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grooves on caliper slides

truckeejeeper

NAXJA Forum User
So I have these grooves worn into my brake slide where the caliper gets stuck I guess. The shop wants 1k to replace but I read a article somewhere where A guy just put a blog of welding material in the groove an filed it smooth and viola fixed. I can't find the article. I also don't own a welder but for that price I could prob buy one and do it myself, I've done a bit of welding, and I'd love to have a welder. Anyone have any links/info on this? Also, how big of a welder would I need. I'm thinking one of those Miller brands.

thanks for any help!

1991 4.0 Sport 5sp.
 
I did mine with my 175 MIG, with Argon/CO2 mixed gas. The trick to welding this is it takes high heat and gets dirty (carbon fouled) quick, the base metal of the rails is high carbon. The base metal of the rail spits carbon when you MIG it and gets dirty fast, the weld won't stick to carbon dust.

I burnt in a spot weld good, cleaned off the surface (carbon and oxidation) after each spot weld with a wire wheel in a drill and repeated. When I had a good bead built up I used an angle grinder and file to shape.

If you weld much you can tell when a weld or spot weld burns in good, it flows a little around the edges of the weld. The weld lays kind of flat and not as a ball or bead.
 
I could be wrong, but I suspect the anti-rattle springs that clip to the pads helps prevent these low spots wearing into the brake rails. My XJ didn't have the anti-rattle springs on the pads when I bought it, and had deep wear in the rails. Arguably NOT lubing the rails and pads during install with disc brake grease was also a factor. (The anti-rattle springs are those little wrap around springs that go over the slot in the pad backing. That will hold the pad off the rail, and take up any slack so the pad can't bounce up and down with the open space between the pad and two rails, unless of course you're actually braking which then they'll compress and allow the pad backing to press firmly on the rail.)

Oh, and the deep wear spots in the brake rails, combined with worn out shocks and front control arm bushings resulted in death wobble on my XJ when hitting the brakes at high way speed when I first purchased it. Fixing all three of those has resulting in never experiencing it again the last 10 years.

I've done mine also, I did post a pictorial of it when I did it, like 10 years ago. Heck, I may be remembering wrong and it might be on a totally different online forum.

Keep in mind a professional welder will tell you welding cast iron is very specific and has all sorts of special procedures an amateur would never be able to do. BUT, this is for structural strength of the entire cast iron piece, NOT filling a wear spot. I.E. if your steering knuckle was broken in half, I'd say your crazy if you think you can weld it together and think it was safe to drive on, but that's NOT what you're doing. I and others have proven, filling in the wear spot with weld metals works and lasts.

I'm less knowledgeable on welding than 8Mud. In fact I'm very amateurish. Welding with a Mig welder is NOT so difficult that most mechanically inclined amateurs can teach themselves how to do it (with some reading). But it is difficult enough, that if you think you can just buy a cheap used Mig machine, fire it up and weld in that spot with no practice or learning, you're sorely mistaken.

When I fixed up my XJ, I had friend lend me his Mig Machine. I read and practiced several days on scrap metal, before I started welding. First I did all the rust repair on the floor pans, which was a lot and got my skill down, then attempted the brake rails.

In my case, I can't remember the specific details like 8Mud, but I remember some details on my approach that seemed to work.
*thoroughly cleaning the worn spots and surrounding area, like grinding it, power wire brush to take a little metal off the top, so I could get the purist weld with most consistent metal without impurities.
*I turned the Mig Welder up high, made a nice big puddle of molten metal and laid it on thick.
*Since I had to do 4 spots for each steering knuckle, I alternated steering knuckles and even waited in between, to make sure each steering knuckle was cool to the touch before starting the next weld spot. Not only do you want to avoid getting the cast iron too hot, effecting the metallurgy, but also if the steering knuckles are still on the vehicle, wheel bearings, drive shafts, u-joints, ball joints and grease boots can be damaged by the heat as well.

This resulted in a huge glob of metal over the worn down spot, I used a angle grinder to get it down close, a dremel to get it down even closer and then finished it off with a file to get it perfectly flat.

Take the advice of the more experienced welder if they tell you the better approach is to lay down smaller multiple beads, to build up the metal, thoroughly cleaning and allowing it to cool, in between each bead. In my case it worked fine and has lasted, by laying down one huge bead, a big freaking puddle, into the spot all at once, then letting it cool off a long time before going to the next spot.

And then, once you've fixed it, make sure to get the anti-rattle clips for the brake pads and use specific brake grease for the rail/pad interface. Other greases won't stand up to the heat or wash away easily when exposed to the elements.
 
