[JSH]

The same thing happens with a pre-meth tune, which eliminates that variable. It might be the way the RR bites and spins, or the tire might be turning in the wheel.

[ZL1Atlanta]

Originally Posted by JSH

The same thing happens with a pre-meth tune, which eliminates that variable. It might be the way the RR bites and spins, or the tire might be turning in the wheel.

Did you check the bolts on back of the trans? VSS graph smooth when it happens?

[JSH]

Originally Posted by ZL1Atlanta

Did you check the bolts on back of the trans? VSS graph smooth when it happens?

I'm not 100% sure. Which bolts? I don't see VSS on my logs. If it's not there, I'll add it.

[ZL1Atlanta]

Originally Posted by JSH

I'm not 100% sure. Which bolts? I don't see VSS on my logs. If it's not there, I'll add it.

VSS is just vehicle speed. I’d be surprised if you aren’t loogging it, but definitely add it if not. Here is a pic of a log from a couple years ago. Red is RPM and green is VSS. It was very rough up there in 6th gear in this case. There was a slight increase in trans and converter slip, but it wasn’t massive.

The bolts are on the rear cover around the output of the trans.

[JSH]

Originally Posted by ZL1Atlanta

VSS is just vehicle speed.

Yes, we're logging speed.

[JSH]

Originally Posted by JSH

There's a distinct vibration today in 4th between 6000 and 7000. The only change from, say, two weeks ago when this wasn't happening is going down to the 2.75 pulley, so I'm going to replace the belt. It also does it with TC on. I've swapped upper pullies a bunch of times using this belt. At least we'll eliminate a variable.

This same mysterious and unpredictable phenomenon occurred a year ago and happened again this weekend in both outings with my new build. The only thing I remember us doing last year was making a minor adjustment to the driveshaft tunnel. When it first happened on Saturday, I thought the engine had pulled power, but it turned out I had let off the throttle. All the potential issues mentioned last year still apply.