Bad vibration at 3000 RPM's and up

[Badlilstang]

If you pull the drive shaft out and run it through the gears your gonna lose some tranny fluid out the back... id wiggle the pinion around and see if it moves or feels loose.

Valve noise... do you have roller rockers on this car? They tend to be louder then the stocks. Are you getting a good 3/4 turn of compression on the lifters? Are they all ticking or just some? Have you tried to pop the valve covers off and see if you can get them any tighter?

 

[stevesLX]

Yes they are roller lifters. The rockers are non adjustable stock ford rockers. I got 3/4 out of every single one. I pulled the valve cover off just a few ago and started it. Crane Cams told me to do that and rev it up and try to push down on the rocker arm and see if that quiets it. That was about useless trying to do that because they all seem to be noisy on both sides. As far as tightening down farther since they are no adjustable rockers all that will do is stretch the bolt. But yes I tried up to 25FT LBS and still no good. I measured the pushrods that wer in there originally and I was basically coming up with 6 1/4 so I assumed they must be stock and they are 6.258. I measured my preload and I was getting .030 which in reality is good but crane cams says well we really like you to be around .040-.050. So I bought push rods that were 6.272 which should have added .013 which would make .044 for total preload. Well its still noisy. And I tried to measure the preload tonight with the new push rods in there and for some damn reason my scribe marks that I kept trying to make weren't very visible. But I tried to measure the one and dont know how accurate is was but guess what it came up to.030. So I am beginning to wonder if the rod that were originally in there weren't already 6.272. I measured with a tape measure the over all length my dial calipers only go up to 6 inches. I give up.

 

[stevesLX]

Also how can I test to see if the tranny is causing this vibration if I am going to lose tranny fluid when I pull the drive shaft?

 

[91notchbk]

Also how can I test to see if the tranny is causing this vibration if I am going to lose tranny fluid when I pull the drive shaft?

Jack just the rear of the car off the ground. Gravity will keep most of the fluid from coming out. You will only lose a very small amount of fluid.


Also, before you remove the driveshaft check the driveshaft for low spots by touching the rotating shaft with the end of a coat hanger. If the hanger leaves a line all the way around the shaft then the shaft is ok. Do this on the front and also the rear of the shaft. Have an assistand run the wheels around 40mph or so (becareful not to get to close to the shaft when it is turning). I know you said the driveshaft was already checked but it is possible that it still may be the problem. Your vibration sounds exactly like a driveshaft out of balance or possibly incorrect pinion angle.

Rear axles do not make the vibration you describe unless your have a a carrier or differential bearing that has a TON of play. And if it did then you would have a clunking noises and tons of bearing noise too. Differentials almost NEVER cause vibrations.

I would look for maybe a bent axle shaft when you have the rear raised because it is a possibility too.

 

[TheDamned]

Not a drive shaft problem for sure since it always do it at 3krpm, it's not speed-dependent.

 

[Badlilstang]

Not a drive shaft problem for sure since it always do it at 3krpm, it's not speed-dependent.

Not sure which poster we are talking about on this one but if the vibe is when sitting still it can be a number of things. First thing I recommend is removing the surpentine belt and reving the car up to see if it goes away. Atleast then you can eliminate the front acc. Check your front balancer and see if it has spun or moved off the rubber (common with stock balancers). Verify clutch, flywheel, and balancer are tight. If your running any kind of solid mounts expect some vibes to be felt.

 

[Badlilstang]

Yes they are roller lifters. The rockers are non adjustable stock ford rockers. I got 3/4 out of every single one. I pulled the valve cover off just a few ago and started it. Crane Cams told me to do that and rev it up and try to push down on the rocker arm and see if that quiets it. That was about useless trying to do that because they all seem to be noisy on both sides. As far as tightening down farther since they are no adjustable rockers all that will do is stretch the bolt. But yes I tried up to 25FT LBS and still no good. I measured the pushrods that wer in there originally and I was basically coming up with 6 1/4 so I assumed they must be stock and they are 6.258. I measured my preload and I was getting .030 which in reality is good but crane cams says well we really like you to be around .040-.050. So I bought push rods that were 6.272 which should have added .013 which would make .044 for total preload. Well its still noisy. And I tried to measure the preload tonight with the new push rods in there and for some damn reason my scribe marks that I kept trying to make weren't very visible. But I tried to measure the one and dont know how accurate is was but guess what it came up to.030. So I am beginning to wonder if the rod that were originally in there weren't already 6.272. I measured with a tape measure the over all length my dial calipers only go up to 6 inches. I give up.

Take the pedastals to a machine shop and have them surface the bottoms as little as they can. If they go to much you will have to get a shim kit and really spend some time setting them up. I wish we could here how loud they are becuase ive heard alot of roller rockers that are just plain noisey no matter how you set them up. If you keep stepping up the push rod length you will effect the valve geomtery and in the end could put some uneeded wear on the vavle guides. You can buy push rod length checkers if you ever needed to verify if your geometry is good or not.

 

[91notchbk]

Ok, back to the basics? Does the vibration increase with speed? When driving at highway speed and the vibration is felt, push the clutch in and see if the noise goes away. What happens? Does the vibration exist when revving the motor in neutral? These tests will determine if the vibration is from the motor or the driveline. Driveline noise will increase with speed and enigine vibration will increase with rpms.

 

[Mr Grim]

+1 for 91notchbk!
Don't chase the problem with parts...I could fill an entire page with a list of new parts I used to chase a bad computer!

Roller rockers are noisy, some are very noisy. Try to find someone else running rollers, or have some one very familiar with roller rockers listen to your valvetrain. If they are all noisy, I suspect they are working correctly. One or two noisier than the rest might indicate problems.

