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Help With Brakes! Need new Rotors, What SIZE!

66K views 54 replies 18 participants last post by  Richardar6 
#1 ·
Holy cow have I had a hard time just trying to buy the right parts.

I have a 2012 Overland 4x4 Hemi. So Quadralift and such is all on it. The build says HD brake package. Not a single website that I have found will lead me to a definitive size of the rotors. I have 90k on the clock so I will just change out all of them front and rear and new pads.

What size rotors go on my truck!
 
#2 ·
If you want Mopar rotors, but want to buy online rather than local dealer parts, try Factory Mopar Parts - Wholesale Mopar Catalog. You can get close by inputting your year, make, model, trim level, engine, but then you can enter your VIN and get really close.

If you are buying aftermarket, and they can't tell you exactly what you have from your make/model/trim/engine/drivetrain, go to another store.
 
#18 ·
The HD brakes use 350 mm front rotors and 330mm Vented rears
The standard duty brakes use 330 front and 330 Solid rears. So if your rear rotors are vented then you definitely have HD brakes, solid rotors definitely SD.
The normal front brakes are 330mm diameter with solid rear rotors.
The HD brakes are 350mm diameter with vented rear rotors.

Front brake pads/calipers are the same no matter which rotor.

68035012AB [2 required]
front brakes, rotor Grand Cherokee w/Heavy Duty Brakes

I can provide rear OEM part numbers also.
Seems like the best advice is too look at your rear discs, if they are solid, you have a SD brakes, thus the 330mm front discs. If the rear discs are vented, then you have HD braks, thus the 350mm front discs.
Need help with size of grand cherokee rotor 2011
Ummm, what kind of help do you need? Cause its been repeated ad-nauseam how to identify what brakes you have and what size/kind of rotors you need to replace them.
 
#6 · (Edited)
For the first generation WK2 there are only 2 brake packages.
Normal and HD.
The V6 models only come with the 'normal' brakes, even with the tow package. I'm not sure if the V8 came with the 'normal' brakes or just the HD brake package.

The normal front brakes are 330mm diameter with solid rear rotors.
The HD brakes are 350mm diameter with vented rear rotors.

Front brake pads/calipers are the same no matter which rotor.

68035012AB [2 required]
front brakes, rotor Grand Cherokee w/Heavy Duty Brakes

I can provide rear OEM part numbers also.

I have a V6 and intend to upgrade to the HD brakes when mine are worn out. All I will need is the new caliper mounts, the 350mm discs and of course new pads (I won't even need to disconnect brake hoses!).

I intend to go with Frozen Rotors discs, they are located just south of me in Burnsville, MN so I will pay taxes, but no shipping.

High Performance Brake Pads and Brake Rotors - Frozen Rotors
 
#9 ·
So i just got a powerstop 1 click brake kit thru auto zone for my 2014 limited ecodiesel (pn k5952). This kit included front 330mm rotors and solid 330mm rear rotors and pads. After comparing and measuring I confirmed that i need 350mm fronts along with vented 330mm rears. I spoke to a customer rep at powerstop and she gave me the part numbers i need.

Front rotors pn:AR83078xpr (xpr denotes a pair of rotors)
front pads pn:17-1629
rear brake kit (pads and rotors) pn:k5953

right now I am looking into finding a site where i can order these parts using the part number and not the "enter your year/make/model/engine" method that most car part sites use, since that got me the wrong kit in the first place.
 
#10 · (Edited)
The "Frozen Rotors" site that I posted above does a great job of telling you what brake rotor sizes are available, they even note the larger SRT rotors.

They offer Hawk brake pads which are a good product.
EBC is another good product name for brake pads.
EBC Brakes - Brakes for Cars, Motorcycles, Trucks and SUV
And a lot of local auto parts stores carry EBC.

Except for the SRT, the front and rear pads are the same part number no matter which brake package you have. So if you are only looking for new pads, it doesn't matter which brake package you have (HD or standard).

Except for the SRT...
Front rotors are either 330mm or 350mm disc.
Rear rotors are either 330mm solid or 330mm vented discs.

The rear vented discs use a different caliper (to allow for the wider width of the vented disc).

The front discs use the exact same caliper with different mounting brackets depending on your disc size.

