Front torsion bars., What is the life span? |
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Front torsion bars., What is the life span? |
Krieger |
Dec 8 2017, 08:23 AM
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#1
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Advanced Member Group: Members Posts: 4,704 Joined: 24-May 04 From: Santa Rosa CA Member No.: 2,104 Region Association: None |
So these things are getting old. The newest ones are 41 years old! Of course mileage comes into play. I am not taking into account your rubber bushings have sagged to the point your torsion bars are grinding against the a arm (very common). Let's go with an optimum, best case scenario: no grinding and 130k miles and 41 years old. Do they loose there ability to work through there range of motion as intended? Sag?
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Mitox |
Dec 8 2017, 09:25 AM
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#2
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Member Group: Members Posts: 395 Joined: 26-October 15 From: SW Virginia Member No.: 19,302 Region Association: South East States |
Here is an interesting article on the subject; I've wondered about this also.
Torsion_Bar_Fatigue_Study.pdf ( 931.15k )
Number of downloads: 146
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mepstein |
Dec 8 2017, 11:59 AM
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#3
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914-6 GT in waiting Group: Members Posts: 19,253 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
The paper is a bit over my head. My son would understand the calculations but I just zipped to the conclusion. My gut feeling is that while the torsion bars will eventually fatigue, most of the other moving parts will wear first so the bars are sort of the last thing on the list, unless they are rusty, cracked or worn.
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bbrock |
Dec 8 2017, 01:02 PM
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#4
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
The paper is a bit over my head. My son would understand the calculations but I just zipped to the conclusion. My gut feeling is that while the torsion bars will eventually fatigue, most of the other moving parts will wear first so the bars are sort of the last thing on the list, unless they are rusty, cracked or worn. How rusty is too rusty? I was going to post a pic of one of mine when I got closer to suspension work on my resto, but since the subject has come up... The rear bushing had obviously leaked on one and pitted the surface just a little. Not sure whether to repaint and reuse. I had a torsion bar break on my first 914. It broke while parked, which I've read is common. I've no issue with walking out to the garage to find a sagging corner on the car. Less thrilled about the idea of snapping one during a hard corner. (IMG:style_emoticons/default/yikes.gif) |
Cairo94507 |
Dec 8 2017, 01:08 PM
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#5
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Michael Group: Members Posts: 9,723 Joined: 1-November 08 From: Auburn, CA Member No.: 9,712 Region Association: Northern California |
I was told if they have rust on them, replace them. I ordered a new set, from Sway Away, in the stock diameter.
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mepstein |
Dec 8 2017, 01:17 PM
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#6
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914-6 GT in waiting Group: Members Posts: 19,253 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
I was told if they have rust on them, replace them. I ordered a new set, from Sway Away, in the stock diameter. I blasted Michael's / Cairo's old ones, powder coated them and plan to use them on my suby build. (IMG:style_emoticons/default/biggrin.gif) |
Cairo94507 |
Dec 8 2017, 01:36 PM
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#7
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Michael Group: Members Posts: 9,723 Joined: 1-November 08 From: Auburn, CA Member No.: 9,712 Region Association: Northern California |
Glad they found life in a new build.
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Krieger |
Dec 8 2017, 01:41 PM
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#8
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Advanced Member Group: Members Posts: 4,704 Joined: 24-May 04 From: Santa Rosa CA Member No.: 2,104 Region Association: None |
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FlacaProductions |
Dec 8 2017, 03:46 PM
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#9
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Senior Member Group: Members Posts: 1,568 Joined: 24-November 17 From: LA Member No.: 21,628 Region Association: Southern California |
I had a torsion bar break on my first 914. It broke while parked, which I've read is common. I've no issue with walking out to the garage to find a sagging corner on the car. Less thrilled about the idea of snapping one during a hard corner. (IMG:style_emoticons/default/yikes.gif) Funny - I had the same things happen to mine. Drove, parked - all was good. Returned to find a sagging right front corner. I had no idea that they were more likely to fail while stationary. Interesting. |
914Sixer |
Dec 8 2017, 04:57 PM
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#10
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914 Guru Group: Members Posts: 8,872 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region |
Worn out bushings let the bar rub, then the rust starts. Friction and rust then take over.
