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 Anybody have a known-good DS I could borrow?

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toomanytoyz
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Location : East Hampstead, NH USA

PostSubject: Anybody have a known-good DS I could borrow?   Mon Oct 28, 2013 2:29 pm

Hey guys. As some of you know, I'm chasing a vibration in the marshmallow. And thinking back, this car has had a vibration on the highway since we bought it. I even remember my wife mentioning it on the way back from Fred's in Waterloo when we bought it one Wagonfest long ago... Wink

At this point I'm thinking that with the new rear suspension with poly bushings, and the lowering springs, and everything being a bit tighter than when we bought it, the problem has gotten worse.

And of course, I gave away my spare, or tossed it, or something when I moved.

So if you happen to have a known good spare standard length driveshaft sitting around, might I be able to borrow it to do some troubleshooting?

Please and thank you. Smile

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
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No Moa



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Join date : 2009-02-21
Age : 44
Location : Midcoast Maine

PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Oct 28, 2013 3:36 pm

toomanytoyz wrote:
Hey guys. As some of you know, I'm chasing a vibration in the marshmallow. And thinking back, this car has had a vibration on the highway since we bought it. I even remember my wife mentioning it on the way back from Fred's in Waterloo when we bought it one Wagonfest long ago... Wink

At this point I'm thinking that with the new rear suspension with poly bushings, and the lowering springs, and everything being a bit tighter than when we bought it, the problem has gotten worse.

And of course, I gave away my spare, or tossed it, or something when I moved.

So if you happen to have a known good spare standard length driveshaft sitting around, might I be able to borrow it to do some troubleshooting?

Please and thank you. Smile
You need an alum dshaft.
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V8Killer



Posts : 1690
Join date : 2009-03-12
Age : 45
Location : Southern, NH

PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Oct 28, 2013 4:13 pm

No Moa wrote:
toomanytoyz wrote:
Hey guys. As some of you know, I'm chasing a vibration in the marshmallow. And thinking back, this car has had a vibration on the highway since we bought it. I even remember my wife mentioning it on the way back from Fred's in Waterloo when we bought it one Wagonfest long ago... Wink

At this point I'm thinking that with the new rear suspension with poly bushings, and the lowering springs, and everything being a bit tighter than when we bought it, the problem has gotten worse.

And of course, I gave away my spare, or tossed it, or something when I moved.

So if you happen to have a known good spare standard length driveshaft sitting around, might I be able to borrow it to do some troubleshooting?

Please and thank you. Smile
You need an alum dshaft.
X2 Laughing 
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toomanytoyz
Club President


Posts : 6870
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Age : 40
Location : East Hampstead, NH USA

PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Oct 28, 2013 4:30 pm

Hardy harrr. You guys suck. Wink

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
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http://impalass.uniquekind.net/
IMPALADAKID
Admin


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Age : 48

PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Oct 28, 2013 7:47 pm

Everybody who is anybody has a drive shaft.Rolling Eyes 

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Machine-De-Zine



Posts : 512
Join date : 2010-11-16
Age : 60
Location : Wrentham

PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 3:07 am

toomanytoyz wrote:
to do some troubleshooting?

Smile
If you have an hour or so, try the trick with the big diameter HD hose clamps, setting these around the D/S's O.D. @ 180 deg apart initially.

Rotate them in various clock positions to see where it gets better or worse on short test rides. Bad vibes may need 4 clamps instead of two.

Ive done this up on HD jack stands, with a wine glass of water sitting on the dash showing surface ripples well before you can feel it through the NVH isolating seat.

This actually works very well, even with out the expensive electronic NVH test rig.

If no clamp clocking changes made provide any noticeable improvement, its likely to be something else.

I'm assuming you've already tried swapping drums, rotors, tires & wheels, checking motor and trans mounts, bent rear axle flanges, etc.

You know that some tires will balance nicely on the bal/machine w/no load, but then behave terribly while carrying a vehicle-load at the same speed.

Also, D/S vibrations have their own particular kind of signature.

Check on and off the gas at the worst offending speed and then coast back down thru that speed in neutral looking for any differences.


I just fixed a horrific vibration in my Dually.

This vibration was much worse upon deceleration, and it turned out to be the rear U-Joint.

When accelerating, due to spring-wrap the D/S centerline was perfectly in line with the axis of the pinion, but w/engine braking, the angle was worse than when coasting.

