Is this normal for a new Trans???
Thread Starter
Instructor
Joined: Nov 2009
Posts: 247
Likes: 6
From: St. Charles IL
Is this normal for a new Trans???
I have a 1998, A4 with a procharger, LG Pro Headers, Corsa catback and other minor mods....444rwhp. I blew out my transmision after installing the procharger which was expected since I have over 75,000 miles I went with a Stage 5 trans from RPM Transmissions and I upgraded to 3:42 gears with a 3000 stall. When I got the car back from the shop, it was shifting harder than usual at about 42mph which I believe is between 3 and 4 gear. I can't remember exactly what the installer told me but he said it was normal for 97' and 98' vettes to do this with a complete trans swap. I told him it was annoying as hell because that is a very common speed and it happens frequently. He said he could change my shift points and make it happen at 55mph so it is less frequent, which he did but it is still annoying. All I want to know is is this normal? What is causing it? How do I get it fixed? Thank you in advance for any advice you can give.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Are you sure it's not the TCC (converter) locking up in 4th ?? actually will feel like another shift into 5th
Raising the MPH shift in 3-2 would make it shift harder !! The line pressure is determined by engine TQ--- the more TQ the more trans line pressure---So at 40 MPH vs 55 MPH ---- 55 MPH would be at a higher RPM so the eng is making more TQ
He can LOWER the line pressure "by gear"
I suspect however it may be the TCC locking up--Typically the 3-4 is never a harsh shift
BUT the TCC can be----Most all trans rebuilders now remove the pressure check ball in the TCC lock up fluid--In stock trim this pressure is controlled by the ECM and that check ball--It can produce soft lock-ups--But when removed you lose all control of the pressure for the TCC and its simply full pressure all the time----This can make hard creepy lock ups especially at sloweer speeds--anything under 50-55 MPH---
Raising the MPH shift in 3-2 would make it shift harder !! The line pressure is determined by engine TQ--- the more TQ the more trans line pressure---So at 40 MPH vs 55 MPH ---- 55 MPH would be at a higher RPM so the eng is making more TQ
He can LOWER the line pressure "by gear"
I suspect however it may be the TCC locking up--Typically the 3-4 is never a harsh shift
BUT the TCC can be----Most all trans rebuilders now remove the pressure check ball in the TCC lock up fluid--In stock trim this pressure is controlled by the ECM and that check ball--It can produce soft lock-ups--But when removed you lose all control of the pressure for the TCC and its simply full pressure all the time----This can make hard creepy lock ups especially at sloweer speeds--anything under 50-55 MPH---
