Calipers twisting off?

Glassguy54

Have had this happen twice now. I'm going down the road, then I think I hear clanking noises, pull over and discover the disc brake caliper has sheared off of the mounting plate on the axle! Luckily the caliper is captured between the wheel rim and the rotor so it doesn't come flying off,  hitting any other vehicles. When I remove the tire/wheel assembly to extract the caliper, one caliper bolt is sheared off, but the other is missing in action! And one ear on the mounting plate (it is a square piece of steel welded to the end of the axle with a hole in each corner, tho only 2 holes are used to mount the caliper) is torn so that there is no longer a hole, but more like a letter "C" where the open part has torn through the edge of the mounting plate, allowing the caliper to work free and detach. It seems that one bolt must somehow be backing itself out, then with only one bolt left to hold it, the caliper is able to pivot back and forth during braking and fatigue the metal to the point of tearing through. It has been the bottom bolt on both calipers that has disappeared. It is difficult to get a wrench on the bottom bolt to loosen/tighten, so maybe at the factory (Heritage) these don't get sufficiently torqued? Any one else ever have this happen? Its a dual axle trailer for a 246 Captiva. I replaced one caliper in July '13, (first one to tear away) had a caliper replaced Monday in Tennessee because it wasn't releasing all the way and was heating up. Last night outside of Hannibal, Mo. the other one tore free so I've ordered 2 calipers so by next week I will have replaced all calipers. I'm applying thread lock to the bolts and will make darn sure those bottom ones are secure!

Handymans342

Are they all stainless bolts and Calipers? I think there is a special thread lock for stainless but cant remember. 

Black_Diamond

Stainless to stainless fasteners need special anti-sieze, not thread locker. A properly torqued fastener will stay in place. Also make sure you are using the correct grade of fastener. 

Glassguy54

Calipers are zinc coated steel. UFP DB 35 (Unique Functional Products). UFP supplies bolts with Caliper and states Loctite 242 may be used in lieu of star washers.

212rowboat

I'd still use the star washer. I'd seek out nylon lock nuts.  The supplied bolts obviously ain't quality.  There is sheer strength and torsion strength, and it sounds like these things may have the clamping power, but in combo with them working loose, the lack of sheer becomes apparent.  

I'd use red loctite in a heartbeat... It takes heat to release it, and they won't come off without considerable heat.  I'd also step up to stainless grade eight, with nylon nuts securing them.. 

Your problem isn't common, but I bet using the supplied fasteners is, ya know? 

Glassguy54

Bolts pass through mounting plate from inboard side and into threaded lugs on the caliper. Don't see how it would be possible to utilize nylon lock nuts.  

212rowboat

Oh.. thought they went all the way through... 

jhofmann

If you use loctite use the blue. As 212rowboat says it takes heat to release the red loctite and heating the caliper would ruin the seals. 

JC290

Al is right and 212 is right your bolts are junk to be frank about it. Take them to NAPA and replace them with ones made in the USA as they must meet a higher standard than China made ones. 

Glassguy54

Yeah, I don't know where  UFP has their calipers manufactured, but would not be surprised if it were China. And Chinese hardware/fasteners, I am well familiar with their lack of quality and strength.

NRath

Anybody know of a torque spec for the caliper pin?  If is stainless going into galv stl and mine clearly has residue from red loctite and no star washer.  I would hedge my bet that it's never been apart before.

Torque spec for lugs would be nice too, if a # is floating around.  If not, I'll go to 90.

212rowboat

Lugs generally to #120... But not over, because the stud loses its ability to snap back.   I've heard some say 90, and others say 180, and witnessed most tire shops torque them to the air ratchets capacity of #400+... That's frustrating... 

The floating calipers on my super duty are torqued to 80#, and the caliper housing to 120# and using blue loctite..

Realize when you wet the threads, torque specs are only ballpark... Dry is only way to get a specific torque, unless the manuals call for dressing of some sort... We're not talking about internal engine parts or sealing/marrying surfaces, so my guess is tight is good, so long as it stays tight.  

