Replacing rotors, suggestions/advice?

[Jonathan]

As the title suggests, I'm going to aim to do my rotors over the winter and wanted to hear any advice or tips for doing so.

I have all four replacement rotors from DMCMW, along with pad sets for all four and a parking brake pad set too for that matter.

I got the car in 2007 and have rebuilt the front and rear calipers along with new pads before, but have never touched the rotors. I believe them to be original and they don't look awful, but there is some pitting on the back sides of them.

Any do's and don't's with this work?

I rebuilt the front calipers myself and feel pretty good about getting all of that unbolted again to get the front rotors removed, but the rear calipers were rebuilt the year I got my car and I had someone else do it for me. Any significant differences in front and rear in terms of removing calipers and rotors? (other than the parking brakes) I thought I saw mention of there being helicoils in the rears and that is what the caliper bolts tighten into. Am I getting that right? Any potential cans of worms back there to look out for?

I suspect I'll replace all four flexible brake hoses too, but I don't have those parts on hand yet. I'll flush, drain and replace the brake fluid that is in there too of course. My master cylinder was done maybe 6 years ago or so and seems fine at this point in time so I wasn't going to mess with it. Anything else I am missing?

[Patrick C]

I would do the front wheel bearings while you have the front hubs and rotors off. I did this last winter with Josh Bengston's refurbished hubs and new bearings pre-installed.


http://www.deloreanindustries.com/51-front-hub-assy-refurbished-with-bearing/

[David T]

I would do the front wheel bearings while you have the front hubs and rotors off. I did this last winter with Josh Bengston's refurbished hubs and new bearings pre-installed.


http://www.deloreanindustries.com/51-front-hub-assy-refurbished-with-bearing/

If the rotors aren't scored and the brake pedal doesn't pulsate or the steering wheel shake when you apply the brakes, why are you replacing the rotors? And even if you do have some shaking or pulsation, the old rotors can be refaced (cut).

[Jonathan]

I would do the front wheel bearings while you have the front hubs and rotors off. I did this last winter with Josh Bengston's refurbished hubs and new bearings pre-installed.


http://www.deloreanindustries.com/51-front-hub-assy-refurbished-with-bearing/

What's the typical lifespan of the front bearings, Patrick? This was another item I had done for me in the 1st year I had the car, so they are as old as about 2008 or so.

Also, would the hubs need to come off to get the rotors off? I had thought the general steps were to remove the calipers (without necessarily opening up the fluid system and just lying them up out of the way still connected via hose) and then once the calipers are out of the way, the rotors just slide out and off (albeit with some pounding conceivably depending on how rusted on they might be)?


If the rotors aren't scored and the brake pedal doesn't pulsate or the steering wheel shake when you apply the brakes, why are you replacing the rotors? And even if you do have some shaking or pulsation, the old rotors can be refaced (cut).

Good point, David.

Part of the reason, I'll admit, is because I already have the parts (new, replacement rotors). I bought the set knowing I could use them someday and that the backside of the rears showed some pitting. I really don't get much of any pulsating when braking. There is some speed wobble/slight vibration up at speed, but that's without using the brakes. Say around 60 mph or so, perhaps due to tire rubber/flat spots, I don't really know honestly.

I would like to do a fair bit of fluids work over the winter, flushing and replacing coolant and brake fluid, so with the brake system open I was going to put the new rotors in. No reason I couldn't just do the fluid for now though I suppose? It'd be a lot less work.

[David T]

Check the tire pressures and the date codes. If over 7 years old they should be replaced. At the very east get them all balanced, a weight may have fallen off causing the vibration. The brake and clutch fluid should be flushed and replaced every other year. Coolant every 5. Battery every 5.

[Patrick C]

Also, would the hubs need to come off to get the rotors off? I had thought the general steps were to remove the calipers (without necessarily opening up the fluid system and just lying them up out of the way still connected via hose) and then once the calipers are out of the way, the rotors just slide out and off

The hubs are bolted to the front rotors from behind, so you will need to remove them as one piece, unbolt the hub, and re-bolt it to the new rotor. Sometimes the bearings will fall apart when you are removing the hub and rotor assembly (happened on one side for me.)

[Jonathan]

Check the tire pressures and the date codes. If over 7 years old they should be replaced. At the very east get them all balanced, a weight may have fallen off causing the vibration. The brake and clutch fluid should be flushed and replaced every other year. Coolant every 5. Battery every 5.