More important notes:
If you are ONLY changing pads and rotors (or just pads) you should NOT need to bleed the brakes.
Remove the calipers and then use a C clamp to push the piston back into the caliper (slowly!) with the brake reservoir cap off (to allow for the fluid to push back into the reservoir).
If you are not actually holding the caliper after removing it from the mounting make sure you hang it from something! I usually use an old coat hanger and hang it off the coil spring. DO NOT let the caliper hang from the hydraulic hose as you will damage the hose.
If you pads are worn, you may not need new discs (unless they are damaged). Depending on the pads, some discs will last for 2 sets of pads. I don't have the specs handy for minimum rotor thickness. Most people just replace the discs with the pads to be safe, but if you are on a tight budget perform a Google search to find the minimum safe disc thickness spec.
 
#11 ·
If you are ONLY changing pads and rotors (or just pads) you should NOT need to bleed the brakes.
Remove the calipers and then use a C clamp to push the piston back into the caliper (slowly!) with the brake reservoir cap off (to allow for the fluid to push back into the reservoir).

I usually prefer to open the bleeder and push the ugly fluid from the caliper into a can rather than back up into the system..
 
#14 · (Edited)
So I looked through the Part Catalogue for the WK2 and this is what I found.

It appears there were 3 different brake packages.

One is HD, with the 350mm front rotors and 330mm rear rotors that are vented.
One is SD, except 17" wheels.
One is SD, for 17" wheels.

I have a 70th anniversay Laredo, it has a Hemi and QTII, but standard duty brakes. So I don't think having a Hemi means you have HD.

Seems like the best advice is too look at your rear discs, if they are solid, you have a SD brakes, thus the 330mm front discs. If the rear discs are vented, then you have HD braks, thus the 350mm front discs.

How do the same pads fit a 20mm bigger rotor? Easy, comparing photos of both rotors, you can tell the swept are for the pads are the same width, its just the 350mm rotor the swept area is moved out farther from center. Thus they just increase the torque arm of the existing brake pads for more brake power.

There are different part numbers for the calipers and brackets/adapters for the caliper that the pads ride in, for the different combinations of the 3 brake packages.

The rear rotors, the HD vented rear rotor is thicker and thus will need a wider caliper and probably a different bracket/adapter to position the caliper on the rotor.

The front rotors, the HD rotor that is larger in diameter would need the bracket/adapter to position the caliper further out from the center.

And likely the SD package for 17" wheels needs a different caliper or bracket/adapter to keep the whole brake package within the size of the smaller wheel.

Finally, the master cylinders and ABS module has one part number for all three brake packages, so I'm assumming the hydraulics and electronics are all the same for the 3 different brake packages.

So converting SD brakes to HD brakes might be practical if you wanted to do so. i.e. it wouldn't require a replacement of the entire brake system, like many brake packages are, an entirely different system. It would be more difficult than just getting the rotors, you'll also need the adapter/bracket and calipers that go with the package. But you can get rebuilts fairly cheap and turn in the old for cores, maybe get the brackets/adapters from a junkyard.

And clearly, if you have 17" wheels, you are stuck with the SD package for 17" wheels, you'd have to get bigger wheels to upgrade to the HD package.
 
#22 · (Edited)
I have decided that I would just go the stock 330mm rotor route and I found that Hawk Rotors and pads were the best bang for the buck.

Here are the links I used to get the best deal. The seller on ebay only has a few sets of the now discontinued Hawk Quiet Slot rotors left and I offered him $85 each and he took it. He has them listed as REAR rotors but I checked the part number with Hawk and Summit directly and they are FRONT rotors. Summit still has one in stock for $113.91.

https://www.ebay.com/itm/282020389291

https://www.summitracing.com/parts/hwk-hus505

and the best price I found on the pads was $97.93 on Summit Racing but I had to buy a stupid $2.00 sticker to get the $99 and up free shipping...

https://www.summitracing.com/parts/HWK-HB701Y-723


Directly from Hawk website :

http://www.hawkperformance.com/performance-street/pads/hb701y723


Hope this helps.
 
#45 ·
I have decided that I would just go the stock 330mm rotor route and I found that Hawk Rotors and pads were the best bang for the buck.

Here are the links I used to get the best deal. The seller on ebay only has a few sets of the now discontinued Hawk Quiet Slot rotors left and I offered him $85 each and he took it. He has them listed as REAR rotors but I checked the part number with Hawk and Summit directly and they are FRONT rotors. Summit still has one in stock for $113.91.

https://www.ebay.com/itm/282020389291

https://www.summitracing.com/parts/hwk-hus505

and the best price I found on the pads was $97.93 on Summit Racing but I had to buy a stupid $2.00 sticker to get the $99 and up free shipping...

https://www.summitracing.com/parts/HWK-HB701Y-723


Directly from Hawk website :

HB701Y.723 | Hawk Performance


Hope this helps.

