Rear End Damper?

cetstang902003 · Feb 28, 2006

I had a question as to what purpose does the rear end damper serves and can I just remove it is I want? Has anyone else done this with out any troubles? Thanks

slow5poh · Feb 28, 2006

I have heard of people removing it for weight reduction purposes. I have also heard folks say not to remove it. As the name suggests it must have something to do with dampening (sp?) vibrations in the rear end. Or maybe it helps keep the rear end centered? Something like that. If you're doing it for weight reduction in a street car i would just leave it. my .02

thegabrielles · Feb 28, 2006

I removed mine a long time ago and have had no problems, it is made to Dampen vibrations through the car. This also is supposed to make it quieter. Supposed I guess is the key word. The only reason I took mine of was because I was rebuilding/ repainting evertything, and I could not understand why it was so important. Kinda like that little bracket on the back of the stock intake system, anybody put that abck on when they put the intake back on?

RYC CUKR · Feb 28, 2006

I help reduce vibration in the drive line. However most people pull them off when they swap to a lower gear ratio. I pulled mine off and haven't noticed any problems.

matm347 · Feb 28, 2006

I've also not had any problems with the ~10 years I've had it off.

EBW83 · Jun 15, 2019

While doing a "what is this and what does it do" search I ran across this thread. Is this what is being referred to? If not, can you tell me what this is? I don't find it in my Ford shop manual.

FastDriver · Jun 15, 2019

I've always pulled mine off and haven't noticed an issue.

If the car stays smooth at high speed, assuming it was smooth in the first place, then don't worry about it.

jrichker · Jun 15, 2019

Ford is cheap and if they could get away with not putting a part on the car, they would do it that way. The dog bone as it is often called, helps dampen out vibrations in the driveshaft. It allows a greater range of tolerance for driveshaft imbalance. This will help to reduce vibrations and make the U joints last longer.

Wayne Waldrep · Jun 15, 2019

Took mine off in 1989 when I installed my new gears. So far zero troubles.....but then again it's only been 30 years. The old literature (no I can't produce it now) said that the dog bone was only good for the original factory gears. Why? I don't know. But there are many things to worry about on these cars. That isn't one of them.

FastDriver · Jun 15, 2019

It's because the driveshaft must spin faster with numerically higher gears for a given speed. So, actually that means that it's not good enough for higher gears. Then again, the factory hold pinion angle to the tolerances we can, or run an aluminum driveshaft, or road force balance the drive train.

Do you need to do all of that? Maybe... maybe not. Just take it off, go for a fast drive, and see if it feels alright. And ok, replace your U-joints a little more often.

Mustang5L5 · Jun 16, 2019

Keep in mind there were three sets of factory gears and only one damper. 2.73, 3.08 and 3.27. So I don't think they were tuned to a specific resonance.

Like everyone said, remove it, go for ride and if it feels smooth call it a day.

I kept mine even though it's been off for 20 years or so.

topjimmy69 · May 19, 2021

I do vibration testing and it may not noticeably change what you feel, but you gotta wonder why it's there

Mustang5L5 · May 19, 2021

Copy/paste from another post I did

......I believe the purpose of the weight is to counteract the effects of driveshaft resonance due to it's Critical Speed. The CS is the RPM that the driveshaft spins at where it begins to vibrate. This can vary from driveshaft to driveshaft. Aluminum, because its thicker, does a better job of resisting this resonance. I have no idea at what driveshaft RPM this occurs at.

I dont have hard data on this, just some assumptions. There was a great article written by Jerry Wroblewski who was a Ford drivetrain engineer. He touched upon this and the weight and it's impact with the Driveshaft's Critical speed. Unfortunately I do not remember the context of the article and the link I have bookmarked no longer works.

But, for the 86-04 8.8 axles, Ford stuck 2.73, 3.08's, 3.27's and I think the Mach1 got 3.55's. I believe they all got the same weight. Changing your rear axle gearing would not change the (driveshaft) RPM that the critical speed of the shaft is reached. Changing the rear axle ratio would just change the relelative vehicle speed that this CS would occur at. It doesn't negate the purpose of the weight as it would still be doing it's function, but just at a different (vehicle) speed.

But like I said, i'm just speaking of the concept, as I have no concrete data on this, nor any way or desire to go out and get data on it.

