HMMWV REV truck brakes

[T9000]

My 1165A1 truck had about 7,000 miles on it when I got it and the brakes looked good. After driving less than 1,000 miles, the front passenger left brake pad (looking at it from the front) is completely worn out, with the left caliper pistons being extended almost double than the right side:



What could cause such an left/ right imbalance or is it typical? (the pads wear on driver side looks even on both sides)
The 1165a1 manual at 7-3.1 says to replace the pad if the thickness is less than 3/16”. Between what points is that “thickness” measured? The pad base plate alone is thicker than 3/16”, with the back shim measuring 0.25” or 0.2” without it.



This is how much is left on right side pad. I left the worn out one in, thinking to use it with a clamp to push back the pistons, the manual says to use a C clamp and a piece of wood.

How do you guys push back the pistons without removing the whole caliper assembly when replacing the pads on these REV trucks?

 

[williamh]

Looks like the caliper seized

 

[T9000]

Not sure how everyone else is collapsing the pistons in order to replace the pads without removing the caliper assembly and here is the easiest way I could think of, using a screw in place of the pin, combined with the existing pad, before taking it out:



For even faster results, I recommend using a longer screw with a steel spacer such that the screw head extends past the caliper body, which would allow using a socket instead of an open wrench like I did.

 

[MarkM]

Yeah looks like the caliper is frozen and needs to be replaced/rebuilt. These calipers allow for hot swapping the pads which saves a hell of a lot of time. The parts cross reference to the 1987 AMC Eagle 4x4 and will save a lot of money over the Hmmwv listed parts. The brake system for the Hmmwv comes from the Eagle. "The rears will depend on which brakes you have on your truck. Napa SE-4732 (rt) SE-4733 (lft) Oreilly A1-4181 (rt) A1-4182 (lft) You can cross reference..."

Hope this helps.

Mark

 

[T9000]

Yeah looks like the caliper is frozen and needs to be replaced/rebuilt. These calipers allow for hot swapping the pads which saves a hell of a lot of time. The parts cross reference to the 1987 AMC Eagle 4x4 and will save a lot of money over the Hmmwv listed parts. The brake system for the Hmmwv comes from the Eagle. "The rears will depend on which brakes you have on your truck. Napa SE-4732 (rt) SE-4733 (lft) Oreilly A1-4181 (rt) A1-4182 (lft) You can cross reference..."

Hope this helps.

Mark

View attachment 865643

Thank you! I appreciate the details. Are those replacements pads compatible with the 12k GVW and 12” rotors? I have been searching for a while to cross reference pads, as it seems I have the Wilwood Z-150-10479-PS or 5717285, which like you say are not cheap (about $250 for 4 pads). I don’t mind paying more if they would last a while. I thought the H1 Alpha was the closest to the REV in terms of brakes and NAPA didn’t have anything that I could find, only Autozone Duralast MKD1025 and a similar equivalent at O’Reilly

EDIT: I would use the aftermarket pads to troubleshoot the stuck piston then plug in OEM pads if cannot find anything equivalent

 

[MarkM]

I did not know you had the 12k sorry. I will see what I can find for you but I have zero doubt they started out life for the 12k Hmmwv.

Mark

 

[MarkM]

I meant to say they came from somewhere and were not developed for the Hmnwv.

 

[T9000]

Looks like the caliper seized

Yeah looks like the caliper is frozen and needs to be replaced/rebuilt.

I know it’s wishful thinking, but would it be plausible for the left pad to be stuck on the pin and allow the piston to stay extended and advance more than it should?
I am saying this because I had to hammer out the pin, it was totally stuck and a little bent, while the one on the driver side it spins freely.

