M101A2 brakes problem

[TXH3T]

Alright after looking through several threads here I can't seem to find what Im looking for. I bought an M101A2 from a guy recently and have been towing the trailer all over including an 8 hour drive out for a camping trip. While driving I noticed that the trailer jerked the truck while braking sometimes as well as occasionally shaking in intervals of three seconds or so at highway speed. These may not be related to my brake problem but I wasnt sure. I realized they werent working at all when I (not thinking) backed the trailer up my driveway. After parking I stopped and realized the brakes should definitely have applied. I disconnected the trailer and sure enough the darn pintle doesnt move at all when I try to push or pull on it. I'm not really sure where to start with trouble shooting here any help would be greatly appreciated. Heres a picture of the hitch and box. Looks pretty rusty maybe could have seized?

 

[Nonotagain]

Remove the two nuts on the vertical bars and then see if the lunette will move. If not then you will have to remove the bolts holding the master cylinder to the housing out after removing the brake line.

There is a flat piece of metal that activates the master cylinder that is supposed to be held back by a small shock absorber. The shock number is 2044-1. It's mentioned in numerous postings.

While you have the MC removed check condition of the fluid. Should be translucent blue is there is still silicone brake fluid in use. If it's rusty, time for a new or rebuild your current unit.

 

[TXH3T]

Thanks ill post report tonight of what i find

 

[KsM715]

In the photo it looks lke the break-away has been pulled and locked into position. That may have worn the brake shoe down.

 

[Nonotagain]

In the photo it looks lke the break-away has been pulled and locked into position. That may have worn the brake shoe down.

I don't see any teeth showing on the break-away paw. I doubt that it's engaged. I could be wrong.

If the OP attempted pushing the lunette rearwards after the brakes were applied the lunette won't move. If you crack the brake line open and the lunette moves it's probably master cylinder time.

Silicone brake fluid is a curse on vehicles in-frequently used as the water pools in the lowest parts of the system, the wheel cylinders and master cylinder.

I haven't seen a lot a brake issues on master cylinders that are vented via a hose. The ones that are top vented appear to have the majority of the issues.

As my trailers are serviced, I'm replacing the DOT 5 silicone with DOT 4. That way all of my vehicles can use a single brake fluid and I can use my power brake bleeder on all of them.

 

[KsM715]

Your right, I went out and looked at mine to see how far out it sits when not engaged. Came back and compared it to the photo.

 

[TXH3T]

Ok so How much should the Lunette move when I push on it. Its barely noticeable but maybe I didnt remove enough. Here's the nuts I removed.

 

[Nonotagain]

Ok so How much should the Lunette move when I push on it. Its barely noticeable but maybe I didnt remove enough. Here's the nuts I removed.

Remove the straps and see if you can move the lunette in and out. It should move 1-1 1/2 inch maybe a little more in and out.

If it won't move then break the line going to the master cylinder lose and see if the lunette moves.

Usually if you get movement after that it means that the MC is rusted up.

 

[TXH3T]

alright so I removed all those pieces and im getting some movement but I dont know if its working properly. I can get it to move but I cant push the lunette straight back. Heres a video. sorry for quality. http://s293.photobucket.com/albums/mm42/GTO4628/?action=view&current=71984e57.mp4

 

[Nonotagain]

alright so I removed all those pieces and im getting some movement but I dont know if its working properly. I can get it to move but I cant push the lunette straight back. Heres a video. sorry for quality. [media]http://s293.photobucket.com/albums/mm42/GTO4628/?action=view&current=71984e57.mp4[/media]

The video quality is fine.
Part of what you are feeling/
seeing is the shock absorber resistance. There still appears to be a lot of resistance.

Break the line on the MC lose and slowly push the lunette rearward. Stop and hold at that point and tighten the line. Pay attention to the color of the fluid. If brown, it's MC rebuild or replacement time.

 

[TXH3T]

Pushed it back fluid was decently clear but yellow. Quite a bit came out though before I got to tighten the line again hopefully that won't ruin anything. Is it possible the former owner used a different color fluid

 

[Nonotagain]

Pushed it back fluid was decently clear but yellow. Quite a bit came out though before I got to tighten the line again hopefully that won't ruin anything. Is it possible the former owner used a different color fluid

You probably have some air in the system but not a big deal for now.
Different color fluid? Different type, possibly, meaning not silicone.

Jack the trailer off it's wheels, spin the wheels and see if the brakes are dragging. While it's up, have someone push back against the lunette and bleed the brakes, both wheels. Bleed just like a car, pumping the unit, holding and releasing the fluid It will take 5-6 cycles to get the air out from the MC back.

While you've gone this far, pull the shock asorber and see if it's still got resistance. Most older trailers had leaky shocks. This accounts for the jerky brakes on stops and hitting bumps.

Clean and lube the plastic bushings on the vertical flats and attach them back again.

That's trouble shooting the surge brake system.

If your still having problems, I'm at a loss for anything else to try.

 

[TXH3T]

I truly appreciate your help thank you. I will get some equipment to hold up the trailer tomorrow and someone to help me hopefully.