Auto Reverse not working

[gpsguru]

Originally Posted by Sargan

I think the design relies on this ‘trip’ happening based on an expected range of movement .... as trailer ages ... the drums wear (estimate about 4mm off thickness .. therefore 8mm larger diameter) meaning shoes to travel further to ‘brake’
You adjust brakes shoe gaps ... but they will operate at different bearing angle on cam.

I have been following this thread with interest .............. ........... auto reverse is a 'must have' and it would be good to get it working ......... one of my 2T GP trailers has a manual latch reverse and it is a pain in the bum !

If the drums had worn by 4mm, then there would be a 4mm wear ridge on both the inside edge and the outside edge of the drum and this would not only be obvious but it would also make the drums quite difficult to remove and refit easily. 4mm would be a very serious amount of wear (probably several sets of shoes worth !). TBH, with 4mm of wear the actual drum would be paper thin !

I am thinking that maybe in the long and distant past the drums have been replaced, but whoever did the replacement failed to notice that the drum inside diameter was different as it would look the same as the orginal to the naked eye ............. there are probably several drums that will fit that axle as trailer axle stubs are fairly universal amongst different manufacturers.

I have only every come across this issue once with the rear disc's on our Jeep Cherokee. The Disc has an internal mini drum for the handbrake shoes. After I had rebuilt the brakes I was unable to get the handbrake to work to my satisfaction .......... after much cursing, a final stripdown revealed that the internal drum diameter was 1.7mm more than the orignal. The brake manually adjusted perfectly, but it was actually causing a serious issue with the handbrake cable auto adjuster and the brake would not relaibly completely release ........... the correct disc's fixed the issue.

[Sargan]

I explained that there was 4mm wear that was observed - not a guess.
There was a distinct 4mm step around the edge of the drum.
In 2017 start of season service ... I was replacing shoes and new shoes could just catch on the lip.
So I turned off the lip on a lathe, on each drum.
I did not ski anything off the diameter - only the lip.

The boat was fine for a full 12 months after doing that job.

[gpsguru]

Originally Posted by Sargan

I explained that there was 4mm wear that was observed - not a guess.
There was a distinct 4mm step around the edge of the drum.
In 2017 start of season service ... I was replacing shoes and new shoes could just catch on the lip.
So I turned off the lip on a lathe, on each drum.
I did not ski anything off the diameter - only the lip.

The boat was fine for a full 12 months after doing that job.

Ah ......... ok, I am on the same page now and fully understand ......

4mm wear is pretty excessive for drums, but I guess that dunked in the sea and maybe a little stiffness on the mecanism is going to cause some excessive wear.

Like you, I would guess that the little extra wear in the last 12 month is just enough to cause this issue ..............

On my last braked boat trailer I fitted a hub flush as well as bearing savers ............. to be fair the hub flush worked really well when compared to the components condition of previoulsy not having it.

If you have a friendly trailer dealer, they just might let you have new drums on sale or return to try out (I know mine would) ......... drums are cheaper then axles !

[smallribber]

let it lie or you will waste more of your life on this.

[Sargan]

Originally Posted by gpsguru

Ah ......... ok, I am on the same page now and fully understand ......

4mm wear is pretty excessive for drums, but I guess that dunked in the sea and maybe a little stiffness on the mecanism is going to cause some excessive wear.

Like you, I would guess that the little extra wear in the last 12 month is just enough to cause this issue ..............

On my last braked boat trailer I fitted a hub flush as well as bearing savers ............. to be fair the hub flush worked really well when compared to the components condition of previoulsy not having it.

If you have a friendly trailer dealer, they just might let you have new drums on sale or return to try out (I know mine would) ......... drums are cheaper then axles !

4mm wear does seem a lot .. but this is 2.2 tonne and over 5 years, so under 1mm per year .. which then does not seem so bad. Trailers have fairly basic cast iron drums. Being dunked in salt water ... so surface oxidation is considerable.

The SRC 5.5 trailer has hub flush and bearing savers as standard - so both of those in use.

Interestingly I went to Indespension . and fitter advise - hub flush, that your problem, squirting water over mechanism & hubs is causing the issue. I pointed out that you sell trailers with this as standard - and with the whole mechanism being dumped in salt water - washing off with 'Salt away' solution is far better than leaving salt water in place.
'Not in his opinion'


I actually have a tank of solution & pump in my car so it gets flushed out within 2 minutes of coming out of the salt water dip ... so minimises salt attack.

Anyway ... my 'insert pin to reverse up hill' mod works well, so sticking with that, rather than buy 4 x drums.

[gpsguru]

Yes, I think salt water corrosion takes its toll on the drums much more than is acceptable. One of my GP 2T trailers is over 20 years old and and has done a huge mileage both here and on mainland EU, but there is very little wear on the braking sytem.


However, for general driving I find it a complete pain in the butt to have to get out and engage the latch to reverse ........ give me auto reverse every time.


This year I will modify the older GP trailer with a new hitch (currently a Bradley hydratow), new backplates and some new brake components to give me auto reverse. Probably I should really just go and get other new Ifor Williams, but I 'purpose built' this trailer in the early 90's and it has a lot of good features and happy memories.

[Sargan]

I don't have to 'engage pin' to reverse, .... only when reversing up a hill ... which so far is only going up my drive.
US boats with stainless steel disc brakes make so much more sense.
Selling marine trailers with mild steel & cast iron braking components to be used in salt water is frankly poor design ... and prone to failure.

[beamishken]

Originally Posted by Sargan

US boats with stainless steel disc brakes make so much more sense.
Selling marine trailers with mild steel & cast iron braking components to be used in salt water is frankly poor design ... and prone to failure.

US brakes are no better than uk brakes, they still use cast or ally calipers which rust out and sieze just the same and have the added complexity of hydraulics to contend with. And there is no requirement for park brakes on us trailers nor auto reverse.
The uk system is pretty simple and relatively cheap to replace and maintain
As far as I can see you still never determined 100% wether your fault was in the drums or hitch, Untill you actually know what your problem is its all just guesswork