That's a good suggestion, David, thanks. It's entirely possible a weight has fallen off. I looked back at my notes, and I took my rears in about 2 years ago and had them rebalanced. Shop said one of the two was quite a bit off. Might as well take all four in if they are all off doing brake bleeding. Simple enough.


The hubs are bolted to the front rotors from behind, so you will need to remove them as one piece, unbolt the hub, and re-bolt it to the new rotor. Sometimes the bearings will fall apart when you are removing the hub and rotor assembly (happened on one side for me.)

The bearings falling apart upon removal is I think how it was described by my mechanic that first year I had the car. I think I'll just go with the fluid change for the time being and wait to do the rest until necessary.

[David T]

That's a good suggestion, David, thanks. It's entirely possible a weight has fallen off. I looked back at my notes, and I took my rears in about 2 years ago and had them rebalanced. Shop said one of the two was quite a bit off. Might as well take all four in if they are all off doing brake bleeding. Simple enough.



The bearings falling apart upon removal is I think how it was described by my mechanic that first year I had the car. I think I'll just go with the fluid change for the time being and wait to do the rest until necessary.

Do NOT leave it to the shop to check tire pressures. If they check it at all they typically over-inflate them. Fill to the pressures on the tire label which is on the underside of the glove box door. If you don't have a GOOD tire gauge, buy one. They are not expensive, certainly much cheaper than a set of tires prematurely worn out because they were not properly inflated. Over-inflated tires will cause a very hard ride and wear out the center of the tread. Under-inflated tires wear the outsides of the tread, use up more gas, are more prone to road damage, and will cause poor handling. Either is VERY unsafe. Check the pressures, adjust if necessary, and see if the vibration goes away.

[Jonathan]

Do NOT leave it to the shop to check tire pressures. If they check it at all they typically over-inflate them. Fill to the pressures on the tire label which is on the underside of the glove box door. If you don't have a GOOD tire gauge, buy one. They are not expensive, certainly much cheaper than a set of tires prematurely worn out because they were not properly inflated. Over-inflated tires will cause a very hard ride and wear out the center of the tread. Under-inflated tires wear the outsides of the tread, use up more gas, are more prone to road damage, and will cause poor handling. Either is VERY unsafe. Check the pressures, adjust if necessary, and see if the vibration goes away.

I was saying that I would take my wheels into a shop to get them to rebalance them, not check the air pressures. Do you honestly think someone that has had their car for 9+ years and done most of the work themselves over that time isn't checking their own air pressures? Give me some credit please Dave.

[DMCMW Dave]

If time is of the essence, you want to have a set of front wheel bearings on hand (they are relatively inexpensive). Probably 30% of the time you pull off a front rotor, the inner bearing race will stick to the spindle and you'll see the balls from the bearing bounce across the garage floor as you pull the hub off. If this doesn't happen, you don't necessarily need to change them anyway, but it can really ruin your weekend on what otherwise is a fast job.

The bearings don't really have a stated lifespan, I've replaced them on cars from 10K to 100K miles. It's completely environmental.

[David T]

I was saying that I would take my wheels into a shop to get them to rebalance them, not check the air pressures. Do you honestly think someone that has had their car for 9+ years and done most of the work themselves over that time isn't checking their own air pressures? Give me some credit please Dave.

Not picking on you in particular and I don't know if you check your own tires or not. Far too many owners either don't check their tires or they don't know how or what pressure to keep them at. Low pressure can make the wheels shake badly. Good for you, you actually DO check! I check mine often also but occasionally I do find a tire low because it has a leak. If you catch it BEFORE it goes flat or driving on it low for a long time you don't ruin it. Also this time of year when it gets cold your tire pressures go down about 1 psi for every 10 degrees. You can also lose as much as 1 psi per month. Before you know it you can be 3-4 psi down and that is a lot.

[Jonathan]

Not picking on you in particular and I don't know if you check your own tires or not. Far too many owners either don't check their tires or they don't know how or what pressure to keep them at. Low pressure can make the wheels shake badly. Good for you, you actually DO check! I check mine often also but occasionally I do find a tire low because it has a leak. If you catch it BEFORE it goes flat or driving on it low for a long time you don't ruin it. Also this time of year when it gets cold your tire pressures go down about 1 psi for every 10 degrees. You can also lose as much as 1 psi per month. Before you know it you can be 3-4 psi down and that is a lot.

Rest assured, I do enough obsessive compulsive checking and fussing over my car to have a pretty good idea what the air pressures in the tires are.