How to Choose Correct Axle Placement for Tandem 7K Axles with Slipper Leaf Springs

Question

Question:

Hi, Im upgrading to 7k slipper spring tandems. Twin electric brakes. The hangers are larger than the 7k double eye springs. Would you have a placement diagram for the proper placement for the hangers? The trailer frame is of 1980s build, 2.5x2.5x.375 rails.The tongue is 3inch x .375 channel. The side rails are 2inch square tube, 18inch tall, with 2inch square tube top rail, all 3/16inch tubing. 2 5/16inch hitch, rough cut 2x8 oak flooring. The flooring cross supports are set on 12inch centers 1.5x1.5x.250 angle. The trailer from center ball to end rail of trailer is 196. The trailer is a tank, we found it in a field, purchased it an upgrading leds brakes 12k ctr landing leg, rear stabilizers. We are using it for maintenance in field during hay season. Thank you very much

asked by: Ron M

1

Helpful Expert Reply:

Slipper spring setups, like parts # e74SR and # APT6SE for 7K axles, do have different hanger sizes so what you'll want to do is cut off the older hangers and do some mock-ups of your new system before installing the hangers.

Start off by mocking up the center hanger setup about 2/3rds of the way back on your trailer. From there you need to measure your tongue weight and shoot for something in the range of 10 - 15% of the weight of the trailer. If you're outside of that range then you need to move things around until you get inside that range.

I wish there was a set "put the axle here for this weight and length of trailer" but each trailer is different (especially homemade trailers) so there is a bit of trail-and-error when it comes to getting the axle placement right. I've attached a helpful article on axle placement as well as a photo from that article for you to reference.

expert reply by: Jon G

1