Increase in pad slaps

[bdcardinal]

Does Hunter or Coats/Ammco come out and maintain the standard lathe? When I worked at the dealership, the techs liked used the Ammco lathe more than the on-car. I’ve never seen it serviced. The techs taught me how to use it and they never had a comeback for DTV/shimmy and I’ve had smooth brakes when I turned rotors on it.

Hunter comes out, but I don't think he touches the lathe. The invoices I get from him are only for the alignment rack. That being said, its always an adventure trying to figure out the correct bits since whatever I get that matches the model number are wrong per our techs. so

 

[CKN]

This is why I have no mercy for stealers and tell people to patch something up that needs thousands in repairs and dump at their lots.

You have to be smart at new car dealers like any where else. They have trades that total hundreds of units a month. It's their job to look at them. I traded in an F150 with a questionable transmission. A dealer or a potential buyer could have looked up widespread and well known issues with a google search in seconds. (Assuming they (the dealer) didn't already know.

 

[SC Maintenance]

So what is MSRP on rotors? At least $100. So add $400 to the brake job. Yes no wonder people are passing on them.

I personally do pad slaps unless there was an issue before the brake job, or there under OEM specs. Never had a problem. Of course no salt here so that likely has a lot to do with it?

 

[toxic]

I almost always put new rotors on. Generally, they are warped before the pads are worn down enough to need changing. If they arent warped they are usually pretty rusted from all the salt Ohio loves to use.

 

[930.engineering]

The Germans want new rotors every time . . .

Maybe BMW/Mini, but VW and Audi rotors use to have enough meat
(MinTh vs new) for a second set of pads. For example 25 vs 22 mm.

That said, I was quoted >$2000 at the VW dealer for my GTI two years
ago, front and rear, rotors and pads including labour. No thanks, I'll do
it myself this year.
.

 

[930.engineering]

Done it many times over the decades. If you know what you are doing and check and measure what would be the issue?
I check the rotor runout with a dial indicator on mag base, measure rotor thickness with a micrometer if it passes I than prep the surface with brown scotch brite. Just because you buy new rotors does not mean they will not have more runout than what you took off. Without getting into metallurgy or induction hardening issues of some non OEM parts. Not all new parts are better than what you started with. Just because it is new does not automatically make it better. How many people that slap new rotors on actually check rotor runout with a dial indicator. I bet the percent is very small

I complete agree with you due to runout and measuring before
running a new set of pads, no matter if you use new rotors or the
old ones.
However, "induction hardening" is BS. Car brake rotors use gray
cast iron (commonly GG15, GG25 or GG26). You could harden steel
but no gray cast iron. No way.
.

 

[930.engineering]

I almost always put new rotors on. Generally, they are warped before the pads are worn down enough to need changing. If they arent warped they are usually pretty rusted from all the salt Ohio loves to use.

"Warped rotors" are a myth. The common problem is run-out
(mostly due to poor labour) which leds to excessive DTV. That's
what the driver notices, not due to "warping".
.

 

[E150GT]

"Warped rotors" are a myth. The common problem is run-out
(mostly due to poor labour) which leds to excessive DTV. That's
what the driver notices, not due to "warping".
.

What's DTV?

 

[4WD]

What's DTV?

Disc thickness variation

 

[rijndael]

Disc Thickness Variation

 

[930.engineering]

https://www.bendix.com.au/news-events/disc-thickness-variation-dtv-issue-14
https://www.powerstop.com/resources/pulsing-vibrating-brake-pedal-dtv/
https://www.sae.org/publications/technical-papers/content/2019-01-2110/

 

[CharBaby]

Typically, I have to change rotors as well as the pads here in WNY State(salt belt) just due to the rotors rusting/pitting so badly between brake jobs that it only makes sense to do so.

 

[D60]

If I a shop owner, I'd push them because I think a fresh rotor surface increases the chance of a happy customer.

You eliminate things like rust ridges rubbing a new pad (with a slightly different dimension) creating a comeback for excessive noise.

