|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: feets]
#1705763
12/03/14 04:02 PM
12/03/14 04:02 PM
|
Joined: Sep 2003
Posts: 10,645
Houston, Tx
AlexP
I Live Here
|
I Live Here
Joined: Sep 2003
Posts: 10,645
Houston, Tx
|
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: Molloy]
#1705765
12/03/14 06:35 PM
12/03/14 06:35 PM
|
Joined: Sep 2006
Posts: 202
Texas
ef8Cuda340
enthusiast
|
enthusiast
Joined: Sep 2006
Posts: 202
Texas
|
Quote:
Nice write up. My only comment is that I'm not sure what sort of load would allow for a dead straight (and REALLY long) Stage I and Stage II area that runs parallel to the longitudinal axis. Whether sitting or driving it should be torsionally loaded. What stress state would allow the fatigue crack to initiate and propagate in that fashion?
Yeah, we need a closer look, but he's over the pond...
We don't know how long Stage I is and these multiple origins may be small stress risers such as rock dings, mechanical tool marks, or some sort of material imperfection from its orignal bar stock; however I do agree and am puzzled by the long flat Stage II region. I suspect it may be related to a shear component that preceeds a torsional fracture on a solid bar.
Considering the car is "lowered" means the torsion bar may be under zero torque; however, the reverse loading from muliple bumps on the road may be the driving force for a fatigue fracture (essentially a reverse loading scenario).
I agree we would benefit by seeing it after it is cleaned and using oblique lighting to have a better idea of what may be going on.
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: Molloy]
#1705766
12/03/14 06:43 PM
12/03/14 06:43 PM
|
Joined: Jan 2003
Posts: 3,575
The Netherlands
BigBlockMopar
OP
master
|
OP
master
Joined: Jan 2003
Posts: 3,575
The Netherlands
|
I haven't contacted JustSuspension (yet). Being overseas, US warranty stuff still always costs money somehow, especially with heavy & bulky parts. But then again, I don't feel the need to pull a warranty card since the purchase was 'just' over one year, nor have I a grudge against JS. Defects can happen, and I was already contemplating another torsion bar upgrade to either 1.06 or 1.12". I think I'm pretty much set on a set of 1.12" FirmFeel bars, although 1.06's would be fine as well I think. I would be nice if they would send me a new bar ofcourse. Just an hour ago I took some more pics after I cleaned the broken end of the bar. Shown below; Here are a few images showing the broken piece with a little more detail;     For those interested in the original highres photo-images, they can be found here; http://www.bigblockmopar.nl/test/IMG_3691.JPGhttp://www.bigblockmopar.nl/test/IMG_3692.JPGhttp://www.bigblockmopar.nl/test/IMG_3693.JPGhttp://www.bigblockmopar.nl/test/IMG_3695.JPGInteresting to notice is that the crack, or open space seems to run into the hex part. And you can barely see a marking on the outside of the hex flat.
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: ef8Cuda340]
#1705767
12/03/14 06:52 PM
12/03/14 06:52 PM
|
Joined: Jan 2003
Posts: 3,575
The Netherlands
BigBlockMopar
OP
master
|
OP
master
Joined: Jan 2003
Posts: 3,575
The Netherlands
|
Quote:
... Considering the car is "lowered" means the torsion bar may be under zero torque; however, the reverse loading from muliple bumps on the road may be the driving force for a fatigue fracture (essentially a reverse loading scenario).
While typing my previous reply the thought occured to me that the lower stance of the car might very well have something to do with this.
Here's my idea of what could also have caused, or at least helped it happen;
The bumpstops on the car get quite a workout because of all those damn speedbumps overhere, and I wouldn't be surprised that when the bumpstop hits the frame, any remaining downforce of the car will use the tires, but also the bumpstop and LCA as a fulcrum and this force will somewhat be transfered to the LCA's torsion bar socket. This could probably put a bending strain on the bushing, and the torsion bar on the other side.
