Brakes won't lock

[saskrick]

A quick question for the brake experts here. I have a 2010 nt 31bdss with about 600km on it. When I bought it new I didn't think the brakes were all that strong. I recently bought a f150 max tow screw which has the integrated brake controller. I checked the brakes and ended up tightening 3 wheels two clicks and one wheel eight clicks for whatever reason. Still can't lock up the wheels on gravel road. This was at around 40-50 km/h and the brake setting on 10. They do grab pretty good at the low speed but no lockup. Is this normal?

 

[GOTTOYS]

Re: Brakes wont lock

Mine don't lock either. According to one of the manufacturers websites, maybe Dexter, I don't remember, they're not supposed to. I can't see what you would gain if they locked..Don

 

[brianharrison]

Re: Brakes wont lock

I would say that's normal. It sounds like you know the integrated controllers use the vechicle speed to proportion signal to the brakes. It is hard to get them to lock up at any speed.

Set them so that you get a good tug at >30 km/hr. I have my Ford integrated set at 6.5 gain.

Keep an eye on your adjusted brakes and check after a short pull - you may have inadvertently adjusted them too much and have them rubbing without any brake signal. Take care!

Brian

 

[lwmcguir]

Re: Brakes wont lock

A quick question for the brake experts here. I have a 2010 nt 31bdss with about 600km on it. When I bought it new I didn't think the brakes were all that strong. I recently bought a f150 max tow screw which has the integrated brake controller. I checked the brakes and ended up tightening 3 wheels two clicks and one wheel eight clicks for whatever reason. Still can't lock up the wheels on gravel road. This was at around 40-50 km/h and the brake setting on 10. They do grab pretty good at the low speed but no lockup. Is this normal?

I like to check mine at around 10mph on gravel. I set the gain so they will lock up at that speed with the brake full on. By setting it this way they wont lock up at higher speed but will apply enough brake to stop the coach. That is all you want to do is stop the coach on its own, not drag / stop the TV. I have been setting them this way going back to when we tied the brake controllers directly into the brake lines.

 

[TandT]

Re: Brakes wont lock

A quick question for the brake experts here. I have a 2010 nt 31bdss with about 600km on it. When I bought it new I didn't think the brakes were all that strong. I recently bought a f150 max tow screw which has the integrated brake controller. I checked the brakes and ended up tightening 3 wheels two clicks and one wheel eight clicks for whatever reason. Still can't lock up the wheels on gravel road. This was at around 40-50 km/h and the brake setting on 10. They do grab pretty good at the low speed but no lockup. Is this normal?

Dumb question, have you ever pulled one of the drums and looked at the condition of the brakes?
My first set of brakes, I had all kinds of problems. When the tech pulled the wheels, the brakes were shot. Never installed and adjusted properly.
I had them replaced and have not had anymore problems, after 10K miles. (Knock on wood) Trace

 

[saskrick]

Re: Brakes wont lock

no, i never did take them apart. I guess I thought it was new and should be good. When I adjusted them, I snugged them up until they were kind of hard to turn and them backed them off eight turns. For three wheels that ended up being two clicks tighter than previous. One wheel ended up being eight clicks more. I guess if I have time, I'll check, but right now the work list is pretty long.

 

[TeJay]

Re: Brakes wont lock

Tandt is putting you on the right track. Just tightening the star wheel without knowing the condition of the linings can be futile. Also backing off the star wheel 8 clicks seems a bit much. I usually tightened as you did then back them off about 3 clicks. The shoes have to be close to the rotating drum for the self-energizing action to occur. If they are to far away your braking will not be very good. First you should inspect all 4 wheels to determine the condition of the drums, linings, and springs. I just recently read a post where a new low mileage trailer had 3 of the 4 wheels covered with grease from the factory. It's possible the linings and drums have been covered with bearing grease. If so then they both should be replaced. Cast iron is porous and grease will enter the cast iron and it's impossible to get it out. They will never be a good friction surface for the linings and friction is the name of the game when it comes to good brakes. Here's something that just dawned on me after having answered countless questions regarding bearing packing. It is my educated guess that the lubricating system introduced (grease fittings with holes in the axle) to allow easier packing of the bearings is the primary reason many, many brake systems fail. They fail because of a series of conditions. The ability to force feed a lower viscosity (thinner) grease to lube the bearings is providing a real good opportunity to put to much into the system. The inner seals fail and grease is allowed to contaminate the shoes and drums rendering the brakes useless. If they are packed the old fashioned way they should need no service for 30K plus miles. Also always use a good synthetic bearing grease.
TeJay

 

[TeJay]

Re: Brakes wont lock

Two other points. I usually run with a brake controller setting of 3.5. That seems to work for me. We're only pulling 7,500 lbs. so if your rig weighs more then your setting will be higher. I like brianharrison's (post#3) comment. Adjust your controller until you get a good tug. That makes good sense. I think there are to many variables to use locking up the wheels as your indicator.

Hope this helps
TeJay

 

[saskrick]

Re: Brakes wont lock

Thanks for all the replies. I'll give them an try and let you know. It won't be for a week or so.

 

[brianharrison]

Re: Brakes wont lock

Set them so that you get a good tug at >30 km/hr.

I should clarify - the"good tug scenario" is using the manual slide switch on the Ford integrated brake controller; ie manually applying trailer brakes at speed around 30 km/hr (20 mph). Pushing the truck foot brake pedal and feeling a good tug would certainly be too much gain.

Brian