4l80e swap vibration....
05-20-2014, 09:25 AM
#1
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4l80e swap vibration.... Ever since ive had my car done and together its got a vibration that starts at just over 75mph. not only can you feel it you car hear the harmonics thru the chassis. Ive checked and reset pinion angle multiple times, changes the trans mount back to a stock one which made the biggest difference. took it from 65-68mph to 75-78mph. Had a new driveshaft built. took it to multiple shops and balance is good. Changed the rear axle out for a spare I had. I know its not the trans or engine making it. Im pulling my hair out on this one. Does anyone know what the factory trans out put angle is?? Its enough of a vibration I hate driving my car anywhere but in town.
06-17-2014, 03:38 AM
#2
I have the same bad vibration past 65mph since I've swapped 4L80E (with new driveshaft).
For now I'm suspecting my driveline angles are wrong, engine is tilted down 4* in rear and rear end pinion is also tilted DOWN 1.5* in the front so there is 5.5* angle between their centerlines, while from what I read it must be 0.
For now I'm suspecting my driveline angles are wrong, engine is tilted down 4* in rear and rear end pinion is also tilted DOWN 1.5* in the front so there is 5.5* angle between their centerlines, while from what I read it must be 0.
06-17-2014, 07:29 AM
#3
some of the 80E swaps end up with the wrong angle-you push the trans up until it hits the floor, and that's where it stays, lol
since its longer, and now maybe pointing down more, the driveshaft actually comes out and goes up a little-I have had to split the floor open and mod it to get the proper angle
since its longer, and now maybe pointing down more, the driveshaft actually comes out and goes up a little-I have had to split the floor open and mod it to get the proper angle
06-18-2014, 02:13 AM
#6
Yesterday, after loosing a lot of oil through tranny rear seal on 400 mile trip (oil was all over under the car), I checked movement of driveshaft inside tranny and was surprised. It moved quite a lot, but mostly not just play up and down but more like twisting inside tailhousing. On the video it looks twice as bad as it is though, but in reality it's still bad. I also tried to measure play (see picture) and it was only 0.1". But with any movement of the DS I get a bit of oil coming out through oil seal.
Gurus, should I maybe remove tailhousing to check what's inside? Or is this normal play?
I don't know how was it when tranny was new. I suspect that due to vibration I might have done damage to the tailhousing...
Gurus, should I maybe remove tailhousing to check what's inside? Or is this normal play?
I don't know how was it when tranny was new. I suspect that due to vibration I might have done damage to the tailhousing...
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06-19-2014, 02:55 AM
#8
Yes, that looks excessive. It likely needs a new tailhousing bushing, Check the yoke diameter, it should be 1.880" or near it.
Vibration will cause the bushing to wear. You also need to find the root cause of the vibration.
Your pan leak mentioned elsewhere was probably the harness connector and not the pan.
Vibration will cause the bushing to wear. You also need to find the root cause of the vibration.
Your pan leak mentioned elsewhere was probably the harness connector and not the pan.
06-19-2014, 08:31 AM
#9
Yes, that looks excessive. It likely needs a new tailhousing bushing, Check the yoke diameter, it should be 1.880" or near it.
Vibration will cause the bushing to wear. You also need to find the root cause of the vibration.
Your pan leak mentioned elsewhere was probably the harness connector and not the pan.
Vibration will cause the bushing to wear. You also need to find the root cause of the vibration.
Your pan leak mentioned elsewhere was probably the harness connector and not the pan.
Vibration is caused (I believe) by 5 degrees between engine centerline and rear end pinion centerline, from what I read they should be parallel.
So, should I remove tailhousing and check the bearing?
06-19-2014, 06:27 PM
#10
Checked yoke diameter, it's about 1.880".
I removed the tailhousing and to be honest bearing doesn't look beaten... Driveshaft moves considerably inside the bearing but the bearing itself doesn't look too bad...
Should I still replace this bearing, can it be replaced separately, not getting the whole tailhousing? What's the acceptable clearance for this bearing?
I removed the tailhousing and to be honest bearing doesn't look beaten... Driveshaft moves considerably inside the bearing but the bearing itself doesn't look too bad...
Should I still replace this bearing, can it be replaced separately, not getting the whole tailhousing? What's the acceptable clearance for this bearing?
06-19-2014, 10:05 PM
#11
Yes the bushing can be replaced it's a minimal expense. I had a similar experience but my bushing actually walked out of the tailshaft housing and was chilling on the output shaft when I pulled it off. I replaced the bushing and red locktited the bushing in. I had the pinion angles all screwed up as well. I found some good threads on here and I'll see if I can find them again to help you guys understand why you are getting the vibrations that your getting. If you read any vibration thread especially with a 4l80e install then you'll find that they are particular to the speeds you mentioned and they will get worse as speed increased. If your angle on your tailshaft is a negative 4 then you need to make sure the pinion angle matches it at a negative 4. The reason why is because when you have two unlike angles on a driveshaft one u joint is going to try and "accelerate" faster than the other. This type of driveline configuration is called a broken back setup. Here is the link: https://ls1tech.com/forums/suspensio...l#post17323566
06-28-2014, 06:23 PM
#15
OK some update. I've raised the tail of the tranny about 1/2", I'm pretty sure output shaft is now not lower than shaft of T56 was, but I still have the same vibration around 65mph. Now engine/tranny is down 3* at the rear, and rear end is 1* down at the front, so their relative angle is 4*. I'm a bit lost here, because with T56 with this same configuration I didn't have vibration. Maybe problem is in the new steel driveshaft??
07-16-2014, 10:38 PM
#19
my 80e swap had similar issues. I still have a poly mount but shimmed it up about 1/4" and then just pushed the rear up a couple settings on my BMR crossmember. This got my vibs way down. I still have some but alot of it is the fact that i have almost no stock suspension left and subframe connectors(weld in style) Also big tires, dropped doesn't help. The car is not a Benz so i don't get too excited. One big problem with mine was one of my billet specialties street lites was bent in the rear. The outside lip had a small curb rash spot from previous owner and the inside barrel was out of round, likely due to a pothole at one point. I spent $125 to have a local tire shop straighten it and about 95% of my noise and vibrations are gone. It helped a ton and explains why when i had the new rear tires put on that the one out of round was the one registering excessive runout. That's something to check into as well 
07-17-2014, 02:07 AM
#20
I've reduced angle between gearbox and rear end from 4.5* to about 2-2.5 degrees as well as rotated driveshaft 180* in the rear end yoke, vibrations reduced a lot but still far from comfortable cruising
