Torque Converter confusion
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
Torque Converter confusion
We've replaced the L48 engine in our 1980 coupe with a MAS Performance 383 at about 500 HP. I took the Turbo 350 to a friend who has built numerous racing trannies and had it beefed up. When we began to put the refurbished tranny back in, the torque converter had the wrong splines on it. My friend at the shop said that his employee had accidentally put the wrong converter with the trans when I went to pick it up; no problem. Put it all back together and it works fine.....except..... after starting to drive it around the neighborhood on short test-runs I've noticed that it's running horribly high rpm's. At 2000 rpm's it's only turning 45+ MPH. At 60-65 MPH it's turning 3500 or better. (Sorry for the lengthy description.) So, if we again got an improper torque converter, could that cause this type of problem. We kept the lock-up speed stock to make it a bit more user-friendly in daily driving. The car seems to have the original 3.07 differential gears. Could a "faulty converter" cause such a problem? I'm confused.
As always, thanks for any help.
As always, thanks for any help.
Race Director
Joined: Jul 2004
Posts: 12,696
Likes: 329
From: Scottsdale Arizona
It could certainly be a high stall converter (3500 or so) or it could be a damaged converter though it would feel like it's slipping all the time. Be aware that the same converter will have a higher effective stall with a higher HP motor. Could also be that your transmission is slipping. How is the acceleration?
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
Ca-Legal,
Thanx for the quick response. The thing is lightning fast and shifts just like we hoped it would. It's super positive but is just running way high rpm's. It doesn't want to down-shift but I think that's my linkage not being exactly right at this point.
Thanx for the quick response. The thing is lightning fast and shifts just like we hoped it would. It's super positive but is just running way high rpm's. It doesn't want to down-shift but I think that's my linkage not being exactly right at this point.
Race Director
Joined: Jul 2004
Posts: 12,696
Likes: 329
From: Scottsdale Arizona
What do you mean by "doesn't want to downshift?" In auto or manually?
If it accelerates well I'm guessing that your converter isn't damaged and your transmission isn't slipping badly. The simple but unpleasant solution may be to buy a decent torque converter in a more reasonable stall range and change it. I personally like around 2000 to 2200. Still fun but nice street manners.
If it accelerates well I'm guessing that your converter isn't damaged and your transmission isn't slipping badly. The simple but unpleasant solution may be to buy a decent torque converter in a more reasonable stall range and change it. I personally like around 2000 to 2200. Still fun but nice street manners.