Just to give an update on the rotors, I came to realize they are listed CORRECTLY on Ebay so the HUS-505 are in fact the REAR rotors and the front rotors are part number HUS-504.

The ebay seller also has 8 of the FRONT HUS-504 rotors available for a Buy it Now best offer of $110.00 each free shipping.

https://www.ebay.com/itm/Disc-Brake-Rotor-Quiet-Slot-Rotor-TM-Front-Hawk-Perf-HUS504/272226876794

Last thing would be the Hawk LTS REAR brake pads that are also available on Summit Racing for $80.39.

https://www.summitracing.com/parts/hwk-hb702y-662

or Ebay but only 2 sets left.

https://www.ebay.com/itm/263696985983
 
#27 ·
This is another excellent article about brakes and braking power. The whole concept of braking is not guess work its science that starts with the actual composition of the metal your rotor is made out of.

Cheap Auto Zone $40.00 rotors = junk metal, poor braking and short service life.

$140.00 Hawk, EBC etc rotors - Quality engineered, correct metallurgic composition for maximum heat transfer and grip and long service life.


Brake System and Upgrade Selection


CRITICAL!!!

3) Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed - whether racing, touring or towing.


Something people don't realize is that drilled AND slotted rotors actually remove surface area and the holes can actually promote cracking under very hard braking conditions like autocross. For a daily driver I decided to just go with the slotted not drilled.
 
#30 ·
Something people don't realize is that drilled AND slotted rotors actually remove surface area and the holes can actually promote cracking under very hard braking conditions like autocross. For a daily driver I decided to just go with the slotted not drilled.
It depends on the cars and the brakes and what type of "Racing" you're doing. While it might be possible some cars on the street might benefit from additional cooling from holes or venting outgassing from pads with slots. The overwhelming majority of vehicles for even the most spirited driving will see absolutely no benefit from drilled and/or slotted rotors.

Most of the Porsche race teams when they get a new Porsche remove the drilled and slotted rotors and replace them with normal vented rotors, because they perform better.

Most cars on the street, the rotors sink heat, more mass in the rotor increases performance, they do not cool fast enough, for drilling and slots to improve performance, in fact drilling and slotting removes mass, and thus prevents them from sinking heat.

Cheap Slotted and/or Drilled rotors just take cheap regular rotors and drills holes and cut slots in them. This removes mass and strength from the rotor and creates stress risers. That causes them to crack, as well as perform worse and wear away pads faster.

Good Slotted and/or Drilled rotors, are designed from the start with holes and slots, adding mass to make up for the missing mass, cast the rotor with the holes and slots in it, and machined properly.

But the holes and slots shave the pads and wear them faster, cheap discs will have sharp edges that shave them even faster but, even the best discs that campher the holes and slot edges, won't shave as much, its still going to shave some. So your really getting nothing, but faster pad wear in most cases on the street with drilled and slotted rotors.
 
#28 ·
A handy tip is to NOT keep your foot on the brakes at a set of traffic lights after a long downhill or even a high speed run where you've really heated up your brakes.

If you can safely do so, better to put it into Park with your foot OFF the brakes, then into Drive and pull away when the light changes. We tow a lot and try to do that whenever our brakes get heavily applied.
 
#33 · (Edited)
phillybtx perfectly describes how rotors can get pinched, overheat the rotor so the metal has some plasticity, then when they are stationary, then if you stand on the brake as hard as possible, pressure from the pads will pinch the rotor in that spot, and your lateral runout will certainly vary over the surface of the disc. What do you say to a customer when they want to know how the rotor's lateral runout changed?

Ok first things first... I think if you are one of the millions of mechanics out there you have a better chance of getting hitting the lottery 3 times in the same store than you would ever have of getting a customer come walking in the door asking that question. Unless it was you or me that is so just wait until you buy your lottery ticket first before you do it ;)


I'm not really sure why anyone would ever do what you are describing here although I can understand what you are saying. Say your going down a very long steep hill towing a heavy trailer. So your on the brakes hard and you get to the stop at the bottom and your still standing on the brakes instead of just enough to hold you at a stop. I mean maybe the long downhill descent got you all puckered up down there and you just can't release the brake pedal I don't know but yes that could do it.

