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

Question

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

1

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.

expert reply by: Chris R

1

Answer 1

Hubs and drums that can be turned (machined) will have a specification on how much they can be turned cast into the metal of the drum somewhere. Otherwise it is at the brake shop's discretion. Drums do not have to be turned unless there is…

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Answer 2

Because the face of the magnet rides against the armature (inside) surface of the brake drum, any grooves that had previously been worn into the armature surface will cause the magnet to wear unevenly. For optimal braking performance, you want…

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Answer 3

There is always a way to make it work. I can't recommend doing that as I have not tested it and I do not offer a product like that with the exception of the Dexter Trailer Springs Over-Under Conversion Kit part #K71-384-00. This will give you…

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Answer 4

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 5

You will need to measure the diameter of the spindles where the seal and bearings ride. Check out the picture I attached that shows where this is. You will need an exact measurement so either a digital or dial caliper will be needed. To pick out the…

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Answer 6

Installing a 4,000 lb capacity leaf spring on a trailer with a 3,500 lb capacity axle will make the suspension stiffer which could then in turn minimize the risk of the axle contacting the frame. However, this is not what I recommend to fix your…

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Answer 7

The recommended clearance with leaf spring suspension on an unloaded trailer is between 2 - 2-1/2 inches. You should have sufficient clearance with your loaded trailer, as leaf springs only tend to deflect 1-1/2 inch when carrying a load.

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Answer 8

The Timbren Trailer Suspension Enhancement System, part #TTRA1032, can be installed on trailers with I-beam frames. This system provides additional support so you have a comfortable ride. The springs become more rigid as additional weight is added.…

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Answer 9

It sounds like the eye of the leaf spring is coming in contact with the bottom of the trailer frame. If this is the case then your only three options to fix this would entail either replacing the equalizers, shackle straps, or leaf spring hangers.…

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Answer 10

If you look at the backs of the brake assemblies there should be a hole where the magnet wires come out and a little opaque plastic strap. So if you are looking at the back of the assembly and those items are on the left then it is the left side…

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Answer 11

In order to change from an 7,000 pound axle to an 8,000 pound axle you will need to replace the entire axle with an 8K model. You will not be able to add any parts to your current axle to upgrade it to an 8,000 pound capacity. We do not currently…

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Answer 12

To confirm that the Dexter Trailer Hub and Drum Assembly #8-219-18UC3 will fit on your Ron's Trailer axle you will need to measure the spindle on your axles. I have included a picture for the measurement locations for the spindle. You can also…

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

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