Yep, looked just like my pictorial, and looked like the same approach I took. One big bead filling it in as one big puddling bead with one pass, then grinding down to get it close, finishing with filing to get it straight and true.

Doing it in one pass is doable, an experienced welder just knows when he is getting a good bond by the feel and look of the weld. But the only part of the weld that actually holds anything is at the bottom and you want a good bond.

Cast has a high carbon contend, plus whatever changes to soot while welding from the shield gases, the steel itself and whatever, Carbon and soot tends to coat the material to be welded as you weld. It is possible to get so much soot (carbon) build up the weld doesn't want to bond thoroughly or correctly. In school we'd dissected our welds (filed and grinded) and stained them, you could really see what was holding and what wasn't. Carbon melts at right around twice the temperature of steel. Your weld may or may not be melting through the carbon and bonding correctly. That is why I do a spot on cast, thoroughly melting it in, then stop and thoroughly clean around the spot weld and then do it again. The weld is most always going bond to itself (same material) but may or may not bond to the cast if it gets a thick enough layer of carbon dust. I also kept my welding tip and nozzle clean using liberal amounts of tip spray. At the higher temperature the wire tends to melt back into/onto the tip and splatter can become a real issue quick.

Like my instructor used to say "a pretty weld doesn't necessarily mean a good bond". "An ugly weld most always means a poor bond".

In the end whatever works is the right way. :)
 
Safety, I just went through a year and half of eye operations and procedures. The safety equipment now on days is good, use it religiously. I've burnt my eyeballs, lenses and Retina, on numerous occasion. Sometimes from laziness, I'll do just this one weld without the shield laziness. Or from reflected light off a wall into the back of the old style (non wraparound) welding shields. You may not notice immediately, you may feel like you have sand in eyes the next morning or when you get old the injury may come back to haunt you.

Going blind can scare the heck out of you.
 
I just did mine today. Very EASY to do!

I took a map gas torch and heated the knuckles where the brakes slide and cooked all the oil out and pre heated the cast. I then put a bead of weld where the groove was using my Lincoln Pro Mig 135 with flux core .035 wire. On the initial weld I turned the machine up to the highest heat setting which is D and put the wire speed on 3. I then ground the weld down using a gearless air sander with 2' 120 grit discs and a grinder with 4.5" 80 grit flap wheel. Cut the weld down, then if there was any pits I welded them with the machine on power setting C and a wire speed of around 2-2.5 and cut the weld down again. Now they are nice and square and smooth as glass!
 
Safety, I just went through a year and half of eye operations and procedures. The safety equipment now on days is good, use it religiously. I've burnt my eyeballs, lenses and Retina, on numerous occasion. Sometimes from laziness, I'll do just this one weld without the shield laziness. Or from reflected light off a wall into the back of the old style (non wraparound) welding shields. You may not notice immediately, you may feel like you have sand in eyes the next morning or when you get old the injury may come back to haunt you.

Going blind can scare the heck out of you.

I know your pain!! I've torched without glasses and had a huge ball of molted slack pop and it me dead square on the seam of both eye lids and melted the skin together. Luckily I reacted and closed my eye in time and pulled the slag off right away before puling my eye lids apart. Hurt like a bitch!!!

I've had UV blindness or flash blindness a few times.... SUCKS!!

I'm really bad about not putting my safety glasses down over my eyes when they are sitting on top of my head just to do a quick grind... four times I've been unfortunate and gotten a small piece of metal from the sparks embedded in my eye and had to go to an eye doctor to have them drill a hole in my eye to get the metal out and the rust.... I'm religious about using personal protective equipment now and still catch myself occasionally forgetting to slide my glasses down from the top of my head.
 
i just threw my knuckles out and bought another set that were in good shape at the junkyard. i think they were like $20 each?
 
So I have these grooves worn into my brake slide where the caliper gets stuck I guess. The shop wants 1k to replace but I read a article somewhere where A guy just put a blog of welding material in the groove an filed it smooth and viola fixed. I can't find the article. I also don't own a welder but for that price I could prob buy one and do it myself, I've done a bit of welding, and I'd love to have a welder. Anyone have any links/info on this? Also, how big of a welder would I need. I'm thinking one of those Miller brands.

thanks for any help!

1991 4.0 Sport 5sp.

Just take the knuckles off and take them to a welding shop and have them weld them up for you and you can grind them down. Can't cost more than maybe $20-$30 to have them welded.
 
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