I recently talked with tech support at Hawk and I asked a similar question about rotors and how extreme heat affects the metal especially the Cryo treated rotors. He explained something like the cold (-320F) that is used somewhat alters the structural makeup of the metal which makes the metal much stronger and more durable. It's all explained at the link below way better than I can ever explain it if you care to read it.

https://www.thefabricator.com/artic...nic-processingadispelling-the-myths-mysteries

So what happens when you REALLY ride the brake hard is there is a lot of heat generated and like you said if you squeeze that metal VERY tightly in that spot and hold it there until it cools then yes it only makes sense that it will compress the metal and leave a low spot or indentation in the surface of the rotor. It's basically undoing the hardening process but I was told this only happens in extreme conditions where the rotor would exceed whatever temperature limit that particular rotor can take. Not all rotors are made from the same metals so they are all different in heat dissipating characteristics.

https://ebcbrakes.com/articles/the-truth-about-high-performance-brakes/


I also found this on EBC website.


https://ebcbrakes.com/articles/brake-vibration-common-questions-answered/


Brake Vibration: Common Questions Answered

What is Brake Vibration?

Brake vibration is where a shaking motion occurs when the brakes in a car or other vehicle are deployed. This can vary from a slight shaking to a quite severe shuddering, depending on the severity of the condition. It can also be known as rotor shimmying or brake pulsation.

What causes it?

If the brake rotors installed on the vehicle have more than .05mm of run out (where the brake rotor moves from side to side more than a minimal amount of .05mm), then brake vibration will occur through the steering. Usually, this is due to one of two different reasons. The face of the disc may have some rust or dirt on it, which is causing the run out figure to be incorrect. Such build up may occur during the lifetime of the rotor, and this can cause the run out to be up to five times the limit installed by the factory. If the problem is not due to this, it may be that a ‘thin spot’ has occurred on the rotor (where there has been intermittent pad contact instead of a constant motion). When the brake pedal is pressed this causes the brake vibration to occur. This is technically known as Disc Thickness Variation, or DTV for short.

As it is essential that your brakes run true, this must be sorted out as quickly as possible.

I'm not really sure what else to say about "run out" but that's what it's called.
 
#35 ·
I've already explained in detail and posted enough links for anyone who is interested to go ahead and read. If you insist on confusing such a simple issue and never posting any references whatsoever to back up what your saying I'm going to just leave it here. You can do, say and believe whatever you like I'm just relaying information to the group that is common knowledge to people in the industry.

As far as this post goes the topic was Help With Brakes! Need new Rotors, What SIZE! If you have anything more to add that actually pertains to the topic of this post like the part numbers on the brackets that I asked Todd3.6 for that would be very helpful.
 
#38 ·
As far as this post goes the topic was Help With Brakes! Need new Rotors, What SIZE! If you have anything more to add that actually pertains to the topic of this post like the part numbers on the brackets that I asked Todd3.6 for that would be very helpful.
Here is a link to my How To for upgrading to HD brakes; you could have found it easily using the Search Function.

https://jeepgarage.org/f109/how-to-upgrading-from-sd-to-hd-brakes-201178.html

The part numbers and source you can get them for just $20 is in there.

As far as rotor sizes, that was answered ad-nausem 4 or 5 times over, by me and others, within the first 2 pages of this thread.
 
#37 ·
Well when someone behind you fades their brakes to nothing because they rode them the whole way down the side of a mountain, you might think differently. I knew someone that lost their grandfather, because they were rear-ended at high speed in a traffic jam at the bottom of the mountain, the vehicle had lost all brakes from overheating them riding them the entire way down the mountain. Of course the grandfather was the only one in the vehicle not wearing a safety belt, everyone else was uninjured in the vehicle.
 
#40 ·
I'm seriously not denying any of this, I live in Jersey and drive I-295 (suicide hwy) regularly. I firmly believe most people are scared to be behind the wheel of their vehicle and a lot more who could just care less about anyone else on the road. The great majority of these people have no clue about their vehicle as you said and I would like to say except for driving it but that's not even the case here. I also believe as long as the car starts, drives and stops they couldn't care less about it. When it stops running or starts making a noise then they care BUT only if the noise gets too annoying.
 
#44 · (Edited)
Raptor, my apologies, I did think it was BPA that posted the study not you.

Do you have the paper that you could send me, because I'm not spending $28 to read it.

I said the 110 mph stops at every mile was outside of the realm spirited street driving, not that it wasn't relevant in the study, the study said they saw better performance from the cross-drilled after several stops into doing a test of stopping from 110mph every mile. That I think is reasonable to consider outside of the realm of spirited street driving.

I found a synopsis and the synopsis brings up a lot to call it into question. Not to mention they used smaller blank rotors than they did cross-drilled. They repeated again and again that blank disc performed better at lower speeds, despite being smaller than the cross-drilled and the only high speeds the described were the GM abuse test of 110 mph to a stop and they repeated it every mile, then they saw better performance from the cross drilled, but only when they were past several of these stops every mile? There were no tow tests in the study, perhaps there was and the synopsis just omitted it?