NRath

Back to the OP's issue- I think I'm having a similar issue to what I believe would cause your broken pins- the calipers aren't releasing.  I had both my brakes off this weekend as I'd previously noticed one side wouldn't spin relatively freely when jacked up after both unhooking the truck and then using the truck to pull forward a little ensuring no rearward pressure is on the master cylinder.  The other side works as expected.  Pins on both sides were pretty clean with no caliper binding on either.  The brake pads don't really show that though as the caliper side (outside) is almost gone, while the piston side looks to be near 100%.  Apparently the piston isn't returning back into the bore when the brake is released.  Using a c-clamp to push it back in, then the master to push it back out- it seems to be moving pretty freely.  This would seem like a condition that would potentially fatigue and break the stainless pins over time.  Unfortunately, this isn't offering any solutions.  I need to take apart the front end of the brake system to see what's in there to offer any more.

Robs_232

I had a similar issue this spring on my Trailmaster trailer. Brake on one side would not release and was dragging. Opened bleed screw and there was no pressure remaining. Took caliper off and could push piston in with C clamp, reinstalled and tried brakes, would drag again. Pad on piston side was 1/2 as thick as what outer pad was. I removed the caliper to see why piston wasn't releasing. The Zodiak brakes have a piston seal that has a steel piece that keeps it in place. The steel had rusted and corroded around the stainless piston. Piston cleaned up nice. I ended up replacing both complete calipers with pads for about $80 each from e-trailer.com. They work like a dream now.

Robs_232

Regarding torque specs. If you look up Loadmaster trailers they have a service manual section for brakes, hub, axles, etc. which would be pretty consistent across the board I would think, unless stainless. If you look up Kodiak brakes they do offer all stainless brakes, which they should also show torque spec's for these online. 

Glassguy54

I have  a Heritage trailer that came with UFP (Unique Functional Products) calipers that bolt onto the mounting plates on the axle ends. I have now replaced ALL 4 calipers and replaced the supplied bolts with grade 8 bolts and used Blue Loctite. It is going to be standard procedure to routinely check the mounting bolts from now on, and in addition, in the off season, I'll probably dis-assemble the calipers to ensure all seals, pistons, etc. are in good working order. Can't afford to ignore trailer maintenance.

NRath

My aluminum RoadKing Trailer came with TieDown Engineering brakes.  The torque spec for the stainless caliper slide pins is 40 ft*lbs.  Not sure which you have, but over-torquing would be a sure fire cause of failure.  Red loctite is also recommended by Tiedown.

JC290

UFP DB-35 caliper mounting bolts for use with UFP Brand DB-35  brake caliper. 7/16" -20 x 1 1/8" mounting bolts with LOCTITE.

PLEASE NOTE: Mounting Bolts come standard with LOCTITE #242 ( torque each caliper bolt to 55 ft. lb.)  When LOCTITE is used, star washers aren't required..
  
UFP #33090 Caliper mounting bolt for DB-35 series disc brake caliper - Sold as each.

manufactured overseas head marking on them doesn't match any manufacture I know of in the states. They are only grade five from the pictures I've found. If I were you I would use the star washer and lock tight if you are using these bolts and make sure they are torqued to spec and check them periodically. Good Luck 

JC290

UFP DB-35 caliper mounting bolts for use with UFP Brand DB-35  brake caliper. 7/16" -20 x 1 1/8" mounting bolts with LOCTITE.

PLEASE NOTE: Mounting Bolts come standard with LOCTITE #242 ( torque each caliper bolt to 55 ft. lb.)  When LOCTITE is used, star washers aren't required..
  
UFP #33090 Caliper mounting bolt for DB-35 series disc brake caliper - Sold as each.

manufactured overseas head marking on them doesn't match any manufacture I know of in the states. They are only grade five from the pictures I've found. If I were you I would use the star washer and lock tight if you are using these bolts and make sure they are torqued to spec and check them periodically. Good Luck