Re: K frame strength
[Re: Supercuda]
#1900310
08/27/15 11:39 AM
08/27/15 11:39 AM
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Joined: Dec 2003
Posts: 23,295 Here
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
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This is a great topic and one that I have also wondered about. All of the aftermarket replacement front suspension kits have their own version of a "K" frame, but few seem to offer the OEMs robust resistance to "Parallelogramming." (Is that the right description ???) The RMS has a cantilevered outer tie rod connection. THAT looks hokey to me. Parallelogramming is the right word and if you look closely at the Gerst aftermarket K member it's LCA inner mounting points are also cantilevered. Being in double shear, not too sure how that'll play out. Without testing who knows and anecdotal track experience isn't testing per se. Whichever word describes the motion, and I believe on this site it was first used years back by well known guru, on a archieved aftermarket K thread. I have a hard time imagining how of all the distortions the K might be subjected to, that this one is often likely in real world HP driving, short of having one front brake fail, or hit a stationary pole with one corner if the car. Bottom line, its not a very high concern on my list, yet.
" All sorts of things can happen when you are open to new Ideas" Inventor of Kevlar
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Re: K frame strength
[Re: 72Swinger]
#1900321
08/27/15 11:51 AM
08/27/15 11:51 AM
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Joined: Dec 2003
Posts: 23,295 Here
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 23,295
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Any car with only a set of 245's on the front is gonna be slippery. We need threads on how to fit a 295 or 315 on the front of these things. Then with that kind of grip, you might start noticing some REAL advantages to suspension mods IMO. However, 10? years ago, 245 was considered really wide front tire, 295 was recently considered a wide front tire, where as mentioned, 315 is current holy grail. Regardless, any structural improvement found thru the testing suggested, should likely show an improvement on any size tire, just some more then others.
" All sorts of things can happen when you are open to new Ideas" Inventor of Kevlar
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Re: K frame strength
[Re: jcc]
#1900325
08/27/15 11:54 AM
08/27/15 11:54 AM
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Joined: Jul 2006
Posts: 183 usa
csmopar
member
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member
Joined: Jul 2006
Posts: 183
usa
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This is a great topic and one that I have also wondered about. All of the aftermarket replacement front suspension kits have their own version of a "K" frame, but few seem to offer the OEMs robust resistance to "Parallelogramming." (Is that the right description ???) The RMS has a cantilevered outer tie rod connection. THAT looks hokey to me. Parallelogramming is the right word and if you look closely at the Gerst aftermarket K member it's LCA inner mounting points are also cantilevered. Being in double shear, not too sure how that'll play out. Without testing who knows and anecdotal track experience isn't testing per se. Whichever word describes the motion, and I believe on this site it was first used years back by well known guru, on a archieved aftermarket K thread. I have a hard time imagining how of all the distortions the K might be subjected to, that this one is often likely in real world HP driving, short of having one front brake fail, or hit a stationary pole with one corner if the car. Bottom line, its not a very high concern on my list, yet. I'll be honest, I've only seen a couple stock, factory suspension/k frames fail. One was an upper control arm ripping out of the mounts on a 73 duster, another was a lower control arm actually bending, though it's possible the driver hit the rumble strips on the interstate, which likely caused it. And the only other one i can recall was a drivers side engine mount ear ripping out of the k frame but the charger was pretty rough so likely the k frame was as well. but that's all i can recall having seen. Other than a few ball joints ripping out here and there as well, most of the time because the shop the owners used were idiots and pressed the ball joints in instead of screwing them in.
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Re: K frame strength
[Re: jcc]
#1900474
08/27/15 03:59 PM
08/27/15 03:59 PM
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Joined: Aug 2013
Posts: 106 Central IL
Trojmn
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member
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Central IL
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Any car with only a set of 245's on the front is gonna be slippery. We need threads on how to fit a 295 or 315 on the front of these things. Then with that kind of grip, you might start noticing some REAL advantages to suspension mods IMO. However, 10? years ago, 245 was considered really wide front tire, 295 was recently considered a wide front tire, where as mentioned, 315 is current holy grail. Regardless, any structural improvement found thru the testing suggested, should likely show an improvement on any size tire, just some more then others. seems to be plenty of fast(er) 3500lb cars on way less than 315's...