So the synopsis is not the study, you want to send it to me, then I'll read it.

I've seen many informed engineering opinions stating why cross-drilled rotors are not better than the blank on the street, that had sound reasoning.

So that makes it my opinion. But a study I can NOT read, that makes vague claims as to its conclusions, does not convince me. No not because I know better than the engineer that conducted the study, yes, because I can't see the data, the test conditions and test methods, and just being told vaguely what the conclusions are.

I have yet to see someone do an independent test with publish results, they may be out there, and like I said, its been more than a few years since I have even looked for one, that compares blank and cross-drilled rotors under the exact same conditions. I'm not convinced, yes that's my opinion.

I wouldn't have accepted Helicopter Test results like that, of course I wouldn't have had to pay to get the study, but I also would have raised a flag when the test method and conditions stated they were going to reduce size one item to be compared, when the size has a direct affect on performance.

I did like the terms in the synopsis, which I assume are also in the study, I had forgotten the term blank rotors, to often we call blank rotors, solid rotors. But we also call none ventilated rotors, solid rotors. Solid rotors seem more applicable to me to none ventilated rotors, cause they are a solid disc of iron/mild steel. When we compare cross-drilled to none-cross drilled we often call them solid rotors, but they're ventilated, meaning they are not solid discs. I do like the use of the term blank rotors for non-crossdrilled ventilated rotors, it at least removes some of the confusion.
 
#51 ·
This is what I looked up for Sales codes for the brakes.

BR1 Anti-Lock 4-Wheel Disc Brakes, 18 inch Wheels
BR6 Anti-Lock 4-Wheel Disc HD Brakes, 18 inch Wheels
BRY Anti-Lock 4-Wheel Disc Brakes, 17 inch Wheels

I don't know if they have changed the brakes in 2018 or NOT.

Look at your rear rotors, if you have vented rear rotors, you have the HD brakes, if you have solid rotors, you have SD brakes. If you want to be sure, go to an online part source and pull up part numbers for rotors and calipers for a 2011 and a 2018 and see if they are different.

If you want to know if your Caliper Covers will fit, well the fronts are the same calipers, HD just moves the caliper out farther with a different adapter. The rear calipers will be thicker to fit the thicker vented rotor. So if the cover clip around the caliper it might make a difference.
 
#52 ·
My 1.5 Cents
I have a 2012 Limited with the V-8 and got 150000 Miles out of the Stock brakes and Pads, then with the Advance auto lift time pads and rotors, well I am in need of pads and rotors with Only 50000 miles on them.. I get it that it only takes about 2 hours to do the front and rear And they will be free But i'm going to shell out the extra and go back to OEM.
 
#53 ·
Just be careful, the Dealerships have "value line" brake pads, that are aftermarket pads and NOT the actual OEM that were put on at the factory. I would not put it past a Dealer to give you the impression you were getting OEM pads and then install the "Value Line" and pocket the difference in price. The "value line" is even sold through outlets as Mopar I believe, so its possible to buy a Mopar Pad, thinking its OEM and get instead an aftermarket that is not as good.
 
#54 ·
Thanks for the heads up, I did not realize that.
I ended up getting the Akebono Pro-act Ultra-Premium Ceramic Disc Brake Pads (ACT1629A)
 
#55 ·
I know this is an older thread, but I thought I'd ask anyway. I have a 2015 JGC with standard brakes, 65,000 miles. At highway speeds during medium to hard braking, I hear/feel a rumbling sound that I can only describe as the sound/feel of if you were to apply the emergency brake while rolling. The thing is, it's not consistent all the time. (Maybe when the brakes are hot if that makes sense).

I see from this post you can't always tell by looking at the rotors to see if they're warped, and to my naked eye, my rotors look pretty good- no ridges, etching, no markings at all- completely smooth. I've had other vehicles with warped rotors before and the feeling in the steering wheel and brake pedal was different - more side to side and also more of a constant feel , meaning hitting the brakes always produced the shudder. My current issue does not happen all the time. More of when the vehicle has been driven a bit after a couple of hard stops, or braking at 80. Especially notice it braking on a down hill exit ramp. So I wonder if it's brakes or suspension, but I keep coming back to that feeling (and sound) of driving with parking brake on (which is definitely not engaged because I'm always checking and I have only actually used the twice in 6 years).

Any advice or experience is greatly appreciated. Thanks
 
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