Pin Box Adjustment Question

[C130]

I'd like to get some opinions on adjusting a Trailair Rota-Flex pin box, trailer on a Grand Designs Momentum. I know it's not a Keystone but a pin box is a pin box in my opinion but know there's lots of smart people on this forum. There are only two height adjustments and it was at the lowest position. I need more spacing between the bed rails, currently between 5 1/2-6", closer to 5 1/2, as my bed cover isn't flat along the bed rails. Just going through my storage unit facility I have to be careful because there are large storm drains that cause a significant amount of roll and I get with about an inch of hitting. My Hensley TS3 hitch is as high as I can get it and still close my bed cover. I'm sitting a little low (2"-3") in the front also but it tows great and I've had no issues other than not being comfortable wit the spacing.

So, I researched the Grand Designs forum and found some others with the same issue. I can't find anyone that's swapped out their pin boxes and I was willing to try a different one but didn't want to go out and buy a new one without knowing it would fix my issue. I found one guy that moved his pin box down one notch and four out of the five bolts fit. He then drilled a hole to make the 5th bolt fit therefore having the same number of bolts holding the pin box in place. I couldn't find any other options so I did the same yesterday. The guy sent me photos and has towed numerous times with no issues. He had two mechanical engineers in his family look at it before doing it and both said it would be fine. Any opinions or anyone see any issues? I'm not asking for approval or anyone to tell me it's perfectly okay to justify me doing it, just want honest opinions from people who have more knowledge in this area. The only issue I see is there is less of the pin box between the frame it's mounted to but I still have the same number of bolts holding it in place. I can easily add another bolt on each side also. If it's a stupid idea feel free to tell me that also. I can post photos later if that helps.

I really like the Rota-Flex with the TS3 and it's the best tow experience I've ever had but the Rota-Flex is a weird design in my opinion. I'm really surprised it doesn't have more slots for adjustment and it goes almost straight out, hardly any downward angle at all to give it any height. Looked at the Mor/Ryde online but can't really tell if it would solve my issue, need to see one in person. Pin box is rated for 21,000 pounds.

[chuckster57]

Can you move the hitch in the bed UP one set of holes?

[C130]

Can you move the hitch in the bed UP one set of holes?

It's up as high as it'll go without hitting the bed cover. With no bed cover I could raise it up. The TS3 uses spacers. They are a pain to install, not hard, just a lot of work. I actually had to buy smaller ones to get the bed cover to close so I have the larger ones already. My Fuzion pin box was as high as it would go and still set slightly nose high with same truck and hitch. I was surprised to see my new trailer sitting low and thought I'd actually need to move the pin box up one notch.

The drop frame 5th wheels are nice for storage but they don't need to be nose low at all in my opinion. That's another reason I need to raise it, it'll drag if you aren't careful in certain areas.

[Javi]

Sometimes you just can't get where you want to be from where you are now.. This is probably one of those instances..

JMO as an engineer... ;) Ditch the bed cover and adjust the hitch as it is designed to be... not as you want it to be...

[C130]

Sometimes you just can't get where you want to be from where you are now.. This is probably one of those instances..

JMO as an engineer... ;) Ditch the bed cover and adjust the hitch as it is designed to be... not as you want it to be...

Ditching the bed cover isn't an option, at least one I'd consider. I keep too many things back there that can't get wet. I'm going to keep looking at other pin boxes as that's my first choice. Saying that, personally I can't see moving it down being an issue as it's just another hole drilled and the same number of bolts holding it. But, I'm definitely not an expert in this and the reason I wanted opinions. Thanks!

I think a pin box with more holes for adjusting is all I need or one with some angle to it. My plain, stock pin box in my Fuzion came down several inches more than this Rota-Flex and also had more holes for adjusting height. .

[Javi]

Are you sure you bought the correct replacement. Although looking at their website it looks like they are about the same.

How difficult would it be to remove the hitch when not towing? I know it takes me less than 5 minutes to remove mine.

