Brake Stuck On?

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

Post Reply
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Brake Stuck On?

Post by reecewallace »

I just put new tires on my 170b, and once I got it back from the shop my left brake begun sticking.

It rubs quite aggressively, and my plane pulls to the left on taxi. Immediately after taking off, the wheel stops spinning too.

The caliper also doesn't 'float' when I move it by hand as it should—the piston is extended and pushing the pads onto the rotor causing it to rub aggressively.

What could be causing this?

I brought it back to the shop, and my mechanic took the brake apart, cleaned it, greased it, then re-bled the system. This fixed it for just a day, then the next flight the pads were pushed up against the rotor again rubbing.

Suggestions?

Is there a new seal or rebuild kit for these calipers?

Notes*
1. The brake feels good, no squishiness, just rubbing a lot
2. My rotors are worn significantly—they have a small lip at the outer edge (time for replacement soon)
- the mechanic said he believes worn out rotors can cause pistons to push too far out and get stuck in the ON position, though I'm not sure about the validity of this
3. Still lots of pad life left

Cheers from rainy Vancouver, Canada
Attachments
IMG_7123.JPG
IMG_7125.JPG
IMG_7126.JPG
IMG_7127.JPG
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
User avatar
GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: Brake Stuck On?

Post by GAHorn »

The pistons don’t actually “retract” after brake release….. they just don’t apply pressure against the pads. If your caliper doesn’t “float” …I believe that may be at least part of your problem. Are the pins bent? Dirty? Scored?
Are the bores clean and smooth and round? (When I do brakes one of the things I do is run a rifle-bore brush thru them, then lubricate them with dry aerosol lube.)


Meanwhile you might turn your discs to true them up if they’re not too thin already. If you know the part numbers I can look up the minimum for you.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Re: Brake Stuck On?

Post by reecewallace »

GAHorn wrote:The pistons don’t actually “retract” after brake release….. they just don’t apply pressure against the pads. If your caliper doesn’t “float” …I believe that may be at least part of your problem. Are the pins bent? Dirty? Scored?
Are the bores clean and smooth and round? (When I do brakes one of the things I do is run a rifle-bore brush thru them, then lubricate them with dry aerosol lube.)


Meanwhile you might turn your discs to true them up if they’re not too thin already. If you know the part numbers I can look up the minimum for you.
Pins — you mean the bolts which hold the caliper onto the wheel, correct?

Maybe they damaged them when they removed the wheels to change the tires and this could be causing the problem
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
User avatar
GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: Brake Stuck On?

Post by GAHorn »

Reece , here I’ve illustrated the PIN which slides thru the BORE and allows the CALIPER to “float”.
click to ENLARGE
click to ENLARGE
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
User avatar
Bruce Fenstermacher
Posts: 10313
Joined: Tue Apr 23, 2002 11:24 am

Re: Brake Stuck On?

Post by Bruce Fenstermacher »

Your mechanic could be right. Your disks may be to thin. It may be time to remove, flush and clean the caliper of dirt and grime that might be causing the piston to jam. While you are at it polish the pins with Scotchbrite and slide the brake pad over it to make sure it slides easily on the pins and also the caliper slides easily in the bracket. Loosen the hose and reposition it so all this movement happens. Often tension from the hose will make a calper cock of and not slide in the bores as it should.

Easy to measure the disk with a micrometer and look in the Cleveland service limits table in Appendix A.
AWBCMM0001-12.pdf
(979.33 KiB) Downloaded 170 times
Don't know what disk you might have? Look in the Parker Hannifin (Cleveland) product catalog.
AWBPC0001.pdf
(34.81 MiB) Downloaded 185 times
Of course the disk you have should be recorded in your logs either with a 337 field approval or using an STC
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
User avatar
c170b53
Posts: 2527
Joined: Mon Apr 22, 2002 8:01 pm

Re: Brake Stuck On?

