What's up with these driveshafts? Mine's fine @ 150mph

E

eduncan911

Registered
I got a 1995, untouched. It was a program car @ Lincoln before my friend purchased it at 90k miles. He drove it for 5k miles, untouched just changing oil, before he destroyed the engine (double-ringed the gasket, no oil).

I bought it from him as it sat, broke. Pieced togather my old Cobra motor (GT crank for the 6 bolt flywheel, and it's lighter too) with some Navi cams and swapped that in. Dyno'd 235rwhp/278rwtq (Whoa, it's torquie!) in 3rd gear (no 2nd gear cheat). All stock w/paper filter and stock exhaust.

I've since had to replace the tranny. Installed an Art Carr unit, good for anything I can throw at it. :D


I have a one piece driveshaft. Everyone says I have a two piece, but I can tell you it's a solid aluminum DS. Checking on the work history at Lincoln, it was serviced in Jan 1997 for "vibration at high speed". Doesn't say what was replaced or serviced under warranty. Perhaps under warranty they put in a one piece.

Still got the stock gears. Has a custom chip (removed speed limiter, raised shift points, timing, and a/f @ 12.5 across the board).


Sunday was an excellent day. I just lowered the car 1" in the front and 1.5" in the rear and was out for a nice drive. On this very long stretch of road (miles straight) with exists, I see a Mustang with a ricer wing WAAY ahead. I haven't done a top-speed run yet, and with four open lanes, this was a perfect time.

Passed the Mustang at ~140mph. And stayed into it until around 150mph (burried the speedo). The car got a bit floaty (want to convert to springs to get better handling).

Not a single vibration, hickup, nada.


Also on the dyno, I ran out 3rd gear with the chip to 6500rpms to see where the HP dropped off at (due to intake). Uh, 6500rpms with stock gears = 160mph+. I maxed out the dyno. LOL No viration there either.


Did any of these come with solid driveshafts? Or did I just get lucky?
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

they don't put in one-piece driveshafts at the dealer, and wouldn't have any time after 1993. the two piece driveshaft looks like a one piece, for the most part. Just because it looks like it's one piece, doesn't mean it is.

switching to coil springs will probably not improve your handling, and it may hurt it. The floaty feeling at 150 mph is due to lift. You don't have as much weight on your tires at those speeds, regardless of spring construction.

Congratulations, you are one of the very few who does not have a vibration problem. The stars must have been aligned when your car was put together. My car only vibrated slightly at high speed, some may not have even noticed it. The severity of the vibration problem varies greatly.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

[div class="dcquote"][strong]Quote[/strong]
they don't put in one-piece driveshafts at the dealer, and wouldn't have any time after 1993. the two piece driveshaft looks like a one piece, for the most part. Just because it looks like it's one piece, doesn't mean it is.[/div]Humm. I got all the way under my car. From the front of the driveshaft (at rear of transmission) with my head against the DS itself, looking long ways down towards the rear, I can almost see the flange of the IRS. No joint here that I can see.

Also looking from the IRS section, and feeling up above the gas tank, all I feel is a solid unit. I also noticed a driveshaft loop back near the IRS area? Cool, I'm ready for the drag strip! lol

Where exactly is this joint?

[div class="dcquote"][strong]Quote[/strong]switching to coil springs will probably not improve your handling, and it may hurt it. The floaty feeling at 150 mph is due to lift. You don't have as much weight on your tires at those speeds, regardless of spring construction.Congratulations, you are one of the very few who does not have a vibration problem. The stars must have been aligned when your car was put together. My car only vibrated slightly at high speed, some may not have even noticed it. The severity of the vibration problem varies greatly.
[/div]Interesting. My Cobra at 180mph had the "lifting" issue that you are talking about. I know what it feels like. The Lincoln wasn't lifting.

The floating is like that I have felt in stock C5 vettes at around 120mph. I guarantee they have less lift then my car. lol

The floating comes from the stock suspension components. All stock struts, shocks, bags, etc. At 100,000 miles. :( Yes, they are worn out. With nothing to dampen the up and down movement, every slight dip causes the car to bounce up and down slowly. This is what I meant by floating. Hehehe. Ok, might have been the wrong choice for a word to descript it. Umm, "bouncing slowly"? hehe

Switching to a set of stiffer springs and higher dampening struts (I have Bilstiens for the rear, not installed yet) cures a lot of high speed "bouncing". :)

I just hate to loose that 1-1.5" drop at 60mph. And the leveling of heavy loads/passengers.


I still think I have a 1pc shaft. Unless that joint it smaller then 4" and looks exactly like a one piece solid shaft all the way to the rear. I guess when I plumb the -8 and -10 lines for the upgraded engine (removing tank), I'll finally know. :)
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

[div class="dcquote"][strong]Quote[/strong]
have you looed at the DS? if not crawl under and look at the rear portion of the shaft. If it's a 2 piece, you will see something that looks like a groove cut around the shaft....here is a pic of my old destroyed ds, (it's propping the front of the engine up) [/div] Hehehe, I beat you by like 1 second in my previous post. Read it as I answered about crawling under and what I saw. :)

So where exactly is the joint?

Maybe that's my whole problem. When I hear about "two piece driveshaft", I'm thinking it's two seperate driveshafts like what were in the mid 90's Thunderbirds. Two completely seperate driveshafts, with a joint attached to the unibody/frame. Just like those 4x4 trucks that have two piece units 1/2 way down to the rear axle.

Are what you guys calling two piece meaning, welded two pieces into a single longer DS?

