Newbie Axle Question

[tnb97]

First I have to say I have been a lurker for a long time and love the forum. I have learned a lot in my planning phase. I have started building my frame and have a question about my axle measurements. I am building a 5 x 10 and am constructing with wood exterior on the sides. The axle in question is the Dexter #9. This is my concern – My actual frame width is 60”, my wood skin sides are 1/2” with trim of 1/2” which puts the actual width at some points to 62”. The wheels I have chosen are 14” with a Offset +0.5". and the dealer I’m ordering my axle from is requesting two measurement the outside to outside frame width – 60” but I have no idea how to calculate the hub face to hub face measurement, any ideas would help greatly.

[KCStudly]

For a regular leaf spring axle you could lay the rim with tire mounted face down on the floor and put a straight edge across the tire to measure the backspacing at the wheel mounting surface including the tire bulge. Add at least 3/4 inch to this dimension, double the result and add that to your outside wall/trim dimension. However, with the torsion style axles you will need to allow for the trailing arm to make sure that it clears your wall/trim and the tire clearance can be a little closer (if you want, or depending on your chosen fender fits).

Some people end up cutting a small amount of the bottom of the wall extension away to allow for trailing arm clearance.

I believe that Grant Whipp (a very experienced builder) covers how to plan for the trailing arm clearance very thoroughly in one of his posts, if not on his web/facebook page. Perhaps someone will be able to link to the specific details. Here's another thread on the subject with some input from Grant

Found a post from Alaska Teardrop (another experienced TD manufacturer) stating that the hub face to trailing arm inside is 6.2 inches on the #9.

[tony.latham]

Perhaps this will help. I'm on my second five-wide. I build my chassis frames a half inch narrower than the cabin to allow room for the bottom of the trim thus they are 59.5" wide. The cabin is a true 60". Here's what works for me:

Axle: #9 Torflex with hubs
• Trailer weight: 1500#
• Start angle: 22.5" Down
• Hub Face: 74"
• Trailer width: 59.5"
• Hub Diameter: 6.5"
• Bolt Pattern: 5 on 4 - 1/2" (with standard studs)


From the outside of the arm to the hubface is 4 7/8" with a #9. To the inside, I measure 6 1/8".

Ignore that tape measure, the camera lens came in from an angle. It's 4 7/8".

On my first 'drop I used a hubface to hubface of 75" and there's a bit more gap between the inside of the arm -and the inside of the tire and the cabin– than I care for thus the 74" on this new build. It's bolted to the chassis and I'm happy with it.

Thus I think a 76" hub face measurement should work for a 62" wide cabin with zero offset rims. Dunno about the half inch offset issue. I know there are a lot more posts on this forum about this subject 'cause it's a head scratcher. Seek 'em out.

But enjoy your build.

Tony

[angib]

Here's an ancient diagram I did showing the important bits of information (sadly, for a zero-offset wheel):

axle-width-4.JPG (38.24 KiB) Viewed 907 times

So:
- you know your maximum body width;
- minimum sensible tire/body clearance is 1" per side, but you can have more;
- you need to know the tire width -

With a 14" wheel, you will probably be using 205 width tires at 9.0" mounted width, or 215 tires at 9.6" mounted width (those are Dexter's numbers).

So your required track width (centre of tire to centre of tire) is body width + 2 x tire/body clearance + 2 x tire half-width.

Let's try at 61" body width (you say there is some trim but you can stop that inside the fenders), plus 2 x 2" tire/body clearance, plus 2 x half of 9.0" tires = 61" + 4" + 9" = 74" - the same as Tony Latham suggested.

Now if you are using 14" Dexter wheels with +0.5" offset, I believe those are inset wheels, so the hubface dimensions needs to be 2 x 0.5" bigger than the track, or 75" in the example above. I suggest you get that confirmed by the dealer, since they will be able to get that checked by Dexter. I suggest you specify the track dimension and let the dealer/Dexter get the right hubface dimension, so they get that detail right.

[alaska teardrop]

Thus I think a 76" hub face measurement should work for a 62" wide cabin with zero offset rims. Dunno about the half inch offset issue.

Agreed, the 76" measurement will give you .8" clearance between the body trim & swing arm on both sides. However, I would add 1" (77") to make up the offset for the tire to body clearance. This of course, as KC mentioned, would depend on wheel width & tire size.
In this picture the distance between the frame & swing arm is 1.8" The wheel is 14x5.5 with 1/2" inset (+1/2" offset) & the tire is a 195/70/14.


Also, take into account the fender width. This picture shows that same setup with 10-1/2" fender.

[tnb97]

Thank you for your responses, this helps tremendously. I'm going to get my tires and wheels and now armed with a much better understanding will be able to come up with a measurement. Thanks Again!

[martymcfly]

When I ordered my torsion axle, the place had a sheet that I had to fill out with all of the dimensions. I had no clue, so I copied the dimensions from a build That I found on here. Here is the link. http://www.grossepointegothic.com/LT/source/3.htm I have my frame all done except paint and it looks pretty good. I have not done anything with wood yet though.