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: BigBlockMopar]
#1705768
12/03/14 07:21 PM
12/03/14 07:21 PM
|
Joined: Jan 2003
Posts: 21,802
San Jose,CA
migsBIG
YouTube is my go-to news source
|
YouTube is my go-to news source
Joined: Jan 2003
Posts: 21,802
San Jose,CA
|
When I was looking for new torsion bars for my project, I had narrowed my choices down to Mopar Performance, Hotchkis, FFI and Just Suspension. I know Ma Mopar was going down hill and heard a few stories on torsion bars and leaf springs, so they were out. I was about to pull the trigger on Just Suspension bars when I saw all over the net of the problems folks were having with them and flaws in craftsmanship and decided to check out Hotchkis instead. Very nice piececs, thought still waiting to be installed. Glad the OP and his car is fine, but that is something that should never happen with that new of a part.
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: ef8Cuda340]
#1705770
12/03/14 08:29 PM
12/03/14 08:29 PM
|
Joined: Dec 2003
Posts: 23,515
Here
jcc
If you can't dazzle em with diamonds..
|
If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 23,515
Here
|
Quote:
Quote:
Nice write up. My only comment is that I'm not sure what sort of load would allow for a dead straight (and REALLY long) Stage I and Stage II area that runs parallel to the longitudinal axis. Whether sitting or driving it should be torsionally loaded. What stress state would allow the fatigue crack to initiate and propagate in that fashion?
Yeah, we need a closer look, but he's over the pond...
We don't know how long Stage I is and these multiple origins may be small stress risers such as rock dings, mechanical tool marks, or some sort of material imperfection from its orignal bar stock; however I do agree and am puzzled by the long flat Stage II region. I suspect it may be related to a shear component that preceeds a torsional fracture on a solid bar.
Considering the car is "lowered" means the torsion bar may be under zero torque; however, the reverse loading from muliple bumps on the road may be the driving force for a fatigue fracture (essentially a reverse loading scenario).
I agree we would benefit by seeing it after it is cleaned and using oblique lighting to have a better idea of what may be going on.
You completely lost me on the "reverse loading" comment. Care to explain?
However are we talking about swapping the TB's and loading them in reverse to previous useage?
Not a solution for material defects, but I have been for past few years Cryoing my TB's, for a little extra assurance, I'm just kinda shy about concrete walls at speed.
"When one’s appeal is emotional, it does not matter if there is no substance."
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: BigBlockMopar]
#1705771
12/03/14 08:48 PM
12/03/14 08:48 PM
|
Joined: Jan 2003
Posts: 28,114
Irving, TX
feets
Senior Management
|
Senior Management
Joined: Jan 2003
Posts: 28,114
Irving, TX
|
Were the bars shipped to you by container or were they flown?
I was wondering if it was possible for the bars to have been abused during transit. Perhaps they suffered multiple impacts in the same place rattling around in a big can with a bunch of other stuff while transiting a quarter of the globe.
Naturally, crap material and craftsmanship are possibilities too.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: feets]
#1705772
12/03/14 10:00 PM
12/03/14 10:00 PM
|
Joined: Jan 2003
Posts: 6,480
USA
Molloy
master
|
master
Joined: Jan 2003
Posts: 6,480
USA
|
The thing about T-bars, I'm sure all of you know, is that they take an insane amount of abuse, by design. They are hanging down there, totally exposed, for the life of the car. They will all have rock dings, impacts, dents, etc. I know have I have beat the living snot out of mine taking them off and putting them back on multiple times. As-manufactured they already have a pretty rough surface, so I don't think the little stress raisers from over-the-road abuse are going to have much effect. In a nut shell, they have a very high damage tolerance. I think it's pretty rare to even see broken bars in 40+ year old iron. They just don't usually break. At least that has been my impression having been in the hobby for 20+ years.