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Re: K frame strength
[Re: GoodysGotaCuda]
#1900486
08/27/15 04:22 PM
08/27/15 04:22 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
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Goody, I have a couple tons of bar stock and heavy flat stock at home. It wouldn't be hard to put together a rig like your model. That was what I had in mind. Load testing for the engine weight could be done using an inverted stand. Simple hydraulics could apply the load measured using my proving ring. I have the general Dynamics calibration sheet on the ring that defines loads to 5500 lbs in 50 lb increments. The proper rig would allow testing deflection in heavy cornering due to engine weight as well.
My other gauges and instruments could measure deflection down to .0001" in multiple places.
In my opinion, some tests should demonstrate the strength of the K frame separate from the chassis. Any deflection would show additional load placed on the chassis. The K should stand on it's own as much as possible and not rely on a relatively flexible chassis for support.
Thoughts?
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
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Re: K frame strength
[Re: feets]
#1900506
08/27/15 05:06 PM
08/27/15 05:06 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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One thing to consider, looking at most, if not all, the aftermarket MII based K members out there is that the inner LCA pivots are not nearly as well braced as the factory K member. I suspect over time usage will spread those inner pivots outward.
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.
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Re: K frame strength
[Re: Supercuda]
#1900516
08/27/15 05:20 PM
08/27/15 05:20 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
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One thing to consider, looking at most, if not all, the aftermarket MII based K members out there is that the inner LCA pivots are not nearly as well braced as the factory K member. I suspect over time usage will spread those inner pivots outward. That can be tested rather easily. These tests would not be destructive in nature unless the frame is substantially under built and fragile. I'm not interested in testing them to failure. That makes for good video but that's about it. Simple deflection tests would be sufficient. The assemblies should have the ability to deform slightly and return to their original state. The fun part of these kinds of tests are when you use a long lever arm to apply a load (like Goody's example). The end of that arm can sweep a pretty wide arc. Years ago, I was present for frame testing on light duty trucks. You could use the Toyota frame like a diving board.
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
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Re: K frame strength
[Re: feets]
#1900518
08/27/15 05:22 PM
08/27/15 05:22 PM
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Joined: May 2005
Posts: 723 Houston Tx
Uhcoog1
super stock
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super stock
Joined: May 2005
Posts: 723
Houston Tx
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Goody, I have a couple tons of bar stock and heavy flat stock at home. It wouldn't be hard to put together a rig like your model. That was what I had in mind. Load testing for the engine weight could be done using an inverted stand. Simple hydraulics could apply the load measured using my proving ring. I have the general Dynamics calibration sheet on the ring that defines loads to 5500 lbs in 50 lb increments. The proper rig would allow testing deflection in heavy cornering due to engine weight as well.
My other gauges and instruments could measure deflection down to .0001" in multiple places.
In my opinion, some tests should demonstrate the strength of the K frame separate from the chassis. Any deflection would show additional load placed on the chassis. The K should stand on it's own as much as possible and not rely on a relatively flexible chassis for support.
Thoughts?
Ya'll need to do this. And get it in a magazine. With as many K frames as you can get your hands on.
-'02 Dodge Viper Ex-World Challenge racecar -'73 Duster, 6.1 based 392 hilborn hemi, tko600, full floater rear 9", Hellwig custom bars, viper brakes, built for road course
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Re: K frame strength
[Re: Trojmn]
#1900523
08/27/15 05:26 PM
08/27/15 05:26 PM
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Joined: Nov 2006
Posts: 1,074 Manitoba Canada
67autocross
super stock
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super stock
Joined: Nov 2006
Posts: 1,074
Manitoba Canada
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Any car with only a set of 245's on the front is gonna be slippery. We need threads on how to fit a 295 or 315 on the front of these things. Then with that kind of grip, you might start noticing some REAL advantages to suspension mods IMO. However, 10? years ago, 245 was considered really wide front tire, 295 was recently considered a wide front tire, where as mentioned, 315 is current holy grail. Regardless, any structural improvement found thru the testing suggested, should likely show an improvement on any size tire, just some more then others. seems to be plenty of fast(er) 3500lb cars on way less than 315's... I would be looking at tires in the same size range as the new Mustang GT 350 if I was buying some for a car now, 295/35/19 front and 305/35/19 rear. on 10 and 11" rims.