 

[Action]

Yeah looks like the caliper is frozen and needs to be replaced/rebuilt. These calipers allow for hot swapping the pads which saves a hell of a lot of time. The parts cross reference to the 1987 AMC Eagle 4x4 and will save a lot of money over the Hmmwv listed parts. The brake system for the Hmmwv comes from the Eagle. "The rears will depend on which brakes you have on your truck. Napa SE-4732 (rt) SE-4733 (lft) Oreilly A1-4181 (rt) A1-4182 (lft) You can cross reference..."

Hope this helps.

Mark

View attachment 865643

No no no. Those are not amc calipers. Those are Wilwood gnx4. Retail on a set of 4 pads is over $300. I was wondering how long it would take for an REV owner to need brake pads.

 

[MarkM]

No no no. Those are not amc calipers. Those are Wilwood gnx4. Retail on a set of 4 pads is over $300. I was wondering how long it would take for an REV owner to need brake pads.

Thank you for the correction. I was assuming it was a standard Hmmwv setup. If he has the ability to rebuild it himself or send it off to be rebuilt as it will sure save some coin in this case.

Mark

 

[Retiredwarhorses]

Of course the piston at one side would be farther extended than the other if the pad thickness was different, doesn’t mean the pistons are frozen, any caliper requires the piston to be compressed to install new pads.
it’s not uncommon also for one pad to wear different than the other, but verify all of This this after pads are in and use the bleeders if need be, takes 2 people to check…one inside At the brake pedal.
I’ve done several Wilwood pads slaps in minutes…

 

[T9000]

Of course the piston at one side would be farther extended than the other if the pad thickness was different, doesn’t mean the pistons are frozen, any caliper requires the piston to be compressed to install new pads.
it’s not uncommon also for one pad to wear different than the other, but verify all of This this after pads are in and use the bleeders if need be, takes 2 people to check…one inside At the brake pedal.
I’ve done several Wilwood pads slaps in minutes…

RWH do you have any experience with ComTac Parts (also going by Wolfer-Parts) brake pads? Are they selling genuine OEM parts or Chinese copies?
The have a Z-150-9841K/ 5717285-SP REV set of 4 pads for $120, while Kascar and MacMotors sell it for about $230 (also a set of 4).

Brake Pad Kit with Hardware; ECV HUMMER ; Z-150-10479-PS 57K6207 57172

ECV BRAKE PAD SET (4 Pads, 2 Clevis Pins, 2 Hairpin Clips - Per Kit) ( In Stock - available now ) _______________________________ Fits: HMMWV with Wilwood style brake system , M1151A1 , M1152A1 , M1165A1 , M1167 , M1114 , Alpha , KIT BRAKE PAD 300K 4 PADS REV , etc...

comtac.parts

I am constantly looking out for vendors who are infiltrating the supply chain with Chinese parts (and not disclosing the country of origin, or worse pretending they are US made), who are pushing products from vendors like this, selling the fake Wilwood pads for as low as $5 a pad:

Wholesale OEM HMMWV M1151 Military Truck Brake Pad 2530-01-568-4462 5717285 12835400 Suppliers -Samarlanny

www.lroemparts.com

 

[Retiredwarhorses]

RWH do you have any experience with ComTac Parts (also going by Wolfer-Parts) brake pads? Are they selling genuine OEM parts or Chinese copies?
The have a Z-150-9841K/ 5717285-SP REV set of 4 pads for $120, while Kascar and MacMotors sell it for about $230 (also a set of 4).

Brake Pad Kit with Hardware; ECV HUMMER ; Z-150-10479-PS 57K6207 57172

ECV BRAKE PAD SET (4 Pads, 2 Clevis Pins, 2 Hairpin Clips - Per Kit) ( In Stock - available now ) _______________________________ Fits: HMMWV with Wilwood style brake system , M1151A1 , M1152A1 , M1165A1 , M1167 , M1114 , Alpha , KIT BRAKE PAD 300K 4 PADS REV , etc...

comtac.parts

I am constantly looking out for vendors who are infiltrating the supply chain with Chinese parts (and not disclosing the country of origin, or worse pretending they are US made), who are pushing products from vendors like this, selling the fake Wilwood pads for as low as $5 a pad:

