Rotors + Wheel Bearings? Your thoughts.

[uhhair]

Okay so tonight I'm going to replace my brake pads + rotors on my D. The rotors are entirely warped, and I really didn't feel like dealing with trying to figure out if they're salvagable or not so I just bought all new ones, as I know I have the originals on all four. The front brake calipers were replace by the PO a few years back, so I'm not planning on doing any caliper work unless I discover a frozen piston in the process. Hoping I can just push the piston back in and the calipers will be good to go for awhile.

My question is, how much additional work is it to replace the wheel bearings while the rotors are off, and is it recommended? No indication any of mine are bad, I do have all 4 as a replacement just in case though.

Also, are both hubs the same bolt size (36mm) to get off? Just double-checking on that one.

Thoughts on all this?

[Delorean Industries]

Okay so tonight I'm going to replace my brake pads + rotors on my D. The rotors are entirely warped, and I really didn't feel like dealing with trying to figure out if they're salvagable or not so I just bought all new ones, as I know I have the originals on all four. The front brake calipers were replace by the PO a few years back, so I'm not planning on doing any caliper work unless I discover a frozen piston in the process. Hoping I can just push the piston back in and the calipers will be good to go for awhile.

My question is, how much additional work is it to replace the wheel bearings while the rotors are off, and is it recommended? No indication any of mine are bad, I do have all 4 as a replacement just in case though.

Also, are both hubs the same bolt size (36mm) to get off? Just double-checking on that one.

Thoughts on all this?

Most likely the wheel bearing will come apart with the front hub.

[uhhair]

Most likely the wheel bearing will come apart with the front hub.

That's why I have the extra ones, don't want to have to stop the job if it happens. If it does come apart, do you just grease up a new bearing and install it though? If it's that simple, just wondering if I should go ahead and do it for all 4 anyways.

[Mark D]

You might as well go ahead and replace the bearings if you've got the hubs off. The'll probably separate into two halves anyway like Josh is saying. You just need to remove a spring clip and press out the old bearings, press in the new ones and replace the spring clip.

As far as the hub nut sizes go you may want to check before you start tearing everything apart. The two common sizes are 32mm and 36mm. I had 32mm nuts on the inside of each steering knuckle and larger 36mm nuts on the outside securing the hub. A while back I think someone explained there was a running change
between sizes so you could have one or both sizes.

The rear bearings are much more difficult to replace than the fronts and require either a special puller tool or a bunch of different sized rings and discs to use on a press to get them in and out.

[uhhair]

Okay, so from what I'm gathering, to replace the front rotors, the hubs MUST come off, the the wheel bearings will most likely fail when I pull one or both of them off.

For the rears though, the hubs to NOT have to come off to replace the rotors? In which case, I won't need to replace the bearings (they give no indication of being bad).

Also, keep hearing this "press" term for the front bearings. I need to go to a machine shop to "press" them in? This isn't something I can do myself? Please elaborate on this for me (and others who may not be full of the mechanical terminology that I am also apparently lacking.

[Mark D]

The bearings fit in the rotors with an interference/press fit which means the bearings are actually slightly larger than the opening the fit into. Using a hydraulic bottle jack type press is the easiest way to remove and replace. If you don't have one they are around 100 bucks at harbor freight, or you can spend 20-30 bucks and have a local machine shop or auto service station press the bearings in and out for you.

Here's what a typical hydraulic press looks like:
http://dmctalk.org/attachment.php?attachmentid=16287&d=1360013485
http://www.harborfreight.com/garage-shop/shop-presses/12-ton-shop-press-33497.html


This was when I was doing the bearings on the rear hub carriers:
http://dmctalk.org/attachment.php?attachmentid=16283&d=1360013471



The front rotors are bolted to the hubs with four M8 hex bolts and to remove the rotor you need to remove the rotor+hub sub assy from the spindle. Here's a pic of a front rotor separated from the hub
http://dmctalk.org/attachment.php?attachmentid=19003&d=1368206421

and the front rotor bolted to the hub ready to bolt on:
http://dmctalk.org/attachment.php?attachmentid=19004&d=1368206428

The rear rotors slip over the top of the hubs and you will not need to remove the hubs to get the rotors off. You'll just need to remove the large 32mm or 36mm nut and then pull the rotor off the hub assy.

Here's the rear suspension with rotor (and caliper) still installed:
http://dmctalk.org/attachment.php?attachmentid=19006&d=1368207061

Here's the rear suspension with rotor removed:
http://dmctalk.org/attachment.php?attachmentid=19005&d=1368206865

[Jeff K]

I restored my entire suspension this winter.

Get new bearings. Installing them was very easy. I used a trick someone on here posted.

I heated up the hub in the oven for an hour at 375 degrees. I froze the bearings overnight.

Use gloves, and the bearing dropped right in. Zero pressing. I did one at a time, so they parts did not cool down/heat up waiting for me to drop it in.

The rear axles have to be pressed in, my local shop did it for 20 bucks.
Jeff

[uhhair]

Hmms, nice trick with the front hubs + bearings. I will definitely try that tonight/tomorrow morning and see if that works before taking them to a local mechanic in the AM if they don't shove right back in.

As for the calipers, has anyone ever just replaced the pads without doing the calipers? I am assuming I can use a block of wood (or old pad) with a c clamp and push them right back in as before, right? And a few pumps on the brake pedal will quickly tell me if they're frozen or not.

[uhhair]

Great pictures btw, those are extremely helpful. I appreciate it! Just hoping that I don't have to cut/press any old bearing material out. That seems like the only x-factor in this job that can eat up a lot of time and effort.

[Mark D]

Getting the old bearings out of the front hubs will probably be the most difficult part if you don't have a press. I don't think I'd try cutting them out since the bearing outer race is made from pretty strong material and you would be risking damage to the hub. Any auto shop in the area should be able to get the old bearings out for you in 10-15 minutes. You'll save quite a bit of frustration and time this way and it's well worth the 20 bucks they'll charge you.

The freezing and heating trick that Jeff described sounds like a great idea for getting the new bearings installed without a press.

[uhhair]

Honestly, if they don't fall out, I might as well just take both the old + new bearings to a shop and have them press the old ones out and the new ones in at the same time. No point to have them do half the job when I could just wait an extra 20 min and probably 10 bucks to do both.

I'll try to get my front hubs off first thing tonight and run these up to a local garage and see if they can press them tonight for me.

[vwdmc16]

When you do the rear rotors dont forget after you remove the large center nut there is a 1/8th in thick plate under that you need to remove, it covers a small phillip head screw that also holds the rotor to the hub. That thin plate might be corroded on very well like mine was, and may take some careful prying or tapping with a hammer to dislodge it. Even then on the driver side rear rotor of my car I removed that plate and found no screw but I could not remove the rotor by hand or wailing on it with a rubber mallet. This was worse case scenario and I had to remove my entire rear carrier and have the rotor pressed off too. but this is not likely to happen unless your car is a rust bucket like mine was.

[Bitsyncmaster]

I've done the freeze and heat trick to get piston pins installed back in the old days. I have a 20 ton press now.