1991 240 sedan. wanted to replace front brake lines to calipers, do pads and rotors. found one of the shops I'd been to in college had used rtv behind the pads a some point instead of grease to quiet ceramic squeal. they also rounded the nuts for the hard lines, so I took the car to our shop to do the lines, rotors and pads since they have better tools. got the car back and it had significant pull left when braking hard. it had never done this before. took it back to the shop. they have replaced a caliper, bled several times, swapped lines, yet it still pulls left. next stop is replacing the master cylinder. if anyone has any thoughts on what might be causing the pull left, I'd sure appreciate it. the guys at the shop have always been good to me but none of us are finding the problem, and replacing parts is gettin pricey. thanks, scott

if anyone has any thoughts on what might be causing the pull left, I'd sure appreciate it.

Your problem could result of IF the "new" RF caliper is pre-ABS, as Art inquired about), AND the rebuilder mismatched the inner and outer halves when reconditioning it. In which case air cannot be bled from the lower-outer caliper cylinder.

For a history on this problem, go to the "SEARCH" window in the upper right corner and enter

LUCID: Mismatched

then press SEARCH.


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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

"Pricey" - for them not you I trust.

Speaking of throwing pricey parts at it, I'm not sure what the thought is behind swapping the master, although for other reasons (like bleeding technique) it may have been ruined.

In 1991, ABS was optional on a US 240.


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Art Benstein near Baltimore

All the trouble I've ever been in started out as fun.....

thanks Art. non ABS. did not swap master cylinder. swapped the new lines from left to right to see if there was any difference. then did the right side caliper to see if something had occurred that made it weak. when doing the original work, we found pinched hard lines on the right, which were replaced. the strange thing is that we've replaced stuff on the right side as if that side was weak, but it still pulls left. I can't speak to the bleeding technique as I've not watched them. they've done brake work for me before, and their shop is always full so they should be competent. it just odd that the car did not pull prior to the repairs, but now it does.

I've never had a symptom like that, so my guess that you're correct to suspect the right caliper isn't acting with equal force on the rotor is only theory. Seems like the correct theory to me.

But if you say the hard lines were smashed, was there a collision, perhaps with a curb? How'd they get that way? And when you speak of "lines" you are including the flexible hoses I assume, and there's no chance the upper and lower circuits were reversed when the pipes were replaced.

Lucid suggests the common fault of the rebuilder mixing up caliper halves, but I did not consider that, thinking the symptom when that happens is a very spongy pedal -- air in the unbleedable chamber -- more than a pull to one side, it would keep an ordinary soul from ever getting to the test drive segment. Could be, though, just check for the dimples.

Calling the bleeding technique into question is the result of many, many masters needing to be replaced AFTER brake work with bleeding. This happens when the pedal is used to bleed the system and it is pushed beyond its normal travel, causing the rusty back halves of the master cylinder to scratch up and lodge rust in the seals. Once that happens, the master is trash. Or core. And it isn't the owner's fault, it is the fault of the fixer. But that is unrelated to the pulling. The symptom of the scratched seals is slow sinking of the pedal with constant force. That's why most of us use a pressure bleeding technique, or just gravity bleed - no pedal action at all.

I'm afraid I haven't helped much...



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Art Benstein near Baltimore

What do you call a fish with no eyes? A fsh.

well you didn't say which caliper was replaced so i would say at first you should replace calipers in pairs not just on one side. hope that helps.
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'92 240 208k totalled 4/14 - '91 240 192k miles

Yes I was thinking the same thing, which caliper?

I was told that when it pulls to left the right side caliper is the one not working as well as the left one. So,it's that wheel try's to run around the other.

Is that right?

Phil

yeah, replaced the right side caliper to see if it was weak. didn't change the pull. what's tough is that it didn't pull before replacing the lines so it's been tough to determine what the issue is. either something weakened the pressure on the right side or increased the left. increase seems unlikely to me. they've bled the lines several times and everything looks good but the problem remains. I still wonder if sone crud hasn't managed to get into something, but they have swapped lines and bled enough that you'd think we'd have found something.

and of course we know the front tires have enough air and no other defects, been swapped f + r, right?