2007 XC-70 front brake job pad too tight?

[twooldvolvos]

Dear Matthews,

I did a front rotor and pad job on my 2007 Volvo XC-70 yesterday and I ran into an issue I have never experienced in prior brake jobs on this car. I was using Akebono pads. Passenger side went fine. But the driver's side outside brake pad would not fit in the caliper. It was very close but a bit too tight. So I carefully scraped the casting and blew it clean. Still too tight. So I put some layout fluid on the pad and tried tapping it into place. The tight spot was on the bottom of the steel part of the pad. So I carefully ground the high spot and eventually got the pad to fit squarely. But it is tight with no giggle in it. Is this a problem? Does the outside pad need to float freely? It seems to me that leaving it tight should not be a problem since the outer pad's movement comes only from the iron sliding part that it is in, and not from the pad itself sliding like the inner pad. Any thought? BTW, the car seems to brake very nicely.

Thanks in advance. Dan.

[xHeart]

Dear Matthews,

I did a front rotor and pad job on my 2007 Volvo XC-70 yesterday and I ran into an issue I have never experienced in prior brake jobs on this car. I was using Akebono pads. Passenger side went fine. But the driver's side outside brake pad would not fit in the caliper. It was very close but a bit too tight. So I carefully scraped the casting and blew it clean. Still too tight. So I put some layout fluid on the pad and tried tapping it into place. The tight spot was on the bottom of the steel part of the pad. So I carefully ground the high spot and eventually got the pad to fit squarely. But it is tight with no giggle in it. Is this a problem? Does the outside pad need to float freely? It seems to me that leaving it tight should not be a problem since the outer pad's movement comes only from the iron sliding part that it is in, and not from the pad itself sliding like the inner pad. Any thought? BTW, the car seems to brake very nicely.

Thanks in advance. Dan.

Zeroing the piston at each caliper makes the brake pad fit easily unless you're using aftermarket calipers?

[firstv70volvo]

Dear Matthews,

I did a front rotor and pad job on my 2007 Volvo XC-70 yesterday and I ran into an issue I have never experienced in prior brake jobs on this car. I was using Akebono pads. Passenger side went fine. But the driver's side outside brake pad would not fit in the caliper. It was very close but a bit too tight. So I carefully scraped the casting and blew it clean. Still too tight. So I put some layout fluid on the pad and tried tapping it into place. The tight spot was on the bottom of the steel part of the pad. So I carefully ground the high spot and eventually got the pad to fit squarely. But it is tight with no giggle in it. Is this a problem? Does the outside pad need to float freely? It seems to me that leaving it tight should not be a problem since the outer pad's movement comes only from the iron sliding part that it is in, and not from the pad itself sliding like the inner pad. Any thought? BTW, the car seems to brake very nicely.

Thanks in advance. Dan.

The outside brake pad needs to release from the rotor well enough when not braking so it doesn't create continuous friction and heat. If the pad is binding too much in the caliper carrier, the channels where the pads slides, then this could potentially be a problem. This is where an infrared thermometer comes in handy. After brake jobs I always check the rotor temps after a drive to see if the temps are similar side to side, front and back will be different but front and rear side to side comparison should be close.

[twooldvolvos]

Thanks, Oro.

But since the outer pad slides with the the caliper, wouldn't the critical part that would allow the pad to release be the sliding mechanism? In my case, that would be the 2 pins, wouldn't it? Even though it still seems to work fine, I'm still uncomfortable that the pad has no wiggle room in the carrier. I think the right thing for me to do would be to take it out, carefully clean the carrier and if the pad is still tight, grind it until it has some clearance. I can also measure the new and old pads with a dial caliper to confirm that it is a manufacturing error. I have the original calipers on the car. I should have done that in the first place.

Dan

[scot850]

Have you compared the 2 caliper pistons are going back equally as far into the body of the caliper. Rebuilt calipers may use different sources for pistons that may be of different thicknesses.

If you have compared the overall thickness of the pads and they are all the same? If they are then the caliper has to be the issue.
Measure the distance from the piston face to the inner face where the opposite pad sits against. Is this the same on both calipers?

Silly question, you don't have too much brake fluid in the reservoir do you?

Neil.

[Oro]

Dear Matthews,

I did a front rotor and pad job on my 2007 Volvo XC-70 yesterday and I ran into an issue I have never experienced in prior brake jobs on this car. I was using Akebono pads. Passenger side went fine. But the driver's side outside brake pad would not fit in the caliper. It was very close but a bit too tight. So I carefully scraped the casting and blew it clean. Still too tight. So I put some layout fluid on the pad and tried tapping it into place. The tight spot was on the bottom of the steel part of the pad. So I carefully ground the high spot and eventually got the pad to fit squarely. But it is tight with no giggle in it. Is this a problem? Does the outside pad need to float freely? It seems to me that leaving it tight should not be a problem since the outer pad's movement comes only from the iron sliding part that it is in, and not from the pad itself sliding like the inner pad. Any thought? BTW, the car seems to brake very nicely.

Thanks in advance. Dan.

Back to basics:

Did you pull out the caliper pins and clean them; make sure the caliper(s) are truly floating as designed?

The calipers “float” and are not fixed. IME, if you find yourself trying to jam in pads, you have a caliper problem, not a pad problem. I went through this a few weeks ago with a high performance late model Lexus. Final result was, the pins were stuck. I may have missed this, but did you in fact dis-mount the calipers, clean and polish the caliper pins? That’s part of every brake pad job.

Before you jammed in and ground the new pads, did you pull the caliper pins, clean and re-lube them? That’s step one.

[ignatz]

I've been using this file for 50 years (sad but true). A wire brush with steel bristles and this Sil Glide stuff has been in my toolbox for years.

[scot850]

Did you check my questions above?

Neil.