Driveline vibraton found. Coming from rear of transmission.
01-07-2009, 09:52 PM
#1
Driveline vibraton found. Coming from rear of transmission. I have been tracking down a driveline vibration for weeks now, but have finally determined that it is coming from the rear of the transmission and has nothing to do with driveline angle.
When you drive 70 MPH on the street and the vibe starts, if I push the clutch in to disengage the motor from the transmission, the vibe remains. This tells me the vibe must be between the tranny and the rear end and should not be related to the motor.
I have had the drive shaft balanced by one shop and verified by a second shop and the DS balance is dead on. I replaced both u-joints too, both of which actually showed damage to the plastic disks inside the caps as well as scoring on the ends of the journals. No apparent reduction in the vibes by replacing these u-joints.
For testing purposes only, I have the driveline angles set to zero meaning the crank, tranny output shaft, drive shaft and pinion are perfectly in-line so there is no chance of driveline angles causing the vibe. It's a straight shot from the harmonic balancer all the way to the pinion. BTW it required shimming the transmission up 1/2" in order to accomplish this. To do this, I placed a pair 1/4" square washers between the tranny mount and the tranny crossmember to raise it. Once the vibe is terminated, the pinion will be set to -2 degrees.
I currently have the car up on jack stands with the rear suspension loaded for testing. I also have the wheels and rotors off and the vibe remains when going 60 MPH in the air. There appears to be NO abnormal run out on the axles.
I then decided to place an impact gun on the gas pedal to get it to run a constant 70 MPH to induce the vibe, then crawled under to find the vibe. I put my hand on the rear end and felt nothing. Put my hand on the back of the transmission and it is vibrating like mad. This is clearly the vibe I feel in the seat when driving over 60 MPH on the street.
I can also visually see some flutter by the front drive shaft yoke where it inserts into the transmission while the vibes are occurring. I put a dial indicator on the yoke and there is a bare minimum of .020" slop which allows the yoke to move up and down. Assuming the DS is properly balanced, clearly there appears to be problem with the tail shaft bushing. I also noticed that there are very few markings on the front pinion yoke that one might expect to see, right where the yoke might rub the current bushing. That is another indicator of a worn bushing, at least I would think.
I have already purchased the Rockland gear bronze "no walk bushing" and it is ready to be installed. It definitely fits nicely on the front drive shaft yoke plus it is longer so it should provide even more support for the yoke than the original. I plan on removing the transmission tail shaft housing in the next day or two.
I am now very optimistic that once the bushing is installed, the vibes will be gone. If even then these PITFA vibes remain, there must be some freakish issue with my drive shaft which will immediately be replaced by a decent aluminum shaft.
Wish me luck. I will post my results.
When you drive 70 MPH on the street and the vibe starts, if I push the clutch in to disengage the motor from the transmission, the vibe remains. This tells me the vibe must be between the tranny and the rear end and should not be related to the motor.
I have had the drive shaft balanced by one shop and verified by a second shop and the DS balance is dead on. I replaced both u-joints too, both of which actually showed damage to the plastic disks inside the caps as well as scoring on the ends of the journals. No apparent reduction in the vibes by replacing these u-joints.
For testing purposes only, I have the driveline angles set to zero meaning the crank, tranny output shaft, drive shaft and pinion are perfectly in-line so there is no chance of driveline angles causing the vibe. It's a straight shot from the harmonic balancer all the way to the pinion. BTW it required shimming the transmission up 1/2" in order to accomplish this. To do this, I placed a pair 1/4" square washers between the tranny mount and the tranny crossmember to raise it. Once the vibe is terminated, the pinion will be set to -2 degrees.
I currently have the car up on jack stands with the rear suspension loaded for testing. I also have the wheels and rotors off and the vibe remains when going 60 MPH in the air. There appears to be NO abnormal run out on the axles.
I then decided to place an impact gun on the gas pedal to get it to run a constant 70 MPH to induce the vibe, then crawled under to find the vibe. I put my hand on the rear end and felt nothing. Put my hand on the back of the transmission and it is vibrating like mad. This is clearly the vibe I feel in the seat when driving over 60 MPH on the street.
I can also visually see some flutter by the front drive shaft yoke where it inserts into the transmission while the vibes are occurring. I put a dial indicator on the yoke and there is a bare minimum of .020" slop which allows the yoke to move up and down. Assuming the DS is properly balanced, clearly there appears to be problem with the tail shaft bushing. I also noticed that there are very few markings on the front pinion yoke that one might expect to see, right where the yoke might rub the current bushing. That is another indicator of a worn bushing, at least I would think.
I have already purchased the Rockland gear bronze "no walk bushing" and it is ready to be installed. It definitely fits nicely on the front drive shaft yoke plus it is longer so it should provide even more support for the yoke than the original. I plan on removing the transmission tail shaft housing in the next day or two.
I am now very optimistic that once the bushing is installed, the vibes will be gone. If even then these PITFA vibes remain, there must be some freakish issue with my drive shaft which will immediately be replaced by a decent aluminum shaft.
