Driveline angles and launch shudder.
06-07-2011, 09:46 PM
#21
Did you guys get a shim that bolts into the leaf pack? With flip kit it offsets rear axle back farther so conventional shims with the hole in the middle probably won't work right. At least they won't sit square under the flip kit saddle.
06-07-2011, 10:45 PM
#22
This is why I used weld on perches and made my pinion angle -3 in relation to the ground. I get a little u-joint "click" at slow cruising speeds, but no,NO, vibrations. Oh and my driveshaft balance was way off!! I had Texas DS specialist straighten her out.
06-13-2011, 06:39 PM
#24
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The pinion angle is no guessing game. The very first problem we NNBS guys have is our actual drivetrain angle is 6 degrees negative. THis is the center line through the crank out the transmission and runs parallel with pinion line. This angle is fine when the truck is stock because the driveshaft angle is within 3 degrees of the drivetrain angle. These two angles need to be within 2-4 degrees of each other or inertia will start to show its ugly head.
Take your truck and my truck because we both have CC NNBS trucks. We both have 6 degrees negative at trans and 6 degrees positive at rearend. Our driveshaft angle is zero so we are out of the 2-4 degree window. This can be fixed by lifting the rear of the trans do bring it to 4 degrees negative and bringing the rear end down to 4 degrees positive. The problem comes that we cant lift the trans because the floorpan is very close to the trans and driveshaft. My truck is tunneled and I still cant get it to 4 degrees. So then we look at lowering the front of the motor so the trans will pivot at the rear mount but the oil pan will then hit the subframe. A corvette oil pan will let you though but you will have to do some tunneling for driveshaft.
My truck lasted for 3K miles setting like this at 404 whp (Im supercharged) before I started getting vibes on hard throttle. THe problem came to be the output shaft bushing that keeps the driveshaft yoke stable was wornout already. SO back to my original statement of 6 degrees negative and 6 degrees positive will keep your U joints happy but it excedes 3 degrees from driveshaft sets inertia into play. THe inertia is transfered out to the yoke and the pinion bearing causing them to wear.
Go check your driveshaft at front and see if you have up/down play in it. Not in and out but up and down. If the yoke wobbles in the trans then your output bushing is gone. Also check your rearend and see if you are showing seapage of dif oil at the pinion seal or worse up down motion there.
It all boils down to the NNBS has too steep of a drivetrain angle to make them 100% solid with just a drop kit and adjusting the pinion angle. SOme will not have any vibes and my not agree with this, but in time all of us will be having this issue. Adding big power adders are just going to speed this process up as mine was gone in 3k miles but I also am drifting my truck and daily launches and burnouts to sample it for customers.
My truck can be viewed at the Lysholm website in their blogs.
Take your truck and my truck because we both have CC NNBS trucks. We both have 6 degrees negative at trans and 6 degrees positive at rearend. Our driveshaft angle is zero so we are out of the 2-4 degree window. This can be fixed by lifting the rear of the trans do bring it to 4 degrees negative and bringing the rear end down to 4 degrees positive. The problem comes that we cant lift the trans because the floorpan is very close to the trans and driveshaft. My truck is tunneled and I still cant get it to 4 degrees. So then we look at lowering the front of the motor so the trans will pivot at the rear mount but the oil pan will then hit the subframe. A corvette oil pan will let you though but you will have to do some tunneling for driveshaft.
My truck lasted for 3K miles setting like this at 404 whp (Im supercharged) before I started getting vibes on hard throttle. THe problem came to be the output shaft bushing that keeps the driveshaft yoke stable was wornout already. SO back to my original statement of 6 degrees negative and 6 degrees positive will keep your U joints happy but it excedes 3 degrees from driveshaft sets inertia into play. THe inertia is transfered out to the yoke and the pinion bearing causing them to wear.
Go check your driveshaft at front and see if you have up/down play in it. Not in and out but up and down. If the yoke wobbles in the trans then your output bushing is gone. Also check your rearend and see if you are showing seapage of dif oil at the pinion seal or worse up down motion there.
It all boils down to the NNBS has too steep of a drivetrain angle to make them 100% solid with just a drop kit and adjusting the pinion angle. SOme will not have any vibes and my not agree with this, but in time all of us will be having this issue. Adding big power adders are just going to speed this process up as mine was gone in 3k miles but I also am drifting my truck and daily launches and burnouts to sample it for customers.
My truck can be viewed at the Lysholm website in their blogs.
06-13-2011, 06:52 PM
#25
The pinion angle is no guessing game. The very first problem we NNBS guys have is our actual drivetrain angle is 6 degrees negative. THis is the center line through the crank out the transmission and runs parallel with pinion line. This angle is fine when the truck is stock because the driveshaft angle is within 3 degrees of the drivetrain angle. These two angles need to be within 2-4 degrees of each other or inertia will start to show its ugly head.
Take your truck and my truck because we both have CC NNBS trucks. We both have 6 degrees negative at trans and 6 degrees positive at rearend. Our driveshaft angle is zero so we are out of the 2-4 degree window. This can be fixed by lifting the rear of the trans do bring it to 4 degrees negative and bringing the rear end down to 4 degrees positive. The problem comes that we cant lift the trans because the floorpan is very close to the trans and driveshaft. My truck is tunneled and I still cant get it to 4 degrees. So then we look at lowering the front of the motor so the trans will pivot at the rear mount but the oil pan will then hit the subframe. A corvette oil pan will let you though but you will have to do some tunneling for driveshaft.
