ok,here's another one,at around 65-70mph in 5th gear(T-5 tranny,posi rear end) I get a VERY noticable vibration that seems to come from the rear end,but i drop into 4th,it's not as bad,it was like this when I got it,and it hasn't changed even after a new clutch,u joints,and wheels/tires which are balanced perfectly!,think it might be a bad axle,or driveshaft out of balance?,or maybe the torque arm?I've talked to some people with other F bodies,and they have the same problem,any ideas?

 

I'm having the exact same problem with the vibrations and can't seem to figure it out someone help us. Since writing this I have found out that my driveshaft is slightly bent causing the mysterious vibration in the rear end. This should fix that problem whew.

 

I'm wrestling with this problem at this time I've had the tires balanced, replaced the u-joints, had the driveshaft balanced and still it vibrates. I checked the pinion angle several times and still no fix. According to a few people I've spoken to it could be the poly trans mount. Polyurethane does not dampen vibration like rubber and my problem started when I installed the ES poly trans mount. The ES mount does have a different dimension than factory so it could effect driveline angles. I've got a factory part waiting to be installed this weekend will post the results. If that doesn't fix I'm going to have the driveshaft shop recheck their work.

 

anyone ever think that it might be one of the shafts in the gearbox???????????? just wondering i think i read something bout that happenin to manual gearboxes

 

It could be high mileage wear in the trans.

 

possible,since my car has 125,000 ORIGINAL(documented) miles on it,i guess I need to rebuild it! BTW,me and my G/F just closed,and moved in our new house this weekend,which has a HUGE shop,and 8 acres of land, HOOPTY HEAVEN!

 

Sounds like the driveshaft. As much as I hate to say it, I just got rid of a mustang with a T-5 in it that had the same problem when i got it. It had a bad vibration on the highway but only in 5th gear -remember the driveshaft is spinning much faster in 5th than 4th. Anyway, I bought a new aftermarket aluminum driveshaft that was better balanced (and lighter) and my prob dissappeared instantly. good luck.

 

mmmmmmmmmmm, i have just had my broken rubber trans mount replaced with the same mount as you, i now have vibration too! car was silky smooth before this mount was fitted. vibes seem to go more with engine speed than road speed, when i floor it it vibes, cruise and its smooth, any speed. Even revving in park causes vibes. the mount is being removed ASAP, everything else checked and is OK, and there was no problem before.

i'm thinking now, unless you are uprating loads of other stuff things like poly mounts are a bad idea, I had a classic ford built for great handling (Cortina GT) with poly bushes in the suspension and driveline. it was a great thrash car but ride and harshness were unbearable for more than 50 miles.

 

Only thing to consider here is that the prop and axle are turning relative to road speed, so any vibration will not change with gear at cruising speed, provided you aren't accelerating, as their speed / load has not changed. Prop vibes usualy get steadily worse with speed and then sometimes dissapear at even higher speed. Bad u joints usualy depend on load as well as speed

(any technical guru's feel free to correct me on this)

I personaly would look to the tranny. good luck with that one.

 

Well I installed the factory part. The vibe is still there but it is above 80, below 80 smooth as can be. HMMM, maybe I need to look at the driveshaft again. The car does have 203,000 mi with a 75,000 mi transmission I may also need to look at other parts. Rear end bearings, R & P wear, and even the trans could need a look see. If I want to keep it I guess I need to spend a few more bucks. Hell, you guys know how it is, we 3rd genners are hard core car nuts.

 

Im tellin you,.... its the driveshaft.....

 

as vibe is speed sensative it could well be driveshaft, the softer gearbox mounting is simply alowing the box to move a little as well so less is transmited through the car.

my vibe deff. is not the driveshaft axle or wheels as the car vibes even when standing still! my prob is the tranny mount for sure, no poly mount no vibe, poly mount = vibes the first time i boot it!

the conclusion has been reached that it is normal engine vibration that is being transmited through the hard tranny mount and then the whole body is amplifying it. the other clue to this is that the vibes come from everywhere, not front or rear.

