4L80E Guys - Any Suggestions?
4L80E Guys - Any Suggestions? Hey everyone.
I did the 4L80E swap last year and couldn't be happier with the setup performance-wise. I have been battling a vibration issue at high speeds though. I originally had 2.73s in the rear and the vibration would occur around 100mph+. It wasn't a big deal since I'm rarely at those speeds anyway.
I switched to 3.42s and now the vibration occurs around 75mph+. This is more annoying. I've checked my tranny mount (using a stock 80e mount) and rotated the driveshaft 90 degrees. No change.
I've ruled out tires being out of balance, b/c the speed at which the vibration occurred changed with the gear swap.
I disconnected the yoke/driveshaft from the transmission and ran the tranny up to an indictated 90 mph. No vibration.
I swapped out the rear yoke b/c the old one only had about 1.5 inches of spline contact. I thought maybe this could be the cause. It wasn't. I now have about 3 inches of contact.
I am using the same driveshaft as when I had my 4l60e (with no vibration), so the balance should not be a factor. I thought about getting it rebalanced but even the guy at the shop didn't believe this would be the issue, though he would be happy to take my money to give it a try.
I am thinking it is a pinion angle issue. I am a little skeptical that this is the problem though, because I haven't heard anyone on here have the same issue. I know several people are using the 80 with the stock driveshaft. Plus I don't really want to buy an adjustable torque arm and longer driveshaft when I'm going to end up going with a MWC 9 inch later on. I'm going to go pick up a magnetic angle finder and check the tailshaft vs. pinion.
Anyone have any input/suggestions as to a possible solution I might be missing? Thanks in advance.
Also, can I check the angles by driving the rear up some ramps to get under the car since I'm measuring the angles in relation to each other as opposed to in relation to the ground?
I did the 4L80E swap last year and couldn't be happier with the setup performance-wise. I have been battling a vibration issue at high speeds though. I originally had 2.73s in the rear and the vibration would occur around 100mph+. It wasn't a big deal since I'm rarely at those speeds anyway.
I switched to 3.42s and now the vibration occurs around 75mph+. This is more annoying. I've checked my tranny mount (using a stock 80e mount) and rotated the driveshaft 90 degrees. No change.
I've ruled out tires being out of balance, b/c the speed at which the vibration occurred changed with the gear swap.
I disconnected the yoke/driveshaft from the transmission and ran the tranny up to an indictated 90 mph. No vibration.
I swapped out the rear yoke b/c the old one only had about 1.5 inches of spline contact. I thought maybe this could be the cause. It wasn't. I now have about 3 inches of contact.
I am using the same driveshaft as when I had my 4l60e (with no vibration), so the balance should not be a factor. I thought about getting it rebalanced but even the guy at the shop didn't believe this would be the issue, though he would be happy to take my money to give it a try.
I am thinking it is a pinion angle issue. I am a little skeptical that this is the problem though, because I haven't heard anyone on here have the same issue. I know several people are using the 80 with the stock driveshaft. Plus I don't really want to buy an adjustable torque arm and longer driveshaft when I'm going to end up going with a MWC 9 inch later on. I'm going to go pick up a magnetic angle finder and check the tailshaft vs. pinion.
Anyone have any input/suggestions as to a possible solution I might be missing? Thanks in advance.
Also, can I check the angles by driving the rear up some ramps to get under the car since I'm measuring the angles in relation to each other as opposed to in relation to the ground?
Last edited by usmc320; Aug 5, 2009 at 05:00 AM.