[C130]

It's not an easy hitch to take in and out, way too heavy. I think it's about 300 pounds. The pin box is the original one, what came on it. Here's what it looks like adjusted down one notch. The bolt in the center was the one drilled and added.

http://www.keystoneforums.com/attachments/photobucket/img_188161_0_a42fc4549e138e366f25f5d5e80b1a9f.jpeg (http://s1160.photobucket.com/user/KTM85SXS/media/Mobile%20Uploads/image_zpsjozzvjet.jpeg.html)

[Javi]

I don't think what I see in your photo is a problem, but didn't you say that you need more to level up

[C130]

I don't think what I see in your photo is a problem, but didn't you say that you need more to level up

That's the pin box moved down to where I need it. It was in the position one notch up originally with three bolts in the front and two in the rear. To keep the same number of bolts the center hole was drilled and the 5th bolt added there. I could easily add a 6th bolt but don't really think it's needed.

I've been told the Mor/Ryde or Rota-Flex pin boxes are the best combination with the Hensley air ride hitches. So far I'd have to agree as it tows incredibly well with no chucking and very smooth. I'll have to look at a Mor/Ryde in person and see how they compare. I just looked at a photo of my Fuzion stock pin box and it angled downwards much more than the Rota-Flex. Guess that's why it was all adjusted all the way up and still slightly nose high but was about perfect.

[bsmith0404]

Since you can't have the cover on/closed while towing, and the hitch is too heavy to remove and install easily, is it an option to just remove the hitch head? That would allow you to raise the hitch to a level needed for towing, but close your cover when not towing. I remove the hitch head on mine all the time.

[C130]

Since you can't have the cover on/closed while towing, and the hitch is too heavy to remove and install easily, is it an option to just remove the hitch head? That would allow you to raise the hitch to a level needed for towing, but close your cover when not towing. I remove the hitch head on mine all the time.

Thanks for the suggestion but it's actually not the hitch head that hits. The TS3 has an arm across the back that the hitch pivots on and that's the highest point and the part that hits. I have a hoist so it's not hard to lift but a pain. I have to use the Ford adapter plate and the hitch has four legs that fit down in the slots in the adapter plate. Really prefer to keep the hitch in the truck. I was hoping someone had already switched pin boxes to alleviate the issue but can't find anyone yet. Someone posted a photo of them busting the front cap though when they hit the bed rails. It's not an issue normally and I've been careful with no issues but really don't want to have to worry about it.

Now, I could get rid of the TS3 and get a lighter hitch where I can take the head off or take it out but after using the air ride hitch I don't want to go back. I'm going to try and do some more research on the Mor/Ryde or even a regular, plain pin box.

[bsmith0404]

I'm not sure how much difference the hitch makes, I have the same pin as you with a Reese 20K hitch and it tows great.

[Javi]

Just as an observation, if I had so much chunking as to cause me to have to buy a special hitch and pin box to make it manageable I'd probably be looking for the cause rather than another bandaid.

[C130]

Just as an observation, if I had so much chunking as to cause me to have to buy a special hitch and pin box to make it manageable I'd probably be looking for the cause rather than another bandaid.

I didn't have any chucking except on an occasional concrete highway with joints before the air ride hitch but I can tell you it's much smoother towing and much easier on the truck and trailer. I've taken quite a bit of video of the hitch moving and those forces would be transferred to the truck and trailer if it weren't for the hitch. It's kinda like a dually, once you use one you'll never go back. I got a great deal on the Hensley hitch at $900, it's worth every penny. I'm not saying it's a bad ride if you don't have one, just saying it's better with it.

[gearhead]

I would think you are OK.
I would replace the bolts with grade 8 bolts myself. Tractor Supply usually has them. Have a gold/yellow tint to them. Should have 6 lines on top of the bolt head. Do one at a time.
If you have a torque wrench I would torque them to spec. Clean and dry threads, no oil or grease.

[old timer]

Ii would use a high torque thread dressing on the threads. That way you will get a better torque on the bolts. They will not loosen up with that on the threads. Get it at a good parts house. Grade 8 or better on the bolts for sure. The black automotive bolts may have a higher torque rating than grade 8 but you need to ask someone at the auto parts store.

