rear and simply pull up on the rear seat directly in front of the door. You should see the connection right there, closest to the door. (A firm pull up should reveal the wire connection, you should not have to undo any fasteners or bolts holding onto the rear seat. Don’t yank, just feed your fingers under the seat, grab hold, and firmly pull up so you can see under it)
13. Undo the connection and pull out the ABS speed sensor wire from the wheel side.
14. Clean off the weather seal area with a scraper and feed your new sensor through into the cabin and make the connection under the seat. Click in the new weather seal by firmly pressing up. Put in the first fastener immediately following the weather seal but hand the wire out of way for a minute, we’ll come back to it.
15. Using your T55 torque bit, undo the 4 bolts holding your wheel hub from the rear. This step may take you a while because they are in there tight and they’ve used some Loctite to hold it in. If you have an impact wrench, this is a great time to use it. For those with hand tools, remember to try to use leverage to try to break those loose.
16. Once they’re loose, remove the bolts. Once you do that, the whole entire assembly will be break off, brake shoes and all, so it may be a good idea to strap up the brake shoe assembly or have someone hold it.
17. Clean off the surface of where the old hub sat (nothing special, just wipe it down and make sure there is no crud on it for when you put in the new part)
18. Apply some grease to the surface
19. Bringing the otherside of the ABS speed sensor, you should have enough slack in the line to insert and tighten down the sensor into the new wheel hub. Once done, insert your new hub making sure to line up the brake shoe holes and the hub holes.
20. Tighten up the torque bolts as much as you can (I hand tightened them first then used a socket wrench, followed by a medium setting with my impact wrench. I don’t know if there is a torque specification for the bolts but they’re in there pretty tight but not tight to the point where I don’t think I wouldn’t be able to get them off again… if that makes any sense.)
21. While you’re under the car, go ahead and put in the other fasteners to hold the ABS speed sensor wire in place.
22. Put your brake disc back on, making sure to push it in all the way. You may need to use your rubber hammer to get it back in place all the way. Note: My wheel hub that I got from Advance Auto did not come with holes for the screws to attach the disc to (which is fine). Being that the wheels will be tightened down on top of the disc, I will not have to worry about the disc wobbling while rolling.
23. If you can put your caliper assembly back on without removing the brake pads, GREAT! If not, remove the brake pads and install the assembly using the 17mm bolts.
24. Using your 12/14mm bolt, loosen up the top bolt for the rotating arm of the caliper piston and remove the bottom one. Rotate the piston assembly up.
25. Feed in your pads from an angle, pointing to the inside of the hub first. Use the retaining clips as a guide.
26. Using your c-clamp, push in the piston on the caliper. Rotate the piston assembly down and tighten it down using the 12/14mm bolts.
27. Put everything back on, drop the car, and make sure you pump the brakes about 2-3 times before you start rolling. Need to make sure you push the fluid back into the piston you just pushed in.

That’s about it. Sorry I don’t have any pictures because everything is put back together and didn’t feel like snapping them as I was going.

Hope this helps and let me know if I’m terribly wrong anywhere.

Thanks!

[Raider]

Welcome! Great first post!

[swanky_x]

Hi,

One of my wheel bearings is humming/whirring awfully bad. I had the other side replaced last year, but I'm considering doing it myself this time.

Question: is it necessary to replace the ABS sensor? Can I get away with just replacing the hub? Can I just replace the bearings, or does the whole hub assembly really need to be replaced?

Thanks!

EDIT:

Okay, reading that document now I see they claim its the improper shape of the sensor causing the humming. That sucks. This whole project is more expensive than I thought. Can you give me a difficulty rating? I'm pretty good at basics (replace brakes, rotors, etc), but that's about it.

[Raider]

Well the guy who posted, has not been back since. It looks like an intense job if you are not too skilled. I would try it out if you are good with brake jobs. Post pics, too!

[swanky_x]

Well, I attempted this job and failed. *Pix are below.*

My experience/observations:

1a. (edit): Note that I believe the instructions above are for a front wheel drive model, and I have AWD. The part numbers different and costs are significantly higher.

