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View Full Version : Brakes Engage While Travelling Down Hill


Skipper
06-11-2008, 02:23 PM
The brake actuator engages the brakes while driving down long hills. This causes the brakes to be applied while driving at highway speed going down hill. As a result the brakes are hot, damn hot. The actuator disengages when driving up the other side of the hill.

Can I simply replace the shock absorber inside the actuator to resolve this issue? If not, where can I find that type of actuator ('95 Prostar, single axle, drum brakes)?

Notes:
I have tested the brakes by raising one wheel off the ground, spinning the tire, then pushing the actuator inward. The wheel stopped turning. When I pulled the actuator back out, the wheel was free to spin again. (did both sides)

I have cleaned and lubed the actuator. I ensured that it moves freely forward and backward. When pulling away from the drive it disengages. When stopping, it engages.

I have removed, cleaned/inspected, and reinstalled the brake shoes and hardware. I have tested the wheel cylinders with a "C" clamp and they function properly.

I have replaced the bearings, races, and grease seals. Gonna have to do it again once I finally resolve the hot brake issue.

ShamrockIV
06-11-2008, 02:27 PM
i have the same issue when i pull my trailer empty!!! it locks up tight and jumps!!!
knoxx2 says he has the same problem!!

is ur issue with the boat on there???
i figure mine is because it is setup for a load!!

sorry if i threadjacked u!!!

flipper
06-11-2008, 02:28 PM
Are you down shifting? That will make the brakes engage.

TMCNo1
06-11-2008, 02:36 PM
The shock absorber inside has probably failed.
If you have a UFP (Unique Functional Products) actuator, axle and breaking system, see their site here, http://www.ufpnet.com/ , click on "Actuators" review the PDF's and they can direct you as to what is going on if the tutorials don't help, if you contact them.

russlars
06-11-2008, 03:09 PM
You may also consider taking it to a brake or tire shop that works on brakes and have them check it. (Les Schwab is where I go) It seems to me that they were able to adjust my actuator on one of my trailers to make it less sensitive so that it engaged only on hard braking.

Skipper
06-12-2008, 07:32 AM
Problem is the shock absorber in the actuator. Turns out my friend had a similar problem. Said it is an easy fix to pull the guts out and replace the shock absorber. The tough part is getting all the pieces to stay in the right place when putting it back together. 34 bucks for a new shock absorber and an hour of work.

Skipper
06-15-2008, 09:42 AM
I replaced the shock absorber on the brake actuator. The system is fully mission capable again. It was very easy work. I was able to download the manual from the internet. Found a parts supplier on the internet. I spent less than $50 on parts. Replaced the shock absorber, bushing, bolt, and emergency cable assembly.

I ran into a little trouble from years of corrosion. But the repairs took less than two hours. Spent another 30 minutes to bleed the brakes. The old shock absorber was clearly inoperative.

TMCNo1
06-15-2008, 09:53 AM
I replaced the shock absorber on the brake actuator. The system is fully mission capable again. It was very easy work. I was able to download the manual from the internet. Found a parts supplier on the internet. I spent less than $50 on parts. Replaced the shock absorber, bushing, bolt, and emergency cable assembly.

I ran into a little trouble from years of corrosion. But the repairs took less than two hours. Spent another 30 minutes to bleed the brakes. The old shock absorber was clearly inoperative.


Good to hear Bill, that was my first though, glad it worked out!