Left rear brake disc (yes, rear disc) overheated last trip out to the point the brake fluid boiled and disc was smoking. Whether it was a sticking piston or internal kink in the final section of brake hose is moot now. Need to replace hose and caliper seals at a minimum. Left rear was the only one with an issue as I limped home (only 20 miles) by stopping every few miles and checking the temperature of each disc. Only left rear was overheating. Even with frequent stops, it got over 400 degrees by time I reached the house.Talked to resident automotive expert at work and he said the disc was probably softened due to annealing, the seals in the caliper ruined due to overheating and grease cooked away in the bearing. Been researching and I read the pads get glazed and ruined when overheated.So now what was going to be new hoses and maybe a caliper has turned into, at minimum; new caliper piston seals, new pads, new hoses and repacking the bearing.At worst it could be all that and new bearings and new caliper instead of rebuilding.I will replace all the brake hoses. I think 25 years is more than long enough.Anyone ever had a dragging rear caliper like I described? What was your experience with the work required to set things right again?

Doubtful that the bearings got overheated as they are probably oil bath. As for the caliper and rotor? Replace everything. Rotor is probably warped, the pads are shot and the caliper is probably already got serious issues. Would not hurt to replace the hose too. Then your entire brake system needs to be flushed and refilled with clean proper grade fluid.

Replace brakecaliper. Check both rears for cracking of the rotor.Check the rubber lines. There is three, one on each wheel plus in the center. Overheating could have been caused by fluyid not releasing back to the master cylinder.

Common problem, happens all the time. It can be a couple of different things. People always point at the sliding pins on the calipers but I have never had them be the culprit. More often the pads seize in their slots and very often a piston will seize due to swollen seals. I've had bad seals in the caliper piston bores only stick when the caliper is hot - when it cools off the piston freed up.Always replace brakes in axle sets - if you do one side, do the other side too. If you replace the discs you should replace the pads as well, and vice versa. Discs are not heat treated, are cast iron not steel, and can't be annealed. Heat won't hurt them, only abnormal wear. What can be damaged by heat are pads, caliper seals and brake fluid.Edit: bad on me for being unclear. Cast iron brake discs are indeed heat treated, but not to harden them. In the manufacturing process the discs are brought up to around 900 degrees Celsius (1650 F.) for around 4 hours. This is cherry red, and would probably cause the tire to catch fire. This anneals them, although I call it normalizing. Brake discs are also sometimes cryogenic treated, which involves taking them to a very cold temperature, which makes them a lot more wear resistant.Brian

The replies have given me hope this will be easier than my worst fears. I know I need to determine make of rear axle. I think it is a Dana 70 but it could be a Dana 80. If it is the oil bath variety I won't worry about the bearings.JD had several variants of chassis, some with the 70 and some with the 80. The parts and shop manuals I have list both axles.So new brake hoses everywhere is definitely in the plan. New calipers and pads across the rear sounds like a wise move. More money but mechanically easy to do. Maybe I can find new seals and rebuild the calipers cheap.

I would have a professional look at the rotors. If they have heat stress cracks they should be replaced. Easier to do when it is torn apart then to do it later.

Rotor and pads and bearings. Oh my! | Good Sam Community

23 Replies

ScottnSherrie
Explorer
Nov 02, 2013
Ok. I may be making progress. Oreilly got hits on 1994 F700 Dayton brakes with 2.5 inch pistons. At $12 a pop I'll by one rebuild kit (after some more research) and see if they are a match. I already ordered one new complete caliper specific to the JD chassis so the old one can be my R&D unit.
ScottnSherrie
Explorer
Nov 02, 2013
j-d wrote:
....That's a $4 Front Caliper Kit from ACDelco. As the article notes, most if not all the matchup is done by Piston Diameter. Your calipers are probably Dual Piston. Might take two front caliper kits for a Chevelle to fix one of your rear calipers. Quote from the article....

Are you saying a Chevelle caliper seal is the right size for the dual 2.5 inch pistons in the Dayton Walther brake calipers on my John Deere chassis? I would gladly take the time to rebuild all the calipers if I could find seals that are the right size.

