Air Breaks: Meritor Disc Brake Helper Springs

There was quite a bit of discussion about these Meritor helper springs in the past because some folks have found brake disk pads very heavily worn on one end because only one slide pin was stuck. This was generally on the rear brakes.

I had driver side front brake stay engaged sufficiently to become smoking hot. I could smell the burning brake pads from the driver seat. I stopped and pounded on the caliper, which cleared it so that I could get home. At home, I cleaned all the brake caliper pins in place using cut strips of plastic scrub cloth. Awkward but doable. Calipers have not stuck for the last two years because I clean them annually without dismantling. Wyatt 96 U320 40

Here are some pictures of the Meritor disc brake helper springs and some installation and greasing tips.  If you have the brakes inspected and the slide pins cleaned you should have the helper springs installed. I cannot imagine much-increased cost beyond the cost of the spring kit (about $18.00) at the time of pin cleaning because the pins have to come out to be cleaned and the springs just slide in. The spring kit (Meritor P/N KIT15018) contains the two springs required, one for the upper pin and one for the lower pin. The thread at the end of the slide pin is a 3/8 -16 and using a 3/8 bolt makes it easy to pull the pin and hold it while cleaning it. The maintenance manual allows light lubrication of the slide pins after inspection and cleaning;

 “18. Clean, inspect and measure the slide pins and bushings. Refer to Section 12 for information about cleaning the brake components.

A. Clean the slide pin. Remove any paint or other material from the pin. Replace the pin when you find burrs, nicks, corrosion, or other damage. Lubricate the slide pins lightly with WD-40, Spray CRC or a similar product.”

I use a silicone spray that leaves a dry film.

There has been a lot of talk about not greasing the calipers too much. I would say the real issue is improper greasing. You could grease the calipers once a month if you wanted to. You just have to do it correctly. Just follow the instructions in the maintenance manual. Of course, it is not necessary to grease that often and it has been 4 years (about 15K miles) since my brakes were inspected and greased. Upon regreasing, the old grease looked ok but the pins had some residue on them. At one point I had some brake squeaking and I sprayed some of the aforementioned silicone sprays on the pins and that seemed to take care of the squeak. 

The residue on the pins looked like it had been on there for a while and not accumulated as a result of the silicone spray. I took the pins out, cleaned and inspected them and reinstalled with the helper springs and greased the calipers. I now have a baseline for the condition of all four of my brakes and have formulated a maintenance schedule for them based on their current condition and depending on what mileage I put on.

GREASING TIP; Slack adjustment pawl may be locked open with a small ignition wrench, the one seen in the pic is an 11/32 about .090 thick.

In each kit, there are two springs and that will do 1 caliper, one for top pin, one for the bottom pin. So for a 2 axle coach you need 4 kits. I do not know what there are for brakes on a tag axle. I bought from here KIT15018-MERITOR-KIT-SPRING. They have gone from $17.66 per kit to $20.08 today

Here are some before and after cleaning on my coach. Rick D. 1995 U-300SE 40′

There is a soft recall for our brakes and Meritor recommends the helper springs. It prevents the brake from dragging.  I had a front brake drag a bit and that started the whole process.  I know a friend had one drag on the way to a rally too.  I have not had any issues since the helper springs were installed. They are recommended for the front wheels by Meritor. John S.2001 U320 42′

This shows the corrosion and if you run your hand along with it you feel ridges where the destruction is easily felt as well as seen. Mike 2001 U320 40′