But when they do break, in only 1 YEAR after purchase, all sorts of alarms should go off in your head. I think we all agree that there are some fatigue features. But usually 70-80% of a fatigue life is consumed in initiating a tiny crack. 20-30% is consumed in growing/propagating the fatigue crack to final rupture. Maybe this bar started cracking 8 months after installation? What lowered the threshold to fatigue initiation?
And that long flat planar feature? What stress state would cause THAT?
I say infant mortality...
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: Molloy]
#1705773
12/03/14 10:48 PM
12/03/14 10:48 PM
|
Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
Back when my 64 300 was only (?) 30 years old I had the threads on the T bar adjuster rip out.
Similar stance.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: BigBlockMopar]
#1705774
12/04/14 12:09 AM
12/04/14 12:09 AM
|
Joined: Jul 2008
Posts: 240
Plano, Texas
68cuda440
enthusiast
|
enthusiast
Joined: Jul 2008
Posts: 240
Plano, Texas
|
I would be curious how these were formed. Was it somehow folded onto itself in a forging process which left a void? John Molloy - you are the real metallurgist here, I'm just an armchair hack with a few classes and labs (and plenty of experience breaking things) - does it look like this was a void that created a weak area to you? That would be my guess looking at the picture without getting it in hand with a magnifying glass or scope. -Michael Quote:
http://www.bigblockmopar.nl/test/IMG_3692.JPG
Michael
1968 Barracuda Notchback Coupe
440 EFI 6-pack, T56 Magnum 6-spd
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: 68cuda440]
#1705776
12/04/14 02:03 AM
12/04/14 02:03 AM
|
Joined: Jan 2003
Posts: 6,480
USA
Molloy
master
|
master
Joined: Jan 2003
Posts: 6,480
USA
|
Quote:
I would be curious how these were formed. Was it somehow folded onto itself in a forging process which left a void?
John Molloy - you are the real metallurgist here, I'm just an armchair hack with a few classes and labs (and plenty of experience breaking things) - does it look like this was a void that created a weak area to you? That would be my guess looking at the picture without getting it in hand with a magnifying glass or scope.
-Michael
Quote:
http://www.bigblockmopar.nl/test/IMG_3692.JPG
Mike! 'Sup!
I'm no more a metallurgist than you are a mechanical engineer. Speaking of which, I always try to consider the stress state that would drive a crack. This one is a little more complicated since it's dynamically loaded, and even if there was a weird bending moment due to lack of preload and pot holes, it still can't explain the orientation of the vast majority of the fracture surface. At least not to me. Maybe a mechanical engineer can clear it up?
Not a forging expert either, but I do know that there are lots of bad things that can happen in a forging process. If it was possible to do metallography of a cross section we could probably put this to bed.
PHJ426, yeah I see it, and can't explain it. What would really clinch this is if you could find paint in the opened crack. We routinely open cracks by back cutting and then using cryogenics to assist (at least for most steels). Paint in the opened crack, even the tiniest amount, infers pre-existing defect.
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: BigBlockMopar]
#1705779
12/05/14 12:07 PM
12/05/14 12:07 PM
|
Joined: Jun 2007
Posts: 2,432
NorCal
RylisPro
top fuel
|
top fuel
Joined: Jun 2007
Posts: 2,432
NorCal
|
The bar that snapped was the "L" or left side bar correct? Would it matter if the right and left bars were swapped? I would still get thicker Firm Feel bars 
|
|
|
Re: My JustSuspension 1" T-bars - 1 down, 1 to go....
[Re: RylisPro]
#1705780
12/05/14 04:56 PM
12/05/14 04:56 PM
|
Joined: Jan 2003
Posts: 3,575
The Netherlands
BigBlockMopar
OP
master
|
OP
master
Joined: Jan 2003
Posts: 3,575
The Netherlands
|
Only one bar is broken, no need for 2 new ones. People don't get 4 new tires if one comes apart prematurely do they?  There's no left or right bar with the JS bars. Both are the same. Ofcourse when you used them in a car before it's advisable to keep them at their initially installed side.
|
|
|
|
|