I Googled for '2.5 inch brake caliper seal' and didn't get any promising hits.
John_Joey
Explorer
Nov 01, 2013
ScottnSherrie wrote:
...snip...Anyone ever had a dragging rear caliper like I described? What was your experience with the work required to set things right again?

Spent too much time by salt water, and my left rear did exactly that. I got that hot also, but I broke mine free by going in reverse and hitting the brakes several times. Drove a thousand miles before replacing the caliper with a new top of the line loaded one. Been working like a champ ever since.

ON EDIT

BTW, I did both rear. Loaded top of line for two was under $200 at O'Rielly
j-d
Explorer II
Nov 01, 2013
YES! The bearings are lubed by an "oil bath" and that bath, as I posted before, is the gear lube that you fill and check at a plug in the differential. Make sure that's full, and your bearings will stay lubed.

At $170 I'd be tempted to not replace the other caliper too. But there's an option of doing your own caliper reconditioning.

This Article Tells How and there are YouTube videos also. Some kits will include more parts than others, but some will only be two parts like this one

That's a $4 Front Caliper Kit from ACDelco. As the article notes, most if not all the matchup is done by Piston Diameter. Your calipers are probably Dual Piston. Might take two front caliper kits for a Chevelle to fix one of your rear calipers. Quote from the article:
"Don't be lazy and rebuild or replace only one side. Brakes should always be maintained as an axle set, not one corner at a time."
enblethen
Nomad
Nov 01, 2013
I also used ceramic pads purchased from O'Reilly's.
ScottnSherrie
Explorer
Nov 01, 2013
enblethen wrote:
I would take the other side off the mount, inspect it, clean and lube it good.
Just a little more labor but may save issues.
Make sure you get good brake lube. use plenty on the slide areas and the wedge keeper.
I used a small Dremel style grinder to clean the slide areas.

Yep. Left that out of the published plan. I will be removing all the calipers for inspection, cleaning and greasing. If front pads need replaced, that will get done as well.
enblethen
Nomad
Nov 01, 2013
I would take the other side off the mount, inspect it, clean and lube it good.
Just a little more labor but may save issues.
Make sure you get good brake lube. use plenty on the slide areas and the wedge keeper.
I used a small Dremel style grinder to clean the slide areas.
ScottnSherrie
Explorer
Nov 01, 2013
RE: Replacing both calipers.

After much research and soul searching I am going to replace the one caliper. The split seemed pretty even between "don't skimp on brakes" and "if it ain't broke, don't fix it" schools of thought.

One suggestion made good sense; replace the one caliper and see how it brakes. If it pulls to the side with the new caliper, then replace the caliper on the other side.
ScottnSherrie
Explorer
Nov 01, 2013
j-d wrote:
...I'd agree with New Pads and New/Reman/Recon Calipers on BOTH rear sides, along with the Hoses you've committed to...

Grrr. I know you are probably right about the calipers and pads. That will add at least $170 to the project, and I am one cheap SOB.

At least I can take the bearings off the list. I found the following in the shop manual I have for the chassis; "The wheel bearings are packed to provide initial lubrication until axle lubricant flows into the wheel hubs and bearings during vehicle operation."

Unless I am way off base, that would mean the rear bearings are lubricated by an oil bath that others have posted about.
j-d
Explorer II
Nov 01, 2013
What do the rotors look like? If they're serviceable, I'd agree with New Pads and New/Reman/Recon Calipers on BOTH rear sides, along with the Hoses you've committed to. Neither myself nor any shop I've heard of, changes one caliper on an end. In the case of our coach, the prev owners' shop replaced both rears. I've done a number of front disc brake jobs and always replaced or Recon'd both.
Unequal Front Braking, side to side, will feel like somebody's taking the steering wheel away from you. Feels like an uncommanded turn. Unequal REAR Braking (on a dual rear wheeled vehicle), you'll have more like an uncommanded lane change.
You won't be doing a "100%" job because you aren't replacing or resurfacing the rotors. Don't shortcut it any further.