Wholesale OEM HMMWV M1151 Military Truck Brake Pad 2530-01-568-4462 5717285 12835400 Suppliers -Samarlanny

www.lroemparts.com

As a business owner, for liability reasons and just plain reliability, I only use OEM, NOS and distributor supplied parts, especially on braking components.
I only do business with HPG, Mac and Kascar, unfortunately the company’s you listed are more than happy to play with words and unsuspecting new owners to the hobby don’t really know any better, so buyer beware is the old saying.

 

[Coug]

RWH do you have any experience with ComTac Parts (also going by Wolfer-Parts) brake pads? Are they selling genuine OEM parts or Chinese copies?
The have a Z-150-9841K/ 5717285-SP REV set of 4 pads for $120, while Kascar and MacMotors sell it for about $230 (also a set of 4).

Brake Pad Kit with Hardware; ECV HUMMER ; Z-150-10479-PS 57K6207 57172

ECV BRAKE PAD SET (4 Pads, 2 Clevis Pins, 2 Hairpin Clips - Per Kit) ( In Stock - available now ) _______________________________ Fits: HMMWV with Wilwood style brake system , M1151A1 , M1152A1 , M1165A1 , M1167 , M1114 , Alpha , KIT BRAKE PAD 300K 4 PADS REV , etc...

comtac.parts

I am constantly looking out for vendors who are infiltrating the supply chain with Chinese parts (and not disclosing the country of origin, or worse pretending they are US made), who are pushing products from vendors like this, selling the fake Wilwood pads for as low as $5 a pad:

Wholesale OEM HMMWV M1151 Military Truck Brake Pad 2530-01-568-4462 5717285 12835400 Suppliers -Samarlanny

www.lroemparts.com

For the Wolfer/Comtac link, they list that as being every part number associated with that particular NSN
That's not how the part numbers are supposed to work. Those part numbers listed are all from different manufacturers, meaning that if it is one of those part numbers, it can't also be a different one.
Wolfer definitely uses deceptive language, and tries to make it sound like their parts are OEM. They'll say a part meets OEM, and the next line they will claim it's 25% stronger than OEM, which is impossible as material specs for the military tend to be pretty specific, so if it's stronger than OEM, it can't actually be OEM.
Also a clue, if you find images of the actual Wilwood pads, they have WILWOOD stamped right into them. The images on the comtac page don't have any markings of any type that I can see. I suppose it might be one of the other suppliers, but as I said before, Wolfer has a reputation for deceptive wording and cheap crappy parts with high failure rates. Brakes are one of the places you really don't want to cut corners and try out cheap parts.


As for the second link, further down on the page it lists country of origin as "CN"
Don't show the same markings as the WilWood, but they at least show some type of marking.



Now, I suppose there might be other OEMs that don't mark their pads like Wilwood does, but if the price is that different than the reputable vendors, but after you get ripped off a few times on parts that are crap, you find out that most of the time paying the money for the right parts saves you money in the long run.

 

[T9000]

For the Wolfer/Comtac link, they list that as being every part number associated with that particular NSN
That's not how the part numbers are supposed to work. Those part numbers listed are all from different manufacturers, meaning that if it is one of those part numbers, it can't also be a different one.
Wolfer definitely uses deceptive language, and tries to make it sound like their parts are OEM. They'll say a part meets OEM, and the next line they will claim it's 25% stronger than OEM, which is impossible as material specs for the military tend to be pretty specific, so if it's stronger than OEM, it can't actually be OEM.
Also a clue, if you find images of the actual Wilwood pads, they have WILWOOD stamped right into them. The images on the comtac page don't have any markings of any type that I can see. I suppose it might be one of the other suppliers, but as I said before, Wolfer has a reputation for deceptive wording and cheap crappy parts with high failure rates. Brakes are one of the places you really don't want to cut corners and try out cheap parts.


