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'93 W250 with clunk from the front caliper -- FIXED!

14K views 45 replies 6 participants last post by  SuperBurban 
#1 ·
As stated above, patient is a '93 W250 which has a D44 w/Chrysler calipers and 12.8" rotors.

At low speeds there is a noticeable "clunk" as the wheel turns - I jacked up the front and turned the tire -- it seems like the pad is catching on a high spot on the rotor causing the caliper to move up (vertically) and then return once the high spot passes.

I removed the wheel and turned the hub by hand and confirmed that there is drag on this (slightly) high spot.

When on the brakes at low speed the clunk does go away; it also seems to get less noticeable at normal cruising speeds.

I've replaced the caliper retaining hardware (thinking it was fatigued), however it didn't make any difference. I've also greased the calipers/slides and freshly bled all 4 brakes and the RWAL module.

Should I have the rotors turned and slap new new pads on or is there something more I might be missing?
 
#2 ·
vertically?  Thats a new one on me. Almost needs to be a good worn grove to cause something like that.  Can you see the spot?  Can you feel the movement in your foot on the brake pedal?  If no to those, I think I would take a grinder, and grind a small 45 deg chamfer on the bottom edge of both pads.
 
#3 ·
seen it plenty of times / the pads are chucking in the caliper bracket / the bracket is shot because of the grooves the pads wore in it / to verify it take the caliper off and move the pads vertical up and down in the same plain the rotor turns / if they chuck the brackets shot / you can try shimming them or just live with it
 
#4 ·
SuperBurban said:
vertically? Thats a new one on me. Almost needs to be a good worn grove to cause something like that. Can you see the spot? Can you feel the movement in your foot on the brake pedal? If no to those, I think I would take a grinder, and grind a small 45 deg chamfer on the bottom edge of both pads.
Yes, as in moving towards the upper caliper retainer and then resting back into it's normal position. There is a deep groove about 1/3rd of the way around the outer surface of the rotor -- not very thick, but a groove nonetheless. Towards the trailing end of it (wheel turning forwards) you can feel (not see) where the rotor has a high spot.

I tried lightly sanding the area which helped some but I didn't want to go too crazy on the rotor -- I didn't think to grind a chamfer on the pads though -- good tip.

As far as feeling it in the brake pedal, when driving around at low speeds when the clunking is the loudest you can definitely feel it...however once you get on the brakes it's less noticeable. When braking from higher speeds you only feel it once you get back down to lower speeds.

When I had the truck in for the alignment they noted that since they had to remove the caliper to repack the wheel bearings that they must have loosened it all up. To compensate they put some sticky stuff on the back of the inner pad which helped for a while (how that worked I don't know since it's the outer surface that's "warped", but said that if it started doing it again then they'd have to dive into it further. I'd like to avoid having to bring it in to them as I think I'm able to fix it on my own.

Another question, how tight should the outer pad be on the caliper fingers? I did have to hammer the outer pad a little as it was very loose -- it took a little force to get it on, but it's on there fairly tight now.

DODGEBOYS said:
seen it plenty of times / the pads are chucking in the caliper bracket / the bracket is shot because of the grooves the pads wore in it / to verify it take the caliper off and move the pads vertical up and down in the same plain the rotor turns / if they chuck the brackets shot / you can try shimming them or just live with it
Yes! The pads definitely have vertical play!

Is there a shim kit available or how would you propose to shim them. It a pretty bad clunk at low speeds and I'd like to eliminate it.

Would it be worth it to get a new caliper bracket if they're still available? Could I just move the rest of the parts over to a new bracket?
 
#5 ·
DODGEBOYS said:
seen it plenty of times / the pads are chucking in the caliper bracket / the bracket is shot because of the grooves the pads wore in it / to verify it take the caliper off and move the pads vertical up and down in the same plain the rotor turns / if they chuck the brackets shot / you can try shimming them or just live with it
I've seen that, but never seen that cause the caliper to move vertically. the grove worn in the caliper adapter, is easily fixed by using a file, and file the caliper groves down until the worn spot is cleaned up.
 
#6 ·
Just look at the adapter, you will easily see if there is a grove worn where the inside pads rest.

