Hit the Stud

[JWCIV]

This one will be difficult to explain.... But here it goes.
I want to mount these on my floor. The plate stays and the arms are removable when not in use. https://riskracing.com/blogs/news/be...e-buyers-guide
Watch the video to get the full understanding.
I plan to mount them offset (forward to rear) over the axles to avoid having the handlebars of 2 moto's side by side (Dual Sport moto's - aka street legal dirt bikes). Ultimately I would like to tap into the metal studs that run width-wise of the camper to provide maximum strength. I love these mounts because they eliminate the need of a front tire keeper and the need for straps running in 20 directions drastically compressing the front suspension. The plates can be mounted with either 8 counter sunk wood screws or 8 countersunk bolts with washers and nuts or a combination of the two. My huge fresh water tank (with mounting wings) is right in the spot where I will need to mount these. The studs are 16 inches on center. There is about 2 inches of clearance between the tank and the bottom of the floor (no worries of penetration of the tank). My problem ... I can't PRECISELY (without drilling multiple pilot holes) determine where these 2 inch studs lie from within the RV. I am PRETTY CLOSE.... within a half inch ... but I want to be exact.
The existing tiedown loops (outer 2) are not mounted into the beams and are screwed into plates that have been added for support. The center one is screwed into the wide metal place running down the middle of the underside.
Thoughts on how to accomplish this task?
I'm worried that if I proceed and use the measurements I have now which are mostly close I will either deflect and miss or will only catch the rim of the beam. If I go with the screws and forget about the beam I thought about pre-drilling the holes and filling with liquid nails as I insert the screws.

[sdelam]

I had the opposite problem with my set up. I use a Biker Bar for the Harley and it comes with backer plates that needed to miss the beams. Lots of measuring trying to find a spot I could get a consistent measurement both inside and out of the trailer.

Can you make a similar back plate, maybe 4" aluminum square like a big washer? Seems it would be easier to get your first whole where you want it from the underside if you weren't trying to hit a cross member.

If you really want to hit a crossmember have you tried a stud finder like you would use for drywall?

https://www.bwtrailerhitches.com/product/biker-bar

[JWCIV]

Really cool similar concept. Yes, I have tried the stud finder and it does put me very close ... but I sure would like 100% confirmation. I have also considered the backing plate but the water tank is blocking that entire area.
I guess the manufacturers thought the tie downs were the only thing needed.
And I guess that's what most people use since lots of people have looked at this post but haven't commented.

[WanderMore]

You could use a trick I saw a roofer use. Take a coat hanger wire and bend it into a U shape. Drill a small hole and insert one of the uprights for the U. Slowly turn the U until it hits the stud. Where the U stops on the stud the exposed part of the U will indicate where the side of the stud is.

[JWCIV]

I've thought of that since my plate is rather large and would hide the "seeker" hole.

[klutchdust]

Are there any existing holdowns that are screwed into the beams you could use as a reference point. Go underneath and measure beam to beam.

[RockDodger]

Instead of off-setting them, why don't you just put them side by side and put one bike in forward and the other backward, thereby avoiding the handlebar clash. Would make your installation much easier I would think.

[The Evil Twin]

I use the Pit Bull TRS in my TH. The cross beams were not where I could use them and I couldn't put all the bolts in the beam anyway. So I just drilled through the wood floor and used aluminum angle (2"x 1/8") underneath. The angle spans the distance between the floor beams. Tens of thousands of miles like that in multiple trailers.

[JWCIV]

Originally Posted by klutchdust

Are there any existing holdowns that are screwed into the beams you could use as a reference point. Go underneath and measure beam to beam.

All the existing tiedown cleats are backed by added or existing plate (which I can't add above the axle area due to the ridiculously large fresh water tank) ... and none of them are "into the studs" that I am trying to hit.

[JWCIV]

Originally Posted by RockDodger

Instead of off-setting them, why don't you just put them side by side and put one bike in forward and the other backward, thereby avoiding the handlebar clash. Would make your installation much easier I would think.

