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Torsion bar lifespan? #104231 08/13/08 12:19 PM 08/13/08 12:19 PM
Joined: Sep 2006 Posts: 1,164 Los Angeles, CA JF_Moparts OP super stock
JF_Moparts OP super stock Joined: Sep 2006 Posts: 1,164 Los Angeles, CA	How long should a pair of torsion bars last, and still provide a solid spring rate? The ones in my car were custom made in 1990 at 205 lb/inch and when they were new the car felt really responsive. Today it doesn't seem to be as responsive. Could the anti-sway bar (also bought in 1990) be a factor here? Do they have a certain lifespan? Thanks. Jim

Re: Torsion bar lifespan? [Re: JF_Moparts] #104232 08/13/08 01:49 PM 08/13/08 01:49 PM
Joined: Mar 2003 Posts: 18,678 Fresno, CA Jim_Lusk I Live Here
Jim_Lusk I Live Here Joined: Mar 2003 Posts: 18,678 Fresno, CA	I don't know what the lifespan is, but I'm fairly certain that my original 1968 340 bars (over 150,000 miles) are worn out.........

Re: Torsion bar lifespan? [Re: JF_Moparts] #104233 08/13/08 01:51 PM 08/13/08 01:51 PM
Joined: Apr 2008 Posts: 84 ohio 2 2264PLY member
2264PLY member 2 Joined: Apr 2008 Posts: 84 ohio	Right before they break.Sorry couldn't resist.Unfortunely they usually don't get replaced until they do break. Last edited by Bill W; 08/13/08 01:57 PM.

Re: Torsion bar lifespan? [Re: 2264PLY] #104234 08/13/08 02:18 PM 08/13/08 02:18 PM
Joined: Mar 2003 Posts: 18,678 Fresno, CA Jim_Lusk I Live Here
Jim_Lusk I Live Here Joined: Mar 2003 Posts: 18,678 Fresno, CA	Quote: Right before they break.Sorry couldn't resist.Unfortunely they usually don't get replaced until they do break. Actually I think mine have been worn out for many years. I've just never done anything about them. Next time through the front end I plan on new bars and probably slightly larger.

Re: Torsion bar lifespan? [Re: JF_Moparts] #104235 08/13/08 02:21 PM 08/13/08 02:21 PM
Joined: Jan 2003 Posts: 18,425 UPPER MICHIGAN, MARQUETTE COUN... N NITROUSN I Live Here
NITROUSN I Live Here N Joined: Jan 2003 Posts: 18,425 UPPER MICHIGAN, MARQUETTE COUN...	I dont believe they are worn out untill they can no longer support the weight designated for or they break. Breaks are most commonly caused by fracture than fatigue.

Re: Torsion bar lifespan? [Re: NITROUSN] #104236 08/13/08 02:24 PM 08/13/08 02:24 PM
Joined: Feb 2003 Posts: 913 C CrazyD super stock
CrazyD super stock C Joined: Feb 2003 Posts: 913	I have a set of 68 Dart 340 bars that look like they are bent - has anyone ever seen a bent bar?

Re: Torsion bar lifespan? [Re: CrazyD] #104237 08/13/08 02:32 PM 08/13/08 02:32 PM
Joined: Feb 2003 Posts: 913 C CrazyD super stock
CrazyD super stock C Joined: Feb 2003 Posts: 913	I went out and took another look - it might be that the hex end is not centered exactly on the bar centerline...

Re: Torsion bar lifespan? [Re: JF_Moparts] #104238 08/13/08 03:14 PM 08/13/08 03:14 PM
Joined: Sep 2005 Posts: 6,516 Santa Cruz, California L Lefty master
Lefty master L Joined: Sep 2005 Posts: 6,516 Santa Cruz, California	There's no way of knowing how long they will last with their initial spring rate. Basically when you can feel they are geting soft it's time to replace them.

Re: Torsion bar lifespan? [Re: CrazyD] #104239 08/13/08 03:14 PM 08/13/08 03:14 PM
A Anonymous Unregistered
Anonymous Unregistered A	I'm curious to see how mine are going to hold. They are the original /6 bars and i'm using them when i put the 440 in

Re: Torsion bar lifespan? #104240 08/13/08 03:52 PM 08/13/08 03:52 PM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	Still using original 318 t-bars under my 440. I like the way it handles so I've never felt a need to change them. Do the t-bars actually break? I've never seen that happen. I've seen the frame that holds the bars break, but never a broken bar itself. Not saying it can't happen or anything, but must not be all that common?

