Im a tech who does occasional brake jobs now and ill be havine a hell of a lot more in the future. Id like a caliper to be able to check rotor thickness so that in the future I can possible start to machine them or just recommend them with more solid reasoning than "theyre rusted and scored and old looking". Pretty partial to mitutoyo and id like it to be a buy once cry once deal but the prices look insane on these. ~650 bucks for a necked one with pointed tips sound reasonable? Alternatives? Oil and dust resistance is a plus but id like you guys opinions and if theres another route please say.
Caliper for checking brakes as a tech
- Thread starter joman767
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For something like measuring rotors I wouldn't really care to use a mitutoyo or starrett or other expensive caliper. Honestly a $20-30 one will do just fine for the tolerances you're dealing with. You could also use a micrometer in that application, given it will deal with getting over the lip and rotors are typically less than an inch thick.
I think I spent $100 on mine. I don't think you need anything that high end for rotors and micrometers are more accurate if that's what you're looking for. If the rotors are close to the machine to limit or discard, just replace the rotor. If I've got less than .030" over discard, I won't machine
I'm not a big fan of machining rotors, after machining they are thinner and more likely to warp and they don't always feel as good as new rotors.
I'm not a big fan of machining rotors, after machining they are thinner and more likely to warp and they don't always feel as good as new rotors.
driftpin
Well-known member
I bet this would work well for your application: cheap, accurate-enough for your intended use, durable-enough with a bit of care. If you're really going to be using this that-much, I think I'd buy two at this price. What I like about it is that you set it on the rotor surface, get the thickness, take the reading, and you immediately know if it falls within spec or-not.
https://www.rockler.com/igaging-8-digital-outside-caliper
https://www.rockler.com/igaging-8-digital-outside-caliper
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Bogie1632
Well-known member
What ever you buy, make sure they aren't parallel flat jaws. They need tips on the end to reach past any lip worn in on the rotor. But usually if there's a lip the rotors is pretty much shot at that point.
I used a Fowler that I got at Autozone but it got smashed when I loaned it to a friend. Not sure why I do that...
https://www.autozone.com/clamps-and...h-rotocal-with-twin-conical-anvils/186492_0_0
V/R
Bogie
I used a Fowler that I got at Autozone but it got smashed when I loaned it to a friend. Not sure why I do that...
https://www.autozone.com/clamps-and...h-rotocal-with-twin-conical-anvils/186492_0_0
V/R
Bogie
I agree not worth a mitutoyo or starrett. I like Iguauge for my cheap measuring tools. I have quite a few. While the caliper feel cheap, they have tested out as accurate or better then my Mitutoyos on the standards I have. The DRO scales I have are almost 8 years old and still going strong.
https://www.igagingstore.com/Digital-Brake-Rotor-Gauge-Disc-Gage-Caliper-Microm-p/203944.htm
https://www.igagingstore.com/Digital-Brake-Rotor-Gauge-Disc-Gage-Caliper-Microm-p/203944.htm
Rabid Badger
Well-known member
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I'd skip digital:
https://www.amazon.com/60mm-Vernier-Brake-Disc-Caliper/dp/B00NI1N3S4
Or if you want to get fancy:
https://www.misterworker.com/en-us/facom/disc-brake-vernier-caliper-df18-01/6424.html
https://www.amazon.com/60mm-Vernier-Brake-Disc-Caliper/dp/B00NI1N3S4
Or if you want to get fancy:
https://www.misterworker.com/en-us/facom/disc-brake-vernier-caliper-df18-01/6424.html
Amazon has plenty for $30 and up.
https://www.amazon.com/s?k=digital+rotor+gauge&i=automotive&ref=nb_sb_noss_1
https://www.amazon.com/s?k=digital+rotor+gauge&i=automotive&ref=nb_sb_noss_1
2ndGearRubber
Well-known member
Buy a basic set of digital ones via amazon with pointed tips for measuring scores in the surface. Digital also let's you convert between sae and metric with the touch of a button.
Chevy-SS
Well-known member
I've been doing brake jobs for ~50 years now. In the old days, we turned drums and rotors continually. We even went so far as to re-contour the brake shoes (on drum brakes) to match the new inner diameter of the machined drums.
Anyway, my $.02 is this - if the rotor looks questionable at all, just buy a brand new one, don't even bother measuring. I am all done with machining rotors (or drums), sold off that machine many years ago. Brand new rotors/drums are inexpensive, and machining old rotors/drums often (almost always actually) leads to problems.
