=
> Followup...
> =
> today I took the rear brakes apart again to replace the rear wheel
> cylinders that I bought on Monday. I figured while I had it apart I
> would clean and paint the backing plates (didn't do that before, in my
> hurry to get the car on the road.) Here's where I found something
> interesting; on BOTH backing plates, all of the little "pads" that the
> shoes ride on were in excellent shape, EXCEPT two of three for the
> primary shoe - the top one by the anchor pin and the bottom one by the
> star wheel were deeply grooved. Again, this was on both sides, and the=
> wear patterns were similar. I wonder if maybe someone had the drums cu= t
> and whoever did it left a little "spiral" on the wearing surface and th= e
> shoes were chattering? =
The top and bottom tend to get the grooves because the movement of the shoe tends to follow the direction of the edge of the shoe. At the middle it's is moving at 90=B0 to the edge. The problem tends to develop when you stick on new shoes and the groove is in the wrong place (the edge of the shoe is riding on the edge of the groove instead of the middle). You will probably notice the shoes have a little wrinkle in the edge where they contact the backing plate. If designed right that goes along way to spread the load and keep the edge from knifing into the backing plate. But some designs tend to cut in worse then others. Old Ramblers come to mind.
who knows... Now I wouldn't have noticed this
> if I hadn't taken the backing plates off the car, as those pads are
> difficult to look at when you're bending down to look under the quarter=
> panel. The middle one by the hold down (the one that your eye is
> naturally drawn to) was fine. I don't have any explanation for this,
> but I went ahead and laid a bead of MIG weld down on there and ground i= t
> back smooth. I am fairly certain that this issue does not exist on the=
> fronts as I cleaned and painted the front backing plates when I rebuilt=
> the suspension.
> =
> The paint on the rear backing plates is drying now so I will reassemble=
> tomorrow and see if it did anything. Will bypass the anti-creep valve
> before bleeding.
> =
> I've put a few more careful miles on the car, and since I cleaned
> everything real well last weekend I can see exactly where the shoes are=
> contacting the drums. The secondary shoes are making maybe 50% contact= ,
> but the primaries a lot less, almost as if the grooves really were
> holding the shoes up. =
Which 50% is making contact? Is it in the middle? one end? or both ends? That doesn't sound good, it shouldn't take much wear to get 100% contact if they are at all close to the right size to begin with.
-jim
Also it may be my imagination but even after
> putting maybe only 50 more (careful!) miles on the car since the last
> time I posted the rears feel less "grabby" - I haven't had the brakes
> lock up in traffic at all, although when I really tested them in front
> of my friend's house the rears still locked before I thought they
> should. So I am wondering if really the fact that the rear shoes aren'= t
> completely worn in is the main problem. Well, anyway, we will see if > this helps...
> =
> I haven't pulled the driver's side front yet since my original post; I
> am curious whether or not it is still getting more dust than the pass.
> side. However, in retrospect, I think most of the dust that I saw may
> have been rust wearing off the drum - IIRC that wheel had a completely
> seized wheel cylinder when I got the car and that drum had more surface=
> rust on it than the others. If I have time tomorrow I will probably
> pull it again just to make sure nothing is amiss.
> =
> nate
> =
> (I just want to drive my car! Is that too much to ask?)
> =
> --
> replace "fly" with "com" to reply.
>
Ah, so if we can assume the shoes themselves are right ones for this car then probably the remanufactured linings are a lot thicker than the original manufacturers lining. So that isn't altogether bad since eventually they will wear to the right size.
That 'really' implies the shoes are the wrong size. The arc is wrong. Might only be too big by a little but.... If you can get them to finally break in, then you will have to watch them close as they wear. The ends will go metal on metal long before the center is worn out....
There are shops local to me that will take the old metal shoe frames and put new friction material on them. I think I would be looking at that rather than trying to drive with shoes that don't grab evenly....
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
formatting link
(More Off Road album links at bottom of the view page)
not "long" but probably... they'll never get to that point, though, I do try to take care of my vehicles :) I think it's probably only out by a few thousandths.
I already turned in my cores, I don't think there's anything wrong with these, the problem is that they probably do need to be "arced" but I don't have an old school brake and clutch shop anywhere around, or if I do, I don't know about it. :/
I put everything back together today and I really don't know how I could have done anything better. Everything is spanking clean, unless it's supposed to be lubed in which case it has fresh white lithium on it. New wheel cylinders, hoses, and MC, new linings from the same source all around, only difference is that the fronts have maybe 1-200 more miles on them than the rears. I did NOT get a chance to bypass the anti-creep today as I had to take the time to drill out a busted parking brake cable retainer bolt (fun fun fun) and needed to get the car back together and out of my friend's garage.
The rear brakes are still locking up prematurely, but I swear that the more I drive it the better it seems to brake. I think I am going to remove the anti-creep valve next weekend anyway just to eliminate all possibilities, but tell me if this sounds like a dumb idea - set the car up on jackstands in the driveway (or on a lift if it is warm enough to keep the garage door open,) run it up to about 50 MPH wheel speed, brake to zero under light power, lather, rinse, repeat until the rear shoes are worn in. THEN go for another test drive and see if it is still being a pain in the arse.
If *that* doesn't work, I will take apart the fronts AGAIN and do the same careful inspection of all components and see if anything pops out at me (like the grooves in the backing plate that I'd missed before) and then if I don't find anything I will have to admit defeat and simply install a prop valve.
BTW to the other poster who mentioned the springs; I thought of that but they all appear to have been replaced at the last brake job as they all still have paint on them. If wearing in the shoes doesn't fix the problem I do have Wagner part numbers for the springs, I will see if my FLAPS can hook me up.
nate
PS - on the upside, I think I am close to resolution of another problem with this car that's keeping it from being a nice driver; I picked up a "condition unkown" steering box at a swap meet a couple weeks ago and started cleaning it up today. Not only is it nice and tight, but I filled the gearbox up with gasoline and it seems to be holding (which is better than the one in the car, which gear oil runs right through and chassis grease kind of oozes out of after a while)
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