I don't think I would crawl under the car with a buddy revving it at 40 mph on jackstands....You might become a candidate for the Darwin Awards! No offense to the poster suggesting that, I just don't trust jackstands that much. Before undertaking a courageous move, I always ask myself: "If this goes south, will it make the front page of the newspaper"?
You could run it up with the wheels, then remove the wheels, then remove the drive shaft and see if that has any effect on the vibration.

And you aren't bothering anybody....I learn something new every time I log on here....It's a great site!:SNSign:

 

[stevesLX]

O.K. for the record I have sat still in neutral and ran the motor up to 5000 RPM and just the neveryday normal vibration. But now when I drive it thats a whole differnt story. It starts in 5th gear at 2500 RPM approx. 70 MPH you get a vibration thats vibrates stops vibrates stops vibrates stops it does that every 1-2 seconds consistently. From that point if yo accel faster and say 3000 RPMS approx 80-85 now we are talking loud constant steady vibration. If you push in the clutch it still continues to vibrate until you slow down.

*** THE CAR HAS VIBRATED LIKE THIS SINCE THE DAY I BOUGHT IT. NOV 16, 2006


This is what I have replaced or fixed on the car since Jan 20,2007.

1. 4 new wheels and 4 new tires
2. new steering rack
3. new power steering pump
4. 4 new shocks (front and rear)
5. 4 new springs(front and rear)
6. new Camber/Caster plates
7. new tie rod ends
8. new ball joints
9. Aluminum driveshaft balanced and U joints checked out.
10. Lower half engine rebuilt
11. WC T5 rebuilt

 

[Badlilstang]

Man thats a driveline vibe no matter how you look at it.. that sounds just like bad U-joints. Ive had it happen to me on two different cars exactly how you describe it. Do me a favor and try this. Get up under your car and remove the 4 bolts on the end of the drive shaft (at the rearend). Turn the drive shaft one bolt over and thread them back in tight. Make sure you mark where you were orginally and try bolting it up all the different ways possible. See if this changes anything.

 

[stevesLX]

O.K. I will do that as soon as I get home tonight and let you know. It will probably be around 7ish EST before I am able to do it.

 

[89fiveohman]

hey steves lx 1 more suggestion check and make sure the pinion nut itself is pretty tight and not backed off any that will result in a vibration dont over tighten it though that could make the pinion bearings to tight and eventualy lock them up good luck man dont give up!

 

[stevesLX]

O.K. this is what I have done so far. I pulled the drive shaft and I ran the car on jackstands thru all the gears and no vibration at all. But low and behold as soon as I stuck the shaft back in I had the vibration again. I had noone to help me so as far as using a hanger to hold up against the drive shaft while it is turning at 40MPH I couldn't do that. I did move the driveshaft one bolt hole at a time and tried that. I only moved it twice though and I still had the same vibration. Someone was telling me theres something right behind the pinion that has some fastners attached to it. Its like a dog bone or something and it is calibrated to the gear that you are running. It is also some kind of dampner. Anyone know anything about that?

 

[86bluecobra]

yes the dog bone. Many guys on this site have removed them once they put gears in there cars. They are not really needed. It is there to dampen vibration. So if you push on your driveshaft to check the u-joints they are fine?

 

[Mr Grim]

The last thing I would check, just to completely rule out the engine or trans, are the mounts. With the DS removed, there is no load on the engine/trans and a bad mount might not reveal itself. Grab the tailshaft of the trans and torque it to see if there is any play....same with the engine. Might be time for some poly-urethane's!

 

[stevesLX]

When you say push on the driveshaft ho ware we pushinig side to side or in and out towards the rear and tranny and what is acceptable? Also Mr.Grim how are torqueing the tranny and motor and you say poly urethanes not quite sure what you mean. Sorry this is all new to me. I was looking at my rear end last night and if I had to guess this whole rear end is out of a sn95. If you want give me your email and I will send you some photos.

 

[Mr Grim]

When I say "torque" the trans and then the engine, I mean crawl under the car and grab the tailshaft and push it in all directions, up-down, side-to-side, to see how much play there is in the rubber mount that connects the trans to the cross-member. The tailshaft should be fairly solid and you should have to really apply some force to get any movement at all. The rubber mounts deteriorate and break down over time. Polyurethane mounts are a little stiffer and last longer.
Same test for the engine. If you can push side-to-side on the engine and there is significant play, one or both of the mounts might be shot. sometimes you can see big cracks in the rubber, or chunks of rubber hanging out between the engine and the k-member. Again, polyurethane motor mounts are a nice upgrade.
Lastly, check that all of the mount bolts are tight.

For the u-joints, I would grab the DS near rear with both hands and wiggle it in all directions. It should be solid with the pinion flange. If you feel clicking, or play, between the DS and the flange, that's not good.

 

[Badlilstang]

Those U-joints should be able to move very freely without rough spots. If you got a buddy with a stang see if you can try his drive shaft.. atleat then you can rule it out.

 

[stevesLX]

O.K. I will do that. I hope its something that simple like U joints and not axle bearings. Remind you this is all new to me. But what is the difference between axle shaft bearings and axle bearings? Is one like the rear wheel bearings or do I have it all mixed up as to what is what. I just would like to know what I am trying to chase down and looking for if it turns out not to be the drive shaft. Also I will do the torque thing on the tranny and motor but my tranny mount is less than 2 weeks old just put a new one in. My motor mounts on the other hand I am not to sure about. I do know for some stupid reason the one on the passanger side is a solid mount and the one on the drivers side looks to be a stock factory mount. If you guys give me your email address I can show you photos of the mounts. I noticed last night that the rear disc and calipers and all the hardware and everything was Ford so I am assumeing the previous owners yanked a whole rearend out of another mustang. The calipers and disc and that are all for sn95.