On the rare occasions when a rotor looks good enough to re-use, I will sand off the edges with a orbital sander, and then measure with one of my many measuring calipers just to be sure there is min thickness.
The only time you REALLY should be measuring is for checking rotor runout, and for that you need a dial caliper (arghh, DIAL INDICATOR). Mount the new rotor onto vehicle with lug nuts (if necessary), then position dial indicator so you can read runout as you rotate rotor by hand. I like max of .003" runout, but I try to get as close to zero as possible..........
Bottom line: use new rotors 99% of the time.
Good luck!!
Anyway, my $.02 is this - if the rotor looks questionable at all, just buy a brand new one, don't even bother measuring. I am all done with machining rotors (or drums), sold off that machine many years ago. Brand new rotors/drums are inexpensive, and machining old rotors/drums often (almost always actually) leads to problems.
On the rare occasions when a rotor looks good enough to re-use, I will sand off the edges with a orbital sander, and then measure with one of my many measuring calipers just to be sure there is min thickness.
The only time you REALLY should be measuring is for checking rotor runout, and for that you need a dial caliper (arghh, DIAL INDICATOR). Mount the new rotor onto vehicle with lug nuts (if necessary), then position dial indicator so you can read runout as you rotate rotor by hand. I like max of .003" runout, but I try to get as close to zero as possible..........
Bottom line: use new rotors 99% of the time.
Good luck!!
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davethorik
Well-known member
Fixed that for you. It is a good idea though.
wolf_from_wv
Well-known member
Dial indicator?
bob15
Well-known member
Either that or a drop gauge. Definitely not a dial caliper.
to check for warped rotors
I don't have one, I try to test drive the car first if possible, If there's a brake pulsation? new rotors it is
bob15
Well-known member
Wolf was responding/correcting the previous post who mentioned using dial calipers for checking rotor warpage instead of a drop gauge or a dial indicator.
Chevy-SS
Well-known member
LOL, thanks... brain fart......................
I actually DO have the tool.
In this pic, the rotor is pressed onto the hub, so lug nuts not needed to check runout.
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sberry
Banned
Worn, rusted, scored some, delaminated, cracked, there is another word I am looking for but all reasons to toss them. For brake parts I like to find a good local store, get the white box they carry and its nice when its all in stock. Brake parts are relatively competitive local as internet.
Lassen Forge
Well-known member
Brake disk width caliper? I'd rather mess up an el producto chinesium HF than a multi-hundred Mitutoyo. You're not measuring a mirror for a telescope, you're checking whether your disk is out of tolerance or not... Same with pads, they make (for cheap) a set of plastic comparison gauges (that're even color coded red, yellow, and green) for the pads or shoes.
For a dial indicator to check for warpage, it's kind of the same thing - unless you're working on high $$$ ceramic brakes, what you're looking for is deviation in the .001 range, not the .00001 range... (If you're working on Konigseggs or Lamborghinis, well, you wouldn't be here asking!)
BTW - If I have to replace components, I'll usually recommend better than **** components to customers, unless it's a beater they're using as a farm truck, a 300K mile commute bucket, or a "I'm broke and need to get it on the road" situation. The question I ask is "if it were my (or my kid's or spouses) car, what would I put on it?"
Now, if it were my exes car... I think they'll be fine, just ignore the noise, that's normal, those are "cooling fins"...
(As in you run these very long, your body will be cooling to room temp shortly)
For a dial indicator to check for warpage, it's kind of the same thing - unless you're working on high $$$ ceramic brakes, what you're looking for is deviation in the .001 range, not the .00001 range... (If you're working on Konigseggs or Lamborghinis, well, you wouldn't be here asking!)
BTW - If I have to replace components, I'll usually recommend better than **** components to customers, unless it's a beater they're using as a farm truck, a 300K mile commute bucket, or a "I'm broke and need to get it on the road" situation. The question I ask is "if it were my (or my kid's or spouses) car, what would I put on it?"
Now, if it were my exes car... I think they'll be fine, just ignore the noise, that's normal, those are "cooling fins"...
