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Discussion Starter · #1 · (Edited)
I've hauled bikes a lot of differerent ways, from the fork mounts in the bed of my truck and the hang racks on the back of my camper I made, to throwing them inside a wagon and loading 5 on a Yakima rack (archive picture below). My very first concern with the JX was how to get lots of bikes around. JX roof "rails" and cross bars weren't going to cut it for us. So even though I thought hitch racks are for sissies, it looked like that was the only way to go.

We specified the tow package on the JX we ordered so we could use a hitch rack, and when that deal went south, the Pathfinder's metal roof rails looked good for putting Yak cross bars on. But, the PF stands a lot taller than our XC70 wagon, which is already a hand full to get a the middle bikes on. Soooo, back to the hitch rack concept for the PF's receiver hitch which is standard on the Platinum model. The PF and JX use the same Society of Automotive Engineers specification compliant Class III hitch, meaning certified to 500lb tongue weight and 5000lb tow capacity. The PF has the full 500lb tongue weight rating, while the JX is derated to a 350lb rating (based on 10% of the 3500lb tow rating), because of the JX's different transmission. But the JX can take a 500lb tongue weight, as the bikes and rack are no where near the tow capacity.

BUT, it's not just tongue weight, it's the torque from how far from the hitch the centroidal weight of the combined load is located that's the concern. My set up shown below looks like the weight is out there a mile, creating a tremendous torque load. I did some weighing and measuring, including putting the loaded rack on a balance fulcrum to accurately find that centroid. It ends up an effective 201lb at 32" from the hitch. That's 536 ft*lb of torque(!) If you condsidered a ball 12" draw bar loaded at 500lb is 500ft*lb, then yeah, this bike rack set up is extreme loading. In fact, I am surprised they don't give more detailed warnings with the rack instructions, which only say the maximum bikes weight limit is 160lb, which creates an enormous torque (our mtn bikes are 114lb).

I did some more measuring to determine how close I could move the hitch to the car. I then cut off the rack's tongue and welded a new cinch nut inside it 6" shorter. That moves the centroid 6" closer and reduces the torque 433 ft*lb, an impressive 19% reduction for very little hassle. I feel totally fine with the rack set up now. 4 mountain bike tires effectively block the car's tail lights, so I made a harness for some LED light bars that I attach to the end wheels so the bikes won't get rammed. The rack holds the bikes remarkably secure. Life is good. Oh, yeah, those are my Blizzak DM-V1 snow tires on Murano wheels. I like them.

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Nice job. What does the cinch nut look like?

I had a Yakima a number of years back (not a class III) and I remember it was just a hole in the side of the tongue that allowed for the lock pin.
 

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Discussion Starter · #6 · (Edited)
Here is a picture of the piece I cut off the rack's tongue. It's hard to see, but that flange nut inside is welded in the tongue piece. The "pin" is a custom bolt made for this application. The bolt threads engage the flange nut threads with a healthy M12x1.75 pitch, so you can really put the muscle on it. That pulls the tongue sideways against the reciever tube's inner sidewall, which eliminates lateral or rotational flop. It's a nice system.

You may notice that the piece doesn't look like it's 6" long, even though I said above I shorted the pin spacing 6". The front of the receiver tube is open, so the tongue can go all the way forward to the spare tire. I lowered the spare, set up the minimum clearance from the rack arms to the rear hatch (the limiting factor on shortening), and marked the tongue for cutting so that it brushes against the spare. That gives about 4" more tongue/tube engagement. The flange nut on the table is what I used for the new holes I drilled as the shorter length. It was pretty tricky getting it set up and welded way inside the tongue.

Sincure, it's funny that you picked a watersports theme. Our MasterCraft ski boat and trailer weigh about 4000# together, and the tandem trailer has 4 disc brakes. But we will NEVER try to tow it with the Mallfinder, even with its 5000# capacity. These are nice cars, but workhorses they're not. Oh, yeah, the loaded bike rack puts more load on the hitch than our boat would(!)

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Thanks for sharing. Yes, that looks a lot better than the class I I had on a Jetta a number of years ago. That Yakima used a cotter pin to hold everything in place.

Did you treat everything to prevent corrosion?
 

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Discussion Starter · #8 ·
It's work in process, I want to clean up their crappy welds with my angle grinder. I also want to measure gauge the vertical "slop" gap between the tongue and tube and weld in some shim stock for a closer fit. Then I will paint the parts I've molested. When I did the lights, I shrink tubed all the solder joints and wrapped the wires with wide harness tape, so at least that part of the project is complete.
 
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