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11-01-2015, 07:41 AM
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#1
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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Pin Box Adjustment Question
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.
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2015 Ford F450
2015 Momentum 385TH
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11-01-2015, 08:22 AM
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#2
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Site Team
Join Date: Jul 2014
Location: Modesto
Posts: 20,234
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Can you move the hitch in the bed UP one set of holes?
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2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.
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11-01-2015, 08:59 AM
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#3
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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Quote:
Originally Posted by chuckster57
Can you move the hitch in the bed UP one set of holes?
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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.
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2015 Ford F450
2015 Momentum 385TH
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11-01-2015, 10:13 AM
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#4
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Senior Member
Join Date: Aug 2012
Location: Waco, Tx
Posts: 5,456
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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...
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2015 Ford F350 DRW 6.7 Diesel XL
2020 Avalanche 313 RS
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11-01-2015, 04:26 PM
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#5
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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Quote:
Originally Posted by 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...
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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. .
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2015 Ford F450
2015 Momentum 385TH
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11-01-2015, 04:39 PM
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#6
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Senior Member
Join Date: Aug 2012
Location: Waco, Tx
Posts: 5,456
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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.
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2015 Ford F350 DRW 6.7 Diesel XL
2020 Avalanche 313 RS
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11-01-2015, 04:59 PM
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#7
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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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.
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2015 Ford F450
2015 Momentum 385TH
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11-01-2015, 05:20 PM
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#8
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Senior Member
Join Date: Aug 2012
Location: Waco, Tx
Posts: 5,456
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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
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2015 Ford F350 DRW 6.7 Diesel XL
2020 Avalanche 313 RS
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11-01-2015, 05:29 PM
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#9
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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Quote:
Originally Posted by 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
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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.
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2015 Ford F450
2015 Momentum 385TH
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11-01-2015, 06:30 PM
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#10
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Senior Member
Join Date: Mar 2014
Location: Las Cruces
Posts: 4,665
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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.
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Brent
2013 Alpine 3500RE
2019 Silverado 2500HD Duramax
U.S. Air Force Retired (25 yrs)
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11-01-2015, 06:52 PM
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#11
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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Quote:
Originally Posted by 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.
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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.
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2015 Ford F450
2015 Momentum 385TH
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11-01-2015, 07:13 PM
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#12
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Senior Member
Join Date: Mar 2014
Location: Las Cruces
Posts: 4,665
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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.
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Brent
2013 Alpine 3500RE
2019 Silverado 2500HD Duramax
U.S. Air Force Retired (25 yrs)
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11-01-2015, 07:33 PM
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#13
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Senior Member
Join Date: Aug 2012
Location: Waco, Tx
Posts: 5,456
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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.
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2015 Ford F350 DRW 6.7 Diesel XL
2020 Avalanche 313 RS
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11-02-2015, 04:45 AM
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#14
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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Quote:
Originally Posted by 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.
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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.
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2015 Ford F450
2015 Momentum 385TH
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11-25-2015, 09:53 PM
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#15
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Senior Member
Join Date: Jul 2013
Location: Liberty, Texas
Posts: 5,021
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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.
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2018 Ram 3500 Laramie CC DRW LWB 4X4 Cummins Aisin 3.73
Reese Goosebox 20K
2018 Heartland Landmark 365 Oshkosh
2008 Bigfoot 25C9.4 LB Cabover
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11-26-2015, 10:29 AM
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#16
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Senior Member
Join Date: Apr 2015
Location: Livermore Ca.
Posts: 138
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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.
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11-26-2015, 11:30 AM
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#17
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Senior Member
Join Date: Jan 2013
Location: Magnolia, TX
Posts: 404
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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!
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2015 Ford F450
2015 Momentum 385TH
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11-26-2015, 08:02 PM
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#18
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Senior Member
Join Date: Jul 2013
Location: Liberty, Texas
Posts: 5,021
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Quote:
Originally Posted by 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.
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Tell me more about thread dressing and getting a better torque please.
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2018 Ram 3500 Laramie CC DRW LWB 4X4 Cummins Aisin 3.73
Reese Goosebox 20K
2018 Heartland Landmark 365 Oshkosh
2008 Bigfoot 25C9.4 LB Cabover
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11-27-2015, 09:57 AM
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#19
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Permanent User Ban
Join Date: Jul 2014
Location: Folsom, Ca
Posts: 204
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Quote:
Originally Posted by 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!
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How are you enjoying your Grand Design? Keep hearing wonderful things about their customer service. Sounds like some pretty solid built trailers.
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11-27-2015, 09:58 AM
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#20
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Senior Member
Join Date: Apr 2015
Location: Stafford, CT.
Posts: 269
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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.
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Jason & Wendy
2014 F350 Lariat 6.7L PSD
2015 Keystone Montana 3711FL
B&W Patriot 16k fifth wheel hitch
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