Engine has been checked for any abnormal vibes and has been declaired totaly sweet. (102,000 carefull, full service history, lady owner miles)

 

After 102,000mi you could still have wear induced vibrations relating to the trans. and another that is age sensitive what about crank shaft harmonics. The balancer on my son's Mustang was causing a vibration based on rpm. The outer ring had slipped forward due to an accident but upon further comparison to the new balancer the rubber ring had deteriorated to the point that the outer ring had turned a bit. This engine felt as if it were doing backflips when it was revved up. New balancer installed and it revved perfectly.
I think my problem is the driveshaft. That's the next part on my list.

 

Go composite and never look back

http://iedls.com/driveshafts.html

They have them ready to go for our cars. $800.00, may be a little hefty of a price, but consider the upsides especially if you have any kind of torque at all.

NO Vibration
Lighter than an aluminum drive shaft (More HP to the rear wheels)
Reduces damage to vehicle and driver by shredding itself in case of component failure - Imagine your driveshaft in an accident coming up and saying "hi" it would not be pretty. Anyone who goes fishing on a regular basis and has seen a graphite rod "shatter" instead of break like fiberglass knows what will happen with this thing in a wreck. It could feasibly help save your life.

I am having one made up for the vert. I want to plant all of my power before I make it :-) That way I make the best use of the HP I have.

James

 

Well,I've been chasing the same problem for some time now. Mine started with replacing the U joints due to one going dry. After it took three trips to three different shops before it finally stopped. Some time later it started again. Checked the tranny and rear end,pinion angle,mounts,even went so far as to experiment with things that you wouldn't think could be related. Finally swapped out the steel shaft for a 1LE aluminum shaft and it stopped again. Now I'm after what is more of a harmonic instead of a true vibration. It comes on at 60 mph and usually fades off when you reach 65 mph. I'm looking at replacing the 3.73 gears with 3.23 gears along with new bearings in the hopes that it will help. I'll also be replacing the rod end on my adjustable torque arm to see if it will help. I also have a question about U joints: how do you tell if they are bad with no visible signs? I had the shaft out of mine and noticed that the joint moved freely on the axis that sits in the driveshaft yoke but the axis that sits in the pinion side was quite tight. Could this be a sign?

 

the reason i'm so sure it's the trans mount is simple, 12:30 pm no vibe at all 12:33 new mount, 12:34 vibe city! no progresive detiriation, it was like someone turned on a vibe switch, it was even noticable firing up the engine to drive off the ramp.

I can pinpoint the exact moment the vibe started.

 

OK, this is what I'm getting at in all of my posts philoldsmobile yes your problem was quite possibly aggrivated by the poly mount. You still could have a wear induced vibe that the natural rubber mount dampened. If you used the 3/16" shim Energy Suspensions included with their mount you added another vibe possibility these cars are extremely sensitive to driveline angle issues at high speed. The factory total pinion angle is about 0* checked by subtracting the pinion angle from the driveshaft angle. If you raise the tail of the trans by 3/16" with the shim what does that do to your total driveshaft-pinion angle? I replaced my poly mount with a factory mount the vibe is still there, it comes on about 80 mph now. Looks like a driveshaft to me. I will probably have a new shaft made, steel of course due to the hp levels I plan. I've seen carbon fiber shred it self I'll be damned if I'm going to spend 800.00 - 1500.00 for an inherent POS. I work with carbon fiber products at work every day on airplanes. It is too tender for heavy duty uses in the auto driveline. I wonder if carbon fiber is the new deal why real high hp cars use steel. Steel is stronger If hp is something you're worried about spend your money on a good steel driveshaft and you will still have money for parts that will give you some real horsepower. Check out the Nitrous ready unit from Denny's Driveshaft Service.

 

Well from my experiences airplanes do not use carbon fiber composite, but true graphite, and just call it carbon fiber, because graphite is even lighter. My family have owned planes my whole life, so I too can speak from a bit of experience.

I have seen graphite shred. Light line rod on 80lb bluefin, the rod shredded in my hands, due to the fact that the hollow graphite had a dent in it providing a weak spot, something GRAPHITE is notorious for.

However, I have been involved in tests with graphite that would amaze you in it's strength. Hence why it is very often compared to steel in it's strength and durability.

I would trust a composite driveshaft in my convertible. Alcohol burning engine maybe not, but you don't care about highway vibration in a 1/4 mile only fuelie. A daily driven care you do. Steel driveshafts are going to be nothing but vibration over 60mph, at the very least go to a 1le driveshaft, aluminum. I still say composite.