Wish me luck. I will post my results.
Last edited by wrd1972; 01-09-2009 at 09:41 AM.
01-08-2009, 02:46 PM
#4
DS should be the correct length. It was built by Strange to Eric at Midwest Chassis specs for the fabricated 9" rear end. The distance from the output seal to the yoke end is about 3/4" or so. I will measure the DS just to be on the safe side.
BTW, the tailshaft housing was a snap to get off. Took longer just to get my damn ORY off and out of the way than it did to pull the housing.
I am having a shop install the Rockland bushing right now. The old one had some slop no doubt but showed no major visual wear or tear. The Rockland does fit the yoke much more snug and I assume it will be even a tad more snug once it it is pressed into the housing. The Rockland bushing is a good 1/2" longer than the stocker, that should be a major benefit.
BTW, the tailshaft housing was a snap to get off. Took longer just to get my damn ORY off and out of the way than it did to pull the housing.
I am having a shop install the Rockland bushing right now. The old one had some slop no doubt but showed no major visual wear or tear. The Rockland does fit the yoke much more snug and I assume it will be even a tad more snug once it it is pressed into the housing. The Rockland bushing is a good 1/2" longer than the stocker, that should be a major benefit.
01-08-2009, 05:41 PM
#7
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i think i might have the same vibration as you.... coming from around the tranny area. I can't really tell when it starts because my exhaust is so damn loud, but i can sure feel the plastic around my shifter vibrating at highway speeds. I don't know the exact mph because my speedo is off from the gear change.....
let us know what you find!
let us know what you find!
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01-08-2009, 09:06 PM
#8
Well I have the Rockland bushing installed and everything back together, but I don't have enough transmission fluid to test it tonight.
Some information on the Rockland bushing (T56NWB). I had a transmission shop remove the old bushing and press in the Rockland bushing into the housing using the proper install driver to ensure it does not get goober-ed up going in. The housing went back together without a hitch.
The clearance with the old bushing and front DS yoke averaged .012". The clearance with the Rockland bushing averages .0015" which is considerably much more snug and desirable. The drive shaft slid right in the transmission effortlessly without requiring any hammering like I read in a few other posts. This dude really fits snug.
When I try to move the front drive shaft yoke up and down like before, it moves less than .002" which is another terrific reason to remain optimistic. I will definitely be testing the setup tomorrow.
Some information on the Rockland bushing (T56NWB). I had a transmission shop remove the old bushing and press in the Rockland bushing into the housing using the proper install driver to ensure it does not get goober-ed up going in. The housing went back together without a hitch.
The clearance with the old bushing and front DS yoke averaged .012". The clearance with the Rockland bushing averages .0015" which is considerably much more snug and desirable. The drive shaft slid right in the transmission effortlessly without requiring any hammering like I read in a few other posts. This dude really fits snug.
When I try to move the front drive shaft yoke up and down like before, it moves less than .002" which is another terrific reason to remain optimistic. I will definitely be testing the setup tomorrow.
01-09-2009, 04:49 PM
#9
Drove the car today with the new Rockland bushing and the reduction in vibes is significant over 60MPH. 
There is a very tiny amount of something still there and I am convinced it will come down to fine tuning the balance of the drive shaft. If it is not a tiny balance issue, I can safely say it must be the normal stuff to expect from the rearend and tunnel mount TA. I am going to cut the suspect weight off of the rear of the DS and try various size washers along with a big hose clamp to dial it in. I did this with my jeep and had good results.
It is now no longer annoying to drive the car like it was before. The Rockland bushing is a success and I strongly recommend it if you have vibes like I detailed in this post. You can get it from Rockland but you have to call them, its not on the website. It costs $35.00 plus a ridiculous $16.00 to ship it. Installing it was a piece of cake.
There is a very tiny amount of something still there and I am convinced it will come down to fine tuning the balance of the drive shaft. If it is not a tiny balance issue, I can safely say it must be the normal stuff to expect from the rearend and tunnel mount TA. I am going to cut the suspect weight off of the rear of the DS and try various size washers along with a big hose clamp to dial it in. I did this with my jeep and had good results.
It is now no longer annoying to drive the car like it was before. The Rockland bushing is a success and I strongly recommend it if you have vibes like I detailed in this post. You can get it from Rockland but you have to call them, its not on the website. It costs $35.00 plus a ridiculous $16.00 to ship it. Installing it was a piece of cake.
Last edited by wrd1972; 01-13-2009 at 06:53 PM.
01-09-2009, 05:11 PM
#10
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I had my bushing walk out on me, apparently the stock bushing didnt like 150+ and it would start vibrating really loud all of a sudden at almost exactly 155. I backed out immediately a few times but one night i just kept it going and after about 10-15 seconds of continued speed it completely stopped and was smooth as silk.
It was sitting on the shaft still but outside the transmission and tranny fluid just flowed like Niagara.
It was sitting on the shaft still but outside the transmission and tranny fluid just flowed like Niagara.