A new iron curtain drawn across the 49th parallel
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Re: K frame strength
[Re: Trojmn]
#1900528
08/27/15 05:31 PM
08/27/15 05:31 PM
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Joined: May 2005
Posts: 723 Houston Tx
Uhcoog1
super stock
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super stock
Joined: May 2005
Posts: 723
Houston Tx
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Any car with only a set of 245's on the front is gonna be slippery. We need threads on how to fit a 295 or 315 on the front of these things. Then with that kind of grip, you might start noticing some REAL advantages to suspension mods IMO. However, 10? years ago, 245 was considered really wide front tire, 295 was recently considered a wide front tire, where as mentioned, 315 is current holy grail. Regardless, any structural improvement found thru the testing suggested, should likely show an improvement on any size tire, just some more then others. seems to be plenty of fast(er) 3500lb cars on way less than 315's... *thread diversion* I for one am not sold on wider always equals better. Data points: - Corvette road racers on hoosiers - faster on some tracks with 275's square vs 315's square (275's faster on high speed tracks). - Tom - faster on 275's square with a better compound vs 285/315. My current line of belief: -tire compound matters most -tire temperature matters second -tire size matters last So sure, wider is better, but only if you get the first 2 right. I also think R compound tires may 'buck the trend' a bit past a certain point. Whereas 200tw tires hold the rule a bit better.
-'02 Dodge Viper Ex-World Challenge racecar -'73 Duster, 6.1 based 392 hilborn hemi, tko600, full floater rear 9", Hellwig custom bars, viper brakes, built for road course
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Re: K frame strength
[Re: 67autocross]
#1900533
08/27/15 05:36 PM
08/27/15 05:36 PM
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Joined: May 2005
Posts: 723 Houston Tx
Uhcoog1
super stock
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super stock
Joined: May 2005
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Houston Tx
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I would be looking at tires in the same size range as the new Mustang GT 350 if I was buying some for a car now, 295/35/19 front and 305/35/19 rear. on 10 and 11" rims.
Z28: 305/30/19 square GT350: 295/35/19 front, 305/35/19 rear GT350R: 305/30/19 front, 315/30/19 rear 305/30/19 is a good price in the RS3. Want.
-'02 Dodge Viper Ex-World Challenge racecar -'73 Duster, 6.1 based 392 hilborn hemi, tko600, full floater rear 9", Hellwig custom bars, viper brakes, built for road course
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Re: K frame strength
[Re: Uhcoog1]
#1900541
08/27/15 05:48 PM
08/27/15 05:48 PM
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Joined: Nov 2006
Posts: 1,074 Manitoba Canada
67autocross
super stock
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super stock
Joined: Nov 2006
Posts: 1,074
Manitoba Canada
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I would be looking at tires in the same size range as the new Mustang GT 350 if I was buying some for a car now, 295/35/19 front and 305/35/19 rear. on 10 and 11" rims.
Z28: 305/30/19 square GT350: 295/35/19 front, 305/35/19 rear GT350R: 305/30/19 front, 315/30/19 rear 305/30/19 is a good price in the RS3. Want. Could you fit a 305 on the front?
A new iron curtain drawn across the 49th parallel
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Re: K frame strength
[Re: Uhcoog1]
#1900542
08/27/15 05:50 PM
08/27/15 05:50 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
feets
OP
Senior Management
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OP
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Goody, I have a couple tons of bar stock and heavy flat stock at home. It wouldn't be hard to put together a rig like your model. That was what I had in mind. Load testing for the engine weight could be done using an inverted stand. Simple hydraulics could apply the load measured using my proving ring. I have the general Dynamics calibration sheet on the ring that defines loads to 5500 lbs in 50 lb increments. The proper rig would allow testing deflection in heavy cornering due to engine weight as well.
My other gauges and instruments could measure deflection down to .0001" in multiple places.
In my opinion, some tests should demonstrate the strength of the K frame separate from the chassis. Any deflection would show additional load placed on the chassis. The K should stand on it's own as much as possible and not rely on a relatively flexible chassis for support.