The seized U-Joint did not like being asked to do anything except deliver it's power in a straight shot though.

If it IS the D/S, then ALUM-X3.
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toomanytoyz
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PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 9:57 am

Thanks for that, Glenn. But I don't have the place to do that currently.  It's easier to try a known good.

I have tried 2 rear ends, 5 or six sets of tires, and just about everything else. Driveshaft was out and ujoints seem tight.

And they're busting my balls about the aluminum driveshaft cuz Glen has one that he won't sell me. Wink

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
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http://impalass.uniquekind.net/
No Moa



Posts : 3871
Join date : 2009-02-21
Age : 44
Location : Midcoast Maine

PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 10:01 am

toomanytoyz wrote:
Thanks for that, Glenn. But I don't have the place to do that currently.  It's easier to try a known good.

I have tried 2 rear ends, 5 or six sets of tires, and just about everything else. Driveshaft was out and ujoints seem tight.

And they're busting my balls about the aluminum driveshaft cuz Glen has one that he won't sell me. Wink
I need it for my six speed project. I have a couple regular ones, they are still in the cars, and I don't think you want to drive to maine to get one
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V8Killer



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 11:30 am


Just pop it out and bring it to these guys :

Gilberts Driveline Services
340 Massabesic St Manchester, NH 03103
(603) 623-3061

That's who has done mine. Resonable, quick, great work. cheers 
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Machine-De-Zine



Posts : 512
Join date : 2010-11-16
Age : 60
Location : Wrentham

PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 2:43 pm

toomanytoyz wrote:
Thanks for that, Glenn. But I don't have the place to do that currently.  It's easier to try a known good.

I have tried 2 rear ends, 5 or six sets of tires, and just about everything else. Driveshaft was out and ujoints seem tight.

And they're busting my balls about the aluminum driveshaft cuz Glen has one that he won't sell me. Wink
Can you describe exactly under what conditions it (the car) vibrates?

What does it specifically do when it vibrates, is is always predictable or is it intermittent and randomly occurring?

It is actually easier & faster to strap on a couple hose clamps than to swap the whole D/S out.

Its even simpler and faster than changing just one tire, and can be done anywhere a tire can changed.

It would suck big time if you had changed the entire rear in search of a vibration and it turned out to be the D/S.

...
I wish I was nearer to you, you could try mine out from my 95 RMW, all someone has to do is lend you theirs for an hour so you can get your answer.

Does anybody know for sure if the same D/S will fit a wagon if borrowed from an LT1 9C1 sedan? Axle width differences shouldn't matter in this case.

Obviously the 8.5" axle housing requires a slightly shorter drive/shaft than what was originally installed in cars having the smaller R&P rear axle housing.

...
It would be a good idea to go to a good D/S specialist and have them spin yours on their dynamic balancing rig to see how bad it actually is, as suggested by V8Killer.

Many driveline shops (even very good ones) do not spin balance check D/Ss, they simply build them with all new component-parts and verify T.I.R. (total indicated run-out).

With brand new tube and yoke ends, this procedure is very good alone to predict balance, many shops routinely hold this tolerance to under 0.010".

However if your old tube is very rusty, T.I.R. is better than nothing, but it still could have advanced partial tube thinning causing load induced bending or static out of balance.

I imagine that they would be willing to do that test for free with the possibility that it is bad so that they can build you a new one from scratch.

...
Aluminum is not definitely not stronger than steel when comparing the same volume of material, but it does have more rigidity per pound of material.

This is why alum D/Ss are less prone to out of balance issues, but they have to be larger physically to accomplish this rotational inertia vs ultimate torsional strength advantage.

Some of the best D/Ss made (big $$$) are made from carefully oriented carbon fiber soaked in resin and wrapped around aluminum tubing to retain it's cylindrical integrity.

If you decide to have a D/S made, make sure you tell them every factor that will contribute to their calculation of worst case scenario critical speed. (tire size, top MPH, R&P ratio)

Meaning, if you plan on switching from 2.73:1 R&P to 4.11:1 R&P, but still want to go 100 MPH as your top anticipated speed, then you need to prepare for that in critical speed calculations.
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sdstick



Posts : 4278
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PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 10:03 pm

Cant believe no one has a DS laying around

I'm so flat out its gonna kill me to try to pull one outta my resting DD

Did we hear from Mike yet?....he's all in LS limbo right now isnt he?

