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time to replace brakes?

Timeking
Explorer
Explorer
These are Dexter self-adjust that I have dragged 15,500 miles. At zero miles (i.e., new) the pads are 0.18 inch (9/32) and after 15,500 they are 0.08 inch (1/8). So I am figuring that the pads are losing 0.01 inch every 1550 miles. If you are supposed to replace the brakes at 0.04 inch (1/16), I only have 6200 more miles until worn.

I figure (My brain hurts!!) that if we are planning to go from Florida east coast to California and up to Canada, I need to go ahead and do this thankless job. I've done this before on previous trailer.

All that said, I wanted to see if I am figuring this right or not.

In advance
Thanks
24 REPLIES 24

deltabravo
Nomad
Nomad
ford truck guy wrote:
Throw ALL those Math problems Into the trash can and stop over thinking.

IF the brakes a low, AND your taking that multi thousand mile trip ( 6,000 - 10,000 ) , just replace them and be done with it..:S


DITTO

ford truck guy wrote:
piece of mind = priceless


Correction: "peace" of mind
A piece of someone's mind makes them only have a partial brain...LOL
2009 Silverado 3500HD Dually, D/A, CCLB 4x4 (bought new 8/30/09)
2018 Arctic Fox 992 with an Onan 2500i "quiet" model generator

monkey44
Nomad II
Nomad II
test - ignore
Monkey44
Cape Cod Ma & Central Fla
Chevy 2500HD 4x4 DC-SB
2008 Lance 845
Back-country camping fanatic

JBarca
Nomad II
Nomad II
Chum lee wrote:
JBarca wrote:


A good machine shop can handle 0.005" TIR and less without issue. But, some auto parts places will not guarantee much of anything. I gave up around here trying to get the local auto parts store to turn brake rotors or drums. After getting them back worse than when I gave them to them, I gave up and just bought new brake drums & rotors.



John


In modern times, once brake drums/rotors are out of tolerance, a good machine shop can get them round/flat again, BUT, the problem is that when they remove material, it takes the castings out of tolerance from a thickness variation standpoint. Once the rotors/drums are heated up in use, they usually go out of tolerance again very quickly because the thickness variation causes too much differential heating (expansion/contraction) and the shuddering/pulsing returns. The older "boat anchor" style drums/rotors no longer exist because engineers are trying to save unsprung weight and reduce rotational inertia to the detriment of durability/longevity.

Best bet: once drums/rotors are out of tolerance for any reason, replace them with like and kind. (new) Truck/trailer components are usually more robust, but, . . . . do you feel lucky?

Chum lee


Hi Chum lee,

I fully agree with you. The issue is the trailer industry (the smaller types used in RV's) quality is not like years ago. A brand new brake drum running 0.015" TIR out is, well, poor. The 2 bearing bores can be dead on, just the shoe surface diameter runs out in relation to the bearing bores. The shoe diameter can be dead true also, it is just that the machine was allowed to run off center when turning the shoe diameter. Either the operator just plain set it up wrong or they allow the machine to drift since the spec is, 0.015" TIR, and they let it run.

On a standard manual adjust brake, many folks may never know or realize you have a problem. When you are adjusting the brake, you tweak the adjuster close and listen/feel for the drag while spinning the wheel. Well, when the drag skips, then gets hard to turn, the skip is the drum rotating off center. You are setting the drag to the part of the rotating surface that touches the shoes, whatever portion of less contact in the 360 degrees of the drum. If the shoe surface ran true, you would have even light-drag the full 360 degrees.

Now insert the self-adjusting trailer brake. If the shoe surface runs out much more than 0.015" TIR, and even some may be a little under that, over time when the shoes press into the max out of the round area, the adjuster has enough travel to move a click on the adjuster. The first click is not a problem, that click may only be a 0.0005" movement. But, after enough stopping sequences, the adjuster keeps on adding 0.0005", and soon that turns into a lot of thousands. Now the brake is too tight and there is no way to back it off automatically. You end up with a locked-on mega hot brake.

I have said before, one learns a lot more when things do not work right. If I had not had this happen to me, I never would have realized it. In today's modern machines, holding a brake drum to spin true within 0.005" TIR is a walk in the park. Automotive does it all day long on disk brake rotors that have to run close to dead true. Why does the trailer industry allow such wide tolerances that they ship all the time? It all comes down to $$$.

Sorry for the rant, I come from a machine shop background and it's just poor the stuff we get that could easily be made lots better with just a little more time and pride added.

Thanks for listening...

John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.

Chum_lee
Explorer
Explorer
JBarca wrote:


A good machine shop can handle 0.005" TIR and less without issue. But, some auto parts places will not guarantee much of anything. I gave up around here trying to get the local auto parts store to turn brake rotors or drums. After getting them back worse than when I gave them to them, I gave up and just bought new brake drums & rotors.



