Well I broke it, in Canada

[The Artisan]

Pugs sorry to Jack your thread, I have learned a great deal from the replies.
Kevin

 

[nicknoxx]

One point I haven't seen mentioned is that a chassis CANNOT twist aft of the rear-most spring mounts so behind that, it's acceptable and indeed desirable to use rigid mounts as that will help stop the cabin from moving about.

 

[westyss]

One point I haven't seen mentioned is that a chassis CANNOT twist aft of the rear-most spring mounts so behind that, it's acceptable and indeed desirable to use rigid mounts as that will help stop the cabin from moving about.

Well it might not twist there but it certainly is affected and there is considerable movement there so having a rigid mount aft is a bad idea as I believe the movement aft will be accented. It seems that the frame pivots about the rear wheels where if the frame goes down on one side in front of the rear wheels the frame in the rear will go up, independently of the other frame rail These frames do not behave in what I would call a normal manner and must be viewed in person to actually see the effects. Again rigid mounts have not been successful on FG's and with so much information available now on this forum using the mitsu's builders manual and ATW's methods seems the best method of mounting for these on trucks.
Also I believe with a rigid mount aft of the rear-most spring mount and the weight of the camper will create undue stress on the frame from rolling side to side. I definitely think having a mount aft would be a big mistake and maybe a costly one too.

 

[pugslyyy]

One point I haven't seen mentioned is that a chassis CANNOT twist aft of the rear-most spring mounts so behind that, it's acceptable and indeed desirable to use rigid mounts as that will help stop the cabin from moving about.

The further you get from the cab, the worse the deflection will be. What you are saying makes no sense.

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[gait]

One point I haven't seen mentioned is that a chassis CANNOT twist aft of the rear-most spring mounts so behind that, it's acceptable and indeed desirable to use rigid mounts as that will help stop the cabin from moving about.

the two rails twist relative to each other. For there to be no twist behind the rear wheels the chassis rails would have to bend. They bend a bit, but not that much. Separately, if they bend differently between front and rear wheels it appears as twist behind the rear wheels.

in addition, by way of illustration, if contemplating a 3-point mount the "fixed" mounts are better at the front, body roll relative to road is minimised for that type of mount.

 

[pugslyyy]

Finally had a chance to replace the bolts with 1/2 inch grade 8 hardware. Bit of a PITA since I needed to drop one of my boxes to get access for the drill to enlarge the holes.

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[The Artisan]

Pugs see any advantage if i go to a 3/4"?
Kevin

 

[SkiFreak]

Bit of a PITA since I needed to drop one of my boxes to get access for the drill to enlarge the holes.

At least Doug designed things so you could drop the box; many other designers/builders don't plan for when you may need to do repairs.

Pretty toolkit, BTW...
All my tools normally live together in a canvas bag.

 

[SkiFreak]

One point I haven't seen mentioned is that a chassis CANNOT twist aft of the rear-most spring mounts so behind that, it's acceptable and indeed desirable to use rigid mounts as that will help stop the cabin from moving about.

What do they say... a picture is worth a thousand words.
Again I will use a picture of Westyss and his truck doing its thing. Look closely at the front vertical edge of the camper compared to the cab and the angle of the rear bar compared to the body.

 

[pugslyyy]

At least Doug designed things so you could drop the box; many other designers/builders don't plan for when you may need to do repairs.

Pretty toolkit, BTW...
All my tools normally live together in a canvas bag.

I really like the blow molded tool kits like this- makes it really easy to check that you have all your tools. I got this one at costco for $99 years ago. I've had to add a few things like larger wrenches, but for the price I've no complaints.

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[westyss]

What do they say... a picture is worth a thousand words.
Again I will use a picture of Westyss and his truck doing its thing. Look closely at the front vertical edge of the camper compared to the cab and the angle of the rear bar compared to the body.

View attachment 409544

Thats maximum flex with the right rear tire just off the ground. Made an odd noise at this point too??

Pugs, it sucks to have to do those away from home repairs in the dirt, if I were there I'd lend you a hand! Doesn't look like you get too stressed about it though which is a good thing.

 

[pugslyyy]

Pugs, it sucks to have to do those away from home repairs in the dirt, if I were there I'd lend you a hand! Doesn't look like you get too stressed about it though which is a good thing.

Today was absolutely beautiful weather. Mid-60s, sunny, nice breeze, no bugs. Got to spend it outside wrenching on my truck in a nice state park campsite - what could be better?


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[SkiFreak]

Got to spend it outside wrenching on my truck in a nice state park campsite - what could be better?

Pretty much the same conditions, only without a broken truck maybe...

 

[dlh62c]

Finally had a chance to replace the bolts with 1/2 inch grade 8 hardware. Bit of a PITA since I needed to drop one of my boxes to get access for the drill to enlarge the holes.

A good mechanical engineer always incorporates a part into the design that will sacrifice itself for the good of the whole.

 

[dlh62c]

View attachment 409544

What i see is a parabolic suspension doing its thing.