TrailManor Owner's Forum - View Single Post

**rickst29** · 02-26-2010, 12:43 PM

I don't know if this is still an issue for Mac_Falls. Following my promise to take a careful look at my own, I went out to the garage and saw that I'd hidden access to underside of my TM (where I store all the Trailer paraphernalia) under tons of building materials. (Yes, TONS.) I'm only now far enough along to pull it out and take a look. I apologize for not posting my lack of access right when I found it, months ago.

Yes, I used 4 of the supplied washers. For my 1000lb model, the "adjustment bolt" which locks along the bottom, provided by Robin, has 4cm of cylindrical body length available for "use" before you've run the bolt head all the way against the hitch assembly. Mine is nearly all the way in: I only have about 2 threads, plus a tiny bit of un-threaded cylinder, left before reaching the bolt head. This is optimal, and that's why I recommended exactly four washers.

I believe that they use the same set of hitch-head bolts in all 4 versions of the round-bar hitch head (600, 800, 1000, and 1400lb systems all use "head assembly parts package" part # 20002). I also think that they use the exact same head assembly, and the exact same adjustable hitch bars (all with capacity 1200 lbs, even though the head and spring bars of the 1400 lb kit exceed the rating of the hitch bars.) If I'm right about this, then the difference between all of these "versions" is purely in the supplied spring bars (stronger and more stiff, versus weaker and less stiff).

Using more of the washers supplied for the top of the head assembly pushes it out, and that pushes the bottom IN (closer to the hitch bar). It seems to me that you tried to used less than 4 washers. More washers pushes the top away, and the bottom closer. With less than 4, there's too much space between the hitch head assembly and the hitch bar at the bottom of the head assembly. That's exactly the problem you describe: The distance between is longer than the bolt's shank length.

I can't even think of a way in which "loose" assembly could leave the top bolt-head and washers too short. (For those of you without Robin hitches, it's not something you screw into place-- it's already welded in.) I could be wrong with this guess, of course. Any sort of "looseness" would leave the top too far away, and the bottom even closer (the opposite of your problem).

If your bolt for the bottom looks about the same as mine, but runs out of Threads before reaching the height-adjustable bar on the hitch mount assembly, AND you're sure that everything concerning the two bolts which attach the head assembly to the hitch bar was done correctly, then you can add one or two more washers at the top. More washers at the top == more vertical, and more vertical == shorter bolt distance at the bottom. And Robin supplies 7 in bag of assembly parts, they aren't concerned with your use of more than 4.

But it sounds to me like something is wrong. Either at the top washers, or some bit of Crud is stuck between the hitch head assembly and the hitch bar (partway down). All of these Robin-supplied parts are identical. 4 washers SHOULD be adequate, and 5/6/7 washers creates an angle which isn't as optimal for the spring bar mounting (when the Spring are riding nearly-level under load, AND sprung up to proper tension for my 2619). It's possible that differences in the weight versus angular moment of the 2720 versus 2619 make 5 washers a better choice overall. But more likely than either of these two specific cases, would be the possibility that the change in angle doesn't make a durn bit of difference at all (in the real world). So, when you take it apart, if you DON'T find crud, feel free to add another washer or two.

Crud in between would leave the adjustment screw unable to tighten all the way-- the crud on the hitch bar would actually be working as the "adjustment screw", preventing the head assembly from getting "close enough in" at the adjustment bolt mounting. So I'm guessing that you will see a problem when you take it apart (which you'll have to do anyway, to put another washer on). Before you do it, be aware that you used Nylock nuts on the long bolts attaching the head assembly to hitch bar-- you'll want a pair of new ones when you put it back together.

02-26-2010, 12:43 PM	#9
rickst29 yes, they hunt lions. Join Date: Aug 2005 Location: Reno, NV Posts: 1,318	Finally got access to the Robin Hitch Head.... I don't know if this is still an issue for Mac_Falls. Following my promise to take a careful look at my own, I went out to the garage and saw that I'd hidden access to underside of my TM (where I store all the Trailer paraphernalia) under tons of building materials. (Yes, TONS.) I'm only now far enough along to pull it out and take a look. I apologize for not posting my lack of access right when I found it, months ago. Yes, I used 4 of the supplied washers. For my 1000lb model, the "adjustment bolt" which locks along the bottom, provided by Robin, has 4cm of cylindrical body length available for "use" before you've run the bolt head all the way against the hitch assembly. Mine is nearly all the way in: I only have about 2 threads, plus a tiny bit of un-threaded cylinder, left before reaching the bolt head. This is optimal, and that's why I recommended exactly four washers. I believe that they use the same set of hitch-head bolts in all 4 versions of the round-bar hitch head (600, 800, 1000, and 1400lb systems all use "head assembly parts package" part # 20002). I also think that they use the exact same head assembly, and the exact same adjustable hitch bars (all with capacity 1200 lbs, even though the head and spring bars of the 1400 lb kit exceed the rating of the hitch bars.) If I'm right about this, then the difference between all of these "versions" is purely in the supplied spring bars (stronger and more stiff, versus weaker and less stiff). Using more of the washers supplied for the top of the head assembly pushes it out, and that pushes the bottom IN (closer to the hitch bar). It seems to me that you tried to used less than 4 washers. More washers pushes the top away, and the bottom closer. With less than 4, there's too much space between the hitch head assembly and the hitch bar at the bottom of the head assembly. That's exactly the problem you describe: The distance between is longer than the bolt's shank length. I can't even think of a way in which "loose" assembly could leave the top bolt-head and washers too short. (For those of you without Robin hitches, it's not something you screw into place-- it's already welded in.) I could be wrong with this guess, of course. Any sort of "looseness" would leave the top too far away, and the bottom even closer (the opposite of your problem). If your bolt for the bottom looks about the same as mine, but runs out of Threads before reaching the height-adjustable bar on the hitch mount assembly, AND you're sure that everything concerning the two bolts which attach the head assembly to the hitch bar was done correctly, then you can add one or two more washers at the top. More washers at the top == more vertical, and more vertical == shorter bolt distance at the bottom. And Robin supplies 7 in bag of assembly parts, they aren't concerned with your use of more than 4. But it sounds to me like something is wrong. Either at the top washers, or some bit of Crud is stuck between the hitch head assembly and the hitch bar (partway down). All of these Robin-supplied parts are identical. 4 washers SHOULD be adequate, and 5/6/7 washers creates an angle which isn't as optimal for the spring bar mounting (when the Spring are riding nearly-level under load, AND sprung up to proper tension for my 2619). It's possible that differences in the weight versus angular moment of the 2720 versus 2619 make 5 washers a better choice overall. But more likely than either of these two specific cases, would be the possibility that the change in angle doesn't make a durn bit of difference at all (in the real world). So, when you take it apart, if you DON'T find crud, feel free to add another washer or two. Crud in between would leave the adjustment screw unable to tighten all the way-- the crud on the hitch bar would actually be working as the "adjustment screw", preventing the head assembly from getting "close enough in" at the adjustment bolt mounting. So I'm guessing that you will see a problem when you take it apart (which you'll have to do anyway, to put another washer on). Before you do it, be aware that you used Nylock nuts on the long bolts attaching the head assembly to hitch bar-- you'll want a pair of new ones when you put it back together. __________________ TM='06 2619 w/5K axle, 15" Maxxis "E" tires. Plumbing protector. 630 watts solar. 450AH LiFePO4 batteries, 3500 watt inverter. CR-1110 E-F/S fridge (compressor). TV = 2007 4runner sport, with a 36 volt "power boost".