My truck lasted for 3K miles setting like this at 404 whp (Im supercharged) before I started getting vibes on hard throttle. THe problem came to be the output shaft bushing that keeps the driveshaft yoke stable was wornout already. SO back to my original statement of 6 degrees negative and 6 degrees positive will keep your U joints happy but it excedes 3 degrees from driveshaft sets inertia into play. THe inertia is transfered out to the yoke and the pinion bearing causing them to wear.
Go check your driveshaft at front and see if you have up/down play in it. Not in and out but up and down. If the yoke wobbles in the trans then your output bushing is gone. Also check your rearend and see if you are showing seapage of dif oil at the pinion seal or worse up down motion there.
It all boils down to the NNBS has too steep of a drivetrain angle to make them 100% solid with just a drop kit and adjusting the pinion angle. SOme will not have any vibes and my not agree with this, but in time all of us will be having this issue. Adding big power adders are just going to speed this process up as mine was gone in 3k miles but I also am drifting my truck and daily launches and burnouts to sample it for customers.
My truck can be viewed at the Lysholm website in their blogs.
Take your truck and my truck because we both have CC NNBS trucks. We both have 6 degrees negative at trans and 6 degrees positive at rearend. Our driveshaft angle is zero so we are out of the 2-4 degree window. This can be fixed by lifting the rear of the trans do bring it to 4 degrees negative and bringing the rear end down to 4 degrees positive. The problem comes that we cant lift the trans because the floorpan is very close to the trans and driveshaft. My truck is tunneled and I still cant get it to 4 degrees. So then we look at lowering the front of the motor so the trans will pivot at the rear mount but the oil pan will then hit the subframe. A corvette oil pan will let you though but you will have to do some tunneling for driveshaft.
My truck lasted for 3K miles setting like this at 404 whp (Im supercharged) before I started getting vibes on hard throttle. THe problem came to be the output shaft bushing that keeps the driveshaft yoke stable was wornout already. SO back to my original statement of 6 degrees negative and 6 degrees positive will keep your U joints happy but it excedes 3 degrees from driveshaft sets inertia into play. THe inertia is transfered out to the yoke and the pinion bearing causing them to wear.
Go check your driveshaft at front and see if you have up/down play in it. Not in and out but up and down. If the yoke wobbles in the trans then your output bushing is gone. Also check your rearend and see if you are showing seapage of dif oil at the pinion seal or worse up down motion there.
It all boils down to the NNBS has too steep of a drivetrain angle to make them 100% solid with just a drop kit and adjusting the pinion angle. SOme will not have any vibes and my not agree with this, but in time all of us will be having this issue. Adding big power adders are just going to speed this process up as mine was gone in 3k miles but I also am drifting my truck and daily launches and burnouts to sample it for customers.
My truck can be viewed at the Lysholm website in their blogs.
06-13-2011, 08:09 PM
#26
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My truck is bagged and lays frame. My ride height is set about an inch lower than your truck and my truck spends 99% of its time at that level.
Not sure on the trans spacer because I am opting to lower the front of my motor. When you raise the rear of trans the driveshaft will get close to the bottom of the cab. You will be ok since your static, but since I lower mine with the bags my DS would end up binding on the floor of cab.
Just undo the bolt inside the trans crossmember and lift the trans with a jack. Measure the angle on the yoke until you have it lifted to where you want it and insert spacer and tighten down. I dont think you can go more than a 1/2 inch without running out of threads.
Did you have play in the yoke?
Not sure on the trans spacer because I am opting to lower the front of my motor. When you raise the rear of trans the driveshaft will get close to the bottom of the cab. You will be ok since your static, but since I lower mine with the bags my DS would end up binding on the floor of cab.
Just undo the bolt inside the trans crossmember and lift the trans with a jack. Measure the angle on the yoke until you have it lifted to where you want it and insert spacer and tighten down. I dont think you can go more than a 1/2 inch without running out of threads.
Did you have play in the yoke?
06-13-2011, 08:40 PM
#27
My truck is bagged and lays frame. My ride height is set about an inch lower than your truck and my truck spends 99% of its time at that level.
Not sure on the trans spacer because I am opting to lower the front of my motor. When you raise the rear of trans the driveshaft will get close to the bottom of the cab. You will be ok since your static, but since I lower mine with the bags my DS would end up binding on the floor of cab.
Just undo the bolt inside the trans crossmember and lift the trans with a jack. Measure the angle on the yoke until you have it lifted to where you want it and insert spacer and tighten down. I dont think you can go more than a 1/2 inch without running out of threads.
Did you have play in the yoke?
Not sure on the trans spacer because I am opting to lower the front of my motor. When you raise the rear of trans the driveshaft will get close to the bottom of the cab. You will be ok since your static, but since I lower mine with the bags my DS would end up binding on the floor of cab.
Just undo the bolt inside the trans crossmember and lift the trans with a jack. Measure the angle on the yoke until you have it lifted to where you want it and insert spacer and tighten down. I dont think you can go more than a 1/2 inch without running out of threads.
Did you have play in the yoke?
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