I think I would go ahead and get the disk ground down, or even go ahead, and get 2 new rotors, and new pads & rebuilt calipers.

Front brakes are one area that I have no problem spending the money and doing it right, and doing it all.
 
#7 ·
SuperBurban said:
I've seen that, but never seen that cause the caliper to move vertically. the grove worn in the caliper adapter, is easily fixed by using a file, and file the caliper groves down until the worn spot is cleaned up.
I think I'm a little confused as I need to take a closer look and/or pictures to show what's going on. I don't see any major signs of wear, but there definitely is vertical slop for the inner pad and caliper.

While looking around online earlier (and don't fault me for this but) on the Autozone repair guides they specify that (on the Chrysler calipers) "The inboard shoe must always be installed on top of the retainer spring plate." Now neither side on my truck are assembled this way however the passenger side doesn't appear to have any vertical play that I've observed. I've had both apart and look identical.

SuperBurban said:
Just look at the adapter, you will easily see if there is a grove worn where the inside pads rest.

I think I would go ahead and get the disk ground down, or even go ahead, and get 2 new rotors, and new pads & rebuilt calipers.

Front brakes are one area that I have no problem spending the money and doing it right, and doing it all.
I really don't recall seeing any unusual wear, but I was thinking getting new rotors, pads, and rubber lines as well as rebuilt calipers just to be safe.
 
#8 ·
Another question, the caliper hardware kit came with 4 rubber bands (which no repair guides I've seen so far make any mention of) however the Dodge parts listing shows #8 below as a "RUBBER BAND, Frt. Disk Brake Hsg. to Adapter". Where is the rubber band supposed to go?

 
#9 ·
I have never figured that out, I have asked at some Dodge dealer shops, on here, and other sites over the years, and never gotten any real answer. I've played around putting them on there, and cannot see any way for them to go, how they should fit on, and do anything. Some of the Dodge shop manuals show them with about the same picture, but do not go into any more detail on how to fit them. Just says if they were there before, put them on.
 
#10 ·
Maybe you use the rubber bands to hold keep the anti-rattle spring from falling out while you place the caliper?  Then you can either leave it there or cut it after the installation.
 
#11 ·
Maybe, but I didn't find installing the caliper retaining clips, anti-rattle springs, and the bolt all that challenging. It doesn't seem like they'd hold up long if left in place. You'd think the heat alone would make for a short life span for them.

Back to DODGEBOYS thought about shimming the calipers/adapters -- any thoughts on how to do that in the interim?
 
#12 ·
If you are getting new rotors, and the spot where the caliper slide on, on the caliper adapter is flat all the way across, I see no reason to do any thing, but put it all back together.

If there is rust on the slide area, I usually clean it up with a file, then coat it all with something like never sneeze.
 
#13 ·
It was pouring and cold last night so I didn't get a chance to pull the wheel off -- but from what I remember the surfaces on the caliper and adapter were flat -- no grooves or odd wear. I also did grease them lightly as per the manuals.
 
#14 ·
you can "quote me" on this /  they wrap around the caliper bracket and and sit in the groove the end of the pad sits in to act and a cushion anti rattle type of thing
 
#15 ·
See that's what I figured...but I figured they'd get torn up pretty quick. I'll give it a go when I have to take everything apart again. Thanks!
 
#16 ·
i have had to do various things withe these calipers,small tack welds and a file to fill in the worn areas,wedging a chisel behind the edge of the brake pad and bending the ears to tighten them on the caliper,the rubber band works,as the caliper barely moves once all set in place and bled.the rubber takes a while to scrub itself off unless it in a real gritty enviroment.
 
#17 ·
offroader_dodge said:
i have had to do various things withe these calipers,small tack welds and a file to fill in the worn areas,wedging a chisel behind the edge of the brake pad and bending the ears to tighten them on the caliper,the rubber band works,as the caliper barely moves once all set in place and bled.the rubber takes a while to scrub itself off unless it in a real gritty enviroment.
So where exactly do the rubber bands go? I put them on the caliper...they're kinda wedged between the retaining clips and the caliper. It didn't seem to make sense to put them on the adapter as they didn't really seat well (fit around the adapter and sat flush on the side which contacts the pad/caliper, but not around the back side of the contact surface).