John


In modern times, once brake drums/rotors are out of tolerance, a good machine shop can get them round/flat again, BUT, the problem is that when they remove material, it takes the castings out of tolerance from a thickness variation standpoint. Once the rotors/drums are heated up in use, they usually go out of tolerance again very quickly because the thickness variation causes too much differential heating (expansion/contraction) and the shuddering/pulsing returns. The older "boat anchor" style drums/rotors no longer exist because engineers are trying to save unsprung weight and reduce rotational inertia to the detriment of durability/longevity.

Best bet: once drums/rotors are out of tolerance for any reason, replace them with like and kind. (new) Truck/trailer components are usually more robust, but, . . . . do you feel lucky?

Chum lee

JBarca
Nomad II
Nomad II
Timeking wrote:
Tired of worrying. Ordered new nev-r-adjust brakes. there was something ground into one of the pads that cut grooves in the hub. Will have the hub turned or buy a new hub (btw ALL "new" hubs are out of round, as in ALL have to be turned).


Out of round hubs, yeh. A heads up, when the drums come back from the machine shop, ideally you check the drum shoe surface for total runout with a dial indicator. I can attest to the fact, the drum shoe surface (diameter) has to run within 0.015" total indicator reading (TIR) with the hub bearing bores. Ideally they are down in the 0.005" or 0.010" TIR range. Being at the edge of the Dexter spec of 0.015" is on the ragged edge. You will have issues with the brakes over-adjusting and getting hot if the drum runout is much over 0.015" TIR. Been there and proved that. Trailer tolerances are way different than auto tolerances.

A good machine shop can handle 0.005" TIR and less without issue. But, some auto parts places will not guarantee much of anything. I gave up around here trying to get the local auto parts store to turn brake rotors or drums. After getting them back worse than when I gave them to them, I gave up and just bought new brake drums & rotors. Also, make sure the magnet surface is good and cleaned up.

Good luck and let us know how this comes out.

John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.

Timeking
Explorer
Explorer
Tired of worrying. Ordered new nev-r-adjust brakes. there was something ground into one of the pads that cut grooves in the hub. Will have the hub turned or buy a new hub (btw ALL "new" hubs are out of round, as in ALL have to be turned).

Cummins12V98 wrote:
ford truck guy wrote:
Throw ALL those Math problems Into the trash can and stop over thinking.

IF the brakes a low, AND your taking that multi thousand mile trip ( 6,000 - 10,000 ) , just replace them and be done with it..:S

piece of mind = priceless

and by the way... agree with the above .080 is 80 thousands where 1/8" is .125, or 125,000.... 45,000 thicker ( .045 ) than .080 now my brain hurts


Agree, but I would also check the bearings, change seals, repack and adjust.


I would as well, and assumed that would be done anyway... If I were taking a trip like that, I would go over every bit of that trailer with a fine tooth comb... and a few spare parts may not be a bad idea. I know I carry the essentials.
Me-Her-the kids
2020 Ford F350 SD 6.7
2020 Redwood 3991RD Garnet

JBarca
Nomad II
Nomad II
Timeking wrote:
These are Dexter self-adjust that I have dragged 15,500 miles. At zero miles (i.e., new) the pads are 0.18 inch (9/32) and after 15,500 they are 0.08 inch (1/8). So I am figuring that the pads are losing 0.01 inch every 1550 miles. If you are supposed to replace the brakes at 0.04 inch (1/16), I only have 6200 more miles until worn.

I figure (My brain hurts!!) that if we are planning to go from Florida east coast to California and up to Canada, I need to go ahead and do this thankless job. I've done this before on previous trailer.

All that said, I wanted to see if I am figuring this right or not.

In advance
Thanks


Hi,

As was pointed out, you mixed up the math but you are past that now. I'm picking up on the 15,500 miles comment. I'm just passing this info along to try and help you, plus gets some more learning in. One never stops learning.

What is the size of your brakes? 12" x 2" or 10" x 2 1/4"? And what year was the set new?

Three other questions, what is the weight of the camper?

Tell us some about the 15,500 miles. Long cross-country trips, weekend warrior 2 to 3 days trips 100 to 200 miles from home, just lots of them?

How many years did it take to accumulate the 15,500 miles? This sort of ties into the type of camping you had over that 15.5K mile period.

I was one of the first here on RV. net to report on the Dexter self-adjusting brakes. It is shown here in this post from 2009. I was still working then, and now retired but our trips were more weekend warrior short trips still, but a lot to them, until 2016 when I retired. I still have and use that camper. https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23458294/srt/pa/pging/1/page/1.cfm

My camper weighs just under 10,000# loaded. It has 12 x 2" brakes and I did the brake wiring upgrade to # 10 AWG wire to each coil and got rid of the wire in the axle tube. Both hot wire and ground are direct to the 7-wire cord. No rusty frame ground in the middle of the brake wiring or corrosion in the connections. The wiring makes the power transmission more dependable and the best you are going to get from an electric brakes setup.