(As in you run these very long, your body will be cooling to room temp shortly)
richfinn
Well-known member
We had to measure brake rotor thickness for lease companies when I was at the dealership
I just used a micrometer, cheap enough fairly robust
I just used a micrometer, cheap enough fairly robust
sberry
Banned
Sometimes its too much work to make it cheaper, way more easier money in branding, just cause it cost more doesn't always mean its better. There are some products so uber cheap they cant make it for that, the 9.99 hf grinder is one but you can get a pretty good one for 30$. Good parts stores are willing to pay a dollar or 2 more for the better one if they don't have comebacks. Makes 5 bucks difference in the sales price not 50 to fo the same work.
Just like some tools,,,, could double the cost of production to a Stanley wrench and it wouldn't need to add a whole lot to the sale price.
Lots of places are best cheapest. Stanley adds some QC to the product for Walmarts and in turn Wally doesn't have to be a return center for busted sockets every day. The cost is another dollar, they raise the price 5, lose a couple sales, make a little more on the ones they do make and keep customers.
I was in one recent and they had a lot of CH stuff for air, quite a little stuff and some nice 3/8 regulators really ideal and priced right for that crowd. I wouldn't have a problem using as replacement if I needed it now.
That Centric is sposed to do that with brakes but I think they may have just been another step to batter the mfgs down in pricing another level. You can cheapen some stuff if you buy enough.
Just like some tools,,,, could double the cost of production to a Stanley wrench and it wouldn't need to add a whole lot to the sale price.
Lots of places are best cheapest. Stanley adds some QC to the product for Walmarts and in turn Wally doesn't have to be a return center for busted sockets every day. The cost is another dollar, they raise the price 5, lose a couple sales, make a little more on the ones they do make and keep customers.
I was in one recent and they had a lot of CH stuff for air, quite a little stuff and some nice 3/8 regulators really ideal and priced right for that crowd. I wouldn't have a problem using as replacement if I needed it now.
That Centric is sposed to do that with brakes but I think they may have just been another step to batter the mfgs down in pricing another level. You can cheapen some stuff if you buy enough.
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I'm a buy once and cry once type of person as well, but...for this application, I wouldn't buy or use a high dollar precision tool used by machinists. I would use a $20 digital micrometer to measure out the rotor. You don't need a lot of precision for this task. If you ding up the measuring faces, you're not going to cry about it, you'll keep using it or replace if it's needed. I will second the iGaging if they offer something, reasonable quality for not a big price, but I wouldn't shy away from Harbor Freight for this application either (and I don't exactly love Harbor Freight).
sweetk30
Well-known member
check the specs . lots of them anymore have no real spec for cutting . there good or discard . plus the price of new most of the time is so cheep compared to the labor time to cut and hope you get it setup and cut right its not worth it .
i use to cut a LOT of drums and rotors back in my day on the BIG blue amco brace lathe .
i use to cut a LOT of drums and rotors back in my day on the BIG blue amco brace lathe .
I have tested the HF Pittsburgh caliper vs our certified gauge blocks and certified Mitutoyo calipers (they are cal'd annually by a third party along with a bunch of other equipment). The HF read within .001" of each of them.
Don't waste your money on a Mitutoyo for this application.
Don't waste your money on a Mitutoyo for this application.
atnfromatl
Well-known member
I've been doing brake jobs for ~50 years now. In the old days, we turned drums and rotors continually. We even went so far as to re-contour the brake shoes (on drum brakes) to match the new inner diameter of the machined drums.
Anyway, my $.02 is this - if the rotor looks questionable at all, just buy a brand new one, don't even bother measuring. I am all done with machining rotors (or drums), sold off that machine many years ago. Brand new rotors/drums are inexpensive, and machining old rotors/drums often (almost always actually) leads to problems.
On the rare occasions when a rotor looks good enough to re-use, I will sand off the edges with a orbital sander, and then measure with one of my many measuring calipers just to be sure there is min thickness.
The only time you REALLY should be measuring is for checking rotor runout, and for that you need a dial caliper (arghh, DIAL INDICATOR). Mount the new rotor onto vehicle with lug nuts (if necessary), then position dial indicator so you can read runout as you rotate rotor by hand. I like max of .003" runout, but I try to get as close to zero as possible..........
Bottom line: use new rotors 99% of the time.
Good luck!!
Completely agree with this. It's more profitable and efficient and better for the customer as well. You can get a pair of rotors off Rock Auto for about $60.
Mr. T
Well-known member
I also use a micrometer for this job. I use my nice Starretts but then again I’m only ever measuring my own brakes. So no real worry about repeated abuse in a harsh environment.