1. The main problem was that I didn't have the proper tools to reach the T55 torx heads in step 15 -—there's almost no clearance in there. I have a T55 socket, but there's a gear in the way (for the AWD I assume? Someone smarter than me can clarify) and almost no lateral clearance. The actual torx bit-end is okay, but the socket widens up to a collar which interferes with that gear. I could only barely get it in place on one or two of the heads (just enough to start stripping the head when I tried to turn it), and couldn't get it into the other two at all.

2. With my car up on jacks, I got a lift from a neighbor to Advance Auto and then Sears hoping to get either a long T55 allen wrench or better still a T-wrench, but neither had such a thing in stock. Advance did have a cheap set of Allen-key torx wrenches, but the T55 wrench was much to short to get any leverage on it. I could get it in place no problem, but that was it...could barely get a hand on it, much less really crank on it.

3. I think with a T-wrench you could get into the Torx slots AND have enough leverage to actually turn the damn thing. Note that the exterior ends of those bolts had a lot of rust on them, so you'll need to use BT Blaster on these too.

4. I'm not sure how someone with an impact wrench was even able to do this job....not sure what those kind of sockets look like, but the standard hand-tool bits have too wide of a collar to get in place.

5. So, I reassembled, leaving the ABS sensor disconnected and taped up out of the way. Tomorrow I bring it to the garage and ask nicely for them to clean up my mess.

6. On the plus side, my rear brakes *really* needed to be changed, so this gave me an opportunity to do that. 90K miles, btw, and first rear brakes change. They had a few miles left, but not much.

7. The interior brake (inside the drum) was a pain in the ass. It was very difficult to get the rotor off, as the brake and a spring were hanging on tight. I finally got it, but not without messing up that spring. Now that its reassembled, I'm not 100% sure I got the spring back in the right place.

8. While replacing the ABS sensor is VERY easy, if you live in an area prone to rusting, take time soaking the 10mm bolt holding it in place with BT Blaster. I found it can be seized up. I learned the hard way and snapped off the head. This after being so damn careful with the Phillips screws for the rotor. I really took my time with those, soaking with BT Blaster, letting it sit, tapping the heads and resoaking. Oh well.

I did take pix while I had everything apart, and as soon as I figure out how to upload them I'll post them.

[swanky_x]

The first pic shows the rotor and brake caliper assembly with the wheel removed. Phillips heads have been soaked with BT Blaster. Leave caliper on until you remove those heads...you'll need the brakes to hold the wheel still. Second pic shows the caliper removed and tied up to the spring. You'll see the Phillips screws are still in the rotor....don't do this, remove the screws first and then do the caliper (unless you have NO rust and the screws are easy to turn).

Note: click on thumbnails to see larger version!

[swanky_x]

These pics show the ABS sensor. The first pic shows the sensor at bottom center. Top center is the bracket that holds the brake line (brake line and spring clip have been removed).

Second pic shows the sensor closeup but still installed; third clip shows the tip of the sensor after it has been removed.

[swanky_x]

These pics show the ABS sensor wire/clips.

1. First pic shows the clips, which are easy to remove on the old one without breaking them (in case you wish to be careful).
2. The 2nd clip shows the weatherstrip/entry into the exterior underside of the cabin.
3. Third pic shows the entry hole in the cabin under seat.
4. Last pic shows the actual plug.

[swanky_x]

This pic shows the interior view where the four T55 torx heads are. Sorry its so dark you can't actually see the heads...they are right next to, and about 1 cm behind, that gear. I took a bunch of other pics but it was too dark and they did not come out well.

The space you have to work in is about 5" by 5". The bolts are recessed in this opening, 3 or 4 inches deep. The gear, that boot, and a bunch of structural things are in the way and make it very difficult to work on. If you are on your back in the driveway like I was this is not fun.

[swanky_x]

This final pic is the last pic with some notes added. Those circles show the placement of the T55 bolt heads, which you can't see because it was too dark under there.

[Hectik1]

I did my wife's rear hub. Not too bad except for two things...the damn assembly for the rear parking brake needs to be disassembled and literally falls apart when done so and the fact I needed a BFH to get the backing plate off the old hub, which I didn't have LOL.

BFH- BIG FUCKING HAMMER!

[swanky_x]

Hah! I was ready to take a BFH to this thing as well....local garage fixed my mess in a few hours. Its running really well now, and I'm happy...except for the fact that the hub for the AWD was $255 (not the $155 2WD model I had bought).