Thoughts?
Ya'll need to do this. And get it in a magazine. With as many K frames as you can get your hands on. I'm up for it if they are.
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
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Re: K frame strength
[Re: 67autocross]
#1900555
08/27/15 06:14 PM
08/27/15 06:14 PM
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Joined: May 2005
Posts: 723 Houston Tx
Uhcoog1
super stock
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super stock
Joined: May 2005
Posts: 723
Houston Tx
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I would be looking at tires in the same size range as the new Mustang GT 350 if I was buying some for a car now, 295/35/19 front and 305/35/19 rear. on 10 and 11" rims.
Z28: 305/30/19 square GT350: 295/35/19 front, 305/35/19 rear GT350R: 305/30/19 front, 315/30/19 rear 305/30/19 is a good price in the RS3. Want. Could you fit a 305 on the front? Probably. But could I turn? Who knows, haha. Started playing with fitment last night. I need to get my hands on a 1.0-1.5" wheel spacer to check fit. More than likely it'll be too much of a compromise to run it. We'll see though.
Last edited by Uhcoog1; 08/27/15 06:14 PM.
-'02 Dodge Viper Ex-World Challenge racecar -'73 Duster, 6.1 based 392 hilborn hemi, tko600, full floater rear 9", Hellwig custom bars, viper brakes, built for road course
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Re: K frame strength
[Re: feets]
#1900565
08/27/15 06:33 PM
08/27/15 06:33 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
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Posts: 14,889
up yours
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I've used stacks of washers on three lugs as temporary spacers to check fitment. Works better than buying a bunch of different spacers to test fit stuff.
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.
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Re: K frame strength
[Re: Uhcoog1]
#1900569
08/27/15 06:39 PM
08/27/15 06:39 PM
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Joined: Nov 2006
Posts: 1,074 Manitoba Canada
67autocross
super stock
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super stock
Joined: Nov 2006
Posts: 1,074
Manitoba Canada
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I would be looking at tires in the same size range as the new Mustang GT 350 if I was buying some for a car now, 295/35/19 front and 305/35/19 rear. on 10 and 11" rims.
Z28: 305/30/19 square GT350: 295/35/19 front, 305/35/19 rear GT350R: 305/30/19 front, 315/30/19 rear 305/30/19 is a good price in the RS3. Want. Could you fit a 305 on the front? Probably. But could I turn? Who knows, haha. Started playing with fitment last night. I need to get my hands on a 1.0-1.5" wheel spacer to check fit. More than likely it'll be too much of a compromise to run it. We'll see though. I keep meaning to try the 285/35/19s off my Mustang an the front of my Valiant, might try in in a few months when I put the winter wheels on the Mustang. I would guess that that would be about as big as you could hope to fit without beating the front fenders out.
A new iron curtain drawn across the 49th parallel
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Re: K frame strength
[Re: feets]
#1900600
08/27/15 07:47 PM
08/27/15 07:47 PM
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Joined: May 2005
Posts: 723 Houston Tx
Uhcoog1
super stock
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super stock
Joined: May 2005
Posts: 723
Houston Tx
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Studs aren't long enough for 1"+ of spacer. I tried! Ha
-'02 Dodge Viper Ex-World Challenge racecar -'73 Duster, 6.1 based 392 hilborn hemi, tko600, full floater rear 9", Hellwig custom bars, viper brakes, built for road course
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Re: K frame strength
[Re: feets]
#1900605
08/27/15 08:09 PM
08/27/15 08:09 PM
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Joined: Feb 2011
Posts: 4,302 Nebraska
72Swinger
master
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master
Joined: Feb 2011
Posts: 4,302
Nebraska
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I based my tire suggestion mainly on whats available in a 200TW. A 305/30/19 is actually pushing it on an A-body already. BUT, those on an E or B body should be a breeze.
Mopar to the bone!!!
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Re: K frame strength
[Re: Uhcoog1]
#1900678
08/27/15 09:50 PM
08/27/15 09:50 PM
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Joined: Dec 2003
Posts: 23,295 Here
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 23,295
Here
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A picture is worth a 1000 words
" All sorts of things can happen when you are open to new Ideas" Inventor of Kevlar
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