_________________
Steve


96BBB 28K 3.42 Bolt-ons
95BBB 100K 3.73 383 New DD...already broke fixt the 4L60E twice
95 Black WB4 Hole...ee...grail
96 Black WB4 No holes in this
95BBB 189K 3.08 Old DD Stolen...by Matt. Cool
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toomanytoyz
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Posts : 6870
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Location : East Hampstead, NH USA

PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Oct 29, 2013 11:32 pm

I'm going to pull it in the morning and bring it to that place in Manchester. Hopefully I'll get it back in the afternoon and my problems will be solved. Al drove it tonight and thinks it may be the problem... We'll see.

If this doesn't fix it, then I'll definately post up here all conditions. But it's basically above 45mph, gradually worsens as speed increases, slightly worse on the throttle, REALLY worse at WOT, but present all the time above 45-50mph. It's just an up-down-up-down-up-down vibration you feel in the whole car, but more in the seats and floor. You can be cruising on the highway at 75, then all of a sudden it gets really bad, dashboard jumps up and down 1/2", and then it goes away(ish).

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
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tonyc712000



Posts : 126
Join date : 2013-10-04
Location : Ct.

PostSubject: Re: Anybody have a known-good DS I could borrow?   Wed Oct 30, 2013 5:19 pm

toomanytoyz wrote:
Hey guys. As some of you know, I'm chasing a vibration in the marshmallow. And thinking back, this car has had a vibration on the highway since we bought it. I even remember my wife mentioning it on the way back from Fred's in Waterloo when we bought it one Wagonfest long ago... Wink

At this point I'm thinking that with the new rear suspension with poly bushings, and the lowering springs, and everything being a bit tighter than when we bought it, the problem has gotten worse.

And of course, I gave away my spare, or tossed it, or something when I moved.

So if you happen to have a known good spare standard length driveshaft sitting around, might I be able to borrow it to do some troubleshooting?

Please and thank you. Smile
I seem to have the same issue with my Cappy. Its a loud mono-tone hum. It gets louder with speed....scratch 
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Machine-De-Zine



Posts : 512
Join date : 2010-11-16
Age : 60
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PostSubject: Re: Anybody have a known-good DS I could borrow?   Wed Oct 30, 2013 5:31 pm

tonyc712000 wrote:

I seem to have the same issue with my Cappy. Its a loud mono-tone hum. It gets louder with speed....scratch 
Hey Tony, I would be surprised if that noise & vibration was your D/S.

But it certainly is worth your efforts in eliminating that as a possible source, but I sat directly over that rear axle for several hours, and I think its most likely inside the rear axle itself.

Can't remember if you told me if your tires and wheels have been properly excluded from being considered as the culprit.
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toomanytoyz
Club President


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PostSubject: Re: Anybody have a known-good DS I could borrow?   Wed Oct 30, 2013 8:19 pm

Spun it on a balancer today and it looked like a wet noodle. lol. Poor manufacturing. The driveshaft guy HATES three river driveshafts. He rebalanced it, as good as he does race cars, guaranteeing it's the best that shaft will ever balance. Dude knew his stuff. Wink

I'll throw it in tomorrow and cross my fingers.

But an Aluminum driveshaft is definately in my future, Glen or not. Wink

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
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http://impalass.uniquekind.net/
sdstick



Posts : 4278
Join date : 2009-03-20
Location : Revere, MA

PostSubject: Re: Anybody have a known-good DS I could borrow?   Wed Oct 30, 2013 9:47 pm

NICE!...so I can continue to plan jobs....& not do them?

_________________
Steve


96BBB 28K 3.42 Bolt-ons
95BBB 100K 3.73 383 New DD...already broke fixt the 4L60E twice
95 Black WB4 Hole...ee...grail
96 Black WB4 No holes in this
95BBB 189K 3.08 Old DD Stolen...by Matt. Cool
Whine..eee...Silver LS6
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toomanytoyz
Club President


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PostSubject: Re: Anybody have a known-good DS I could borrow?   Wed Oct 30, 2013 10:39 pm

sdstick wrote:
NICE!...so I can continue to plan jobs....& not do them?
Yes. It's not like you had any volunteers to give you a hand, anyways... Suspect 

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
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http://impalass.uniquekind.net/
sdstick



Posts : 4278
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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 6:18 am



....Razz 


Hey....unless your Father Time....& could create a window to work in......you cant help MY problem.

