When I still worked on trucks and when I got my ASE certifications the correct answer is do both sides the same.

 

To get the new studs in use an old lug nut and some washers. Push the stud in as far as you can and then put the washers and lug nut on. Then use an air impact and slowly/ a little at a time tighten the nut on the stud. The washers will take up the difference(not bottom out the stud) and spread the force a little bit. This way you don't have to turn brand new rotors, usually rotors should only be turned once. Also, I have heard arguments for and against replacing both rotors here and other places. My recomendation in this case is replace both. If one side is obviously bad the other is probably not far behind. And the big difference in wear could possibly be the result of only one having been replaced previously. Also buy new studs, you will probably trash the old ones trying to drive them out of the old rotor.

T. Roberts
UFD Local 1147

 

Well, the bottom line is that everyone's entitled to their opinion, and furthermore, it's your truck, so you can replace whatever you see fit.

But I stand by what I said - I've replaced one rotor or drum on LOTS of vehicles, Fords, Chevys, Dodges, BMWs, VWs, Hondas, Nissans, Toyotas, you name it, I probably did brakes on it. Never had a problem with pulling, uneven pad wear, or anything else.

 

Forgot one thing. Does the truck pull to one side or the other when braking? You may want to check your calipers also if you are getting obvious uneven wear.

T. Roberts
UFD Local 1147

 

well. here you go.

its fact that if you have uneven rotors, where one is bigger then the other, the bigger side WILL break harder, because the master cylinder pushes fluid to them evenly.
Unless your master cylinder pushes oil to all 4 breaks individually.

When you push down your pedal also, the first break will clamp down, and it wont break tight untill the other one is tight also. I've seen that a lot.
Thats more common then the one ahead, which andym is talking about, where he see's no difference. The result in this case is slow break responce time, becasue they have to even out the pressure.

 

My two cents. Rotors are not that expensive. I Recentally did front brakes on my 88 f-150. And they were like 45 bucks each. The real issue is i think that you said that this was on an 87 while you have the rotors off, you should do the wheel bearings. ( Let's see if this starts an argument) I would replace both rotors and the front wheel bearing. Also my rotors came with the lugs already in them.

 

Depending on the year and I can not remember on these the rotors may or may not be attached to the hub. Either way the bearings will have to be at the least cleaned and repacked and new seals installed. I personally prefer to use preloaded calipers since I had one fail after replacing just the pads (piston froosen) as a safety feature and I've not had one fail.

 

yep. we tottaly forgot about bearings.

that is important to repack or replace while your there too.
there about 8 a piece.
i'd replace those with new, you could do the old ones. but your better off doing new.
Cause then thats less maitinence to do later.
Pack those babies up.

i think some of the rotors you can buy come with bearings?

Oh yes, make sure you have your new rotors turned, sometimes those fers aren't strait. So have a mechanic or somebody who knows how to operate the turner check em to see if they are true.

Remember your front breaks do 70% of your breaking.

 

Did anybody mention that unless he wants to buy the $100 + rotor he will need to get the hub pressed out of his old rotor and into his new one? Might as well go through that PITA once for both sides nad not have to worry about it for years.

 

here are my 2 cents about the rotor replacement "fiasco" I've always been taught that brake components are replaced in pairs. I've always done it that way. I'll probably always do it that way. That being said, the concept of uneven wear due solely to uneven rotor thickness is inaccurate. That's not the way hydraulics work. As long as both front wheels are driven by the same master cylinder (they are), then the system is inherently self-adjusting.

In an otherwise healthy brake system where one rotor is thicker than the other, the very first time pressure is applied through the system (after a proper bleed) will be the only time that one side catches before the other. The fluid will fill both calipers at the same rate, but the caliper on the thinner rotor will take more fluid than the other. The thicker rotor makes contact first, then the thinner one. This only happens the first time. Once filled, the reverse flow is drawn evenly from the two calipers and thus they will take the same amount of fluid to recompress. They are now "adjusted."

To limit misunderstandings, here is a hypothetical situation using assumptions and large numbers to illustrate the concept. Both wheels have a brand-new caliper which has just been installed. The brake system has been bled properly, and is ready to be adjusted and driven.

L side
------
New Rotor, 1.5" thick, caliper needs 100cc for piston extension to reach rotor, holds 75cc with piston fully compressed

R side
------
Old Rotor, 1.25" thick, caliper needs 125cc for piston extension to reach rotor, holds 75cc with piston fully compressed

Since we have identical calipers, they hold the same amount of fluid at full piston compression. One rotor is thinner than the other one, so it will take more piston travel to reach the rotor. When the pedal is pressed, each caliper will continue taking fluid until we either run out, or the caliper is full. Once both calipers are full, we withdraw the pedal and a certain amount of fluid is drawn from the calipers back into the master cylinder. Since we know that the pistons do not fully retract each time, we must assume that the amount withdrawn is smaller than the amount originally forced in. Here's the situation now, after 50cc has been removed from the system:

L side
------
New Rotor, 1.5" thick, caliper needs 25cc for piston extension to reach rotor, holds 150cc with piston partially compressed

R side
------
Old Rotor, 1.25" thick, caliper needs 25cc for piston extension to reach rotor, holds 175cc with piston partially compressed

Now, since the calipers need the same amount of fluid to reach the rotors, they will contact their respective rotors at the same time. Remember that fluid flows atthe same rate to both sides.

I hope this helped explain the concept of why (all things being equal) a turned rotor and a new rotor will not pull or wear pads unevenly. Other brake parts will have different effects on the system; this example holds true for rotors only. Sorry for the long post, but I thought you guys might like some in-depth info

 

Thanks for all of you insight into this question. After pricing around for new rotors and new brakes and bearing seals and repacking the bearings it would have cost me more to do it myself. I had two new rotors, new lifetime pads, new seals and bearings cleaned and repacked for 200.00. I thought that was a great price. Better yet, i went to school with the guy who did it so i know it was done right.

 

djjoshuad-excellent discription of how they really work.
the same would be true if the pads were not equal wear/thickness.
yes, i was taught to replace pads and bearings in pairs but not drums/rotors/hubs.
take that truck to a shop and they will replace the bad one, turn the second and your good. after 27 years of turning a wrench and 100's of brake jobs, doing exactly this-I'll still stick to my post "yes you can"

 

glad to here your fixed up. great thread. good choice on letting someone else do it, saves the hassle and you got a warrantee to boot.
Randy

 

Yes, this is true, and I probably should have mentioned that as well Of course, replacing drums/rotors/pads in pairs will also make sure that you don't have to do brake maintenance in a "staggered" manner so it's still not a bad idea. If you are fortunate enough to find a truly honest shop, they will tell you all of this. Problem is, many of the shops (especially around here) either don't know better, or are trying to maximize profit :-\

I guess it boils down to this: I agree with ssn randy. "yes, you can."