Engine/Transmission (1998.5 - 2002) 2000 automatic transmission

[Bill Johnson]

I have a 2000, 2500 with 140000 miles on, I recently had a billet tq converter installed and valve body worked on . transmission shifts ok but when I'm driving slow it shifts up and down while driving about 30 to 35 mph. speed limit won't let me go faster, to many smokies in area. the truck didn't do this before. Does anyone have any idea why it does this?

 

[JLandry]

Bill,



When this happens, is it shifting between 3rd and 4th gear, or is it possibly staying in 3rd gear but locking and unlocking the torque convertor?



John L.

 

[Bill Johnson]

It feels like its shifting between 3rd and 4th gear.

 

[JLandry]

Bill,



When you get a chance, turn the OD switch OFF when driving under these conditions and let us know what it does.



More questions:



Who built, installed, and adjusted the transmission?



How many miles since the rebuild?



Has it always done this since the rebuild or did it suddenly start?



Does your new torque convertor have a single-disc or triple-discs?



What axle ratio does your truck have?



Something to consider:



A triple-disc TC with higher line pressures from a modified valve body will cause very firm shifting and very noticeable TC engagement/disengagement compared to stock. Some folks like this feel, some don't. I like it at times, other times I find it a bit annoying.



I only mention this because the shift behavior of your transmission could actually be the same as before, but you never paid much attention to it when it was soft. At least that's what I experienced after installing a Goerend triple-disc/high pressure transmission.



On my truck, speeds between about 35 and 45 in traffic are about the worst place to be for the transmission because it constantly alternates between 3rd gear <-> TC lockup <-> 4th gear <-> TC lockup. Slight changes in speed, throttle position, and load cause a shift change. Turning the OD off which forces the transmission to stay in 3rd gear helps, but of course at the cost of higher engine rpm.



Regards,



John L.