Jim5870

The next time you do the front disc brakes on your 2WD D250 or D350 you might find some of these tips helpful. The big problem with this system is the
wear that occurs on the caliper support slides and caliper, the wear causes the
caliper to apply un-evenly and this results in un-even brake pad forces applied to the rotor.
I'll demonstrate the steps I have used to get 2WD front disc brakes working again on this old D350 front end that I salvaged for parts.





As usual for a brake job, get your rotors turned or replaced, some reconditioned
calipers would be nice, and some new brake pads. Here is a tip for the folks with
a D250, use D350 brake pads! The inner pads are identical but the outer pads
for the D350 are 3/8" wider, this means extra brake pad surface area which
means more braking for the same brake pedal force. You can see the difference in pad widths, D350 outboard pad on top and D250 outboard pad on bottom.



Next, unbolt the caliper supports and clean them up. My photos for this demo are of the right side brake.





If you carefully examine the caliper support you will see wear groove on the middle area where the inboard pad transmits its braking force to the support.
The area where the caliper transmits the force from the outboard pad the support slide show wear on the right and left corners.



That vertical groove in the center is a big problem for the inboard pad.
When the caliper applies force, the inboard pad edge is forced into that groove and prevents it from sliding across, kind of like getting your wheel stuck in a deep rut that you cant drive out of. You'll notice on your old pad
that the top end will have lots of pad left because it couldn't slide over but the bottom end will be worn down because it was able to move.
The result is that 50% of the inboard pad doesnt get used, and caliper force
is wasted. If you think about it, if half a pad on each side doesnt get any force, that equals 1 whole pads worth of material is not getting used, in other words, only 3 out of the four pads are doing useful work.
On the bottom side of the support, there will be a groove also, weld that one too. The areas where the caliper slide on the lower support will have minimal wear, you may or may not have to weld the bottom slides, depends how bad they are.
The cure for the worn spots is to put a bead of weld on the worn areas and carefully grind them down back to original.



I'd like to point out here before somebody says "I shouldn't weld on those parts" that I used a low heat setting on the welder and I only welded a few seconds at a time so that I didn't overheat the support. The object is to add a little metal to the low areas, then grind the weld down to reduce the various clearances, kind of like a bodyman using Bondo to fill a low spot then block sanding. At no time did I get the welded areas anywhere near cherry hot or anything like that.







Here is my support after welding and grinding, if your welder is better than mine and if you use a better grinder than I did and if your eyes are better than mine then you can get decent results. Weld and grind the groove on the bottom half of the support also. then repeat the process on the other support.

Jim5870

So now you have your caliper supports welded and smoothed out, here is an option for you. Does the lower support slide area look better than the top area you fixed? Then what you can do is turn the support top to bottom and swap them from left side to right side. Turning them around like this will put the
hardly worn lower slide from one side to the more important top position on the other side. In this photo the gray support is the right side and the red support is from the left side.



Now they are swapped



The top slides are more important than the bottom because only the top slides
take the load from forward braking so it makes sense to but the best slides on the top. Next we need to test fit the new inboard pad to the support.
Temporarily bolt the support to the hub but don't torque them yet, you may have to take them on and off a few times for checking, welding, grinding
until they fit well. Next step is to get the inboard pad ready for test fitting
but first we'll need to prep it.



The new pad will have a ragged edge from its manufacturing process where it contacts the support,
draw file the pad on the contact area to smooth it out. This will de burr
the edge so it will slide easier and contribute less to making a new groove on the support. On the ears of the inboard pad I like to use these abuttment
clips, I think they help the pad ear slide easier. The clips I used are leftover bits from a Chrysler Intrepid front brake job. Unfortunately they aren’t sold separately, they come with the Intrepid brake pads, but if you know anybody that does brake jobs maybe they have some kicking around their shop. It’s an option if you want to use some.





Now check the fit of the inboard pad in the support. If the clearance is too great then weld and grind the support in that area again until you get about
.010 to .020 clearance.



