I have had a built trans in the car for about 3 years with a billet 3800 stall converter. Since install it has had a noticeable vibration under light acceleration until converter locks. Pretty sure It happens in all gears. It was really bad in 3rd gear until I went back to the stock mount. Under full or pretty hard acceleration I don't seem to notice it. I have finally gotten some other things taken care of on the car and want to see about fixing this. I am thinking it may be an internal converter balance issue.

I have unbolted the converter, rotated and reinstalled it and issue is the same.

Thanks for the help.

 

There have been a number of vibration complaints related to "The Beast" sun shell. Especially when I read "really bad in 3rd gear" I suspect that. This is one of the reasons an increasing number of performance builds now use the Sonnax Smart Shell.

For a quick history of sun shells:
Pre '03 the stock sun shell was a weak point in the 4L60E and The Beast was the only and much stronger alterative.
In '03 GM started to heat treat the stock sun shell and failures plummeted; some builders have told me they have never seen the newer heat-treated one fail, but other builders have seen a few. In short the later heat-treated ones are very durable and no longer a major failure point.
Sometime in the last last 5(?) years Sonnax introduced their "Smart Shell". It looks to me like a reinforced version of the GM heat-treated one. The spline area when it engages the sun gear is reinforced. It also includes a torrington bearing and custom roller clutch so that side forces are transferred through the strong roller clutch instead of the small inner bearing of the rear planetary.

The top-of-the line transmissions from all vendors here use the Sonnax Smart Shell now.

 

Thanks for the reply. Saw you are in Ann Arbor. I used to live in UP an still have family there.

I had seen a couple of you posts referencing the sun shell during my searching. Could I have an issue with both converter and sun shell since it seems to be in all gears? If it is sun shell do I need to worry about it causing any issues?
Thanks.

 

The sun shell does not move in 2nd or 4th gears and therefore cannot contribute to problems there. If you have vibration in those gears it helps to determine if they are more RPM or MPH related. RPM related points toward the converter (or even engine) while MPH related points toward the driveshaft.

I hope to get to the UP next month; we missed going there last year. The beach on Lake Superior near "Little Presque Isle", a few miles west of Marquette is one of my favorite places on earth. Miles of perfect white sand and nearly empty. And even swimmable in August.

 

Thanks again. Definitely rpm related. No vibration at any rpm when in park or neutral. Any long term concerns if my sun shell is out of balance? I will report back after I take it for another ride and pay closer attention to gears vs vibration.

I lived a little east of Marquette on M28 for about 10 years then just a little south of Sault Ste Marie for about 8 years. I know the UP pretty well. Small world.

 

Since there is no vibration at any rpm in park or neutral, it is not likely to be the converter. The heaviest part of the trans, the input drum, is also spinning in park and neutral, which rules that out.
If the vibration is only in 3rd (also 1st but no one notices that), then I suspect only the sun shell. I don't think there is any long term concern.
I now see that you have a Performabuilt; they were using The Beast, but seem to be switching to the Smart Shell in at least some of their models.
Why not contact Frank at Performabuilt, he is on here almost every day and gives excellent service and advice.

 

Thanks again for the help. Was replacing ball joints, bushings, tie rod ends and just got things back together. I am pretty sure it is only noticeable in 3rd gear. I have not driven it much since it needs an alignment. Going to contact performabuilt after I confirm what is going on. Bad thing is that I already contacted them just after I got the trans because vibration in 3rd was so bad with the poly mount I though car was going to come apart. He said swap out the mount and it of course got better. At that time Frank specifically said it should not be trans since nothing inside could do that. Sounds like knowledge has changed in the last few years. I will post back with anything exciting.

 

You ever find out anything? I've got a 3rd gear vibration as well. It's only in third. It doesn't matter if I'm just cruising into third or hard on the gas into 3rd. Of course on the gas the vibration is worse. I've seen it could be in the drive line as well.

 

I have not had time to talk to performabuilt but it is only 3rd gear I notice. Probably going to just live with it for now.

 

Here are some of the similar threads I could find:

https://ls1tech.com/forums/automatic...-3rd-only.html
https://ls1tech.com/forums/automatic...sun-shell.html
https://ls1tech.com/forums/automatic...e-rebuild.html