Disc Brake Lag, Pressure vs. Time

[dznf0g]

Originally Posted by boondockdad

Did you use a bleed pump?
Last rebuild, I had my son pull the breakaway plug to pressurize/bleed.
Discovered, those little things don't like being dis/connected repeatedly... it melted. (maybe a bad switch?)

I know what you're saying about servicing yourself.
I won't have J/C touch my A/S, after the last few "service" experiences down there....

Don't have a bleed pump. Tried the MightyVac, but there was too much leakage around the bleeder threads....and I had a lot of air in the calipers....wore my hand out.

You must have had some switch issue, I've used my actuator many times while bleeding, testing, etc, and never even had a hint of warmth to the touch on the switch. They can corrode and have high resistance...that's what I would suspect.

[GCinSC2]

Rich,

For general use the vacuum pump is a good tool. One way to improve its efficiency is prior to use remove the bleed screw and apply 2-3 turns of Teflon tape on just the threads. Not on the seat. The tape helps seal up the threads a lot and really improves efficiency of the tool.

But it doesn't stand a chance of pulling a bubble down from the inboard casting, just like I think you mentioned previously.

If you come back with a frown after this trip I'll loan you my pressure gage setup if you want to static test and see delay vs psi on a video and it's not hard to add the steel lines and create an inboard bleed.

[dznf0g]

Thanks, Gary.....duh, teflon tape....well, it wouldn't help much anyway, as you say the inboard half is the bugger.

Yeah, this was a bit of a rush repair so I can go soon. I'll fiddle with an in-line bleeder later, but I really don't think it would offer any advantage over the cracking the line method.

I won't have a frown either...just a bit more work. I had all the air out prior to this repair, and I am sure I can get there again.

[GCinSC2]

Rich,

Don't see why your method of cracking the inboard hose wouldn't work. You're giving the bubbles an escape path.

The one down side to cracking the inboard hose, hose position or twist when you finally get it tightened. And the hose flare is rotated and compressed to the adapter seat each time you crack it and tighten it. The adapted setup Im using has a steel line and nut at the connection to the caliper. So you're loosening the nut, bleed, tighten nut, returns to correct line position and the nut is just acting as a clamp to the line, no scrunch, loosen, scrunch etc.

OK, lets say I get real bored some winter and redo the whole chassis to axles connection system. Here's my wish list.

1. Route down the axle arm from the front, not from the rear like current setup. Compare this to a motorcycle rear wheel swing-arm, they come off of the frame and down the swing-arm, minimal flexing.

2. Connection to the caliper. I like the banjo bolt type connection with the copper washer seal top and bottom. I think you might even be able to find this combo with a bleed screw built in to the bolt. IIRC, somebody rigged this up already, quite a parts list.

Rich, have a safe trip.

Gary

[slowmover]

How'd that boredom thing work out?

[GCinSC2]

Something about a sleeping Rottweiler and if it ain't broke don't touch it comes to mind.

Brakes are AOK ready for next trip. Just need to be able to do more trips.

[Al and Missy]

Guys,
I am not happy with the performance of the 12x2 drum brakes on my trailer so I'm seriously considering a disc brake conversion. After some reading of several threads on here I have sort of settled on the Kodiac integral rotor with their single piston caliper coupled with the Carlisle actuator. Until reading this thread I was going with the Dacromet coated caliper. The gist of this thread seems to be that the different metals of the piston and caliper are perhaps the leading cause of corrosion, which has me thinking about paying the premium for the stainless calipers.

I'm aware of the advantages (and disadvantages) of the 4-piston caliper and have settled in favor of the single piston for ease of bleeding.

I know that most on here have the Airstream-fitted disc brakes (Dexter) but I wonder if anyone has any information that might indicate my choices are not optimum.

Kodiak publishes some dyno test data for their brakes. Is similar data available for the Dexters?

Thanks,

Al

[GCinSC2]

Al,

No experience with Kodiac.

I can't prove this but my theory on MY situation started with axle replacements. The reason alone is a different story.

Axles ordered (AS paid the tab to boot!) Dealer calls, Gary you axle arrived. Huh, 1 axle, my 30' uses two axles. Call back to AS sorted that out.

Now the theory kicks in. The 1st axle was left outside and got rained on. Yes, we hope boots would have prevented rain getting in and NO I cannot prove my theory. That rainwater started corrosion between steel piston and cast iron caliper. Corrosion prevented pistons from returning and not creating brake drag. Brake drag overheated ONE axle only. That is the source of my theory.