That being said, 0-1” and 1-2” Starrett mics aren’t a whole lot of money on the used market. I also am a fan of Mitutoyo.
That being said, 0-1” and 1-2” Starrett mics aren’t a whole lot of money on the used market. I also am a fan of Mitutoyo.
visionguru
Well-known member
The following is more than enough.
https://www.harborfreight.com/6-in-long-reach-digital-caliper-63714.html
While it's understandable to spend big bucks on a tool for critical applications, spending $600 for measuring a rusty/dusty rotor (often cheap to buy new) is a total waste.
I use this to measure rotor thickness. It's more than 10 years old from Harbor Freight. Find two flat objects, stack them together and measure with the caliper, hit "zero" button, then place the objects on each side of the rotor, the read out is the rotor thickness. I use coins, but for a professional, two megnets might be better.
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rlitman
Well-known member
I've found that most rotors I have can be measured directly with these sort of standard 6" calipers. I like the digital sort for rotors, because of the easy metric conversion.
The relief at the back of the blades is usually sufficient to clear any rusty ridge at the edge to give a good measurement of the thickness at the friction surface.
I've resorted to a metric micrometer when that ridge was too much, but that hasn't happened many times.
If I were a tech, I'd do the unthinkable, and take a grinder to the inside of a pair of digital caliper jaws (or maybe to a step further and weld on tip extensions) to give more of a relief near the base. I'd rather do that, and spend $10 on such a dedicated tool than waste several times that on an inferior dedicated tool. In fact, now that I think of it...
davethorik
Well-known member
Most machinists don't know how to accurately read verniers, I doubt a non-experienced shade tree will. HF long reach digital were made for this.
rlitman
Well-known member
I own several nice verniers. I'm not using them on rotors. The HF long reach digital looks like a good choice. I admit, I haven't seen those before you just got me to look. The only thing they're missing is an inside measurement for drums.
tomalophicon
Well-known member
I picked up a used Mitutoyo 0-25mm micrometer for $25 recently. That will be more than satisfactory for the job at hand. Beats mucking around with coins or washers as above poster recommends.
ChevyEFI
Well-known member
I have a feeling the fold out leaves for pad thickness check will save you time in weeding out the vehicles that even warrant your time inspecting rotor thickness.
That, plus removing the inside measuring blades, and you'll be able to measure most any rotor.
Rabid Badger
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- Apr 2, 2018
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Even if that was true, it takes all of about a minute to learn. They aren't complicated.
visionguru
Well-known member
Digital is many times easier to use. Even a digital caliper with straight arms, you can stuff anything between the arms, hit "zero" button, then whatever measured is the added distance. With a non-digital caliper, a calculator might be needed, plus good eyesight too.
T VETTE
Well-known member
The following is more than enough.
https://www.harborfreight.com/6-in-long-reach-digital-caliper-63714.html
While it's understandable to spend big bucks on a tool for critical applications, spending $600 for measuring a rusty/dusty rotor (often cheap to buy new) is a total waste.
I use this to measure rotor thickness. It's more than 10 years old from Harbor Freight. Find two flat objects, stack them together and measure with the caliper, hit "zero" button, then place the objects on each side of the rotor, the read out is the rotor thickness. I use coins, but for a professional, two megnets might be better.
I agree 100% on that! I own a small shop and we really only turn rotors that are vented, all others are tossed. Also, I just sold our old drum lathe the other day. Taking up space and never used anymore.
davethorik
Well-known member
Youre totally right, that's why all shops have verniers hanging on the wall for measuring brakes
WittHay
Well-known member
Central, ATD and Fowler are some brands that are digital and reasonable priced. The Fowler's have double points. The others are 1 point and 1 flat tip.
They are called digital or electronic rotor gauges
They are called digital or electronic rotor gauges
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sberry
Banned
I havnt measured a rotor for 40 years, a guy can look at them and see if they are fit for service, same for pads.
jg4660
Well-known member
^^^This^^^^.
sberry
Banned
One of the biggest benefits to buying a tool is to learn to estimate and get a feel. A cardboard in a matchbook is maybe 015 or so, a sheet of paper 003, most points at 018, old spark plugs 035 , 1/16 065 and 1/8 .125 5/16 grade 5 at 25 and 3/8 at 35#, So much of this was used in routine engine work,,,, now that engines outlast the cars its not done and guys don't get the feel for all this.