_________________
Steve


96BBB 28K 3.42 Bolt-ons
95BBB 100K 3.73 383 New DD...already broke fixt the 4L60E twice
95 Black WB4 Hole...ee...grail
96 Black WB4 No holes in this
95BBB 189K 3.08 Old DD Stolen...by Matt. Cool
Whine..eee...Silver LS6
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No Moa



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 8:28 am

toomanytoyz wrote:
But an Aluminum driveshaft is definately in my future, Glen or not. Wink
I'm about 99.99999999999999999999999999 percent sure, thats a not. Very Happy 
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toomanytoyz
Club President


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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 8:48 am

No Moa wrote:
toomanytoyz wrote:
But an Aluminum driveshaft is definately in my future, Glen or not. Wink
I'm about 99.99999999999999999999999999 percent sure, thats a not. Very Happy 
Doh. Wink

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
Back to top Go down
http://impalass.uniquekind.net/
sdstick



Posts : 4278
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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 8:52 am

No Moa wrote:
toomanytoyz wrote:
But an Aluminum driveshaft is definately in my future, Glen or not. Wink
I'm about 99.99999999999999999999999999 percent sure, thats a not. Very Happy 
So...there's a chance?

_________________
Steve


96BBB 28K 3.42 Bolt-ons
95BBB 100K 3.73 383 New DD...already broke fixt the 4L60E twice
95 Black WB4 Hole...ee...grail
96 Black WB4 No holes in this
95BBB 189K 3.08 Old DD Stolen...by Matt. Cool
Whine..eee...Silver LS6
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toomanytoyz
Club President


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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 9:13 am

https://www.youtube.com/watch?v=KX5jNnDMfxA&feature=youtube_gdata_player

_________________
Bill "The Verb" Crovo - Resident Car Slut & Unicorn Hunter

A Toasted Marshmallow, A Long German, A Lame Suburban and expensive dreams...
Missing all my previous B's, D's and V... Sad
American Ricer
www.badassofne.net
"Ooooh! Look! Something shiny!"
NO MORE UNICORNS!!!!!

LOWER IT!!! Wink
Back to top Go down
http://impalass.uniquekind.net/
No Moa



Posts : 3871
Join date : 2009-02-21
Age : 44
Location : Midcoast Maine

PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 9:16 am

There's always a chance.
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JaySS



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 1:32 pm

toomanytoyz wrote:
But an Aluminum driveshaft is definately in my future, Glen or not.
Machine-De-Zine wrote:
If it IS the D/S, then ALUM-X3.
If it's because it's cool mod, then so be it, but I wouldn't throw out a good steel shaft because just everyone says they're inferior.

I'd argue most issues are the results of mis-matched yoke & pinion angles trying to tear it apart every 1/2 turn.

And don't start with the critical speed comments, how many people can determine the critical speed of the OEM driveshaft? (Hint: the diameter is not constant, so your internet calculators aren't going to get it right.)

Factory shaft & 4.10's are doing just fine, thank you.

- J



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Machine-De-Zine



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Thu Oct 31, 2013 5:30 pm

JaySS wrote:
toomanytoyz wrote:
But an Aluminum driveshaft is definately in my future, Glen or not.
Machine-De-Zine wrote:
If it IS the D/S, then ALUM-X3.
If it's because it's cool mod, then so be it, but I wouldn't throw out a good steel shaft because just everyone says they're inferior.

I'd argue most issues are the results of mis-matched yoke & pinion angles trying to tear it apart every 1/2 turn.

And don't start with the critical speed comments, how many people can determine the critical speed of the OEM driveshaft? (Hint: the diameter is not constant, so your internet calculators aren't going to get it right.)

Factory shaft & 4.10's are doing just fine, thank you.

- J



All points well taken,

1) But no, I don't care about the cool factor, however a non-ferrous tube should last longer.
An aluminum D/S should better survive many long winters exposed to N/E road salt because as it corrodes, it becomes encapsulated in it's own self-protective oxide.
We have all seen how the iron/steel oxidation process goes, it continues until there is no metal left.