Fast forward. Now I take full owner control of brakes, its now personal and one of us is gonna win.

My 9-5 job gave me a chance to go in deeper along with several decades of DIY skills. I setup a caliper rebuilding, new Dexter parts, lots of TLC and an actual DOT 3 based pressurization test on my bench to test leaking. Estimated max about 400 PSI.

OK, now MY secret sauce.

It took some searching but before I began reassembling the calipers I found grease that was used for caliper INTERNAL lubricating purposes. Remember it was me vs. calipers. I included a liberal amount of grease under dust boots to ward off corrosion.

The proof has been the miles and years of powerful 4 piston brake service.

The only update to this recommends possible annually inspecting the pad anchors for corrosion and applying external caliper grease to the pad anchors.

And as an aside this was a terrible typing experience due to lag as my PC says waiting for a litany of ads, ssp, n8, k stream, v.lqd and other junk at the bottom of my screen.

Disc brakes are good.

[slowmover]

Thanks, Gary.

[dznf0g]

Just as an fyi, and I'm not sure where I left this discussion, i got all air out and have just a barely perceptible lag with the Chevy itbc. Very happy with the setup.

[perryg114]

Consider using DOT 5 in the trailer brakes. It is not recommended for antilock brakes but should be fine for EOH brake. This will eliminate any corrosion issues which are more of a problem with trailer brakes since they sit for long periods of time. There are a lot of urban myths concerning DOT 5 and most are not true. I have a 91 Mitsubishi Eclipse and I put DOT5 in it when new. I still have the car and I have never had to touch the hydraulic system and it still has the same fluid in it.

Perry

[dznf0g]

Perry, I'll have to look again, but I believe my Actibrake info says DOT 3 only. Yes, believe it or not, my Actibrake actuator still works! When it fails, I think I'll go with Tuson.

[dznf0g]

I change my AS fluid every 2 years

[TouringDan]

Originally Posted by Al and Missy

Guys,

I am not happy with the performance of the 12x2 drum brakes on my trailer so I'm seriously considering a disc brake conversion. After some reading of several threads on here I have sort of settled on the Kodiac integral rotor with their single piston caliper coupled with the Carlisle actuator. Until reading this thread I was going with the Dacromet coated caliper. The gist of this thread seems to be that the different metals of the piston and caliper are perhaps the leading cause of corrosion, which has me thinking about paying the premium for the stainless calipers.



I'm aware of the advantages (and disadvantages) of the 4-piston caliper and have settled in favor of the single piston for ease of bleeding.



I know that most on here have the Airstream-fitted disc brakes (Dexter) but I wonder if anyone has any information that might indicate my choices are not optimum.



Kodiak publishes some dyno test data for their brakes. Is similar data available for the Dexters?



Thanks,



Al

Al

I also am not happy about the performance of drum brakes on my trailer. I am planning on installing disc brakes on my 66 Tradewind and have ordered Kodiak single piston calipers because of their ease of bleeding. My understanding is that these are available only for 10" disc brakes with 5 bolt hubs. This then requires new wheels be purchased.

Dan

[Al and Missy]

That may be the smallest size available, but I am ordering 12" brakes for 15" or larger (I have 16") wheels.

Al

[perryg114]

Keep in mind if you want to convert to disk brakes on 15" rims that many won't fit. The calipers stick out too far and hit the rim. I went through this on my trailer with stock alloy rims. Steel rims may offer more clearance. I ended up with self electric brakes. I would prefer disks but after seeing this thread, maybe not.

Perry

[GCinSC2]

A follow up for Dexter 4 piston disc brake systems about bleed screws.

A co-worker bought an Alfa Romeo Guilia and I spotted something that caught my attention, a visible bleed screw on the outboard caliper and a casting that sure enough is a 4 piston system. First time I've got hands on with a real factory automotive 4 piston system.

At the bottom a cross over tube just like Dexter, outboard caliper half has a bleed screw, inboard caliper half has a brake line attaching about in the middle of the caliper and wait here it comes: Another bleed screw on the top of the inboard caliper. Why two bleed screws?

Two bleed screws allows bleeding each caliper half independently of the other to get the last air bubbles out.

If your setup or how your Dexter 4 piston was bled without the use of a inboard bleed system, I bet your brake(s) still has air and the pump just keeps pumping and the lag is overcome with time.

My brakes are doing just fine, just need to use them more re: go camping!

If you pull a wheel, look at the dust boots around the pistons, tears or damage can allow water in and rust can do its thing, not good. They can be replaced but that's a different thread, someday maybe.

Put a log on your campfire.

Gary