I'm hoping that someone might know what this is.

Just replaced the torque converter in my 48RE and now we are getting a 'rattle' in 4th gear about around 1,000 rpm with torque converter locked. I haven't had a chance to set it up so the TC isn't locked. It's not a loud noise, and it goes away when the rpm gets above 1,200. Haven't been able to reproduce it in 3rd, but I don't think the TC is locked in 3rd at those rpms. This is all being controlled by an ATS controller and valve body.

Also have a similar, but louder, sound in reverse when you get beyond just idling.

Any thoughts?

Peter

 

First, check the TC bolts and make sure they are tight. It really sounds like they are loose.

Second, locking the TC at those rpm's is a bad idea. You need some more rpm's before locking the TC. The pump is not making enough pressure to hold the TC clutch and it could be your slipping that clutch also.

The reverse noise still sounds like a loose coupling somewhere. Did you replace the flex plate also? Chekc it closely for cracks? They are prone to cracking and that could also be the source of your rattle.

 

X2. "1000-1200 RPM" and "TC locked in 4th" should never be used in the same sentence.

Nick

 

Thanks for the info, that's very helpful. At what RPM should the 4-3 downshift occur? Perhaps my program has more than one problem. I'll work on getting the TC not to lock so quickly in 4th.

Peter

 

I don't like OD engaged under 40 mph but thats a personal opinon. I would start having it downshift at 1600 rpm's ans see what that feels like.

 

My OD will not stay locked under ~45.