100% this. The average uneducated customer likes to believe it's greed, but shops don't want comebacks.

That said, I'm happy to pad slap if a customer cries broke but I do caveat my work by saying I can't make any promises and can't stand behind it in the unlikely event noise is present or braking performance is poor.

OTOH if I do a "full kit" and the brakes have some issue I'll bend over backwards to make it right/replace/redo at no cost.

I hate fear mongering and will tell them a pad slap is probably fine but no guarantees.

 

[nthach]

I complete agree with you due to runout and measuring before
running a new set of pads, no matter if you use new rotors or the
old ones.
However, "induction hardening" is BS. Car brake rotors use gray
cast iron (commonly GG15, GG25 or GG26). You could harden steel
but no gray cast iron. No way.
.

GM has entered the chat

https://www.heattreattoday.com/heat-treat-radio-117-how-gm-started-grew-fnc-for-brake-rotors/

 

[AutoMechanic]

I can’t think of the last time I did a pad slap on a customer car it’s been a long time. I do hate machining rotors though so if at all possible I will sell rotors but only if they are extremely bad because we also don’t keep rotors in stock except a few for certain models.

 

[Jetronic]

Once again I'm reminded of what I once heard a European automotive engineer say:

"The difference between European drivers and American drivers is:
European drivers don't care if the brakes squeal- just as long as they stop the car.
American drivers don't care if the brakes stop the car- just as long as they don't squeal."

except squealng brakes are extremely uncommon in Europe.

 

[2strokeNorthstar]

Anyone else notice an increase in people wanting to just pad slap cars? Average RO is up but when it comes to brakes people are cheapening out

Honestly for the rears on some of the newer stuff has been fine - newer Audi, BMW, Mini, especially when the cars are sub 50k miles

Everyone wants to save money when they don't have a lot of it. Now is one of those times for many.

 

[Hirev]

I complete agree with you due to runout and measuring before
running a new set of pads, no matter if you use new rotors or the
old ones.
However, "induction hardening" is BS. Car brake rotors use gray
cast iron (commonly GG15, GG25 or GG26). You could harden steel
but no gray cast iron. No way.

Cast iron is used sometimes in machine tools for its stability. Years ago we got a new B axis with a cast iron table for one of our CNC boring mills it was not up to the task of doing setups 1 - 2 times a shift. It was a much softer table than the B axis setup we took off the boring mill. We sent it back to company that made it to fix. Somehow when they made it they said it did not get induction hardened in the process. I assume it was a case hardened deal kind of like some cast iron camshafts.

Heat treatment of gray irons.

https://www.totalmateria.com/en-us/articles/heat-treating-of-gray-irons-2/

 

[JWC86]

IMO there is a difference between “pad slap” and not replacing the rotor.

A pad slap is installing new pads and clips and not checking anything else, lubing slide pins, etc. Hence the name “pad slap”.

As opposed to removing and cleaning the brackets, disassemble and clean slide pins, clean brackets, measure for runout and DTV, etc.

Myself I reuse the rotors if they check out but for a shop it makes more sense to just install a cheap new rotor rather than pay for a tech to do fiddly measurement work they probably don’t want to do so I get it and I would do the same if I was in charge of a shop, push for a new rotor sale.

 

[Andyd95]

IMO there is a difference between “pad slap” and not replacing the rotor.

A pad slap is installing new pads and clips and not checking anything else, lubing slide pins, etc. Hence the name “pad slap”.

As opposed to removing and cleaning the brackets, disassemble and clean slide pins, clean brackets, measure for runout and DTV, etc.

Myself I reuse the rotors if they check out but for a shop it makes more sense to just install a cheap new rotor rather than pay for a tech to do fiddly measurement work they probably don’t want to do so I get it and I would do the same if I was in charge of a shop, push for a new rotor sale.

if you are asking for a pad slap we are doing all but measuring runout and thickness variance. We will make sure it didn’t pulse before and then drive it again to bed them in. But yes it is so much easier as a shop to sell rotors.