In terms of failure mode, I would think what you would see is excessive vibration causing pinion and trans seals to leak, and pinions/trans bearings/bushings and U-joints to begin to fail over time. But it would be tough to prove causation, vs correlation. Many cars don't have their weight anymore, so is that leaky pinion seal because of the missing weight, or would it have happened regardless of if the weight was there.

EDIT: BTW Jerry Wroblewski was the Engineer who devised the "Jerry's Mod" for the SN95 automatic trans.

7991LXnSHO · May 19, 2021

If Ford thought they could have made the car cheaper and lighter without it, it would have not been there. Based on the theory above, I’ll make sure the mounting is good and leave it on my car.

Wayne Waldrep · May 19, 2021

I can't believe we are still talking about the dogbone...
My car was born with one 33 years ago. Kept it ONE year. Been gone for 32 years. Zero difference. Real world results.

7991LXnSHO · May 20, 2021

Wayne Waldrep said:
I can't believe we are still talking about the dogbone...
My car was born with one 33 years ago. Kept it ONE year. Been gone for 32 years. Zero difference. Real world results.

Wayne, you must be well balanced compared to some of our members.
And how big is your dog to use that chunk as a chew toy?

Wayne Waldrep · May 20, 2021

7991LXnSHO said:
Wayne, you must be well balanced compared to some of our members.
And how big is your dog to use that chunk as a chew toy?

Lol.... That would be a big dog. No, I can't speak for everybody. I had a mustang only shop (more like a service) back when all the fun stuff started....Fun Ford weekends, mustang vs grand national, etc. I even wrote a weekly news letter back then for the local folks. I'd forgotten all about it till I ran across one the other day in a box. The first thing I did to most cars after the 10 minute tune up was install 3.55s or 3.73s. No one else was doing it back then. These cars were new and people were still figuring things out from decades of carburetors. Almost every mustang 5.0L in my area was at my place at some point. I took every single one of those weights off. I can only speak from my first hand experience back then, but if you were at any of the big events there were numerous Ford company guys there. One of them told me to my face that those were useless after the original gears were changed. I have no idea why and don't care. 25 years of conspiracy theories later and it's evolved into....whatever it is now...lol. Anyway, last count I've had over 20 mustangs thru the years. I've yet to have a single problem with removing that thing on mine or all the others. You'd think the shear number of cars involved would at least have one that showed some difference.... Nope... None.
That's my story and I'm sticking to it...
I'm not at all bashing continued discussion on the almighty dogbone....I enjoy reading it. It's just surprising something so insignificant would still be interesting.

limp · May 20, 2021

Wayne Waldrep said:
One of them told me to my face that those were useless after the original gears were changed. I have no idea why and don't care. 25 years of conspiracy theories later and it's evolved into....whatever it is now...lol.

But I want to believe...... I have my Tin Foil hat on...... LOL

Mustang5L5 · May 20, 2021

I’m putting mine back on. Need more weight in the back.

2000xp8 · May 20, 2021

The real players buy a torque arm so you can take it off.
But in all seriousness, mine has been gone at least 20 years.

Rear End Damper?

cetstang902003

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slow5poh

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thegabrielles

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RYC CUKR

matm347

EBW83

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FastDriver

I was uncomfortably high & wearing a helmet

jrichker

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Wayne Waldrep

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FastDriver

I was uncomfortably high & wearing a helmet

Mustang5L5

That is…until I whipped out my Bissell

topjimmy69

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Mustang5L5

That is…until I whipped out my Bissell

7991LXnSHO

wanna catch the space herp

Wayne Waldrep

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7991LXnSHO

wanna catch the space herp

Wayne Waldrep

Before I post a pic, do you have one of yours?

limp

wrap a little cheese around it and its a done

Mustang5L5

That is…until I whipped out my Bissell

2000xp8

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Rear End Damper?

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I was uncomfortably high & wearing a helmet

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Before I post a pic, do you have one of yours?

I was uncomfortably high & wearing a helmet

That is…until I whipped out my Bissell

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That is…until I whipped out my Bissell

wanna catch the space herp

Before I post a pic, do you have one of yours?

wanna catch the space herp

Before I post a pic, do you have one of yours?

wrap a little cheese around it and its a done

That is…until I whipped out my Bissell

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