2004 XC70 Brake - Cliper Spring Photo Needed

[haoz129]

Well, what a mess I made of that! If we count the correct placement of each spring end as 25%, then my total score was 25%!

Goldxc70,

After seeing your pictures which are nice, I laughed.
Regarding spring position, you are really creative.

When I did my first brake service on XC70, after all done, I mean wheels tightened, I found spring was sitting on the ground, .

No picky, just enjoy life with XC70 and this forum around, .

Howard

[bwswede]

I changed the pads on our car and found I had a spongy petal afterwords. I looked on the forum and found that I probably had the caliper springs on wrong. I printed the picture of a correct installation and went outside to find my problem. I looked at all 4 wheels and my springs appear to be installed correctly.

I have looked at all the photos of the tensioning springs I could find and they all confirm mine are installed correctly. When I changed the pads I didn't not open any bleeders and the fluid level in the reservoir never got low enough to suck air. With a lot of force I can press my pedal to the stop which really worries me.

Do the springs wear out? Loose their ability to tension? A lot of the posts describe how hard they are to put on, but they don't seem that hard to me. I don't know if it is because I am used to working on trucks or if the springs have become soft. I imagine if they are worn out the caliper will twist when brake pressure is applied. Would someone mind explaining where I should be looking for this twist. Does the outer portion of the caliper push away from the car?

Any suggestions?


TIA,
BWSwede

[Astro14]

Take a picture of your springs - one for each caliper and let us have a look.

Your statement; that the hydraulics were not opened up, means that the pads/springs must be at fault.

If they were easy for you to put on - then you didn't do it correctly. They are difficult to install correctly because you have to apply considerable force. I have done this a couple of times, I know.

I bet your springs are installed incorrectly...I am nearly certain...

[bwswede]

Astro14,

Thanks for the reply, I really appreciate the help. A photo of each spring is attached. Order of photos, driver front, driver rear, passenger front, passenger rear.

Thanks again,
BWSwede

[Astro14]

OK, well...I stand corrected, those springs look good. So, while I suppose it's possible that they lost some tension, I think that unlikely.

What worries me though, is your rotors!

They look completely shot - there shouldn't be a big lip on the edge like that...did you mic them to see if they're below minimum thickness? Did you try bedding the pads in? Rotors should be flat and smooth across the surface, no lips. Bedding the pads in mates them to that flat surface and depsits a thin "transfer layer" of pad material on the surface for good contact/friction. Without a smooth rotor surface to which the pads can mate, you get inadequate friction and poor braking performance.

In your case, those rotors look worn out - rough, grooved surface (so the pads are only touching the tops of the grooves) and some big wear lips at the edges, where the pads may be hitting the rotors. So, in order to apply the brakes, the calipers have to push the pads against uneven surfaces with much greater travel than would be needed against a flat surface, I think that is the cause of your spongy pedal. The old pads had worn those grooves and were a mated pair with each rotor, so there was good contact and minimal travel. Here is a picture of a rotor (slotted, not OE, but the principle is the same) with 40,000 miles on it. Notice that it is flat across the surface - and there is no lip at the edge. Notice too, how thick it is...don't confuse the thin bit of rust at the inner edge with a lip of different thickness, it's a few thousands at the most...

I think your problem is rotors worn beyond the limit, and pads that haven't bedded to the concave shape of the rotor surface.

I would get these mic'd (measured with a micrometer, you can get one for not a lot of $$, get the 0 - 1 inch range). I bet they're below the limit for thickness. If they are replace them. If they're close, replace them, they'll go below the limit during the life of the pads...If they're good, then get them turned, I think your problem is pad/rotor mating at the surface of the rotors...

Rotors are cheap (relatively) compared with the cost of brake failure...

[cattlecar]

I agree with Astro. I have put pads or rotors that had the wear pattern I see on those rotors and had soft pedal that I had to apply extra force to in order to stop. The new pads don't conform to the rotor face when it is so concave like those.
Fronts are almost certainly worn past limit as the front pads are aggressive on softer spec rotors and the rotors wear. Rears may be OK to have resurfaced as the rear pads used are not aggressive to the rotors.
When you get rotors done, go drive and stop hard from 40 mph 3 times and then a couple of more times gently. When brakes cool off the pedal feel will be back and the force needed to stop will be reduced back to the normal level.
New or resurfaced rotors need to have some pad material imbedded into the surface in order for the brakes to work as designed.

[bwswede]

Thanks for the replies guys. It all makes sense.

I have a micrometer. Do either of you know what the minimum thickness the caliber can be and still meet spec?

Thanks again,
BWSwede

[skibo]

I have a micrometer. Do either of you know what the minimum thickness the caliber can be and still meet spec?

From the info on the resource tab:

Front: 23.8mm re-use limit, 23.0 condemning limit
Rear: 10.7 mm re-use limit, 10.0 condemning limit

[bwswede]

Thanks Skibo. I'll measure them after work tonight do determine my course of action.

Best,
BWSwede

[RockitShip]

2nd Astro's sentiments.... Your rotors are shot.
I would replace the springs anyway, they lose tension after a few years/miles.