James

 

Your family may own airplanes but not military craft nor airliners, most of which use carbon fiber composites for lightweight control surfaces and fairings. I've worked in this business for going on 30 years so I pretty well know what is used.
A fishing rod ain't quite in the same league with the high torque application as a drivehaft especially for years of abuse in an automobile. Scratch one real well on road debris and see what eventually happens. I know some of you've spent your big bucks on carbon fiber and to you it's the best, but plastics will go on the body of my car and that's it. go to http://www.dennysdriveshaft.com/html/hd_aluminum.html and read glued together, OK, I rest my case

 

Bullseye! the vibe reduced 100% when the shim was removed and reduced again when 1/4 ins washers were placed between the crosmember and the body. when the prop was checked the mechanic said there was a VERY small amount of movement in the output shaft (maybee .50 mm) of the tranny but not enough to cause the problem. (you can feel it but not see it)

If there is high milage vibration it is at a higher speed than i drive at so it doesn't bother me! this is born out by the fact that 3000 rpm in park produces an identicle vibe to 3000 rpm in any gear. (well over 120 mph in top)
the vibe is livable (its only a buzz) but if i can remove it with £10 worth of rubber all the better.

for the cost of a carbon or graphite shaft i'd say it is the worst performance mod you could make, if your real lucky you might just feel the differance, go with aluminium and spend the rest on budweiser and ******!

 

Well we can agree to disagree

You like what you like and I like what I like, but I do need to point some things out to you.

They are not recommended for any sports car apparently lol Read what their own site says:

"We do not recommend that you use an aluminum shaft in heavy high performance vehicles"

A heavy vehicle to them is:

"Heavyweight vehicles, 3400 lbs or greater"

Well, most Fbodies I have seen are 3,500lbs or heavier, w/out driver. My convertible is something like 4245. I need to go read the build sheet again to double check, and Im a big guy so We are over 4500 with me in it. Their HD driveshaft can't even be used, but the carbon fiber driveshafts have NO problem in these applications. They are even used in most new Garbage trucks. NO fbody is EVER going to be putting out the kind of torque that a refuse truck is, as well most of those trucks are just a tad over 3,400lbs I think

Here is some headlines from the Iedls.com website.

Design Features:
ACPT wet filament wound carbon fiber with no metal substrate. - Not wound around aluminum.
Longer unsupported spans than are possible with metal tubes.
Greater torque capacity than steel or aluminum tube.
Longer fatigue life than steel or aluminum tube.
Lower rotating weight transmits more of available power.
Smooth and stable from 0 to as high as 14,000 RPM.
Dramatically reduces vibrations common to overdrive equipped vehicles.

Notice how they mention better torque and strength capabilites than both Steel and Aluminum?

Safety Features:
Absorbs vibrations that can destroy all metal shafts.
Torque tested through 3900 foot pounds.
Reduces damage to vehicle and driver by shredding itself in case of component failure (Read: Engine, tranny, rear end failure)

No one races them you say?
Dan Gurney's IMSA GTO champion '87 Toyota.
NHRA Pro-Stock trucks.

Also fishing rods are a great way to measure torque. I use to fish saltwater in pro tournaments (BIG fish) and it is widely known that the best rods are made of graphite. Why? Because they can handle the torque of a fish like a 1200lb mako with no problems. The rod is under an uneven pressure at all times. You ever set the hook on a 80lb bluefin? By your comments I am going to guess not lol

No offense, like I said, you can use what you want to use, and i'll do the same, but to recommend a driveshaft to a guy that the manufacturer doesn't even recommend for him to use, might not be the best idea.

James

 

I stand corrected!

the only car i ever owned with an aluminium prop was a volvo 340 1.4!

I personaly doubt they are worth the gain over a conventional prop, if only due to the fact that you can buy many other performance goodies for the money.

 

philoldsmobile

Actually the last post was to 92BLKL98, so don't worry that wasn't pointed at you

I want the ultimate Fbody convertible and I look at it this way; If you are going to spend all that money to make the engine just right, why would you skimp trying to put it to the ground?

Makes no sense to me. I also do a lot of high speed freeway driving so that vibration is horrible. I will also NEVER take my car to the track, just due to the fact that I do not want to put a roll cage in my car, and if you run anything better than 15's you have to in a convertible.

