Vibration Fix
05-22-2015, 10:58 PM
#11
Retired and loving it!
Ours vibrates between 33 and 38 mph, and other than that is smooth as silk.....very interested to know what speeds yours vibrates and if the change in pinion angle completely solved it for you.
05-22-2015, 11:04 PM
#12
05-22-2015, 11:06 PM
#13
The next step for me is to change the pinion angle and shim the carrier bearing.
05-23-2015, 11:56 AM
#14
I don't believe mine is fixed. Its hard to qualify using the SOTP meter. Wish I had test equipment to gain a true scientific measurement. The issue is better, better is relative and not quantified. It is better. Mine vibrates at 72'ish and upward.
A couple of quick observations.
Not sure what to think or concluded about the transfer case pinion angle of 3.8 and the operating angle 2.8° it puts on the connected U-Joint. None of the Spicer/Dana documentation addresses a setup with the angle in this direction. All of their documentation shows the transfer case or transmission being parallel. This is unexpected, and unsure how this affects any secondary induced vibration downstream. Better yet which U-joint is responsible for canceling it's second order vibration.
The 2.5° pinion shims gave me much more adjustment than desired. I ended up with 4.5° of change. I may drop the axle again and re-seat and remove them trying to get around 1° positive on the pinion angle. This would make the U-joints at the carrier bearing and the differential close to the same. At the same time I may need to drop my carrier bearing another 1/4" or 1/2" in total. I'm uncertain If I need to try and get the operating angle of the transfer case U-joint to be equal (opposite direction) as the one at the carrier bearing. Thinking the equal opposite angles of the transfer case and carrier cancel out vibration, and the carrier and differential U-joints cancel themselves. This assumes the carrier bearing U-joint can perform a double duty of sorts.
I had a heck of a time getting the rear end aligned with the front.. I had to take the rear loose from the U-bolts three times. Resorted to using a tie strap to get the thrust angle back close to the OEM alignment. First time the steering wheel was 15° to the right. Second time using a strap to pull the left wheel toward the rear got the steering wheel 7° left, next attempt it's about 2° degrees left of center. I left it there. Worn out taking the 8 U-bolt nuts on and off three separate times. I took the rear loose on my Silverado twice using different blocks and never had an alignment issue upon reassembling.
My F-150 loves to be worked on. I think its self centered, jealous and boarderline psychotic that I might move on to another truck.
A couple of quick observations.
Not sure what to think or concluded about the transfer case pinion angle of 3.8 and the operating angle 2.8° it puts on the connected U-Joint. None of the Spicer/Dana documentation addresses a setup with the angle in this direction. All of their documentation shows the transfer case or transmission being parallel. This is unexpected, and unsure how this affects any secondary induced vibration downstream. Better yet which U-joint is responsible for canceling it's second order vibration.
The 2.5° pinion shims gave me much more adjustment than desired. I ended up with 4.5° of change. I may drop the axle again and re-seat and remove them trying to get around 1° positive on the pinion angle. This would make the U-joints at the carrier bearing and the differential close to the same. At the same time I may need to drop my carrier bearing another 1/4" or 1/2" in total. I'm uncertain If I need to try and get the operating angle of the transfer case U-joint to be equal (opposite direction) as the one at the carrier bearing. Thinking the equal opposite angles of the transfer case and carrier cancel out vibration, and the carrier and differential U-joints cancel themselves. This assumes the carrier bearing U-joint can perform a double duty of sorts.
I had a heck of a time getting the rear end aligned with the front.. I had to take the rear loose from the U-bolts three times. Resorted to using a tie strap to get the thrust angle back close to the OEM alignment. First time the steering wheel was 15° to the right. Second time using a strap to pull the left wheel toward the rear got the steering wheel 7° left, next attempt it's about 2° degrees left of center. I left it there. Worn out taking the 8 U-bolt nuts on and off three separate times. I took the rear loose on my Silverado twice using different blocks and never had an alignment issue upon reassembling.
My F-150 loves to be worked on. I think its self centered, jealous and boarderline psychotic that I might move on to another truck.
Last edited by joedotmac; 05-23-2015 at 02:15 PM.
05-23-2015, 12:33 PM
#15
There's so much fantastic information that can be gleaned from that Spicer document. My truck spits at these practices in disgust.
