Pads or Rotors - Which is responsible for DTV?

Status
Not open for further replies.
T

threeputtpar

Joined
Aug 4, 2011
Messages
2,128
Location
Appleton, WI
The vehicle in question is the Taurus X in my sig. It had new brakes put on by the previous owners right before I bought it, and now 10k miles later it's developing the shakes at highway braking speeds. At lower speeds, it won't shake but I can feel the brakes grab 100% and then back off some and then grab again as the rotors make a full revolution so it's likely DTV or maybe runout.

So assuming that they went with the cheaper pads and rotors just to sell the vehicle, which one is the cause of the variation? I cannot see what the friction rating is on the pads anymore, and I don't know what brand any of the parts are. Just trying to decide if cleaning up the rotors will be the solution or new, better pads or am I stuck with having to do a full brake job? Thanks.
 
If you want it cured most likely new pads and rotors, because the culprit is probably in the rotors. Could be some build up on the wheel hub too that needs wire brushing
 
It's a very common Taurus problem. Standard solution is to do the pads and rotors. There are various fixes proposed, but most of them aren't always successful. One claim is that it's pad buildup on the rotors and a series of hot stops will clear it out. You're also supposed to grease the glide pins when putting in the pads and if you don't do that, maybe the caliper isn't floating that freely. Usually you can get lifetime pads so when it happens every 20-30k, you just pay for a new set of rotors. They're pretty cheap, around $20-$30 each and a set of pads that have a lifetime warranty starts at around $40.
 
Most likely what happend is the Pads were not "Bedded" in properly. If done incorreclty it leaves "Spots" on the rotor and can cause vibrations. Additionally, if the rotors were "turned" they may have taken too mauch material off and thus out of spec. You drove it a while, the new pads wore the rotors down enough to where they warped under braking heat.

I always suggest rotors and pads together, to maximine braking. If you do the work yourself its not much more than what a shop charges just to turn your old rotors. If you cant do it yourself, then buy the parts yoruself and give them to your mechanic to put on. That too will save some moeny.

Change the rotors and pads, and bed them in properly and you will be good for a while
thumbsup2.gif


Jeff
 
If the rotors don't show excessive runout - there will be a factory spec for that - then uneven coating of pad material on the rotor is being suggested more and more often as a cause. A possible fix is sanding each side of the rotor to remove the pad material and doing the pad break in procedure as though the pads were new.
 
Originally Posted By: silveravant
Before you do anything else I would try 5 hard stops from 60 to 10 mph then drive 10 minutes without stopping. Worked for me.


This is always the first thing we do here when our vehicles exhibit pulsation under braking. Most of the time it completely cures the problem.

Note that each vehicle has different braking capacity. On a normal car the above regimen is likely enough, but you must add more speed/stops to high performance vehicles with larger braking capacity and reduce it for small economy cars with nominal brakes.
 
Originally Posted By: threeputtpar
The vehicle in question is the Taurus X in my sig. It had new brakes put on by the previous owners right before I bought it, and now 10k miles later it's developing the shakes at highway braking speeds. At lower speeds, it won't shake but I can feel the brakes grab 100% and then back off some and then grab again as the rotors make a full revolution so it's likely DTV or maybe runout



Try the re-bedding trick described above. If that doesn't fix it, then clean the rotors by hand, and the problem will almost certainly go away. This problem is VERY rarely actual rotor warpage or runout. Its almost always uneven brake pad deposits caused by braking then stopping with the hot pad clamped against one spot on the rotor, happens worst when the pads are new and still outgassing heavily.

Remove the wheel, get access to both sides of the rotor (may mean removing the caliper, in which case you can probably just remove the whole rotor. Hand-rub it with a Scotch-brite pad, spray down with brake cleaner, dry, go over again with a scotch-brite, then brake cleaner again. Reinstall and go. If you replace the pads, the outgassing will start all over again. Turning the rotors is a waste of metal and money, unless the cleaning does not cure the problem.
 
I had suspected it would be the rotors so I'll pull them off this weekend and hit them with some sanding blocks.

Don't know if it means anything but when it's raining out the problem goes away.
 
Update: I pulled both discs and hit them with 80 grit sanding disks to the point where the metallic shine was gone from the swept surfaces.

Took the X out and did the bedding process of 6-8 moderately hard stops down to 5mph with cooling periods inbetween. The pulsation comes back within a week.

Calipers slide easily, I installed new pad shims incase they were binding and caliper cylinders retracted easily. Is this an issue of cheap pads?
 
