So I noticed today a strange issue with my transmission, If I am in overdrive but cruising slowly at around 20mph and go WOT it will downshift to 1st but will slip in first until redline then shift hard into second. I have a handheld diablosport tuner with the diablosport tune at the time so loaded up the factory tune and problem was even worse and at redline it would make a pretty nasty granding noise for a moment then shift hard into second. Everything else seems to work fine on the trans, I guess I'll just avoid that 3-1 shift (probably not a good idea to do this) but hopefully I haven't damaged anything. Could this be a problem with the trans? I never noticed it before.

Car is an 02 ta with just over 100k miles. It has light bolt ons

 

How are you in 4th gear at 20mph? Im assuming you mean 3rd?
How is the 1-2 from a dead stop?

 

Sorry, I did mention from 3-1 later in the post but I did say overdrive earlier. By saying Overdrive I meant the setting on the shifter was on overdrive. 1-2 shift is strong and crisp and will chirp the tires pretty good.

 

The Lo Roller Clutch & the Forward clutches are the only things that have to "Hold" in first gear, A Lo Roller clutch failure can cause slipping in (D4) 1st gear & make noise. The Lo roller clutch is ineffective in other ranges.

 

hmm good info here. Sounds like could be the low roller clutch? It's kind of hard to find info about this part, but from what your saying it does sound like the issue... and that would be a complete teardown of the trans if I wanted to replace that. Thanks for the help.