But if you are looking for straight 1/4 mile performance I would say go with the steel it's cheaper, but if you are looking for the best of all worlds your going to need to pay

James

 

fair comment

as they say it's horses for courses!

 

If I remember correctly torque is a little different (twisting) effect than is applied by a fish so I don't believe your analogy is very good. I also never saw a garbage truck do a pro-stock launch either yes they might produce more torque than some performance cars and definitely out weigh them but as for heavy abuse due to extreme shock loads I doubt it. I agree with your statement about reduced vehicle damage due to catastrophic failure but I've not seen any steel shafts fail at my local dragstrip but I have seen carbon graphite fail. I'm not too sure about the idea of bonding an aluminum yoke end to the carbon graphite composite. As you and I have both agreed on "to each his own". I would rather spend my bucks on a NASCAR quality steel unit ( ~450.00) and use the other 450.00-1000.00 on other performance stuff. Oh why doesn't NASCAR allow these space age plastic wonders if they're so great

 

Well, I don't know that NASCAR doesn't allow them. Can you show me where it doesn't? Also if they are not allowed it is most likely because NASCAR must be based on a stock car that could be a key reason, but than aluminum may not be used either. :nono:

With a nascar pushing 600/600+ a carbon fiber driveshaft would be more than enough and could REALLY help them in the accidents they have. But since I am not a NASCAR guy (seeing a bunch of cars go around a circle couple of hundred times bores the h*ll out of me) there you may have me. HOWEVER, they are used in NHRA and IHRA.

Torque
Torque is considered a twisting force by the shear fact of the measurements we use, because it turns in a 360 degree radius.

webster defines it as:
The moment of a force; the measure of a force's tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force and the force vector.

IE Not twisting like you believe, BUT the rotation around an axis. Which is exactly what a driveshaft does. Torque is also a pressure produced by an opposite affect, hence a fish. So the analogy may not fit perfectly to how you look at torque, but please remember torque is not an automotive only term. Remember what horsepower comes from, the literal term of Horsepower.

Also if you don't think that a garbage truck slams that driveshaft much more than a pro street car ever will at the track, I don't know what I could ever say. Have you ever towed anything before? If so you will know that initially taking off requires some pressing of the pedal to get that puppy to get up and say hello.

One last thing I think should be said, though I have said it with all of my other posts, we are talking about driveability. The original post is talking about high speed vibrations. Steel will make this MUCH worse, while you may get your own piece of mind at the track going 1/4 mile at a time, it is going to suck going 90 on the highway. While a carbon fiber driveshaft, will provide the best of both worlds.

But like I said above, if all you want is 1/4 mile times get the steel it's cheaper, but to pass off carbon fiber as "space age" new fangled stuff is like people who thought that color TV would never catch on, it's just old thinking.

92BLKL98 Hopefully you dont take any offense. Just trying to give a couple of different views so that others can make some good educated decisions. Since we have both already made up our minds

 

No offence taken, as you said just different veiws. The garbage truck thing does make me smile though. I just can't see Roscoe stressing his garbage truck with the same initial shock load as a pro stocker. In the time the race car is beginning to move the truck is lazily beginning to amble along not really requiring too much of it's diesel engine to move. Heck most of them I've seen even have automatic transmissions further easing the shock. As an avid 4X4 offroader I definitely know the torque required to move my 4X as well as towing loads many times heavier than my own vehicle. But then that's another story. Interesting though, maybe we will someday meet and can really talk about all this stuff. Good day.

 

What you running 4x4 wise? I have an 81 Bronco 4x4 Trailer edition, with the 351m, Windsor going in soon. I'm having two custom carbon fiber shafts made for it as well

Different strokes for different folks I guess

Later bro

James

 

'79 F-150, 351M, C6, NP205 xfer case, 9" rear, Dana44 frt, 4" lift, 35x10.50 BFG MT's, Headman LT's into dual 2 1/2" Flowmasters. Also '91 S10 Blazer, Hell it's more fun around here than the big truck, it's smaller thereby easier to maneuver. BTW steel ds in both. I can't justify C/F. Well you know the story.

 

 

i've just replaced my ES poly trans mount with a stock one and my car is smooth as a caddy once again

check this before starting an expensive driveshaft or gearbox rebuild!

 

You will find answers to your questions here:


http://www.ring-pinion.com/gear/g1198.shtml