Picture above shows that clearance is too great, weld and grind it again till its right.



This looks about right. You don't want it too tight because the pad may bind in the support.



Your inboard pad should now be able to slide nicely without getting caught in a groove.



Next, we will be test fitting the caliper, prep the outboard pad ears. Put the pad in the vise and squeeze the ear down. Some folks do this with pliers as the last step after the caliper goes on, but I like doing it this way because I can make the pad fit tighter on the caliper.
Next let’s check the caliper over for defects and get it ready for fitting.

Jim5870

Lets have a look at those "rebuilt" calipers. Check the slides for damage.
Chances are they are worn down on the upper slides, and bashed on the corners because people drop them.
This "rebuilt" caliper had bashed up corners, eliminate the bashed corners by drawfilling.





The rebuilders obviously don't repair the slides on these old things.



Notice the worn down area under the top right caliper slide



This "rebuilt" caliper has obviously been around the block a few times,
Put the caliper on as is just to see how it fits.
Usually the outboard top caliper slide gets worn down the worst. Its worn down because the outboard pad braking force has to go through the caliper and slide on that side.
When the caliper is at rest (not applied) the caliper just basically rests on the lower slides. When the caliper applies, the caliper will move up and contact the top support slides. When the caliper moves up, the inboard and outboard slides should contact the support at the same time to achieve an even clamping force on each side. If they dont, then the forces acting on the caliper will want it to twist it. We'll need to adjust this caliper. In this case the caliper needed some weld on the front edge on one slide and on the bottomside of the other slide.



After welding and smoothing, your caliper should fit good. Notice the abuttment clip.



The goal is to get both upper caliper slides to meet the support slides at the same time when the caliper applies it's force. If there is a gap on either slide, then the caliper will want to twist. Notice how only half of the outboard caliper slide actually sits on the support.



Chase the hold down threads for good measure.



Now you can torque down the support bolts and finish putting things back together the regular way.



Now that the caliper and pads can run in better alignment on the support,
and the extra brake pad area from using D350 pads, you should get good
good braking.

comotionman

nice work. how about a little bit of synthetic caliper grease on the slide contact areas?

Jim5870

Definately lube the slides when you put things back together, I figured you folks
already knew that.
Didn't do that step because this was a junk axle I did the demo on.
Plan to salvage the control arms one of these days, maybe try and use a spindle and hub as part of a rotating mount for a Cummins engine stand

comotionman

well......some of us do

BC847

Stuck!!

BearKiller

I can't see the pictures anymore.

misterbeavers

any way we can get these pictures back up? Looking to do this repair soon unfortunately. looks to be a great write up. thanks

BC847

Folks are checking into it, bear with us.

Jim5870

Sorry folks, the pictures files were transferred to a tech file here,
but somehow went missing. I'll see if i can find the pics and uploaded them again and try to repair that post.

crazzywolfie

i don't know if the pics i got will help or not but i think understand part of what your talking about without the pics. i was cleaning up the sliders on my 93 last week. the build up or wear on the slider was pretty bad. the front brakes on my 93 would usually lockup for a second on a wet morning. when i finished there was still a small low spot where the inner pad sat but is way better than it was when i started. no more front brakes locking up yet. i use a rotary file($5 at Canadian tire) and air drill to remove most of the larger high spots and a file to remove the rest. i also cleaned and repacked my bearings at the same time since the last person to do it used more grease than i would have. also do you think the 1 ton pad trick would work with the 1/2 tons?

before. this picture also shows you how to remove the inner bearing seal without damaging it. remove outer bearing and stuff and put the spindle nut back on and pull the rotor off making sure the inner bearing catches on the spindle nut. has always worked for me with no issue so far.

rust or something in the slider


i also figured since i had it apart i should put some paint on it to hopefully keep it clean. Jim you probably know how hard that is up here. primer

paint. i went a bit overboard

with the paint on the low spots are pretty visible still but i was really not up to messing with welding it. i figure next year i will see about filing more off. the low spot is not that bad compared to what was there.