4L80E Swap Vibrations
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Joined: Jun 2010
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From: Lima
4L80E Swap Vibrations Ive been chasing this vibration for a long time, It feels like a drive shaft bouncing. Its really bad just crusing but when i put my foot in it it seems to get better and not notcible. Not expecting this thing to ride like a caddy but it shouldnt vibrate like this, and i can def feel it in the seat. Ive had the trans rebuilt twice, drive shaft balanced 3 times brand new moser 12 bolt new shocks in the rear adjust panhard and trailing arms. ive had the rear end centered and aligned. I feel like this is a pinion angle issue but ive set it like 4 times with no luck. IM using a UMI cross member and a bmr short torque arm. stock 80E trans mount. Ive read people saying they have to shim the trans up as the 80 tends to hang lower. Does shimming the trans up some and resetting pinion angle sound about right? its all in a 01 ws6 also.
I’m fight my own issues with my 4l80e now but I had to shim my trans mount up pretty high. I have a Dana 60 though. My rear yoke was sitting hire then my output shaft for the trans. I shimmed it as high as I could go tunnel wise and then set driveline angle and pinion angle from there.
There's just no real one fits all answer. What engine mounts, what transmission mount? What are the angles? I've found poly mounts really cause vibration. I can run a trans poly mount, OR engine poly mounts, but not both.
TECH Senior Member
Joined: Jul 2009
Posts: 8,034
Likes: 663
are you running a Poly trans mount? Before remove the original tranns, you should of write down tranns and drive shaft angles. Then try to match it with the new rear
I’ve heard poly mounts can cause vibration issues. Have you ever che led the tranny tail shaft bushing?
I’ve heard poly mounts can cause vibration issues. Have you ever che led the tranny tail shaft bushing?
Most common problem is poly mounts. Gm made the stock mount soft and squishy for a reason some even liquid filled. Note if you left the counter weights off generally mounted to trans at mount they play into vibration absorption also.
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