The offset isn't an issue at all ... plenty of room to go forward or back ... and backing a bike up the ramp might be ok sometimes but there will be instances of non level ground behind the trailer where that won't be fun I'm sure.

[JWCIV]

Originally Posted by The Evil Twin

I use the Pit Bull TRS in my TH. The cross beams were not where I could use them and I couldn't put all the bolts in the beam anyway. So I just drilled through the wood floor and used aluminum angle (2"x 1/8") underneath. The angle spans the distance between the floor beams. Tens of thousands of miles like that in multiple trailers.

I really dig the rig ... have you felt any issues because of your bike mounted aft of the axles?

[The Evil Twin]

Originally Posted by JWCIV

I really dig the rig ... have you felt any issues because of your bike mounted aft of the axles?

Thanks, but that was a random photo of a Pit Bull restraint I found as an example

My rig is below. All bikes are pretty much behind the axles. I will say that putting too much mass too far back can upset handling. I originally had too much weight towards the rear. Depending on how long your rig is, you might be able to move them back where it is behind the tank. Putting them on the axles effectively decreases the % on the tongue. I played around with where to put the bikes. Tried all 3 at the rear (bad idea especially with 30 galons of fuel in the cell), then a triangle (better) and finally what you see. Even with the weight distribution and #'s in the safe zone, there was too much mass at the tail with them side by side. If your bikes are 300ish pounds each you could strap them more to the back the old way to test handling before you commit to drilling.

[JWCIV]

I managed to get 60% right over the axles with 40% to the rear ... I will share a pic here when I have all loaded up. As well, I will report the tow effects.

[The Evil Twin]

Right o!
We're you able to secure it to the joist under the floor?

[JWCIV]

Nope. I honestly could have spent the effort to drill pilot holes based on what my stud finder said ... combined with my guesstimation measurements taken from underneath but these were counter sunk SS screws of decent diameter just a tad bit longer than the 3/4 inch plywood floor ... that I pre-drilled and filled the holes with liquid nails before I sent the screws in ... that I final tightened by hand .... and there were 8 of them per plate.
So if this all fails and now I have holes galore ... I will repair and secure to steel.

[klutchdust]

Once again I went under my 25ULA and couldn't find anywhere i could access to install additional holdowns for my Polaris Ranger. There is only one in front which doesn't give me a huge sense of security. Like was mentioned, that huge water tank is in the way.

[JWCIV]

Heck .... I'm concerned with trying to secure my dual sport bike and my 500lb adventure bike and I think this is a critical deal ... I can't imagine the challenge of trying to secure a Polaris. Based on the size and construction of the frame rails below, I'm not sure there's anything of substance/heft needed that you could secure to. I saw that the wheel well material was pretty thin and you can access and measure easily in that area ... perhaps something that passes through that area and secures to the outer frame?

[klutchdust]

Originally Posted by JWCIV

Heck .... I'm concerned with trying to secure my dual sport bike and my 500lb adventure bike and I think this is a critical deal ... I can't imagine the challenge of trying to secure a Polaris. Based on the size and construction of the frame rails below, I'm not sure there's anything of substance/heft needed that you could secure to. I saw that the wheel well material was pretty thin and you can access and measure easily in that area ... perhaps something that passes through that area and secures to the outer frame?

There are three holdowns across the rear that I use and hold it securely there but in the front there is only one. Halfway up the machine, on either side are two more. The two on the side i use turnbuckles and cable I made up but it's a pain to get under there to secure them. I've transported it numerous times with success but looking to get out of crawling underneath to fasten and unfasten. On my flatbed I installed holdowns and steel plated them on the backside which was very secure, can't do that here. My guess is the tanks are last to be mounted and they get in the way.

[JWCIV]

As promised .... pics of loaded TH
https://www.dropbox.com/s/n9rlnd6764...15934.jpg?dl=0
https://www.dropbox.com/s/7479oeasgz...20013.jpg?dl=0
https://www.dropbox.com/s/ixmdr3gkqo...20200.jpg?dl=0

[The Evil Twin]

Nice!! I like those stands. And KTM's!