Hey Lads,

Bought new vented, cross drilled rotors and new pads but have issues and was wondering if anyone has had this problem.

So I cannot get the caliper back on over the rotors with the new pads? There are three possible reasons:

1) The rotors are too thick.
I checked their thickness against the old rotors which were worn of course. The difference in the thickness is less than 1mm. The amount of room I need to get the caliper on is more like 4-5mm

2) The pads are too thick.
This is what I believe might be the answer but how can that be? They are all the same thickness. Won't know for sure unless someone has a measurement that I can compare.

3) The piston will not retract fully into the caliper
I thought this was the most likely suspect. I originally used a hand clamp to push the piston back as far as I could. I then bought a 65.00 compression tool with no difference. I even cracked the bleeder to see if there was fluid resistance and opened up the master too. It will NOT recess any further into the bore no matter how much force I put on it.

Does anyone have a picture or measurement of the piston retracted as far into the bore as it should go? On mine, the piston doesn't go back much further than the lip of the seal. I have seen them on other vehicles go completely flat to the caliper but that is not the case here.

Some info on any of these items is appreciated.

One more thing.
I originally put the new rotors on with the old pads and they work fine of course because they are worn. I drove the car and the ABS light came on. Maybe I disturbed something on the hub of one side or the other but is there any special about the stock rotors as far as the ABS is concerned? The rotors I bought are aftermarket. They work fine but now I have the light on so maybe I am missing something here. They look identical construction wise except for the venting and cross drilling of course.

Any help is appreciated

For reference, the pads are measuring 20mm in total thickness including plate and shim.
The rotors are measuring 29mm

Bernie

The picture shows how far back I can get the piston into the bore.

 

From the picture it certainly seems that the piston has retracted pretty much as far as is needed. You might get it a bit deeper by using a large nut, or similar packer, sitting inside the recess of the piston. I have used a small "G" clamp, with the "screw" section sitting into the recess and it works fine. Having said that, new pads are often a snug fit.


Regarding the ABS, the different rotors/discs, shouldn't make any difference, as the ABS sensor works in relation to the reluctor ring, on the shaft, behind the hub/rotor assembly. This is a toothed ring, fixed in place and is independent of the rotor. So you may have disturbed the wiring at the sensor. There should also be an earth wire in there someplace, often fixed in place at the brake fluid hose, where it is clipped in place, along the suspension strut.


Others will chime in with more info.

 

Thanks for that!

The ABS light is off now.
Maybe I turned the wheels with the ignition on or else I somehow got the sensor out of joint when I was working with the caliper. Not sure but will look into that further if it comes on again.

I temporarily put the old pads back in which of course fit fine.
There is no way possible to get the piston any deeper into the bore. I tried at least six different ways....lol

I ordered another different set of pads just now. They will be there for pickup between 4-5 so I will take my calipers to check their thickness before buying them. If that doesn't reveal anything I don't know where else to go but to problems in the caliper itself.

Guess doing the other side will reveal if that is what I am dealing with

 

It does sound like an issue with the pads. New pads are generally 16.6 - 17.5 mm. Just checkout online catalogues for the big names. They all have data sheets.

I always use Pagid brakes on everything I work on. Their data sheet is here

brakebook.com - T1200_402

 

Agree with Brendan. Most likely an issue with the pads. Possible the friction material is to thick.
Seen it with a couple Honda civics, and see it all the time with these freightliner mt45s we work on at my shop.

Always have to return them to the store for the pads with thinner material. Which is usually just one number or letter off in the part number. (In the case of the freight liners the thicker pads are part no. 786 and the thinner is 786A)

Sometimes different applications will use the same width, height, and shape brake pad with a thicker or thinner material. Although never seen or heard about it on our vehicles, would be interested to find out.

 

I believe you guys are right.

Picked up another set of pads today from a different store and they measured 18-18.5mm. I thought they had a chance but nope. I can get the caliper on but there is definitely a drag on the rotor and they are off again. I believe 16-17mm max is what this car can take.

No worries, I will check into the link provided and get a set of high quality pads that I have to do once instead of half a dozen times....lol

Thanks guys

Bernie

 

Piston looks pretty well fully retracted to me. I always crack the bleed screw simultaneous to twisting the compression tool, forcing the old fluid out the back instead of back up into the lines and master.... and when I do this, I can feel the piston bottom-out.


Had a similar problem last time I renewed the pads and I ended up putting a new pad on each inboard position, and returning the old pads to their previous outboard positions on the premise that it really didn't need pad renewal just yet but even so it would be easier to see the outboard ones during tire rotations and I will fit the other half of the new set to the outboard when they start to get thin. But I don't think I was 4-5 mm out, more like 1-2 mm. Oh, I did make an emphatic note in the app I use for maintenance tracking: "Don't ever buy AC-Delco semi-metals!!!"

 

I had this issue with some XJ8 AutoZone premium ceramic pads. There is an association of brake manufacturers "standard dimension" chart that shows the dimensions for aftermarket pads, and for the particular one used on the X-308, there are two variants with one marked as "-A" in the part number.

Of course, the weenie at the parts counter explained very carefully to me that I was crazy and he had never heard of such a thing until we laid both sets of pads out on the counter and compared them.

 

It looks like Centric makes a pad that is 16.5mm thick so I am going to see if I can find those here locally. If not, I am going to have to order them in.

Good info for anyone looking at doing a simple brake pad change. This has cost me hours of time with messing with it and multiple trips to the parts store. I should have been done with this in less than an hour ........

 

They were AC Delco semi metallics that didn't fit yours?
That's odd. I used the ac Delco "professional durastop" on the front and rear when I did my rotors and pads about a year ago and they fit fine for me. Wonder why that is.

Also, what app do you use to track maintenance? Would be interested in getting something to track maintenance I do to my car.

 

It was these: https://www.rockauto.com/catalog/mor...69&cc=1178399v
I didn't remember that I changed the rotors at the same time until I just looked up the note. I don't remember now what method, but somehow I convinced myself that the problem absolutely was not that the new rotors were too thick. I measured and noted the thickness of the takeoffs before I boxed them for storage in case I decide to have them turned for the next X300 brake job. Not sure there's quite enough there, though...anybody know how much material is removed in the average rotor-turning evolution?

I use the Android app "Car Maintenance Reminder"


Initially started entering each item as a "task" in Outlook, but that was about like a file-drawer full of paper. Switched to an Excel file and then lost 2 yrs worth of records in a computer crash.


Now keep a database file on the phone's sd card and also back it up to Google.

 

The Centric pads I picked up yesterday finally worked! It raised my premium to 70.00 for the pads but they came with new rubber bushes, caps and also new clips. A bit of a premium for a set of pads but whatever, they went on no problem and the job is done - finally.

Who would have thought that putting a set of brake pads on a car would be so much trouble?

FYI - The data sheet said they were 16.5mm thick but they measured out at 17mm. I thought this still might be an issue but I was wrong. Lots of play with the piston pushed back.

Cheers
Bernie

 

In similar situations, I've taken a belt sander to the pad to remove the excess material. 5 minutes work.

 

Ha!
Don't worry that thought crossed my mind.
I didn't do it for three reasons.

1) Something was wrong and I needed to figure it out.
2) I didn't want that dust flying around everywhere
3) I wanted to make sure the pads sat square to the new rotors.

B

 

I've used the asphalt on the street to do the same thing lol