Difference between a 5200lb axle and a 6k axle

Cord · Apr 13, 2011

I have a tandem axle flat bed trailer that I'm doing some major maintenance on. The trailer was professionally built, but has been well used and put away wet. I'm looking to fix that. My axles are 3" diameter tubes and have 12"x2" brakes. The hubs are 6 on 5.5. The front springs are 5 leaf, 1-3/4" wide double eyes. The rear springs are 6 leaf, 1-3/4" wide double eyes. The rear springs are longer than the fronts, but I can't recall the exact length at this time. It would appear somebody may have replaced the rear springs because the back spring mount is different from the other two and appears to have been field welded. I suspect somebody may have broken a spring and didn't have a direct match. Anyways, I have a broken leaf (haven't seen the spring, was only told so I don't know which one) so I need to replace a spring set. The problem is that I can't figure out what capacity to get. I'm certain that the axle is no less than 5200lb, but it could be a 6,000lb capacity. There is no capacity tag on the axle or frame. I was looking on e-trailers site and they list a 5 leaf 5800lb spring that's a direct swap for the front springs. They don't offer a spring that matches the length of the 6 leaf springs that I currently have. I was planning on replacing the mis-matched mount, so if I go to a shorter rear spring, now would be the time. I was wondering if somebody knew what the difference was between a 5.2k and a 6k axle?

Diamondpilot · Apr 13, 2011

Most 5,200# and 6,000# axle sets I have been around use the same springs and mounts. They also area mostly with #42 spindles. The are some that have different bearings.

I am guessing you have 7,000# springs now on the rear but who knows for sure.

Here is a resource I use a lot.

Figure trailer axle sizes, R and P Carriages

Chris

hrcarver · Apr 13, 2011

I thought 6k axles had 8 lugs? Not 100% sure if they all do or not.

Diamondpilot · Apr 13, 2011

hrcarver said:
I thought 6k axles had 8 lugs? Not 100% sure if they all do or not.

Not that I have seen. I have delt with 100's of trailers with 5,200# and 6,000# axles and all had 6 lug wheels. Only axles I have dealt with that had 8 lug were 7,000# Thats not to say they are not out there but all I have been around were 6 lug on a 6,000# trailer.

Chris

Cord · Apr 13, 2011

hrcarver said:
I thought 6k axles had 8 lugs? Not 100% sure if they all do or not.

Nope, not by a rule. I know for certain that you can get a 6k with a 6 on a 5.5 pattern.

Cord · Apr 13, 2011

Oh, and I didn't make it home with the spring intact. When I was backing the trailer up at my home I noticed the wheel was at a weird angle. Got out and checked, sure enough the long spring with the eye was broken right at the u-bolt. The crack is old because it's rusted. Rather scary because if the spring had broken when I had the trailer loaded, it could have gotten ugly real quick. I noticed the trailer was trying to sway when I was driving home, so it must have broken about half way home.

Raspy · Apr 14, 2011

It seems the main difference between the 5200 and the 6000 is the spindle and the bearing sizes. Axle tubes are the same and sometimes the brakes are the same. They both come in 6 or 8 bolt pattern. 5200 lb axles seem to mostly have 12 X 2 inch brakes, but I think they also come in 12 X 2.5" and, possibly 14" diameter.

I prefer the 8 bolt wheels for the 6000 lb axles, but 6 can be used up to and including 7000 lb axles if you wish, or just want to have interchangeability. But watch out for putting light duty tires and wheels on the heavier duty axles! The best are the 16" with load range E for the 5200 or the 6000 lb setup. I even use the 6 bolt wheels on my 3500 lb axles.

I would not worry about matching the axle with your springs so much as matching the expected load and getting the proper length. You can get them in various lengths and 25 1/4 is the most common for tandem axles, I believe. Be sure to get the proper length for your pin spacing! Then comes the number of leaves. For non tapered leaves it would be 4 or 5 leaves. Get the heavier if you expect heavy use. Get a U bolt kit for the 3" axle tube and that's it. You won't hurt the 5200 lb axle with springs for the 6000 lb axle.

Cord · Apr 14, 2011

Except for the seal, I believe that 5,200, 6,000 and 7,000 lb axles have the same bearings. See here: https://www.etrailer.com/dept-pg-Trailer_Hubs_and_Drums-pc-For_5200_lbs_Axles.aspx 5,200 and 6,000lb can be on 6 on 5.5 and 5,200, 6,000 and 7,000 lb can be had with 8 lug wheels. The same is true for the backing plates. 5,000, 6,000 and 7,000 plates are all compatible, but the the higher capacities have different compounds and larger magnets. What Is The Difference Between the 6K and 7K Dexter Axle Electric Brake Assemblies | etrailer.com