Brake pad shims...

[SAmadei]

So I've overhauling a bunch of stuff on my '89 GMC G3500 Vandura. It started out as a quick quest to fix the brakes from pulling to the left, and to get it through NJ inspection, but after shaking things around, its turned into a mountain of replacement parts... new ball joints, tie rods, rotors, calipers, pads, etc.

This was my late father's truck, and generally he kept things in good shape, as he was a mechanic, but I'm a bit disheartened at the condition, since I haven't put many miles on it in the last six years... I'm surprised he drove it with such a mismatching of worn parts.

So, anyway, I'm on the home stretch. But after taking the brake pads out, there is a missing pad clip and both inner pads have two very thin shims. They are very rusty and were more or less bonded to the pad and caliper. I'm not sure if this was done because the rotors were too thin, or if its because this is a heavy duty van. In all my years, I've heard of brake pad shims, but I've never seen any.

Since I am replacing the rotors, calibers and pads, I'm leaning towards getting new pad clips and just reassembling without the shims. They are _very_ thin... perhaps 2 x .75mm.

Has anyone ever seen these shims used, and do you have an opinion on their reuse or omission?

[SAmadei]

Shims are usually used on brake pads to keep noise and vibration down. If you order a new set of pads they should come with new shims.

New pads and calipers have no shims... which is why I am leaning towards not using them.

Also, I can't seem to even be able to buy new ones.

Edited April 25, 2009 by SAmadei

[daves87rs]

I don't think you can anymore...

[Camino LS6]

I got a shim kit for my old Chevy dump truck, made all the difference in the world on that one.

The clanking of the pads without it was driving me nuts.

I'd get new ones and install them.

[SAmadei]

I got a shim kit for my old Chevy dump truck, made all the difference in the world on that one.

The clanking of the pads without it was driving me nuts.

I'd get new ones and install them.

Nobody had any shims, I searched pretty hard.

Against my better judgement, I was able to scrape most of the rust off, and I reinstalled them on my otherwise spotless, shiny brake parts... and used lots of antiseize, as usual.

Everything seems quiet and tight on the test drive. I just wish I didn't have a 200 round trip test drive tomorrow.

[Camino LS6]

Should be fine.

Thinking back, I believe the shims came with the brake pads when I did it.

[balthazar]

Never had shims come with pads- indeed- perhaps this is a HD thing.

BTW- I see no reason not to reuse them as you did.

[SAmadei]

Never had shims come with pads- indeed- perhaps this is a HD thing.

BTW- I see no reason not to reuse them as you did.

They were really rusty. One was somewhat see-through.

Since rust begets rust, I didn't want to plant any "rust seeds" in my shiny, expensive new parts. ;-) Of course, that silver antiseize is a pretty good rust-block, so the shim got a healthy dosing.

We'll see what happens around 250K (van has 198K) when I poke around.

Of course, my first 60 mile "test run" ended up being a fight with the thermostat.

One reason I stopped using the van, besides its horrible gas mileage (8 mpg), was that after a thermostat and water pump change, it started overheating... but _only_ at high speed on hot days.

Well, today was hot. Tomorrow, I'm taking out the thermostat... it must be screwed up. I really didn't want to start on that Pandora's box since it is going to entail removing a lot of parts eventually to get to a couple broken bolts until I got the van through inspection, but mother necessity is wacking me in the back of the head. Hopefully removing the T-stat will buy me some time.

[Camino LS6]

Never had shims come with pads- indeed- perhaps this is a HD thing.

BTW- I see no reason not to reuse them as you did.

Yup, 1 ton only as I recall.

[Daryl Z71]

They were really rusty. One was somewhat see-through.

Since rust begets rust, I didn't want to plant any "rust seeds" in my shiny, expensive new parts. ;-) Of course, that silver antiseize is a pretty good rust-block, so the shim got a healthy dosing.

We'll see what happens around 250K (van has 198K) when I poke around.

Of course, my first 60 mile "test run" ended up being a fight with the thermostat.

One reason I stopped using the van, besides its horrible gas mileage (8 mpg), was that after a thermostat and water pump change, it started overheating... but _only_ at high speed on hot days.

Well, today was hot. Tomorrow, I'm taking out the thermostat... it must be screwed up. I really didn't want to start on that Pandora's box since it is going to entail removing a lot of parts eventually to get to a couple broken bolts until I got the van through inspection, but mother necessity is wacking me in the back of the head. Hopefully removing the T-stat will buy me some time.

What T-Stat did you get? I usually get an ACDelco, seems like they are the only ones that work right out of the box the first time. How good did you bleed the air out of the system? Im guessing you did it alright, but that COULD be a problem also?

[SAmadei]

What T-Stat did you get? I usually get an ACDelco, seems like they are the only ones that work right out of the box the first time. How good did you bleed the air out of the system? Im guessing you did it alright, but that COULD be a problem also?

The T-stat and water pump were changed about 3 years ago. I think the T-stat was just an AdvancedAuto special... I never had a bum T-stat before. Anyway, before I replace the T-stat and water pump 3 years ago, the truck never overheated, in fact, it cooled so well, I had to put a piece of cardboard in front of the grill to get heat in the winter... but the water pump started to weep, so I replaced both "just in case". After having cooling trouble, I parked it.

Since then, I was using it rarely to work around the yard... without antifreeze, so I drained it every winter... so its had several burp sessions since.

In the few experiments I did try a long time ago, I noticed that the return lines from the heater core do have flow... I can see it in the radiator if its running. But I disconnected the upper radiator hose from the radiator and ran the truck for 20 minutes, and a drop never came out... so I was pretty sure the T-stat was iffy.

Honestly, I was scared I might have installed the T-stat upside down.

So, anyway, I pulled out the T-stat today, and the van ran cooler... not much, however. I did see that there was alot more flow in the radiator... I can see the water squirting out of the radiator tubes. I also removed the upper hose and ran the engine, and needless to say, alot of dirty water ended up in my driveway. What surprised me, however, is that the flow is not constant without the T-stat... so again, I wonder if something is really amiss with the pump and it caused the T-stat to not function properly.

I know how simple this cooling system is, and I'm really baffled why it still runs hot.

I managed to run up to Staten Island and back (200 miles), but I had be real careful. Luckily, I don't have to use the van for awhile... I'm going to squeak it through inspection and pull the front accessories off and go through it with a fine tooth comb... including a high quality AC Delco T-stat... but I think I'm going to get a 185.

I'll update, if anyone is interested.