Post by c170b53 »

Sidewall contact ?
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
Metal Master
Posts: 526
Joined: Thu Dec 02, 2004 1:52 am

Re: Greetings from Brazil

Post by Metal Master »

If your airplane is equipped with Cleveland Wheel and Brake STC for the 170 the kit number will be199-46 the disc for that kit is 164-02601, the minimum thickness for that brake disc is 0.205/5.207 = Inches/millimeters. Unless it has been modified by some other means which I have found to be true of some airplanes I have looked at being re imported back to the United States.
Regards,
Jim
A&P, IA, New owner C170A N1208D, Have rebuilt some 50 aircraft. So many airplanes, So little time!
User avatar
Joe Moilanen
Posts: 596
Joined: Sun Dec 28, 2003 5:45 am

Re: Brake Stuck On?

Post by Joe Moilanen »

c170b53 wrote:Sidewall contact ?
Those were my thoughts also, especially when it just started after the tire change. Different tire brands have different profiles. Are they 800's? When I went from 700's to 800's I had to make a spacer disc to go between the brake disc and the inner wheel half to keep the caliper from rubbing on the tire...

Joe
4518C
User avatar
Richgj3
Posts: 189
Joined: Wed May 27, 2020 3:13 pm

Re: Brake Stuck On?

Post by Richgj3 »

Also check that the brake line is not side loading the caliper which impedes the caliper from floating freely. I had this exact problem on my new to me 170. Brakes were not dragging enough to stop the wheels but they would make a scrapping sound. I took them apart three times to lube them. That lasted one day each time. The local mechanic fixed it by moving the lines so they parallel the gear legs rather than having the loop you show. He said he see that a lot on 172’s.
Rich Giannotti CFI-A. CFI-I SE.
1952 C170B
N2444D s/n 20596
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Re: Brake Stuck On?

Post by reecewallace »

Richgj3 wrote:Also check that the brake line is not side loading the caliper which impedes the caliper from floating freely. I had this exact problem on my new to me 170. Brakes were not dragging enough to stop the wheels but they would make a scrapping sound. I took them apart three times to lube them. That lasted one day each time. The local mechanic fixed it by moving the lines so they parallel the gear legs rather than having the loop you show. He said he see that a lot on 172’s.
Thanks for this. Sounds like it's likely the culprit. I'll adjust the brake line so there's no tension on it impeding proper caliper movement and go from there.

Cheers!
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
User avatar
mmcmillan2
Posts: 161
Joined: Sat Jul 04, 2020 9:30 pm

Re: Brake Stuck On?

Post by mmcmillan2 »

Subscribed. I have a squeaky brake after installing new pads.
170B owner, KCFD, CFI(I), ATP Multi
User avatar
c170b53
Posts: 2527
Joined: Mon Apr 22, 2002 8:01 pm

Re: Brake Stuck On?

Post by c170b53 »

Likely any side load from the brake line is due to the flex lines, no longer flexing. It looks like the normal black color flex lines are whiteish in the pic, a sure sign that they are somewhat due for replacement.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Re: Brake Stuck On?

Post by reecewallace »

Turns out the pistons were seized inside the caliper. Re-bored the caliper and replaced some seals, fixed the problem.

Brake line is the flexi fabric one, so not the issue causing the jam.
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
User avatar
c170b53
Posts: 2527
Joined: Mon Apr 22, 2002 8:01 pm

Re: Brake Stuck On?

Post by c170b53 »

I brought it back to the shop, and my mechanic took the brake apart, cleaned it, greased it, then re-bled the system.
Re-bored ? or just Re-cleaned with Scotch-brite ? :D
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Re: Brake Stuck On?

Post by reecewallace »

c170b53 wrote:
I brought it back to the shop, and my mechanic took the brake apart, cleaned it, greased it, then re-bled the system.
Re-bored ? or just Re-cleaned with Scotch-brite ? :D
Re-bored!
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
Post Reply