Upgrading From 7K to 8K Electric Brake Assemblies on Trailer for Increased Braking Power

Updated 06/11/2018 | Published 06/07/2018

Products Featured in This Question

Trailer Hub and Drum Assembly - 8,000-lb Axles - 12-1/4" Diameter - 8 on 6-1/2

(16)

$203.92

Replacement Trailer Hub Bearing - 02475

(2074)

$16.74

Replacement Trailer Hub Bearing - 14125A

(136)

$15.94

Replacement Trailer Hub Bearing - 25580

(2074)

$21.84

etrailer Electric Trailer Brakes w/ Dust Shields - Self-Adjusting - 12-1/4" - Left/Right - 8K

(331)

$293.37

Digital Multimeter with 42" Long Test Leads - LED Display

(3)

$22.17

Question:

I have a trailer with dexter 7k axles. They use the 12x2 brake shoe and drum. Ive never been happy with stopping power when Im more than half loaded. The dexter 8k axle comes with 12x 3 3/8 inch drums and shoes. Is it possible to replace backing plates and drums to get the bigger brakes, or am i stuck replacing the axles with 8k dexters or disk brakes to get the safety margin i am looking for? It stops well with the trailers weight and a 4,000 to 5,000 pound vehicle. At 75 gain. Trailer has a 10,400 payload and if i load it to it the brakes at 100 are good for a normal stopping, but they shove the truck if i have to stop fast. Ive towed a lot of these and always have the same complaint.

asked by: Grant

Helpful Expert Reply:

You should be able to change out the backing plates, hubs, and brakes on your trailer so you can upgrade to higher rated assemblies, but I do recommend checking a couple things on your tow vehicle first. It's possible that your weak braking is due to a wiring or brake controller issue on the vehicle. If this is the case, changing out the brake assemblies on the trailer won't resolve the issue.

I first recommend testing the vehicle side 7-Way with a Multimeter like # PT89ZR. Make sure the brake controller is set to maximum output and have a buddy apply the manual override slide on the unit while you test the brake output pin (5 o'clock) at the connector. You should have around 12 volts at this pin with the manual override activated. If you have a lower reading, then you will want to check the connector itself for any debris or corrosion around the pins. Also check the brake output wire for any damaged or exposed areas, replacing as needed.

If the brake output is what it should be on the vehicle connector, then upgrading brake assemblies will provide greater braking power. Since it sounds like you have had the same issues with multiple trailers, there shouldn't be a specific troubleshooting issue going on with the trailer side.

In order to change to larger hub and drum assemblies, you will want to determine the bearing sizes used with your current hubs. This is needed to verify that the new hubs will fit your trailer spindles. Most likely, your hubs use the # 25580 inner bearing and # 14125A outer bearing, but you will want to check to be sure. The bearing numbers should be stamped right onto the inside of the bearings themselves.

If this is the case, then you can replace the hubs with the etrailer.com Trailer Hub and Drum Assembly # AKHD-865-8-K. This 8,000 pound hub uses the same # 25580 inner bearing and the # 02475 outer bearing, which features the same 1.250 inch inner diameter as the # 14125A so it will work on your spindle. The hub has an 8 on 6-1/2 inch bolt pattern.

With the new hubs, you can then add the larger Electric Brake Assemblies # AKEBRK-8. This kit includes both the left hand and right hand units.

Since these brake assemblies use a 4 bolt mounting pattern, you will also need to remove and install new brake mounting flanges, as you mentioned. I have attached a link that will take you directly to our selection of mounting flanges that you can look through. The correct replacement will depend on the size of your existing axle. You will also need to have a certified professional with experience in this type of installation weld the new flanges on, as they need to be installed perfectly.