Strange issue with electric brakes on tandom axel trailer

[Myz32300ztt]

Ok so I am new to this forum and hoping someone can help. I have been searching for hours now for similar posts with no luck.

I have a tandom axel equipment trailer with dexter brakes. The trailer got new new pads, magnetos, and backers about 2 years ago. Now I'm trying to get it inspected and neither tire on the rear axel will lock up going forward. After much digging, here's what I know:

When moving forward the front axle locks up rear does not
When going in reverse the rear wheels lock up but front do not.
I have a new break away battery and charger and get 12.8v
At the rear axel I have 9.6v
All the shoes have been adjusted to where they drag slightly when freely spinning the tires
When the wheel is elevated and spun with brakes or breakaway out wheel does not spin either direction
I have also verified the front left and rear left shows and such match.

I'm at a loss here no idea why the the breaks are behaving this way. Hoping someone with. Ore experience may have some direction.

Thanks in advance!!

 

[Diamondpilot]

Are you sure you don't have the L & R break on the wrong side on that rear axle? That would explain why they work in reverse but not forward.

If this is all correct it has to be a wiring issue. Check your grounds.

Chris

 

[Myz32300ztt]

Thanks for the reply... I triple checked to make sure they werent on wrong side. Everything matches on left side (front and rear) and right. I was thinking looking into wiring just seems odd the front lock in forward and rear spins free and opposite when running in reverse.

 

[bcp]

I've been doing a little research on this problem and found this diagram. The diagram makes it look like the brakes are SUPPOSED to be reversed on the rear axle.

Wiring Brakes On Tandem Axle Trailer | etrailer.com

????

Still looking.

Bruce

PS: just seems to be a misleading diagram. Other sites say the actuating arm always goes on the front side of the brakes, which makes it easy to tell which side goes where.

 

[Soundguy]

scotch loks and taps? if so.. loose them...

 

[Myz32300ztt]

No scotch loks or taps all the wires have been soldered and shrink wrapped.

Bruce - thanks for the link I stumbled on that earlier in my research, and everything seems good from a positive electrical side I haven't checked the grounds yet, its on the agenda for tomorrow.

One thing I was thinking was, I know the drums themselves aren't new and there is some grooving on the inside where the magnet grabs, but that doesn't explain why both rear wheels grab in reverse and front grab going forward... I would think that if the magnet surface area of the drum being too worn, brakes wouldn't grab in either direction?

 

[Myz32300ztt]

Update:

Checked grounds and they are run from the truck back and are good. Changed magnets from front to rear on left side with no difference, changed drums from front to rear no difference. On rear wheel I also swapped the longer shoe for the shorter one just to see if by chance I'd get more bite but again no difference. I tested e voltage again at the back and front axle and now that the connections have been re done i get 10v.

I'm really at a loss here.

 

[ovrszd]

Okay, I'll bite.

My trailer does the same thing empty. I'm talking about idling down my gravel driveway and applying the brakes. When going forward the front axle slides on the gravel. When going backward the rear axle slides on the gravel.

If I jack up the trailer and apply the brakes all 4 cannot be turned forward or backward.

I attribute this to high mile brakes and the fact that the equalizer will lift the front axle when going forward and lift the rear axle when going backward if brakes are applied. In the 4 wheeling world we call that axle wrap on leaf sprung buggies.

This being my first heavy duty electric brake, dual wheel, dual axled trailer, bought used, I just assume this is normal behavior?

But what do I know??

 

[JimRB]

Post pictures of the left side front and rear with the drum removed.

I am pretty sure my Dexters with lock up spinning forwards or backwards. Not positive on that and not willing to dig the trailer out to confirm.

What is the resistance between the blue line up at the front of the trailer and the blue line of the left front and the left rear? I am pretty sure blue is the color of the brake wire.

 

[George2615]

I agree with DP. Brakes on trailers are LH and RH. I suspect the OP's rear brakes were installed wrong since they lock up going backward. I replaced mine last year. Bought 4 entire kits from Etrailer.com, 2 LH and 2 RH kits. Pic 1 shows what both should look like on the L side. Pic 2 is the R side. Notice the position of the arm holding the magnet. The arms need to be toward the front of the trailer on each side. They have to be installed this way for them to work correctly. The arms move an eccentric cam that moves the shoes apart to apply the brakes. They do this going forward or backward but are more aggressive (move the shoes more) going fwd.