Upon further inspection the back of the rotor is warped -- bad. Here's the weird thing though the front had a gouge in it...maybe 1mm thick and goes about 1/4 to 1/3 of the way around the front face. The rear face of the rotor is warped outward in the same location, -- what would cause a gouge on one side and it to bow out on the other? I tried sanding it down some, readjusting the caliper, and using the rubber bands -- which all helped to a point but the clunk is still there (albeit less noticeable). It's definitely getting hung up on the bow spot on the back side of the rotor, so new pads, rotors, brake lines, and rebuilt calipers are in order...
 
#18 ·
when you installed the caliper mounting shim/wedge and the backer spring did it just slide in easy/loose or did you have to tap it in place to line it up for the bolt?  it should be just about an interference fit with some hammer tapping to place it.  if it was loose i'm thinking this might be where your issue is.  of course a severely warped rotor might booger up the diagnosis.

and i've never seen/used rubber bands for anything just some anti squeal grease on the back of the pads where it contacts the piston/caliper.
 
#19 ·
Oh there was definitely interference removing and reinstalling the caliper/pads -- using a rubber mallet to help reinstall. When turning the rotor by hand I can definitely feel where the pad starts to drag on the high spot on the back of the rotor and then releases once it passes. When not on the high spot the rotor turns smoothly.

Once the caliper/pads are in as far as they'll go there's still a lot of vertical play until the retainer plates/anti-rattle springs are installed. Once they are installed the caliper still has some slight vertical play (less with the rubber bands installed). There is a wear spot on the upper surface of the adapter, but nothing extreme.

I noticed that if I installed the retainer plates slightly crooked (with them tilted more towards the back edge of the caliper) it kept it a lot more secure than if they're installed level (so they put more pressure on the back edge of the caliper keeping it from moving when it caught on the high spot on the rotor), but it didn't look right so I didn't leave it that way.

Are the anti-rattle springs supposed to be in contact with anything and how level are they supposed to be in relation to the retainer plates? I'm assuming as level as possible...

For reference (excuse the poor diagram) if you look at the lower retainer/anti-rattle clip they're parallel to the caliper/caliper adapter "machined ways", with them installed like that, there is vertical movement of the caliper between the retainers. When I made them tilt towards the rear section of the caliper it kept it much more secure, but I didn't know what effect that'd have.
 
#21 ·
Is that the Bendix caliper (D60) as that looks nothing like the Chrysler calipers (D44)...

This is another (horrible) picture, but you can see that the retainer clip is indeed tilted more towards the back of the caliper rather than the front (since there's more play on the back side anyhow just by nature of the way the inner pad floats rather than being fixed to the caliper like the outer pad).



*EDIT* -- Anyhow, I'm getting tired and really over-analyzing this -- it all went together normally on the passenger side (which isn't having any issues) -- so I think I'll just go with new rotors/pads and be done with it. This isn't that complicated of a system as I'm making it out to be...
 
#22 ·
SCarGo02 said:
I think I'll just go with new rotors/pads and be done with it. This isn't that complicated of a system as I'm making it out to be...
Ditto. You two are talking about two different brake systems. (D60 vs D44) Not har to do, if the slides have no worn spot, just slap it all together, and go.
 
#23 ·
#24 ·
Yes, you just do not have the locking hub, you will have what looks like a big gear in there. You will need a Locking ring pliers, or a small screw driver, or an awl, to get the lock ring off. then you will need the 4x4 bearing lock nut socket to get the bearing nut off.
 
#26 ·
SuperBurban said:
Yes, you just do not have the locking hub, you will have what looks like a big gear in there. You will need a Locking ring pliers, or a small screw driver, or an awl, to get the lock ring off. then you will need the 4x4 bearing lock nut socket to get the bearing nut off.
Are those anything like snap ring pliers?


I'm sure any of the auto parts stores should have the socket? Looks like this, correct?


EricY8s said:
how do you have a 5 lug d44 on your 250?
Just a picture I found online...
 
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