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2014 Impala Front Brake Shims

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New User

Mar 4, 2017, 9:18 PM

Post #1 of 4 (680 views)
2014 Impala Front Brake Shims Sign In

I finished replacing brake pads front and rear, and front rotors on my 2014 Impala LTZ. Everything went smooth,,, but, I noted that the original brake pad shims on the front pads overlapped the brake bad to cover the caliper piston that also overlaps the pad. The new NAPA pads came with shims that fit just the back of the pad. It looked to me like the original shim was covering the excess piston over lap to keep debris out of the piston cup, so I took the new shim off of the NAPA pad and replaced it with the original shim. Do you guys think this will be OK? Should I have used the new shim and not worry about the piston overlap?

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 4, 2017, 9:22 PM

Post #2 of 4 (676 views)
Re: 2014 Impala Front Brake Shims Sign In

Yes, you should have used the new shims as they will fit better and have no wear in them. The overlap was not important and is not there to keep dirt out. It just creates a bigger contact area.

It should be fine the way it is if the shims were in decent shape.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

New User

Mar 4, 2017, 9:28 PM

Post #3 of 4 (672 views)
Re: 2014 Impala Front Brake Shims Sign In

I'm not sure more contact area matters because the piston is much larger than the back of the pad. So that part of the piston is in contact with the shim which is not in contact with the pad (picture a 3 inch diameter piston against a pad that is only 2.5 inches wide or tall.) . In any case, I think you're right about it not mattering as long as the shim was in good shape. I cleaned it up the best I could, applied a thin coat of brake caliper grease, and it seems to work ok... I was just wondering why the manufacturer of the NAPA pads didn't take this into consideration. GM obviously seemed to think it was worth overlapping the pad with the shim to cover the piston.

(This post was edited by Jamn on Mar 4, 2017, 9:32 PM)

Veteran / Moderator
nickwarner profile image

Mar 5, 2017, 2:28 AM

Post #4 of 4 (645 views)
Re: 2014 Impala Front Brake Shims Sign In

GM also thought for years it was worth selling cars with ignition switches that were garbage. Realize that since the marketing and exec people get the final say on what makes the production floor and not the engineers that not every choice is good. Likely that those shims you measured just happened to fit and they already were used on other models or something. therefore the tooling to create them was already done and cost per unit was cheap. I hope you took a file or something to clean the rust off under those shims so it doesn't cause a rust-jacking issue later. With HT on this, I personally would've installed the new shims

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