2) Yoke angles are certainly a common oversight, mismatched and/or excessive. (Lowering addicts take note... Zero angle also leads to early U-joint failures, needles need to be rolling in the cup, less than 3 deg will cause Brinnelling) .

3) I only directed the critical speed comment for the D/S shop making the the shaft to do the calculations. One piece shafts are the worst offenders in this regard and these shafts are pretty long, so they are more prone to whipping.
I don't know if he's got a set of drag race 4.88:1 gears on his shelf and a 250HP nitrous kit to be put in next spring with a 25" tall "R"compound tire, and wants to thrill ride at 6,800 RPM in overdrive on some deserted highway.
Perhaps I am too conditioned to raising these points, because of what most of our customers at the machine shop, as well as what myself and the majority of my friends are doing with our cars for fun.
Most modified performance vehicles I work on are fully capable of D/S destruction had there not been an up-grade to the installation of a critical-speed aspect figured, better constructed propeller shaft.
If a new customer came to me asking me to build him a drive-shaft, and I didn't know or ask these questions about his vehicle and it's operating conditions, it'd be negligence in the performance of my task if I failed to gather this information.  

4) Factory shafts are fine with 4.10:1, but as you surely know, only up to a certain MPH & tire height, and if they are physically & functionally close to being in original condition - regardless of age.
I've come across some older cars with steel tube drive shafts that were rotted only on one side due to the initial partial spraying of paint or undercoating when new, but the other side left bare was literally rust-windowed right through.

Side note: afaik, the diameter of a drive shaft need not be constant, just that they must be larger where whip needs to be constrained, large diameters for the sake of resisting excessive torsional loads is a different matter.
It makes me wonder if the perfect contour of a drive shaft might be more like an elongated or stretched out foot-ball, 3.5" on each end and 5" in the middle, with a gradual, constant radius slight bow shape.
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boojum



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Sat Nov 02, 2013 3:14 am

How would a (good) original driveshaft work with a 4.56 gear, SS size tires, and the correct angles?
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Machine-De-Zine



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Sun Nov 03, 2013 4:32 am

boojum wrote:
How would a (good) original driveshaft work with a 4.56 gear, SS size tires, and the correct angles?  
Here are some of my current thoughts on drive shaft options and their suitability for use in or GM B-bodies.

The drive shaft yokes should be in perfect phase front to rear, and U-joint working angles should be kept close to being the same front to rear, or perhaps just one more degree at the pinion (measured while at rest) to anticipate the rise of the pinion snout upon hard acceleration. These issues become much greater at elevated road speeds.

If you are considering using your 4.56:1 R&P with a stock drive-shaft and 27" tires, and assuming that the drive-shaft is as accurately balanced as it was when new, that the tail housing bushing and slip yoke are good and the U-joints are fresh, then you would still be prudent to hold your top vehicle speed down to match your original top drive shaft RPM by calculating the proportional difference between the two.

For example, lets say you knew you had confidence traveling up to 120 MPH with that same tire height and a 3.08:1 R&P, but no proof higher than that thus far.
Now with a 4.56:1 R&P, you've now got 1.48 times as much drive shaft speed. (in RPMs)
So you could only reasonably know for sure that you were safe up to approximately 2/3rds (66%) of your old known safe top speed.
By doing the math, that's only 81 MPH!
And this is without having any knowledge of how other unmeasured variables like harmonics and natural resonant frequencies might conspire to adversely affect drive shaft behavior.

Another aspect to consider is when the OEMs build into a new car a road speed limiter, its largely based on the known limitations of the tires specified for that exact model, and the drive shaft that they originally installed in that same vehicle.

.....

A few years ago I was interested in installing extended rear control arms in my 96 9C1 to center some larger tires in the wheel well, and I really wanted to use the AMMX (Alcoa Metal Matrix Composite) drive shaft that Ford had put into their P71 police package from 1999-2000 with 3.55:1 R&P.

At that time they were reasonably plentiful and cheap enough to buy if I just added in the small expense of correct "Jump" U-joints to make it work.

But I learned further about how Ford stopped using them, and this may have been partly due to their high initial cost to manufacture, but by observing what they did in response to two separate and catastrophic MMC (Metal Matrix Composite) drive shaft failures which, in both cases occurred during extended high speed pursuits (more than 5 continuous minutes at speeds in excess of 125 MPH), Ford simply stopped installing these drive shafts.
More importantly, they immediately went back to installing the standard 6061 T-6 aluminum drive shaft... and they also lowered the maximum achievable MPH down to 120 by re-programming these vehicle's on-board computers (at their next service), on each & every one of these MMC D/S equipped P71s, preventing further liability.