RULE 1: UNIVERSAL JOINT OPERATING ANGLES AT EACH END OF A DRIVESHAFT SHOULD ALWAYS BE AT LEAST 1 DEGREE.
RULE 2: UNIVERSAL JOINT OPERATING ANGLES ON EACH END OF A DRIVESHAFT SHOULD ALWAYS BE EQUAL WITHIN 1 DEGREE OF EACH OTHER (ONE HALF DEGREE FOR MOTOR HOMES AND SHAFTS IN FRONT OF TRANSFER CASE OR AUXILIARY
DEVICE).
RULE 3: FOR VIRTUAL VIBRATION FREE PERFORMANCE, UNIVERSAL JOINT OPERATING ANGLES SHOULD NOT BE LARGER THAN 3 DEGREES. IF THEY ARE, MAKE SURE THEY DO NOT EXCEED THE MAXIMUM RECOMMENDED ANGLES.
Critical Speed
Every driveshaft has a critical speed. Critical speed is the point at which a rotating driveshaft begins to bow off its normal rotating centerline.
Driveshafts begin to vibrate as they approach critical speed. If they are operated at near critical speed for an extended period, they often fail. This can damage the vehicle and possibly injure persons nearby
Multiple Shaft Installations
For a 2-shaft application, set up the first coupling shaft (sometimes called a jackshaft) so that the universal joint operating angle that occurs at the transmission end is 1 to 1-1/2 degrees.
RULE 1: UNIVERSAL JOINT OPERATING ANGLES AT EACH END OF A DRIVESHAFT SHOULD ALWAYS BE AT LEAST 1 DEGREE.
RULE 2: UNIVERSAL JOINT OPERATING ANGLES ON EACH END OF A DRIVESHAFT SHOULD ALWAYS BE EQUAL WITHIN 1 DEGREE OF EACH OTHER (ONE HALF DEGREE FOR MOTOR HOMES AND SHAFTS IN FRONT OF TRANSFER CASE OR AUXILIARY
DEVICE).
RULE 3: FOR VIRTUAL VIBRATION FREE PERFORMANCE, UNIVERSAL JOINT OPERATING ANGLES SHOULD NOT BE LARGER THAN 3 DEGREES. IF THEY ARE, MAKE SURE THEY DO NOT EXCEED THE MAXIMUM RECOMMENDED ANGLES.
Critical Speed
Every driveshaft has a critical speed. Critical speed is the point at which a rotating driveshaft begins to bow off its normal rotating centerline.
Driveshafts begin to vibrate as they approach critical speed. If they are operated at near critical speed for an extended period, they often fail. This can damage the vehicle and possibly injure persons nearby
Multiple Shaft Installations
For a 2-shaft application, set up the first coupling shaft (sometimes called a jackshaft) so that the universal joint operating angle that occurs at the transmission end is 1 to 1-1/2 degrees.
05-23-2015, 04:21 PM
#16
Another great video that solidifies the practices and operation setup specifications in the Spicer documentation. The Tundra driveline is extremely similar to our F150.
My question then becomes why does our transfer case sit at such an angle? I'm going to go measure mine again, and four different ways to Sunday, to assure the angle I've captured is correct.
Would be interesting to compare with other F-150's. Anyone that can crawl under a truck with a smart phone can do it.
The suggested method to change the working angle of the joint at the transfer case is to shim the transfer case up. That's not for the faint of heart, least from what I can see under the truck.
My question then becomes why does our transfer case sit at such an angle? I'm going to go measure mine again, and four different ways to Sunday, to assure the angle I've captured is correct.
Would be interesting to compare with other F-150's. Anyone that can crawl under a truck with a smart phone can do it.
The suggested method to change the working angle of the joint at the transfer case is to shim the transfer case up. That's not for the faint of heart, least from what I can see under the truck.
05-23-2015, 11:03 PM
#19
Interested as well. Had an '08 and have a '14 F150. Both crew cabs with 6 1/2' beds. Both had/have vibration with a trailer at 50-55 MPH.
Maybe I'll get out and measure my angles Monday too.
Maybe I'll get out and measure my angles Monday too.
05-25-2015, 07:46 AM
#20
Okay, this is my 2nd SCREW 6.5 4X4. Both had/have the issue. I have never lifted a truck before but I put two inch spacers on the front and blocks on the back (with Bilstien 5100's on the back) and the launch shudder is virtually gone. I know it has changed the geometry of the rear drive line and I guess that has helped FWIW.