Re: Torsion bar lifespan? [Re: DaytonaTurbo] #104241 08/13/08 04:07 PM 08/13/08 04:07 PM
Joined: Jan 2003 Posts: 666 Anywhere the British Secret Se... M Moonraker mopar
Moonraker mopar M Joined: Jan 2003 Posts: 666 Anywhere the British Secret Se...	Quote: Still using original 318 t-bars under my 440. I like the way it handles so I've never felt a need to change them. Do the t-bars actually break? I've never seen that happen. I've seen the frame that holds the bars break, but never a broken bar itself. Not saying it can't happen or anything, but must not be all that common? I've seen it happen a few times so its probably more common than you would think.

Re: Torsion bar lifespan? [Re: JF_Moparts] #104242 08/13/08 06:00 PM 08/13/08 06:00 PM
Joined: Apr 2004 Posts: 1,396 Mass dgc333 pro stock
dgc333 pro stock Joined: Apr 2004 Posts: 1,396 Mass	Quote: How long should a pair of torsion bars last, and still provide a solid spring rate? The ones in my car were custom made in 1990 at 205 lb/inch and when they were new the car felt really responsive. Today it doesn't seem to be as responsive. Could the anti-sway bar (also bought in 1990) be a factor here? Do they have a certain lifespan? Thanks. Jim The spring rate will never change. The fatigue life is millions and millions of cycles. The normal range of motion will not come close to the yield strength. What can happen? They can take a set requiring you crank on the adjustment bolt to reset the ride height but this does not change the spring rate. Damage to the bar can cause a stress riser that can result in the bar snapping. Impurities in the bar when manufactured can also result in bar failure. The sway bar is subject to the same conditions but wouldn't be subject to taking a set. Dave Clement Pembroke, MA 03 PT Cruiser GT Turbo 99 Dakota SLT+ CC 4x4 68 Barracuda sport coupe http://home.comcast.net/~dgc333/

Re: Torsion bar lifespan? [Re: dgc333] #104243 08/13/08 07:53 PM 08/13/08 07:53 PM
Joined: Dec 2003 Posts: 22,696 Bitopia J jcc If you can't dazzle em with diamonds..
jcc If you can't dazzle em with diamonds.. J Joined: Dec 2003 Posts: 22,696 Bitopia	Quote: Quote: How long should a pair of torsion bars last, and still provide a solid spring rate? The ones in my car were custom made in 1990 at 205 lb/inch and when they were new the car felt really responsive. Today it doesn't seem to be as responsive. Could the anti-sway bar (also bought in 1990) be a factor here? Do they have a certain lifespan? Thanks. Jim The spring rate will never change. The fatigue life is millions and millions of cycles. The normal range of motion will not come close to the yield strength. What can happen? They can take a set requiring you crank on the adjustment bolt to reset the ride height but this does not change the spring rate. Damage to the bar can cause a stress riser that can result in the bar snapping. Impurities in the bar when manufactured can also result in bar failure. The sway bar is subject to the same conditions but wouldn't be subject to taking a set. Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.

Re: Torsion bar lifespan? [Re: jcc] #104244 08/13/08 08:16 PM 08/13/08 08:16 PM
Joined: Nov 2005 Posts: 589 Fortworth TX M mod5v mopar
mod5v mopar M Joined: Nov 2005 Posts: 589 Fortworth TX	Quote: Quote: Quote: How long should a pair of torsion bars last, and still provide a solid spring rate? The ones in my car were custom made in 1990 at 205 lb/inch and when they were new the car felt really responsive. Today it doesn't seem to be as responsive. Could the anti-sway bar (also bought in 1990) be a factor here? Do they have a certain lifespan? Thanks. Jim The spring rate will never change. The fatigue life is millions and millions of cycles. The normal range of motion will not come close to the yield strength. What can happen? They can take a set requiring you crank on the adjustment bolt to reset the ride height but this does not change the spring rate. Damage to the bar can cause a stress riser that can result in the bar snapping. Impurities in the bar when manufactured can also result in bar failure. The sway bar is subject to the same conditions but wouldn't be subject to taking a set.

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