[C130]

Thanks guys, I can replace the bolts very easily so will buy some new ones. I do have a torque wrench and torqued the original bolts down. Trailers sits about perfect right now but I haven't towed any distance with it yet. I did pull it out of the storage unit yesterday and waxed it, what a job!

[gearhead]

Ii would use a high torque thread dressing on the threads. That way you will get a better torque on the bolts. They will not loosen up with that on the threads. Get it at a good parts house. Grade 8 or better on the bolts for sure. The black automotive bolts may have a higher torque rating than grade 8 but you need to ask someone at the auto parts store.
Tell me more about thread dressing and getting a better torque please.

[sw342]

Thanks guys, I can replace the bolts very easily so will buy some new ones. I do have a torque wrench and torqued the original bolts down. Trailers sits about perfect right now but I haven't towed any distance with it yet. I did pull it out of the storage unit yesterday and waxed it, what a job!

How are you enjoying your Grand Design? Keep hearing wonderful things about their customer service. Sounds like some pretty solid built trailers.

[cw3jason]

Be careful
with lubricating the treads. this is considered a wet torque versus a dry torque and the torque value should be different. remember the torque value for a given aplication takes in account the force it would take to overide the friction of the nut turning on the bolt. if you use a dry torque value on a lubricated bolt, you could over stretch or damage the fastener.

[C130]

How are you enjoying your Grand Design? Keep hearing wonderful things about their customer service. Sounds like some pretty solid built trailers.

We love it so far but have barely had time to use it. We had planned on camping this week but my work schedule didn't work out. I think they have their issues like all the manufactures do but they seem to have good customer service. What I really liked about them is they will generally send you the parts directly. Other owners have had their own RV repair guys do the warranty work and Grand Designs authorized the repair. If I can't fix it myself I'll try that route as I'm not planning on using my local dealer unless absolutely necessary. They informed me up front if I didn't buy from them they wouldn't have time to do any work for me. They were also around $12,000 higher than what I paid so I bought elsewhere.

[gearhead]

Be careful
with lubricating the treads. this is considered a wet torque versus a dry torque and the torque value should be different. remember the torque value for a given aplication takes in account the force it would take to overide the friction of the nut turning on the bolt. if you use a dry torque value on a lubricated bolt, you could over stretch or damage the fastener.
Exactly. You can get in trouble lubing threads and then torqueing to dry specs. There are specs for lubricated threads out there though. For me it's just too much a variable between a drop of 3 in 1 oil, Never Seize, or a lot of grease.

[sw342]

We love it so far but have barely had time to use it. We had planned on camping this week but my work schedule didn't work out. I think they have their issues like all the manufactures do but they seem to have good customer service. What I really liked about them is they will generally send you the parts directly. Other owners have had their own RV repair guys do the warranty work and Grand Designs authorized the repair. If I can't fix it myself I'll try that route as I'm not planning on using my local dealer unless absolutely necessary. They informed me up front if I didn't buy from them they wouldn't have time to do any work for me. They were also around $12,000 higher than what I paid so I bought elsewhere.

I have not had a chance to see one in person yet, but there is a dealer on RV row that carries them, so next time I get into downtown I will see if I can find some time to stop by. Sounds like some other brands could take a lesson from GD's customer service. Hope it doesn't become watered down the bigger they grow.

[C130]

I have not had a chance to see one in person yet, but there is a dealer on RV row that carries them, so next time I get into downtown I will see if I can find some time to stop by. Sounds like some other brands could take a lesson from GD's customer service. Hope it doesn't become watered down the bigger they grow.

Yes, that's the issue they'll have I think as they continue to grow because it'll be hard to keep up the customer service. I contacted several manufactures before buying and they were the only one that responded and they called me. That was one of the deciding factors for me. But, like most every manufacturer they have some quality control issues. I think they are trying to improve upon that because they are building a brand new PDI facility right now. It seems a lot of the issues they have is from Lippert and some of the other parts manufacturers so that issue is the same all across the business.

As I've stated before though we were very happy with our Fuzion and never had a single issue. I occasionally talk to the couple that bought it from me and they are living in it full time while they build a house. They haven't had any issues either and are very happy with it.