As for the second link, further down on the page it lists country of origin as "CN"
Don't show the same markings as the WilWood, but they at least show some type of marking.



Now, I suppose there might be other OEMs that don't mark their pads like Wilwood does, but if the price is that different than the reputable vendors, but after you get ripped off a few times on parts that are crap, you find out that most of the time paying the money for the right parts saves you money in the long run.

Thank you! I also wanted to make others aware about these parts issues and how things are worded. I only buy parts from HPG, Kascar, Mac or AMG and this seemed to be too good to be true, that's why I had to check.

 

[TOBASH]

For the Wolfer/Comtac link, they list that as being every part number associated with that particular NSN
That's not how the part numbers are supposed to work. Those part numbers listed are all from different manufacturers, meaning that if it is one of those part numbers, it can't also be a different one.
Wolfer definitely uses deceptive language, and tries to make it sound like their parts are OEM. They'll say a part meets OEM, and the next line they will claim it's 25% stronger than OEM, which is impossible as material specs for the military tend to be pretty specific, so if it's stronger than OEM, it can't actually be OEM.
Also a clue, if you find images of the actual Wilwood pads, they have WILWOOD stamped right into them. The images on the comtac page don't have any markings of any type that I can see. I suppose it might be one of the other suppliers, but as I said before, Wolfer has a reputation for deceptive wording and cheap crappy parts with high failure rates. Brakes are one of the places you really don't want to cut corners and try out cheap parts.


As for the second link, further down on the page it lists country of origin as "CN"
Don't show the same markings as the WilWood, but they at least show some type of marking.



Now, I suppose there might be other OEMs that don't mark their pads like Wilwood does, but if the price is that different than the reputable vendors, but after you get ripped off a few times on parts that are crap, you find out that most of the time paying the money for the right parts saves you money in the long run.

I contacted Wolfer re.: whether or not one of their items was OEM and or aftermarket, and after many many weeks I am still waiting. LOL. Most vendors answer right away.

I chose not to purchase that part from them.

 

[T9000]

Quick update…I ended up getting the actual Wilwood brake pads (there are several manufacturers approved under the NSN) and they are a piece of art, the way are made with that solid copper backplate.
Initially I thought there was only half of the front passenger side caliper that was stuck (I could easily collapse the other side, but on the stuck side I broke several G8 1/4 bolts and never went in more than 1/2 way). I took the caliper apart and the brake fluid inside was black while the pistons were covered in a gooey sticky film, like in this picture (I cleaned the other one):


After cleaning the pistons and caliper channels inside, I bled it at the top valves, starting with the one furthest from the entry point and everything seems to work well and the pads are running much cooler than before matching the side with normal wear. On to the next thing

 

[juanprado]

Looks like they used way too much assembly lube from factory.

Is your brake fluid Clean? Might Consider a flush and bleed?

 

[T9000]

Looks like they used way too much assembly lube from factory.

Is your brake fluid Clean? Might Consider a flush and bleed?

Yes, the brake fluid looks clear, but as you say I am doing a flush since I have to do a bleed on all 4 calipers as I am cleaning them anyway. Got new DOT5 brake fluid.

 

[T9000]

Here is the easiest and fastest way I found to collapse the pistons to extract the old brakes pads and install new ones in minutes.

I use a 1/4” bolt with 5/16” spacer nuts in order to keep the head raised from the caliper body so I can use a socket to drive it quickly.
the bolt is inserted thru the same holes where the holding pin goes and as you turn the screw, it pulls the pad in towards the caliper body which collapses the two pistons. The I switch it and do the other side, the hex head is always on the outside so a socket can be used.
I had shorter screws at first and many got sheared because the pistons were stuck, that’s how I knew there was a problem. I ended up with the longer bolts because that’s what I could find in GR8, but if the pistons are not stuck then using regular steel bolts would work also.