01-09-2009, 06:50 PM
#11
Drove the car today with the new Rockland bushing and the reduction in vibes is significant over 60MPH.
There is a very tiny amount of something still there and I am convinced it will come down to fine tuning the balance of the drive shaft. If it is not a tiny balance issue, I can safely say it must be the normal stuff to expect from the rearend and tunnel mount TA. I am going to cut the suspect weight off of the rear of the DS and try various size washers along with a big hose clamp to dial it in. I did this with my jeep and had good results.
It is now no longer annoying to drive the car like it was before. The Rockland bushing is a success and I strongly recommend it if you have vibes like I detailed in this post. You can get it from Rockland but you have to call them, its not on the website. It costs $35.00 plus a ridiculous $16.00 to ship it. Installing it was a piece of cake.
BTW these are the driveline angles I am currently running:
There is a very tiny amount of something still there and I am convinced it will come down to fine tuning the balance of the drive shaft. If it is not a tiny balance issue, I can safely say it must be the normal stuff to expect from the rearend and tunnel mount TA. I am going to cut the suspect weight off of the rear of the DS and try various size washers along with a big hose clamp to dial it in. I did this with my jeep and had good results.
It is now no longer annoying to drive the car like it was before. The Rockland bushing is a success and I strongly recommend it if you have vibes like I detailed in this post. You can get it from Rockland but you have to call them, its not on the website. It costs $35.00 plus a ridiculous $16.00 to ship it. Installing it was a piece of cake.
BTW these are the driveline angles I am currently running:
If I were you I would try to split tthat difference. Maybe instead of 4/2 maybe try to acheive 3.5/3.5??
01-09-2009, 06:55 PM
#12
No, that won't work just did some rough figuring, what about putting the level on the front side of the d-shaft by the trans and then at the back of the shaft at the pinion and trying to split those numbers?? If you are 3 at the trans and 1 at the diff try getting to 2 front and rear??
01-09-2009, 07:54 PM
#13
The way I see that is a pinion angle of +2 and a working anlgle of -1?? Man this **** is so confusing. Subrtact pinion from trans angle to get your total working angle.
+2 pinion minus -3 trans angle would give you -1 working angle, no? In theory your are right -1, there should be no vibration there. What other angle have you tried??
+2 pinion minus -3 trans angle would give you -1 working angle, no? In theory your are right -1, there should be no vibration there. What other angle have you tried??
01-09-2009, 08:06 PM
#14
I'm with ya' bro. I can adjust a degree or two each way and it seems to have no effect. Obviously if I go far enough things would start to shake.
What I have never understood is the horizon method or when the say point -2* compared to level assuming the car is level. Depending on tire size and suspension mods and spring sag, that angle could be many different things.
I am referencing the pinion compared to the drive shaft with no regard to horizon or level.
Someone clarify this please.
I found this thread to be very informative:
http://www.ford-trucks.com/forums/12...vibration.html
What I have never understood is the horizon method or when the say point -2* compared to level assuming the car is level. Depending on tire size and suspension mods and spring sag, that angle could be many different things.
I am referencing the pinion compared to the drive shaft with no regard to horizon or level.
Someone clarify this please.
I found this thread to be very informative:
http://www.ford-trucks.com/forums/12...vibration.html
Last edited by wrd1972; 01-11-2009 at 07:40 PM.
01-09-2009, 08:12 PM
#15
I also think you need to lower the trans if I am thinking right. The 9inch sits lower than the 10 bolt so in theory you would need to lower the trans to compensate for that. I would try to put the trans back were it originally was and take some new numbers to see where you are at. Also, how is the car in the air, that could also be part of the problem if the suspension is not loaded properly which is my biggest concern when I go to set mine up. I am wondering if once on the ground it is different then when in the air.
I think if you lower the trans back down you could roll your pinion more positive and be able to split the number. Or even just lower your trans back to normal and be real close without touching the pinion.
I think if you lower the trans back down you could roll your pinion more positive and be able to split the number. Or even just lower your trans back to normal and be real close without touching the pinion.
01-09-2009, 08:29 PM
#18
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One thing I did was while the car was on the ground, I put my angle finder on the wing and took a reading, for example mine was 0 degrees, as I was setting the car on all four jackstands I then took another reading to make sure it still said 0 degrees.
01-09-2009, 08:37 PM
#19
You need to have the jackstands either in front of the crossmember or under the front lower control arms to fully simulate a loaded susp. Just placing 2 jackstands under the frame in the front (if this is what you are doing) is the cause of your problem. The susp would not be fully loaded and you are setting angles that way and when you put the car on the ground the number will change drastically.
01-09-2009, 08:43 PM
#20
You need to have the jackstands either in front of the crossmember or under the front lower control arms to fully simulate a loaded susp. Just placing 2 jackstands under the frame in the front (if this is what you are doing) is the cause of your problem. The susp would not be fully loaded and you are setting angles that way and when you put the car on the ground the number will change drastically.
Okay, I just put ramps under the front tires, and have jackstands under the rear axle tubes. Number are the same.