Ball to teardrop dimension

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Ball to teardrop dimension

Postby QueticoBill » Mon Nov 14, 2016 12:52 pm

I was hoping to not extend tongue on the NT 5 x 8 but think it's inevitable. I'm not sure - will be next week - but I think the frame to ball on the trailer out of the box is just under 3'. My plan the forward most line of the 5' wide cabin is 12" forward of trailer frame, so around 2'. Only rule I could find - e-trailer I think - was half the width plus 8-12" - so 52" from frame, 40" from cabin - all requiring a 16+" extension. All I've read here suggests maybe going a few more inches would be better, making backing a little easier and allowing a wider tongue box - but what do I know. While I've designed mechanical equipment all my life, never much to do with vehicles and high way trailers, so only what I read here and my google fu.
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Re: Ball to teardrop dimension

Postby Dale M. » Tue Nov 15, 2016 9:34 am

Ideally you should be able to jacknife the TV and trailer to almost 90° to each other till bumper on TV (almost) touches the trailer tongue and TV body does not contact the body of trailer or tongue box .... That is idea but it may not be practical. Just keep in mind the shorter the tongue the less angle you can have between TV and trailer body before "contact"... Also keep in mind you are not always backing or towing in straight line...

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Re: Ball to teardrop dimension

Postby bobhenry » Tue Nov 15, 2016 9:47 am

I have found all cargo trailers to be 50% 50% in their wheel placement on the body. (This has nothing to do with the frame we are talking body) For a good towing and backing tiny trailer the wheel placement needs at very least to be 60% forward 40% rear and 70/30 is even better in my opinion. The quick and almost painless way to accomplish this is to do the math. To meet the 70/30 distribution you need to move the wheels back 20% of the body length want to use 8' then .20X96" = 19.2 inches. This is where your 18" has arrived from. These cargo trailers are built to save as much material as they can and the tongue is short to the point of stupidity for this reason. I have extended all of my trailers between 18" and 24". Oh by the way if you are adding a tongue box add it to the body length to arrive at the necessary extension length. I have towed mine before and after and believe me it is night and day difference in road manners. :thumbsup:
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Re: Ball to teardrop dimension

Postby QueticoBill » Tue Nov 15, 2016 11:17 am

Thank you.

I think the 90 degrees is probably the key. I can draw that and see how long the tongue extension has to be. I need to go back and find all that tongue information but I think 2 x 2 x 3/16 (or thicker if that's what I can "promote") back to second or third cross member in addition to the NT A-frame pieces will be easy. I'll try to bolt it all but may need to find a welder. (I'd probably have to hire that as my welding training and experience was when the choice was stick or gas - and all this mig, tig, fcwf is foreign to me.)

As far as the balance - I know I'm moving the axle back on the NT frame - probably to 36" from rear of frame - but maybe a little more. 8' frame - and cabin extends nearly 12" fore and aft. I just don't know where the extension beyond frame ends and tongue box fit into the 30 to 40% from rear guide. Current TV is rated 350 tongue weight, next one might easily be less, so that will enter into it also.

Again, thank you. This site is great because of the knowledge sharers like you.
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Re: Ball to teardrop dimension

Postby bobhenry » Tue Nov 15, 2016 12:23 pm

Most likely your axle is currently 48"+/- from the rear frame member. It sounds like you have a 10' body designed and I will quess an 18" tongue box.
That's 138" total if we go 65 forward and 35 rear which is a good ratio and you do the math .35X138" happens to wind up 48.3 inches from the rear. If you simply shove the body and tongue box forward and concentrate on beefing up the tongue there is no reason to mess with actually moving the axle as you have already done this by extending the tongue. Look close at this picture of the barn and you will see there is no floor in the first two feet. It was later added.

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Re: Ball to teardrop dimension

Postby QueticoBill » Tue Nov 15, 2016 1:39 pm

Thanks. Since I don't otherwise need a floor frame beyond what the NT frame has, I think easier to move the axle - just 8 holes or maybe 6 - and no floor frame. So 3' from rear of 8' is 4' from rear of centered 10' - seems good.
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Re: Ball to teardrop dimension

Postby yrock87 » Tue Nov 15, 2016 2:28 pm

when designing my tongue I wanted to ensure I could jackknife a full 90 degrees if I was so inclined. to get the required length to meet that goal, I measured my tow vehicle (Subaru outback) width and then added 3 inches to the tongue from half of the tow vehicle width. tow vehicle was 68 inches wide, half of that is 34 inches. plus another 3 makes for 37 inches from the front end of the stick to the diagonal braces, which in turn were 12 inches forward of the first cross member. after adding the coupler and gaining another 3 +/- inches I am able to comfortably jackknife the trailer just past 90 degrees. it makes a world of difference when backing up, not needing to worry about striking the corner of the trailer to the corner of the TV.

after saying all of that, I have a pretty long gap between the TV and TD, just over 4 ft from bumper to TD cabin. it probably hurts my fuel economy a bit because of all the space for air to enter between the trailer and TV. but my outback has the power to go above freeway speeds and now I can back up much easier. for what it is worth since axle placement has also been brought up, my axle is right at 36 inches from the rear crossmember, which makes it about 38 inches from the rear of the tear.
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Re: Ball to teardrop dimension

Postby brx017 » Tue Nov 15, 2016 2:38 pm

I did all three to my NT trailer. I extended the frame in the rear, moved the axle back and extended the tongue.

