Trailer Dramas

Hi all,

Just after some advice and help.....Decided to try and do a service on my trailer....I had a mate give me a hand at the start but he had to go before we finished the first wheel so i was sorta on my own  for it.....Plan was to swap out the bearings and disc brake pads. It is a dual axel Dunbier trailer with disc brakes. I finished it late today and went on a little slowish test drive (up to 50-60km max). After a few kms i stopped to check it and found two hubs were very hot and also two of my bearing buddies had come off. After letting it cool for a bit I drove back home slowly and parked it up....thinking i may need to call in the professionals....but thought i would suss out here first in case it is something simple.

I pretty much followed what i had read here/youtubed and mates advice. Some things i noticed during the service....was  that it was apparent the brakes hadnt been working properly for a while (rusted to glazed discs ...?heat damage and pads stuffed). I wash the trailer really well every trip with fresh water, but i am beginning to think that doing it at home and just parking it...hasnt been good....should drrive it to dry the brakes out etc.....will do that from now on......

I took the glaze/ rust off the discs carefully with a grinder and emery cloth...they came up nice and smooth and rust free...not sure if i should have binned them but thought that i would try and restore them. they seemed fine.

When putting in the new pads i had a hard time getting them in (i tried using a g-clamp and squeezing the piston back and releasing the bleed nut.....but it was still very tight and on one wheel i had to gently tap the brake unit onto the disc....this made it pretty hard to turn the wheel....i know it is meant to rotate freely.....this wasnt one of the hot hubs though.

I also made sure to back the castle nut back off a bit so it wasnt tight....but the wheel was pretty hard to impossible to spin freely....guessing this should have been a red flag I was doing something wrong??  .... with the brake unit i tighened up two nuts holding the slides up tight....not sure if this is correct? I also lubed up the slides with Magnesium grease.....used good Japanese bearings and high quality marine grease......

I realise I'm probably doing a few things don't crucify me......just after some advice......the videos etc made it look like a pretty straight forward wrong i was.... :(

thanks in advance

Jackfrost80's picture

Posts: 5040

Date Joined: 07/05/12

Sounds like you may have had

Mon, 2017-11-20 21:58

Sounds like you may have had the castle nut too tight as the wheel should spin freely.

When I put the hub on the axle I rotate the hub back and forward whilst tightening and loosening the castle nut with a wrench about 20 or so times. I then tighten the nut up just 'nut tight' and back it off one notch and I can usually loosen off the nut with my fingers at this tightness. Once I put the split pin through I tighten the nut against the pin and there is usually no or very, very little play in the hub. I regularly drive down south and my hubs are always cool to the touch when I stop after a couple of hours driving.

Hope that makes sense.


If catching wrasse is cool, consider me Miles Davis

Posts: 66

Date Joined: 27/01/10

Brake pistons are not backing off

Tue, 2017-11-21 00:34

Think you will find it is the brakes binding, as you already mentioned. The pistons should be able to be pushed back using both thumbs and a fare amount of force. If you had enough heat/pressure build up to pop the bearing buddies also check the rear seals are still located correctly.

My 12 mth service routine is bearing check/regrease and strip the brake calipers and clean all the pistons. Even stainless pistons get a sticky build up that stops them retracting properly.

Posts: 14

Date Joined: 07/01/16

thanks for the feedback guys.

Tue, 2017-11-21 06:46

thanks for the feedback guys. I think the piston sounds like my problem. I watched a good Youtube video last night where the guy showed how to pop them out (used compressed air.....not sure if this is the only/best method?). Mine pistons were definitly very hard to impossible to budge.......looks like i will have to pull them apart and lubricate them. What is the best lube for them?

I will also re-test the castle nuts.


The Saint's picture

Posts: 337

Date Joined: 30/01/13

Just a heads up, if you use

Tue, 2017-11-21 12:12

Just a heads up, if you use compressd air to pop out the pistons, use a piece of wood to absorb the impact, they come out fast.

And make sure you keep your fingers clear, cos it hurts like f*#k, I know, I done it.

Vinesh87's picture

Posts: 2757

Date Joined: 02/04/11

 Red rubber grease is what

Tue, 2017-11-21 12:33

 Red rubber grease is what you need but not very much!


Use a hand pump not a compressor to push the pistons out and use a rag and block of wood to stop them flying everywhere. Can be quite hard to get back in with the seals if they are tight. I have used a little air to push them out before!

ranmar850's picture

Posts: 2004

Date Joined: 12/08/12

Assuming you have discs on both axles?

Tue, 2017-11-21 07:04

 You'll have to deal with the brake issue first, no chance of getting the bearing preset right with binding discs. Even mechanical discs make checking bearings awkward, as you can't spin them to check for correct tension and listening for rumbles with the pad touching the caliper. You have to drop them off.  Get your calipers off to do as others have described above to get them operating properly, and check your preload with the calipers off. Turn the nut until it bottoms ( not really forcing it,) then back off slightly. Then you need to get the right tension with the split pin in. There is a little trick to this I have found very useful. If the correct tension seems to be halfway between two castellations, try a different castellated nut. These things are not all identical in their relationship between the slots and the thread ramp, and you'll probably find one of your other nuts will be a perfect fit. I've normally got a couple of spares in the toolbox, use them. You should be able to spin the wheel freely, and when it stops, it should just rock back the tiniest bit, IMO. Also no vertical rock when you grab the top and bottom of the wheel and give it a shake. 

Vinesh87's picture

Posts: 2757

Date Joined: 02/04/11

 Yeh sounds like your pistons

Tue, 2017-11-21 09:03

 Yeh sounds like your pistons are not releasing properly. If you lock ypur brakes up while spinning your wheel as soon as you release your brakes the wheel should spin freely again not sluggishly. When ypu push them on with clamp do they sit nearly flush? 


You can remove the pistons and clean then all and install new seals i do this every 2 years now and i have 6 calipers!! 


The heat could also be generated by castle nut too tight or maybe the races are not in correclty? 


What are you brake calipers?

Walfootrot's picture

Posts: 1337

Date Joined: 23/07/12

Take it to a shop and get it

Tue, 2017-11-21 09:24

Take it to a shop and get it fixed, cheaper in the long run IMO


More drum lines, kill the bloody sharks!

Posts: 675

Date Joined: 09/10/06

 Fremantle trailers will sort

Tue, 2017-11-21 15:55

 Fremantle trailers will sort it for you if you get stuck. Sounds like your calipers are trigg hydrolic. I found these easier to service than alkos.  Yes compressed air to remove piston. Watch your fingers. Use fine emery paper to remove any rust build up on piston and were piston sits. . Remember to  put bleed nipples at top and bleed the brakes once fitted.