Why does the Left-rear caliper fail rather than the Right?

[john keefe]

If this is a real road use/service life discrepancy it should have affected Granadas, and Sierras, too. He/they who believe it is should research that.

Well, since it appears we're on either side of the "chicken or egg" perspective on S/D, be my guest. Allowing, of course, for those being right-hand drive vehicles. Personally, I don't have time to, nor would I spend the hours to peruse eBay UK or UK dismantlers' on-line inventories to estimate RR vs LR failures just to try to prove a point of opinion (at this point, without further information). Even if the correlation was mirrored for those UK versions (failed RR calipers), we would likely still draw the same conclusion(s) based on which side of the S/D spectrum we prefer.

Not trying to win anything here. I only offered my quasi-educated opinion based on observation, and a little reasoning. I may be wrong. Perhaps someone like Jeff could help answer the questions. But that's the age-old benefit of discussion, right?

[Ed Lijewski]

Late last December I paid MPM $121.60 shipped for a rebuilt LR caliper w/o slide.

Price today is $158.65 w/o shipping.

Screenshot_20211230-163335_Chrome.jpg (600.34 KiB) Viewed 10021 times

YMMV

[Ed Lijewski]

Personally, I don't have time to, nor would I spend the hours to peruse eBay UK or UK dismantlers' on-line inventories...

Sheesh. I had in mind only querying members of the UK Granada/Scorpio FB group of their experiences. Peeps there don't always respond to we Yanks' Qs but it's an easy effort to ask.

YMMV

[john keefe]

Sheesh. I had in mind only querying members of the UK Granada/Scorpio FB group of their experiences. Peeps there don't always respond to we Yanks' Qs but it's an easy effort to ask.

Ah, OK. Thought you were suggesting I do that research to validate my argument. No prob. I've only dealt with a couple guys at Graham Goode and RS Cosworth Breakers, and I don't do FB or Twitter, so didn't occur to me you were suggesting a group inquiry.

[brokencase]

Never came across a caliper I could not rebuild.

If you have gotten to the point to where the caliper bore is so corroded that it is not rebuildable then there is something wrong with you.

[Ed Lijewski]

^^ Snob.

My two rear caliper purchases were driven by issues with the parking brake adjusters. One froze tightly in applied position. On the other (left rear) on getting the car I found the adjuster arm screw+piston had somehow gotten over-extended and wouldn't retract using the caliper tool or brute force on the arm. The pads weren't binding on the rotor but the PB function couldn't be adjusted. With the PB arm unmovable the PB cable couldn't be moved off the arm (fully loosened cable adjuster). I ended up hack sawing off the arm's hook so the cable could be removed.

I wanted to know why each failed but chose to replace and move on with new/rebuilt units with no regrets.

YMMV

[DPDISXR4Ti]

Never came across a caliper I could not rebuild.

That's not really the question at hand here though. The question is why does the left-caliper lock up more frequently than the right, apparently regardless of the caliper being used. Admittedly the second qualifier is based on a sample size of one (my VW caliper). But while messing with the rear calipers on this car I could see that the issue is primarily tied to the e-brake function, and that the left-side e-brake seems to engage ahead of the right.

[brokencase]

Since I have not yet encountered a caliper failure on a Scorpio there is not much I can say.

However, Brad, even if the e-brake was biased to the left side I fail to see how that would contribute to pre-mature failure UNLESS you were constantly applying the e-brake on highly inclined surfaces. Or perhaps you are yanking the lever too hard?

[DPDISXR4Ti]

However, Brad, even if the e-brake was biased to the left side I fail to see how that would contribute to pre-mature failure UNLESS you were constantly applying the e-brake on highly inclined surfaces. Or perhaps you are yanking the lever too hard?

Good question. I never explored what happened with the stock caliper, but what I found with the VW calipers is that I had the cable tension set too tight initially. When cold it didn't bind, but all it took was a little use, things heated up and expanded, and the caliper started binding. I loosened the adjuster up a little and it's been fine ever since, but I still see that the left side is engaging ahead of the right (e-brake only).

[brokencase]

Presently my e-brake adjustment is a little loose. The handle pulls up quite a bit. But I find even so the rear brakes engage fine.
I don't think it takes much tension to get good e-bakes action.

I think you might be yanking the handle too hard.

[Ed Lijewski]

Easy to overlook or do incompletely: clean caliper pins to shiny (no crud remaining), apply high temp silicone caliper grease, install slide on pins to test; remove all rust from where brake pads rest on calioer assuring pads have a bit of wiggle room and apply same grease to caliper and and contact areas.

Hypothetically the RR caliper if not easily fully activating via E-brake cable transfers applied cable force to LR caliper

Brad will say BTDT. (But I needed to be there to quality check it. )

YMMV

[DPDISXR4Ti]

Brad will say BTDT. (But I needed to be there to quality check it. )

No need to BTDT. Before I hooked up the cable to the new calipers, the e-brake lever for both calipers moved freely and fully retracted when not connected to the cable. Once connected and the adjuster tightened a bit, the LH caliper clearly tightened ahead of the right.

So having worked this through in mind several times now via this "forced march" we've had, here's my theory on what must be happening... The cable is not moving freely over the tightening cam - maybe it's even rust-seized in place. It needs to either be lubed or replaced. Checking this is now on my list of things to do - probably this Spring.

If I find this ^^^ was indeed the problem, is it a typical problem? Does the cam-to-cable seizure typically happen with the cable pulling more on the left side?

[Ed Lijewski]

Once connected and the adjuster tightened a bit, the LH caliper clearly tightened ahead of the right.

If somewhere in the section of the cable from adjuster to right caliper the cable doesn't slide fully freely that would transfer cable movement to the left side first.

YMMV

[DPDISXR4Ti]

If somewhere in the section of the cable from adjuster to caliper the cable doesn't slide fully freely that would transfer cable movement to the left side first.

So I would bet that's what is happening, and to my original theory, that's what has happened to others and is why LH calipers are needlessly replaced more than RH, thus creating today's current NLA situation of LH calipers. Yes, the reasoning is speculation on my part, but it's becoming more sound reasoning to me.

[Ed Lijewski]

I inadvertently didn't include "right" in my original post, now corrected:

"If somewhere in the section of the cable from adjuster to right caliper the cable doesn't slide fully freely that would transfer cable movement to the left side first."

YMMV