As you mentioned, moving the axle back is super easy. Just drill your holes in the side rails before you bolt the trailer together.

For what it's worth, I added 24" to the tongue to clear my future tongue box and still be able to jackknife without hitting the car.

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Re: Ball to teardrop dimension

Postby QueticoBill » Tue Nov 15, 2016 3:58 pm

brx017 wrote:I did all three to my NT trailer. I extended the frame in the rear, moved the axle back and extended the tongue.

As you mentioned, moving the axle back is super easy. Just drill your holes in the side rails before you bolt the trailer together.

For what it's worth, I added 24" to the tongue to clear my future tongue box and still be able to jackknife without hitting the car.

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So the one thing I was considering were the stock fenders, but I guess they are bolt on also, so a few more holes. (I figured a drill press was in my future for this project - something I've long wanted but haven't been able to justify.) And I liked your tongue extension ( :? ). The removable 1 3/4" was quite clever, though the 12 gauge 2 x 2 seems to be thinner than most say here. I wonder if all 2 x 2 with the an inner sleeve splice would allow easy removal of the hitch and extension.

PS: Would also make it easy if another TV needed a different length tongue.
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Re: Ball to teardrop dimension

Postby QueticoBill » Tue Nov 29, 2016 3:44 pm

Still trying to grasp and comprehend this. 8' chassis, with 9" overhang at rear and 15" at front with a design based on the "New Cub" or pretty similar to that. Allow for a tongue box so that is what just what BobHenry - 138" front of tongue box to rear of TD box; thus 48" from rear of TD or 39" from rear of chassis - which is just 3" behind current position. Getting the profile curves of the front and back to align with bottom of fairly deep chassis doesn't allow me to slide TD body further forward. The hitch is now about 37" in front of frame, and it seems I need to extend that almost 36" to be able to jack knife - maybe a little less. All that to say that is from rear of TD to hitch is 14' 9" and based with axle moved 3" its 10' 9" or around 73% to back; whereas if I leave The axle where it is it would be 71% to rear. Just not quite grasping the basis of the 35 or 40/65 or 60 rule of thumb - chassis, teardrop box, teardrop box + tongue box, or hitch to rear. Here's my attempt at using the spread sheet, but weights are guesses, and I think on high side.


TRAILER BALANCE SPREADSHEET

Instructions
Enter your own data in the boxes with red numbers
Read off results in boxes with blue numbers

Basic measurements in
Body length from rear - A 120
Hitch center from rear - B 177
Wheel center from rear - C 51

Extra weight measurements in
Extra weight 1 from rear - D1 12
Extra weight 2 from rear - D2 129
Extra weight 3 from rear - D3 0 Lever Moment
about about
Basic Weights % of Basic lb rear, in rear, in-lb
Basic trailer weight 100% 1000
Weight of tongue 5.0% 50 148.5 7425
Weight of axle/suspension 12.0% 120 51 6120
Body weight (total - tongue - axle) 83.0% 830 60 49800

Extra Weights (not included in Basic) lb
Extra weight 1 150 12 1800
Extra weight 2 100 129 12900
Extra weight 3 0 0 0

Results
Total trailer weight, lb 1250 78045
LCG from rear - X, in 62.4 % of Total
Weight on axle, lb 1137 90.9%
Weight on each wheel, lb 568
Weight on hitch, lb 113 9.1%
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Re: Ball to teardrop dimension

Postby brx017 » Tue Nov 29, 2016 5:40 pm

I'm on my phone now. I'll try to get some measurements of my plan posted up later tonight when I can sit down in AutoCAD for a bit. They may be totally wrong, but it might help us both to compare notes.

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Re: Ball to teardrop dimension

Postby QueticoBill » Sun Dec 18, 2016 11:13 am

brx017 wrote:I did all three to my NT trailer. I extended the frame in the rear, moved the axle back and extended the tongue.

As you mentioned, moving the axle back is super easy. Just drill your holes in the side rails before you bolt the trailer together.

For what it's worth, I added 24" to the tongue to clear my future tongue box and still be able to jackknife without hitting the car.

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The spring hangers and the frame seemed to be punched for the shoulder of a carriage bolt, which doesn't quite make sense to me with bolt shown up through bracket. When you moved the axle back,did you live with round holes and did you have to substitute bolts? Seemed odd but too cold to get every piece out in an unheated garage at sub-zero temps.
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Re: Ball to teardrop dimension

Postby QueticoBill » Sat Mar 18, 2017 10:24 am

I'm about to commence assembling and building and still stuck on the moving axle back and tongue extension. The design resources says fine to 36" - over 200% of minimum required, 300% at just 24". The 36" allows tow vehicle to be 90 degrees to tongue, 24" allows 80 to 85 degrees depending on tongue box. How bad is just 80 degrees?

On the axle, I indicate the percentages from cabin, cabin + tongue box, and overall - I was never sure where that 30-35% was measured. By the balance spread sheet, using a range that is between 1200 and 1450 total weight, I have 125 to 150 pounds or between 10 and 10.5% of the total weight on the tongue - which seems light to OK. (Present tow vehicle is rated 3500 pounds with 350 tongue.) Do you think its safe to leave the axle where it is?

Diagram may help.

Thanks!!!!

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