LOL! Please tell me I didn't just assume the wrong thing all of this time, cause you know what assuming means. But I doubt any of you were part of it. LOL
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

[div class="dcquote"][strong]Quote[/strong]
[div class="dcquote"][strong]Quote[/strong]have you looed at the DS? if not crawl under and look at the rear portion of the shaft. If it's a 2 piece, you will see something that looks like a groove cut around the shaft....here is a pic of my old destroyed ds, (it's propping the front of the engine up) [/div] Hehehe, I beat you by like 1 second in my previous post. Read it as I answered about crawling under and what I saw. :)So where exactly is the joint?Maybe that's my whole problem. When I hear about "two piece driveshaft", I'm thinking it's two seperate driveshafts like what were in the mid 90's Thunderbirds. Two completely seperate driveshafts, with a joint attached to the unibody/frame. Just like those 4x4 trucks that have two piece units 1/2 way down to the rear axle.Are what you guys calling two piece meaning, welded two pieces into a single longer DS?LOL! Please tell me I didn't just assume the wrong thing all of this time, cause you know what assuming means. But I doubt any of you were part of it. LOL
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If you look at the picture I posted........ you will see the back mounting flange. If you look further up the shaft, you will see two lines in the shaft. The first is a weld bead, and the second deeper line is where the 2 pieces come together.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

[div class="dcquote"]If you look at the picture I posted........ you will see the back mounting flange. If you look further up the shaft, you will see two lines in the shaft. The first is a weld bead, and the second deeper line is where the 2 pieces come together.
[/div]
Right. So you are stating it's a solid driveshaft, no joints. Two pieces welded togather.

I'll admit, that's not the best way to construct a driveshaft. But I did the same thing for my Cobra with the 03 Cobra driveshaft I had. The 03 Cobra are shorter because of the T56 and IRS. So I "extended" it at a driveshaft shop. It was fine. Had a slight humm at around 145 to around 150. I always thought it could have been the rear end as I kind of had that before the T56/DS swap at about that speed.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

they arent even welded together.......the weld bead you see is to attatch the rear yoke. the 2 pieces are actually pressed together with a spacer between the two.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

Yes, by two piece we mean two pieces welded together. If i remember i'll take a pic of my old one and show you. Two seperate driveshafts with a carrier bearing in the middle would actually be a better design.

I don't think stiffer springs would help with the "floating"... but better shocks (dampers) definitely will. I know Jeremi was looking at the possibility of putting koni adjustable shocks in the stock air bags, but i don't know the status on that. The rear shocks are easy to replace.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

[div class="dcquote"][strong]Quote[/strong]
Yes, by two piece we mean two pieces welded together. If i remember i'll take a pic of my old one and show you. Two seperate driveshafts with a carrier bearing in the middle would actually be a better design.I don't think stiffer springs would help with the "floating"... but better shocks (dampers) definitely will. I know Jeremi was looking at the possibility of putting koni adjustable shocks in the stock air bags, but i don't know the status on that. The rear shocks are easy to replace.
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Ahh! I was wondering if someone/some company had some type of stiffer struts up front. That's why I have been holding off on the rear swap. They are very much more firm then stock ones. I don't want the front end bouncing out of sync of the rear, you know?

The springs would be most noticable in heavy cornering, I meant to say above. I.e., SCCA. :D But I doubt I'd do more then 2 or 3 SCCA events. Larger sway bars = a must though.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

I wouldn't call larger sway bars a must, myself. They will actually decrease your ultimate cornering ability. They will help the car get settled more quickly on turn in, but will decrease ultimate cornering ability.

I would suggest a slightly stiffer rear sway bar, though. That should shift the handling balance more toward neutral or oversteer, which is better if you really know how to drive.

http://www.mark8.org/users/sleeper/rollstiffness.jpg

I believe that came from "race car vehicle dynamics". I don't have a scan of the pages on spring rates, though.

Where i live, stiffer springs would be counterproductive. They'd just make the ride suck. After reading a lot about suspension design, i came to the conclusion that for a daily driver or occasional autocrosser, there is really no need for serious suspension upgrades. Upgraded shocks, and a stiffer rear sway bar to reduce understeer, that's really it. And on my car, i have enough problems putting the power down that i'd even stay away from a bigger rear sway bar, since it could hamper getting the power down at corner exit.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

Good post. :)

As far as a larger sway bar that you wouldn't get, that's part of the fun to drift OUT of a corner under throttle. :D lol

I'm with you. I do 99% of driving on the street and doubt I'd go with springs. All depends on the amount of power of the final product.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

I'm gonna be looking into putting the Koni Adjustables in the front airbags as soon as I get my hands on the other set I am eyeing, but probably won't ahve that ready to install 'til fall.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

[div class="dcquote"][strong]Quote[/strong]
I'm gonna be looking into putting the Koni Adjustables in the front airbags as soon as I get my hands on the other set I am eyeing, but probably won't ahve that ready to install 'til fall.
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Heck, I'll buy the pieces and tear my existing ones apart.

Has this been done before? I mean, is this a new project to see if it will fit or has it already been done by someone here?

Which shocks are you talking about (specific size/model number)?

Anyone document it yet? If not, and we know it works, I can and post it on the site.


Of course, someone with a used set of worn out struts would help (so I can tear them apart without taking down my "only" driver).
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

the shock thing has not actually been done yet AFAIK. jeremi was going to try it and i haven't heard if he's done it yet or not.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

No, I'll be looking closer at this come fall, and I'll be taking lots and lots of measurements when I do it to make sure it works. From what I can see though after looking at a front strut assembly, it shouldn't be hard to do. It's finding the right shock that will be the tough part.
 
RE: What's up with these driveshafts? Mine's fine @ 150mph

Going to start a few threads asking for some old struts someone ahs sitting around.
 
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