dman93
Adventurer
I have sent them a request, and also contacted a custom spring/swaybar supplier in Michigan, and one in Ontario, CA.
-dman93
Flippac torsion bar
- Thread starter tacollie
- Start date
I have sent them a request, and also contacted a custom spring/swaybar supplier in Michigan, and one in Ontario, CA.
-dman93
DVexile
Adventurer
One last thing to consider, it seems the JK Habitat is also a torsion bar design of roughly similar dimensions to the Flippac. And reading old threads it sounds like AT has been involved in fine tuning the torsion bar for the Habitat. Perhaps they know of an appropriate custom manufacturer?
dman93
Adventurer
I had asked AT for some help in the past and they were, not unhelpful, but non-committal. I understand they no longer re-sell Flip-Pacs. But your post prompted me to contact Ursa Minor, who actually designed and make the J180 as far as I can tell. We'll see what they say. The Ursa Minor website says that the J180's are built to order only, unlike their "30 degree" poptop Element and Jeep campers. The reality is that a 180 degree travel torsion bar is highly stressed and puts large load into the lid and shell. I wouldn't be surprised if Ursa Minor has learned that the hard way.
dman93
Adventurer
Just FYI, I haven't got replies from any of the potential torsion bar suppliers I contacted. I did get an interesting reply from Ursa Minor, sympathizing with our plight but unable to recommend a supplier.
I did take a 3 day trip this past weekend with my wife and daughter (cut short by rain/snow since we don't have a fly) and had a great time. Saw no other FP's camping, but did see just one on the road, on a white double-cab Tacoma on CA 14 northbound near the 395 junction near Inyokern. I still find my t-bar delete a little unwieldy to flip solo, but with two of us it's a piece of cake and it's always more fun to have a companion. The first night camped at Red Rock Canyon the winds were stronger than anything we'd experienced in the FP since we got it, and it held up just fine. It was loud but probably no worse than a tent fly flapping. That night I had the lid supported only by the hood stays; the following night I also braced the tilt poles into the ground but it actually felt less stable .... perhaps with too many support points it rocked a bit more from point to point. By the way, I had taken a similar trip by myself last month, without the FP mounted up. Gas mileage was similar, power and handling definitely were impacted by the load plus two extra passengers and a lot more gear, but I slept better in the FP than in my tent!
-dman93
I did take a 3 day trip this past weekend with my wife and daughter (cut short by rain/snow since we don't have a fly) and had a great time. Saw no other FP's camping, but did see just one on the road, on a white double-cab Tacoma on CA 14 northbound near the 395 junction near Inyokern. I still find my t-bar delete a little unwieldy to flip solo, but with two of us it's a piece of cake and it's always more fun to have a companion. The first night camped at Red Rock Canyon the winds were stronger than anything we'd experienced in the FP since we got it, and it held up just fine. It was loud but probably no worse than a tent fly flapping. That night I had the lid supported only by the hood stays; the following night I also braced the tilt poles into the ground but it actually felt less stable .... perhaps with too many support points it rocked a bit more from point to point. By the way, I had taken a similar trip by myself last month, without the FP mounted up. Gas mileage was similar, power and handling definitely were impacted by the load plus two extra passengers and a lot more gear, but I slept better in the FP than in my tent!
-dman93
tacollie
Glamper
Finally received a tracking number from Flippac that show a torsion bar on its way. Hopefully it last a while.
I plan one carrying the supports for the delete just incase something happens.
My only issue with the delete is my girlfriend can't open and close the lid by herself.
Sent from my iPhone using Tapatalk
I plan one carrying the supports for the delete just incase something happens.
My only issue with the delete is my girlfriend can't open and close the lid by herself.
Sent from my iPhone using Tapatalk
DVexile
Adventurer
Hurray! And as a side note, good news for me as that must mean they have enough of them to build my Flippac sometime next week
When you get the bar could you take some detailed photos of the surface - maybe with angled light - or describe what the surface looks like. I'm curious as to whether the bar is shot-peened. From the little I know it would seem it really should be, but shot-peening is just the kind of thing that is apparently easy to do wrong and that might explain the wide variation in fatigue failures people are seeing.
