Caravan brake backing plate mounting help ...

Submitted: Saturday, Sep 22, 2012 at 16:20
ThreadID: 98173 Views:11536 Replies:3 FollowUps:3
This Thread has been Archived
I finally have got my set of Trojan electric bakes to fit up to the van and i have to weld on new mounting plates to the axel, the brake backing plates bolt up to them, they dont give you any instructions and i cant find anything on the web, i have it fairly well worked out but need to know what the clearance is from the DRUM lip to the backing plate in order to tack up the plates ....
Can anybody please help .....

It is the CLEARANCE between the drum that rotates and the fixed backing plate that the shoes are mounted to ..

Many thanks in advance, i would ring them but no chance of getting anyone on the weekends....

Back Expand Un-Read 0 Moderator

Reply By: Bob Y. - Qld - Saturday, Sep 22, 2012 at 17:01

Saturday, Sep 22, 2012 at 17:01

I'm no 'van mechanic, but the brake shoes would need to "engage" with the brake drum, at least 4-6mm in from the edge you mentioned.

How would it be if you measured from inner edge of brake shoe, to the backing plate, and take 4-6mm off that distance? Also the folded edge on the backing plate is suppose to "guard" the edge of the brake drum, to stop dust/mud, from getting into the brake assembly.

Hope I've made that clear??? As mud he says LOL.

Just OT, we used to get morning glory's when we lived at Planet Downs, back in '86-'87. Magic sight, eh!


Seen it all, Done it all.
Can't remember most of it.

Lifetime Member
My Profile  My Blog  My Position  Send Message

AnswerID: 495422

Follow Up By: Member - Joe n Mel n kids (FNQ - Saturday, Sep 22, 2012 at 17:22

Saturday, Sep 22, 2012 at 17:22
it is a hard one as the shoes hit the in-side of the drum and there is still a gap of about 4 mm, if i cant find out i will probally bolt it all up so it is square and use spring washer as a spacer to get about 3mm and tack it up then remove the washer to give me some clearance .... it is also un-usaul that there is a clear gap between some of the plate and drum so mud could get in very easly ....
Yes the "cloud" is quite something to see, i guess we are both very lucky to had witnessed it eh ..

Cheers and thanks
FollowupID: 771048

Reply By: Nomadic Navara - Saturday, Sep 22, 2012 at 17:36

Saturday, Sep 22, 2012 at 17:36
I would be inclined to assemble the hubs with the mounting plates bolted the backing plates loose on the axle. Then with some suitable packing pieces, clamp the backing plates to the drums. Then you would be able to carefully weld the mounting plates to the axle.
Retired radio and electronics technician

Lifetime Member
My Profile  Send Message

AnswerID: 495424

Reply By: Tim HJ61 (WA) - Saturday, Sep 22, 2012 at 23:37

Saturday, Sep 22, 2012 at 23:37
I've just done this a few weeks ago and am working through the teething problems.

Today I got one trailer brake to lock up, so am pleased I'm getting somewhere. And yes folks, I will adjust the controller so I don't leave rubber all over the road.

I mounted 10" Al-ko electric trailer brakes with Landcruiser hubs onto my trailer as an upgrade. To control them, I installed a Techonsie brake controller a few months back.

I bought my brakes as a set from a reputable trailer parts place in Perth. He said to place a washer in between the backing plate and the mounting plate, do it all up tight onto the backing plate, then dry mount the hubs and tighten up the bearing nut.

I did this and then tacked the backing plate, dismantled it all and welded it on firmly.

On final assembly, I have what I would think is too large a gap in between the brake drum and the backing plate. There is enough room in there for small rocks and stuff to get caught I imagine.

One option I have considered is siliconing a strip of 25mm wide rubber strapping around the backing plate to create a loose seal.
The other option is to pull it all apart again and pack out the backing plate further away from the mounting plate.

But there are other considerations too.
Once I pull the brake drums off, I will be checking where the pads have been rubbing.
Second, I will also check on the placement of the magnet on it's mounting shaft.
I have off road magnets that are hideously more expensive than standard, so want to make sure they are mounted correctly.
Third, is that I have read that all adjustments should be done after 100km of city driving. I can vouch for this as my brakes are improving each time I use them.

From my experience, don't expect them to be fantastic immediately. Not sure why this would be the case, but it seems to be.

Each magnet only draws 3A (times 2 = 6A), but given the distances involved voltage drop is an important consideration - as it any dickyness in the trailer plug connection.
Make sure the earth wire is the same beefy size as the power wire. Not only on the trailer, but on the vehicle side as well.

It was easy enough to run a length of heavy cable back to the trailer plug, but so far I have left the earth wire as standard - quite thin. It is likely to be below par and another job is to replace it with heavier cable too.

I have figured that when voltage is applied to the magnet, it has a degree of magnetism dependent on that voltage. The magnet slides along it's mounting bracket and grips onto the inside of the brake hub on the vertical plane. This is a wearing point, hence worthwhile checking that backing plate to mounting plate distance.
As the magnet grips the rotating brake drum, it tries to rotate with the drums and pulls a lever. This lever actuates a cam, which pushes the brake shoes onto the brake drum.

If feasible, it would be a good idea to remove the axle completely and do all of this mounting away from the vehicle. Welding that backing plate on is not that easy, and needs a lot of paint to cover the results in my case. I suspect it is not under all that much strain really, but it's always nice to have a neat strong long weld.

I hope this is a bit useful, if nothing more than reassuring you that yes, getting the minimal distance between the drum and backing plate is probably a good idea - or so it seems!


Oh, and then there is the pad adjustment. That's another job......
AnswerID: 495445

Follow Up By: Member - Joe n Mel n kids (FNQ - Sunday, Sep 23, 2012 at 10:56

Sunday, Sep 23, 2012 at 10:56
thanks heaps for the reply Tim,
I was thinking that using washers was the way to go so that is todays job, your thinking is exactly as what i though as to how it works and yes there seems to be to big a gap but i am wondering if it may also be required for air-flow to cool the magnet as it involves friction, i dont like the fact that small rocks could get in as well, i also will think about that one ....
I have taken the axels right out for that reson, getting to old to crawl around under stuuf welding, done that in my younger days enough......

Again MANY thanks for that answer, it is exactly what i was looking for, and to all that read this, this is what this site is all about, some WONDERFUL people on here, MOST just sit back quitely and help when needed, yep a few pop up complaining about pathetic thing like "sub-woofers" ect but like liddle mushrooms, they dont last long and the good people are still here .....
So without question i will renew my membership again as per the e-mail today and enjoy another 12 months of really good advice, assistance, "Doug" and al the other good features of the site, what at around $30 bucks????... i pay more than $70 bucks for a carton of 4xxxx GOLD cans .......and they will be lucky to last a week in this heat .............. and maybe David will stop adding all the "things" i will never use and it will speed up again hahahhaha (just kidding) ...
Cheers and many thanks Tim (i also want a 12HT, 1HZ gunna struggle with a van on))
FollowupID: 771086

Follow Up By: Tim HJ61 (WA) - Sunday, Sep 23, 2012 at 11:52

Sunday, Sep 23, 2012 at 11:52
I'll be heading back to trailer parts and asking them about the gap, and also about my idea of siliconing a strip of 25mm rubber around the backing plate.

Pleased my ramblings were useful.

FollowupID: 771095

Sponsored Links