[Sydeburnz]

Hey Guys,

New to the site. I have a 2007 CX-7 FWD and am getting the "howling" noise that I assume is one or both of the rear hubs. i am going to go ahead and change the brake pads today, as my buddy/mechanic is going out of town for two weeks and I want to get those done.

I will be ordering the hub assembly(ies) as I cannot locate them locally so my question is;


According to that bulletin there was an issue with the early model sensors. Knowing that, should I just go ahead and replace both rear hub assemblies ? Or should I just replace the one that is howling and wait for when/if the other exhibits the same issue?

Thanks!

[Raider]

Welcome! I would do 1 first, and see how that goes for you.

[Hectik1]

I have only replaced the passenger side rear hub on my wife's CX7. The other, is fine even at 73K miles.

Replace the one that is bad.

[Alpha Wolf]

I agree with Hecktor

[what-a-geek]

so it's the long way but it is easier do to that

-remove the shock and the upper arm
-remove the lower arm
-whack the cv joint out
- now you can easily remove the T55 bolt
-whack the hub off the back plate
-clean it
-reinstall everything
- clean/inpect the brake while you are here

(the two hub were shut 85K kilometer 5 years old AWD cx-7 2007 I put MOOG at 200$ tx. in. not the one at mazda)

[VIC-CX7]

Just registered, and own an 07 CX7 Touring RWD. I'm on my 3rd set of tires, Bridgestone factory Turanzas were badly worn at just 17k, then a set of 255 wide Cooper Zeons ran for 10k, but bounced on the road like if I had basketballs at all 4 corners, so I switched back to factory 235 size Hankook Ventus AS's, and at 50k on the odometer, they are running great, but the CX7 has developed a consistent howling which is not dependent on road surface condition, so assume it's the hubs. Can't really tell where the howling is coming from, if from the rear, and if the rear, then not sure if LH or RH is bad, or worse than the other. Will purchase one hub and attempt the static hand pull test with the car on jacks, and see how it goes.

My question to the forum members is more aimed at knowing if there is one side more prone to going bad over the other, as I've read the rear passenger side hub going bad on several posts, maybe that's the one that goes first.

Any help would be appreciated.

[ahabion]

Wow, sorry I haven't logged in for a long long time. Life's been busy.

My CX has almost 140k miles on it now and i've only replaced the rear passenger hub assembly.

Yes, the instructions from the original post are from a FWD model. My apologies for not specifying it before.

Time and miles sure do fly by quick!

[tuminatr]

Originally Posted by VIC-CX7 Just registered, and own an 07 CX7 Touring RWD. I'm on my 3rd set of tires, Bridgestone factory Turanzas were badly worn at just 17k, then a set of 255 wide Cooper Zeons ran for 10k, but bounced on the road like if I had basketballs at all 4 corners, so I switched back to factory 235 size Hankook Ventus AS's, and at 50k on the odometer, they are running great, but the CX7 has developed a consistent howling which is not dependent on road surface condition, so assume it's the hubs. Can't really tell where the howling is coming from, if from the rear, and if the rear, then not sure if LH or RH is bad, or worse than the other. Will purchase one hub and attempt the static hand pull test with the car on jacks, and see how it goes. My question to the forum members is more aimed at knowing if there is one side more prone to going bad over the other, as I've read the rear passenger side hub going bad on several posts, maybe that's the one that goes first. Any help would be appreciated.

Vic I don't think one is more prone to go bad than any other. That being said my 115k mile cx7 has a bad rear passenger side hub. I am not going to replace it myself my local shop said $180 labor and I provide the part. as for tires I have had much better luck than you I bought my CX7 used 60k miles and Goodyear fortera tires on it. I replaced them because the former owner did not pay for an alignment it destroyed the tires in 5000 miles. I had the car aligned and i installed Pirelli Scorpion Verde. The Pirelli's are rated for 50k miles and I have 55k on them and they still have half left

[seaexsevenkarl]

Great Post just did mine on AWD CX7 best bet is to remove the entire trailing arm only 6 bolts holding it on. Make sure you support the lower arm of the spring or it will get you.
The Torx bolts on the hub are much easier to get at and you can use impact or a nut driver to get at them. Assembly was quick its nice to have a second set of hands with assembly and lifting the arm up but you can do it. I did take some pics which I will try and post.