Fingers crossed you get your bar soon!
dman93
Adventurer
I don't think shot-peening (or any surface hardening methods) are suitable for torsion bars, because of the stress distribution which is directly proportional to the radius. In a round cross sectionbeam in bending the stress is proportional to the radius cubed ( to the 3rd power). So adding hardness/strength near the surface helps a lot. Whereas for a torsion bar the discontinuity where the surface hardening stops would see a lot of strain. Plus, shot-peening can cause stress concentrations even at the surface. Let's face it, this is not a great design but there is so much else that's cool with the Flip-Pac. Enjoy it!!
DVexile
Adventurer
Actually every reference I find indicates shot-peening is extremely effective on torsion bars. Fatigue studies show it to improve by a factor of 5 to 8 times as many cycles. Now, how much of an advantage it gives depends on how stressed the torsion bar is in the application and as the level of stress increases for each cycle the effectiveness drops. It is quite possible the Flippac torsion bar going +/- 90 degrees is under so much stress that shot-peening is not particularly effective. It is also quite possible that given how few cycles it takes for some people's to fail that this is the result of some other internal or extreme surface defect in the bar that shot-peening would do nothing to improve. But the literature is pretty clear - torsion bars really should be shot-peened in almost all typical applications.
Agreed! I'm getting one despite the risk of torsion bar failures. But there are other products besides the Flip Pac that have +/- 90 torsion bars that don't fail like this. And there are plenty of high usage Flip Pac owners that never have a problem. So clearly a properly manufactured and treated torsion bar can handle the design application just fine.
Oh, and thanks for taking up the torch on trying to track down a manufacturer!
dman93
Adventurer
DVexile, I think you're right about fatigue ... I was thinking more of static stress. I guess that's why they took away my slide rule 35 years ago and promoted to project leader. I thought it was career advancement, but actually they were making sure they wouldn't get sued when my stuff broke. But I still don't think any torsion bar should have 90 degrees of travel.
-dman93
-dman93
tacollie
Glamper
I finally picked up my torsion bar a couple weeks ago. I probably won't have time to install it before June.
It has a very consistent shot peen to it.
In a separate not I wrecked on my mountain bike and did something to my shoulder almost two months ago. I have full range of motion but it sucks opening the lid with the t-bar delete. That hasn't stopped me though!
Sent from my iPhone using Tapatalk
It has a very consistent shot peen to it.
In a separate not I wrecked on my mountain bike and did something to my shoulder almost two months ago. I have full range of motion but it sucks opening the lid with the t-bar delete. That hasn't stopped me though!
Sent from my iPhone using Tapatalk
austintaco
Explorer
Glad to hear that you did get a replacement. On your shoulder, I would suspect that you have a separated shoulder. Don't confuse that with a dislocated shoulder. Two completely different things. I wrecked on my Mtn bike back in December and had a nagging shoulder injury similar to what you described. It took a few months to heal.
DVexile
Adventurer
Thanks so much for reporting back on that! I now have my own FlipPac but of course the torsion bar is covered up by a tube so I can't actually see the surface of it. Presumed it must be shot peened but wasn't sure. From what I've read the shot peen process is easy to do wrong so perhaps that has something to do with the inconsistent quality of the torsion bars.
Anyway - fingers crossed mine doesn't break!
Sorry to hear that
Hope it feels better soon.
dman93
Adventurer
I have been sitting around a lot lately so was checking this thread. Why am I sitting around? Because I broke my collarbone after going OTB on my MTB a week ago. Arm in a sling and almost zero range of motion for 6 weeks. Suddenly a T-Bar and crank would be pretty nice now; I think I could use it one-armed. My wife really can't swing the lid without the T-Bar so even if two of us go camping, we'd either tent camp or sleep in the bed. There goes my summer
tacollie
Glamper
That's a bummer. I have broken my collar bone twice so I literally can feel your pain! Hope it heals fast!
We actually got rear ended two weeks ago with our bikes on the back of the truck. Flippac, dogs, and people are good but truck and bikes are not. We are without bikes and the truck until everything gets sorted with insurance company. Going to try and swap the new t-bar into the Flippac this weekend. Should be pretty easy with it on the ground.
Sent from my iPhone using Tapatalk
We actually got rear ended two weeks ago with our bikes on the back of the truck. Flippac, dogs, and people are good but truck and bikes are not. We are without bikes and the truck until everything gets sorted with insurance company. Going to try and swap the new t-bar into the Flippac this weekend. Should be pretty easy with it on the ground.
Sent from my iPhone using Tapatalk