I replaced my first set of the self-adjusters in August of 2020, about 11 years of use. I would have to go back and add up the exact mileage, but it was in the 20,000-mile range. It could be a 1K- 2K +/- from that. I replaced them as my stopping power was slowly starting to fade. I could tell by the dusting on the truck wheels, the truck was doing more stopping than it use to. With the Ford integrated brake controller that works so smoothly, it was hard to tell the trailer was not stopping like it use to, the truck was compensating.

I was not yet worn to the 0.060" (1/16") target, but I was getting closer on one wheel that had an issue early on with an out-of-round brake drum. And since stopping was fading away, I just changed them out assuming I would get back to the braking I once had. And we were going to head out on a long trip.

Well, nope, the braking/stopping did not change. Now what? I was on all-new self-adjusting brakes that I had burnished in the pads, and it still is not stopping as it should. After about 1,000 miles of this, I pulled everything apart to see what was globally affecting the braking. I checked the current to each brake coil, and the magnet ohms. That all checked out. Hmmm, OK now what?

Well, to make a long troubleshooting search short, the problem was too deep and wide of grooving on the brake drum magnet surface. When the grooving approaches too deep or wide, the magnet does not have enough surface to grip on, the brake coil is not strong enough to power through the air gap, and the issue ends up with the brake power slowly dropping.

The end result learning was, it was not the brake shoes, they were not yet at 1/16", the problem was the magnet surface wore into a grooving pattern first. After I found this, all new brake drums and the new 1,000-mile new brakes worked well again like they always have. It was a global shift as soon as I came out of the shop, it all worked again. If I would have known the groove depth/width that is too much, I could have still used my prior self-adjusters longer. Seeing a level of small scratches on the magnet surface is normal, but when the grooves get too deep and too wide, that is a problem.

Point: Check the magnet surface on the drum.

I have pictures and depth data on this just did not want to make this any longer than it is already. If anyone wants to know about the drum grooving, let me know and I will see if I can dig it up.

Hope this helps,

John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.

midnightsadie
Explorer II
Explorer II
just for fun take a set off go to napa or your choice and see if they,ll do a match for you.if me I,d change those shoes, check bearings,seal,s . and I insist on timken bearings. even that some are made over sea,s.

Timeking
Explorer
Explorer
Not to say something noone wants to hear, but right now a right/left set of Dexter SAdjust are $185, I buy a lot of stuff from Etrailer, but they seem to want $60 more for same things.

Chum_lee
Explorer
Explorer
30sweeds wrote:
Apples and oranges here but when replacing shoes on my Dexter axle boat trailer(surge brakes),Dexter wanted $150 a side.I went to my go to guy at Oreillys and he thought they looked like 80s Chevy shoes.He grabbed a couple boxes from the back and we compared them.One was a direct match,even the stamping marks on the steel were exactly the same.$30 a set for the best ones they had.


YES! Remember, . . . . Dexter doesn't make brakes. They make axles. They outsource the brakes they use from other companies like Bendix, Wagner, etc. who also outsource the friction materials they use from others. When you buy at O'reilly's you cut out a few well paid middlemen. (and their markup) Not all brake friction materials are the same so you are still responsible for choosing the right material durability for your application. When I was younger, we used to have brake shoes relined. Better than new. (about $5.00 a wheel for most automotive applications) Times have changed. Like bearings, there still is a lot of cross compatibility in brakes.

Chum lee

Cummins12V98
Explorer III
Explorer III
ford truck guy wrote:
Throw ALL those Math problems Into the trash can and stop over thinking.

IF the brakes a low, AND your taking that multi thousand mile trip ( 6,000 - 10,000 ) , just replace them and be done with it..:S

piece of mind = priceless

and by the way... agree with the above .080 is 80 thousands where 1/8" is .125, or 125,000.... 45,000 thicker ( .045 ) than .080 now my brain hurts


Agree, but I would also check the bearings, change seals, repack and adjust.
2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"

"HeavyWeight" B&W RVK3600

2016 MobileSuites 39TKSB3 highly "Elited" In the stable

2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD

30sweeds
Explorer
Explorer
Apples and oranges here but when replacing shoes on my Dexter axle boat trailer(surge brakes),Dexter wanted $150 a side.I went to my go to guy at Oreillys and he thought they looked like 80s Chevy shoes.He grabbed a couple boxes from the back and we compared them.One was a direct match,even the stamping marks on the steel were exactly the same.$30 a set for the best ones they had.

RetiredRealtorR
Explorer
Explorer
Change 'em out. As a previous respondent mentioned, peace of mind is everything.

And, if you view it as a "thankless job", remember that there are people that do this professionally. That's the route I'd go.
. . . never confuse education with intelligence, nor motion with progress