How to Measure for Replacement Slipper Spring on a Cox Tent Trailer

Updated 10/23/2024 | Published 08/06/2018

Question:

How shall I measure the broken leaf spring? The slipper end to eye end measures 31 1/2inch long but to the foot of the slipper bend to flat surface the length is 27 1/2inch long. Not clear how to specify length needed. Its 1 3/4inch wide with only two leaves. for an older Cox tent trailer... Thanks!

asked by: George

Expert Reply:

A similar leaf spring that we have is the etrailer 2-Leaf Slipper Spring # e29SR which is 30" long and rated for a 1,800 lb axle. The 30" is measured from the center of the eye to the end of the leaf spring (see attached picture). The spring is 1-3/4" wide and has an eye diameter of 9/16" with the bushing.

Let me know if this doesn't fit your specs and I can see if we have something else for you.

expert reply by: Jon G

click to enlarge

Duane

10/21/2024

I have a similar question as to George I am rebuilding a 1980-90 era cox trailer. This revised trailer will only be carrying a 100 lb. Jon boat the the trailer, w/o suspension, at less than 250 lbs. I notice the 30 inch 3-leaf flat spring (e49SR) has an "A" horizontal distance of 13-5/16 inches which would work but it is much more spring than I need. The center of the fender is at 13 inches from the eye. The 30 inch 2-leaf flat spring (e29SR) has an image that is flipped based on the measurements (and when compared to the e49SR spring image) but its "A" distance is 13-3/4 inches. I'd rather not lose that extra distance since the space under the fender is tight. The trailer came with a mismatch of one 2-leaf & one 3-leaf springs. Both of these springs had an "A" distance that match your 3-leaf spring of 13-5/16 inches. Being the diagram position for the 2-leaf spring is incorrect, is it possible the actual "A" distance for the 2-leaf spring is the same as the 3-leaf spring? Both have identical "C" curvature distances of 15 inches so that is why I am curious. A simple side-by-side comparison would show a half inch discrepancy if it exists. I already bought etrailer's AKIHUB-440-2-G-1K hubs for the project (I got one 4-on-4 and, mistakenly, one 5-on-4 but that was worked out) but I want to avoid any possible rubbing on the back of the fender as I did see such marks during the rebuild. The move from the centerline of 13 inches to 13-3/4 inches is somewhat noticeable on the tight fender well, albeit, a bit picky. If the "A" distance IS different between the e49SR and e29SR springs, is the 3-leaf spring going to be like an axle with no spring at all given the < 500 lb weight I would expect for the boat/trailer combo? If you could take the time to actually compare the two springs, I would appreciate it. Thank you.

Jon G.

10/22/2024

@Duane Thanks for reaching out! I just took a trip out to our warehouse and confirmed that the Leaf Springs # e49SR and # e29SR have the same dimensions, and will match the diagram for the e49SR - I've also sent in an update to have the e29SR changed to reflect this. So for your case it sounds like the # e29SR will work out for you!

Duane

10/22/2024

@JonG WOW! I put my question in late last night and by morning today I got an answer. It doesn’t get any better than that! Thank you for making the extra effort to perform a physical comparison of the springs. That removed some apprehension I had about ordering. I see the update on the etrailer site as well. Great job, Jon! I’ll be ordering soon.

Jon G.

10/23/2024

@Duane Thanks for the kind words - happy to help out!