All of this had made me hesitate to buy this particular P71 shaft.

During this same period, a few premium drive shaft builders were offering MMC tubed D/S assemblies, but they were a lot of money.

I thought they would come down in price as they were expected to increasingly become more widely available, but that turned out not to be the case.

It seemed that unless a company trying to purchase this material stepped up and committed to ordering like $50K of inventory, then the manufacturers of this fairly exotic extrusion stock would not produce anything less.    

From my meager understanding, in the manufacture of the material for this tubing, boron carbide (the third hardest substance known to man, that is also produced in tonnages) is machine process pulverized down to a particle size of around 8 microns, and uniformly mixed in an air centrifuge of some sort with a proportionally specific ratio of a matrix material of a powdered metallurgical formulation.
This powdered metal is usually either predominantly 6061 or 7091 aluminum alloy. Other alloying metals in much smaller amounts are added in to the mix for the special purposes of enhancing strength, machinability and consistency of properties, as well as the sintering and whetting of the micro fibers into the matrix.
Then this mixture is heat over time dried, de-gassed and powerfully compressed at around 65,000 psi into appropriately sized ingots and sintered at carefully controlled temps and periods of time, machined to the correct size to be ram-extruded into various shapes for the myriad of industries to further produce from these extrusions improved products that are much better than those manufactured utilizing lower performing materials.

MMC is weldable, but apparently it's not the easiest thing to do.

Previously (before 1999) the boron carbide was mixed into the aluminum matrix metal at the base metal's molten temperatures, but this had it's practical limitations as far as achieving a homogeneous state of particle dispersion which would negatively affect the qualities of the resultant product.

.....

If you were to compare visually the Ford MMC shaft to the standard Ford 6061 T-6 shaft, you would see that the weld-zone is cleaner appearing on the 6061 example.
However, the MMC shaft is 30% stronger and more stable at higher rotational speeds.

Mark Williams Ent makes extremely well engineered drive line products, and their drive shafts are no exception.
They patented a process of bonding light alloy tubes to 7075 billet yoke ends, thereby eliminating fasteners, welding and the problems associated with those techniques and processes.
I think that their process is called Accu-Bond. These are obviously not cheap parts, in quality or purchase price.

7075 is the best and strongest standard process aluminum alloy that is made in commercial quantities, but surprisingly it was not invented by Alcoa here in the USA during the space race.
It was invented by the Japanese in 1936-37. They used it to build their Zero fighter to enable it to do battle against the usually vastly more powerful Allied fighting aircraft.

.....  

Some examples of MMC extrusions rival equal or exceed important physical qualities and strength properties of chrome-molybdenum or titanium alloys, and yet at a weight that is close to or even lighter than premium structural aluminum alloys.

An aluminum drive shaft weighs about 50%, or one half of the same assembly made from mild steel.
.....

Now, still ... the question remains as to whether or not the stock mild steel drive shaft is "good enough".
An original WX3 SS Impala drive shaft is supposed to be made capable of slightly higher RPMs for longer periods of use than a standard Caprice sedan, but thats with a 3.08:1 R&P, and I'm sure they would have had to include calculations covering the speed rating specific to the tire that was selected by them for that model.

The 4.56:1 gears actually make the job of the drive shaft easier in terms of how much torque is effectively leveraged toward getting the car moving, so the twist loads on the D/S don't change much, but those low gears do have a dramatic effect concerning the dynamics of the elevated rotation speeds (RPMs) of the drive shaft.

Eventually as RPMs rise, any imbalance in the D/S starts to pull the whole assembly off of it's axis of rotation and will "whip" itself toward sudden self-destruction, swinging like an athlete's jump-rope while attempting to pretzel-ize or pogo out from under your car.
.....

If it were me, I'd maintain the RPMs of the actual drive shaft itself to no higher than what the original car's drive shaft was built to turn at.  
This only if assuming all related parts are close to tip-top shape and in good balance.

At anything not too much more than 450 Lbs/Ft/Tq from your flywheel, I wouldn't worry about the drive shaft's torque handling limitations, its the it's RPMs that I'm concerned about.