On our Honda and Acura I have resigned myself to putting on new front pads and rotors every 30-40k miles. I've tried every trick in the book, I clean the hubs carefully, etc. etc.

Nothing is a long term cure.

Fortunately by doing the work myself I have the cost down to something I can live with doing every 2-4 years.
 
Originally Posted By: threeputtpar
Update: I pulled both discs and hit them with 80 grit sanding disks to the point where the metallic shine was gone from the swept surfaces.

Took the X out and did the bedding process of 6-8 moderately hard stops down to 5mph with cooling periods inbetween. The pulsation comes back within a week.

Calipers slide easily, I installed new pad shims incase they were binding and caliper cylinders retracted easily. Is this an issue of cheap pads?


It's usually the pad at fault here in Florida. Iron is iron, and especially older rotors which have been heat cycled a lot in use. Many folks here blame rotors for pulsation...
 
I had this problem on my 01 Tacoma. Premium rotors and pads has helped a lot (as well as proper bedding procedure). But I still expect the problem to recur before the pads are completely worn out.

Sometimes an unfortunate hard stop leads to uneven tempering in the rotor. The rotor will then wear at differing rates leading to variations in thickness (not warping or runout per se). The varying thickness is what you sometimes feel.

Better metallurgy (premium rotors) reduces this tendancy, as well as careful driving, if possible. Rotor runout is not typically something you even feel but can also lead to variations in thickness if excessive.

In my experience, turning rotors is a complete waste.
 
I have similar problem with my van, for a year now. Year a go I've put new discs and pads in front to replace old that was wear out, but true. Than it started. After 2k I had wheel wobble, and pulsation. Than I replaced it with new again - Zimmermann these time, pads too. Again, after 2k, the same. Than took both sets to the shop to be machined, again after 2k or so the same.
Than I had installed some scrapyard worn out ones for testing -again the same. Forgot to mention in the meantime ivw changed calipers, flexible pipes, fluid, cleaned hub for four times. I'm suspecting front left hub now -it seems left side is the culprit.
 
I only have 10k miles of history on this car as I didn't get any repair info from the couple I purchased it from, but I can see that the front bearings are OE by the amount of rust on them.

I've done the tests by grasping the tire at 12 and 6 and 3 and 9, and there is not abnormal play. I think I may just toss a decent set of pads on it and see what happens. Looking for at least an FF rated set.
 
Originally Posted By: threeputtpar
I only have 10k miles of history on this car as I didn't get any repair info from the couple I purchased it from, but I can see that the front bearings are OE by the amount of rust on them.

I've done the tests by grasping the tire at 12 and 6 and 3 and 9, and there is not abnormal play. I think I may just toss a decent set of pads on it and see what happens. Looking for at least an FF rated set.


Take a look at Raybestos Element3 EHT pads. I think they're GG rated in most applications. I just put a set on my Chevy (along with new rotors, on all 4 corners). So far, I'm very happy with them. Always a good idea to replace rotors at the same time, you very well may have some DTV going on, and new pads won't help that.
 
Originally Posted By: threeputtpar
I had suspected it would be the rotors so I'll pull them off this weekend and hit them with some sanding blocks.

Don't know if it means anything but when it's raining out the problem goes away.
yAH 'cUZ YOU'RE STEAM CLEANING THE ROTOR oops
 
Originally Posted By: 440Magnum

Try the re-bedding trick described above. If that doesn't fix it, then clean the rotors by hand, and the problem will almost certainly go away. This problem is VERY rarely actual rotor warpage or runout.


With white box rotors or resurfaced rotors, runout is usually out of spec at least 50% of the time. At least from what I have seen. Without measuring runout and knowing the vehicle's maximum allowed runout, you're simply guessing what the problem is.
 
Originally Posted By: The Critic
...Without measuring runout and knowing the vehicle's maximum allowed runout, you're simply guessing what the problem is.


It seems most DIYers do not want to spend money on a dial indicator and magnetic base.
 
Status
Not open for further replies.

Similar threads

A
Which rear brake pads for 2007 Mercedes S550?
2
Replies
23
Views
655
atikovi
D
Time for new brakes, Saturn Ion Redline
Replies
11
Views
554
doitmyself
wwillson
168k miles on these front rotors and pads - 2014 Durango
2
Replies
23
Views
2K
GMBoy
Twisted1
Needing rotor brand recommendations
2
Replies
28
Views
3K
Nesterenko
S
Pads: EBC yellow, red, MB OEM, or other
Replies
7
Views
1K
si1491
Back
Top