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GeorgeRud |
Dec 8 2017, 05:11 PM
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#11
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Advanced Member Group: Members Posts: 3,725 Joined: 27-July 05 From: Chicagoland Member No.: 4,482 Region Association: Upper MidWest |
I think the state of the rubber bushings determine the lifespan more than anything. Once they deform and allow the bars to rub, the lifespan shortens. Luckily, Sway-a-way provides replacement bars (either solid or drilled).
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Chris914n6 |
Dec 8 2017, 09:00 PM
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#12
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Jackstands are my life. Group: Members Posts: 3,307 Joined: 14-March 03 From: Las Vegas, NV Member No.: 431 Region Association: Southwest Region |
I can't imagine sag being a thing on 914s --- too light. Plus they are easy to adjust so you would never really know if the PO did or not.
I know sag is an issue on first gen 4wd Nissan Pathfinders and Hardbodies around 200k miles. But that's not surprising when it's taken into consideration that 2/3rds of their 4000lbs are on the front axle and offroading is hard on suspensions. Even coil springs sag with that kind of use. |
Mark Henry |
Dec 8 2017, 09:17 PM
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#13
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
I've had one rear that snapped on a 911, it did have large rust pitting.
IRS beetle it tells you to lightly coat with grease before installing. |
Mark Henry |
Dec 8 2017, 09:17 PM
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#14
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
dp
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barefoot |
Dec 9 2017, 08:11 AM
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#15
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Senior Member Group: Members Posts: 1,270 Joined: 19-March 13 From: Charleston SC Member No.: 15,673 Region Association: South East States |
The paper is a bit over my head. My son would understand the calculations but I just zipped to the conclusion. My gut feeling is that while the torsion bars will eventually fatigue, most of the other moving parts will wear first so the bars are sort of the last thing on the list, unless they are rusty, cracked or worn. How rusty is too rusty? I was going to post a pic of one of mine when I got closer to suspension work on my resto, but since the subject has come up... The rear bushing had obviously leaked on one and pitted the surface just a little. Not sure whether to repaint and reuse. I had a torsion bar break on my first 914. It broke while parked, which I've read is common. I've no issue with walking out to the garage to find a sagging corner on the car. Less thrilled about the idea of snapping one during a hard corner. (IMG:style_emoticons/default/yikes.gif) If you can polish out the rust pit the bars should last much longer. Re-paint with a good rust proof coating. It's when a pit leads to the initiation of a stress concentration crack that they fail. The corrosion almost always starts when the rear bushing deteriorates and lets the bar rub in the ID of the A arm and cuts thru the protective coating. then rust pits start |
cal44 |
Dec 9 2017, 08:27 AM
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#16
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Member Group: Members Posts: 165 Joined: 8-October 09 From: Encinitas, Ca. Member No.: 10,910 Region Association: Southwest Region |
Each time we got in a 356 we always ordered NEW bars. They are not expensive, they improve the ability of the suspension to work in harmony with the other NEW bits.
It's like using 40 some year old springs..........They are DOA as springs start dying after ten years and they don't get any better as they age. Buy New bars and rubber bits........be done with it. |
Garland |
Dec 9 2017, 08:44 AM
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#17
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Restoration Fanatic Group: Members Posts: 1,328 Joined: 8-January 04 From: ......Michigan...... Member No.: 1,535 Region Association: Upper MidWest |
Around 78" , got out of the 70' and sat down in a lawn chiar facing the car 10 feet away, with-in seconds of sitting down...."SNAP" short sharp snap noise, and very quickly left frt was slightly lower. I had no idea what happen. But since I was in my driveway, figered it out and replaced both.
I have stored a set for years, and after owning, and driving many 914, this has never happened to me again. Sitll waiting to use them. |
Krieger |
Dec 9 2017, 08:58 AM
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#18
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Advanced Member Group: Members Posts: 4,704 Joined: 24-May 04 From: Santa Rosa CA Member No.: 2,104 Region Association: None |
Elephant Racing has 19 through 25mm. Not sway away. I wonder if they have the 914 spline count?
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Mark Henry |
Dec 9 2017, 10:28 AM
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#19
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
If I wanted new bars Sway a Way would be my first call.
https://swayaway.com/ |
mepstein |
Dec 9 2017, 11:24 AM
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#20
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914-6 GT in waiting Group: Members Posts: 19,253 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
(IMG:style_emoticons/default/agree.gif) that’s where we buy most of our torsion bars and rear axles. |
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