But the big problem all of this here is ... How in the huck do we know what that originally intended RPM limit was or is???

What to do? ... You might could find you a 99-00 Ford P71 MMC drive shaft (Ford part # XW7Z-4206-AA) to be used with your extended rear control arms and HD "jump-joints", and don't forget to check that special shaft for T.I.R. (total indicated run-out) in avoidance of the problems caused all too commonly from junkyard fork-lift damages.

Or ... A similar P71 (NON-MMC) 6061 T-6 shaft, paying close attention to the above mentioned related parts concerning their condition.

Or ... You definitely can not go wrong by having a good drive-line specialist shop build you a decent .083' wall seamless chrome-moly or even mild steel 3.5" diameter all new drive shaft, and having them spin balance it.
This would probably be your best and most cost effective way to protect yourself against expensive or perhaps even dangerous repercussions from your drive shaft failing.

. . . . . . . . . . . . . . .

[Critical speed for the Ford MMC shaft is 9,093 RPM
For the Ford standard 6061 T-6 P71 shaft, 7,930 RPM
Both are light weight aluminum assemblies, 53" long]

[-Note (1) - Roughly figured here,
for a 255/50ZR17 tire,
having an O.A.Diameter of 27.04"
and an engine RPM of 5,500.
with zero trans slippage in O.D. (0.70)
and a tire roll-out of 84.95"
driven thru a 4.56:1 ring and pinion ratio
the rear axle RPMs will be 1,740
and the drive shaft RPMs will be 7,934.]
,,, close enough to 7,930 of the 6061 Ford shaft.

[-Note (2) - This means that,,,
the Ford MMC shaft driven at 160 MPH
will be turning the D/S at 9,070 RPMs.
(Still below it's critical speed of 9,093)
and the engine RPMs will be 6,350.]

[-Note (3) - Mark Williams explains critical speed as a phenomenon with respect to resonance where a drive-shaft has it own natural resonant frequency that is amplified toward imminent self-destruction when the "whirling"- induced frequency coincides.
He recommends constructing any shaft to be lighter, stiffer, larger in diameter with out increasing it's weight to increase it's critical speed threshold.
Also adding that steel shafts tend to be naturally stronger and that aluminum and/or composite shafts can tolerate higher critical speeds (RPMs).

Another question still lingers...
What actuality caused those two Ford police car MMC drive shafts to explode?


Last edited by Machine-De-Zine on Sun Nov 03, 2013 5:43 am; edited 2 times in total
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Machine-De-Zine



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Sun Nov 03, 2013 4:41 am

toomanytoyz wrote:
Spun it on a balancer today and it looked like a wet noodle.
I'll throw it in tomorrow and cross my fingers.
Any results on the newly re-balanced drive shaft?
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boojum



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Nov 04, 2013 1:53 am

I could just go with plan B and use an F-body driveshaft. Smile
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V8Killer



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Nov 04, 2013 9:56 am

boojum wrote:
I could just go with plan B and use an F-body driveshaft. Smile
Plan C: Just get an F-body (even better if it already has a turbo) Razz 
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tonyc712000



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Mon Nov 04, 2013 6:54 pm

Machine-De-Zine wrote:
tonyc712000 wrote:

I seem to have the same issue with my Cappy. Its a loud mono-tone hum. It gets louder with speed....scratch 
Hey Tony, I would be surprised if that noise & vibration was your D/S.

But it certainly is worth your efforts in eliminating that as a possible source, but I sat directly over that rear axle for several hours, and I think its most likely inside the rear axle itself.

Can't remember if you told me if your tires and wheels have been properly excluded from being considered as the culprit.
Have not taken it to the mechanics yet. I have to save up some scratch to fix it. I just hope it isn't going to explode while I'm driving.....
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boojum



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PostSubject: Re: Anybody have a known-good DS I could borrow?   Tue Nov 05, 2013 12:10 am

V8Killer wrote:
boojum wrote:
I could just go with plan B and use an F-body driveshaft. Smile
Plan C: Just get an F-body (even better if it already has a turbo) Razz
A red '91 Camaro with a LT1 and a 9 bolt sounds nice. The turbo part is going to need some work...
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PostSubject: Re: Anybody have a known-good DS I could borrow?   Today at 9:58 pm

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