[VIC-CX7]

Originally Posted by tuminatr Vic I don't think one is more prone to go bad than any other. That being said my 115k mile cx7 has a bad rear passenger side hub. I am not going to replace it myself my local shop said $180 labor and I provide the part. as for tires I have had much better luck than you I bought my CX7 used 60k miles and Goodyear fortera tires on it. I replaced them because the former owner did not pay for an alignment it destroyed the tires in 5000 miles. I had the car aligned and i installed Pirelli Scorpion Verde. The Pirelli's are rated for 50k miles and I have 55k on them and they still have half left

turminatr, thanks for the advice, I did replace the rear passenger side hub on my FWD 2007 CX7, with a factory new hub, and road test did not show any difference in the noise. I rotated the rear driver side wheel with the car jacked up while holding onto the suspension and the spring (based on a tip from a youtube video), and can feel no vibrations or grinding, so I'm now considering either one or both of my front hubs may be having problems. I'm going to do the vib-grinding test on the suspension while rotating the front wheels to see if I find any indications of front hub bearing problems, and go from there.

I also just noted a clackety-clack noise from the front end while accelerating during a sharp left turn, which means I may have a bad CV joint, so that adds to my woes. The SUV has just passed 50K miles, so it's beginning to show it's age, but too early for my wife's mild and my moderate driving habits.

More to come ...

[edavis99]

Round two with the rear wheel hub AWD. Took the advice and removed the trailing link. Did however break the nut to frame weld for the trailing link which required a hole to be drilled in the floor under the rear seat. Did soak it all night before attempting the removal but probably did not penetrate into the cavity where the nut was. The blind nut was barely tacked to the floor an probably the reason it let go. Thankfully it was the inner bold as it would have been a bitch to get to the outer bolt. The other problem is that the blind bolt is round requiring grinding off the bolt head to get it out. Replaced it with a regular grade 8 nut and bolt set. It was a bitch to get it assembled again requiring bolting up everything except the training link to frame bolts then relocating the jack under the spring so I could pull back the whole assembly with a fid. Hopefully I won't have to revisit it again anytime soon. Next project will be the timing chain, adjuster and leaky timing chain cover. What a peice of expensive crap. 4th and last Mazda.

[Raider]

Um, nice first post. Could be worse. I had 30= trips to the dealer for defect with my GMC. At least you have the how-to and ability to fix the problem.

[lildisco]

at 63,xxx miles & had both of my Rear Wheel Bearings replaced at the dealer. I have Mazda Extension Protection Plan so that's why i was able to take it to the dealer. It cost me $0 at the dealer to do this. I don't have the invoice in front of me, but I believe this was done for just over $720. I am AWD with roughly 63,xxx

[Jeff23spl]

doing mine and removing the hex55 bolt was correct but i'm stuck with the axle. Is there anything special holding the rear axle exept the large Nut on front of the shaft itself.

I'm used to remove front axle and sometimes it get seized a little bit but for that one, it is like welded or i miss something.
The bearing was so worn that maybe the heat made this but it react like if there is something else holding it so i want to confirm before i used BFH

[aviator79]

Edit.
no. Just banging out if replacing bearing. Just don't damage diff end. So may have to remote rear controls arms.

[Jeff23spl]

i will try with an heavy puller tonight...

[Jeff23spl]

A 5 ton puller and heating the hub made it! It looks like if some locktite was there on the axle because as soon as it moved the first mm, it went loose...

So maybe having a puller in hand would be a good idea if you try to do yours.

[otheriau]

Hi, thank you very much for all the precious information. I have not get the rear wheel bearing and hub assembly yet and I was planning to order it from the web site https://www.rockauto.com/ to get the part at a much lower price than at the dealer. The problem is that they offer many parts for my 2011 AWD CX7. These are what they offer:

WJB WA512350 CAD$61.37
DURA INTERNATIONAL 29512350 CAD$70.69
MOOG/NATIONAL 512350 CAD$124.47
TIMKEN HA590193 CAD$125.65
SKF BR930710 CAD$193.86

Does anybody have any advices ? The most expensive the better ?

Thanks,

Olivier