I recently had my converter sent off to Circle D and had them make some changes to my converter to help out the slow terrible launch and I had it back and fixed in a week! VERY impressed with their service and how the new converter performs, but I am having shifting issues at WOT. I have had my tuner adjusting shift points down with the little bit bigger stall and for some reason none of the changes are helping. Tuner thinks that it could possibly be blowing thru the converter. Car is a ls1/4l80e 78/75 turbonetics with Tu1 turbo cam, 9" rear with 3.25 gear and 26' mickey T's. Car ran a 10.54 at 128 off the 2 step and foot brake and cut a 1.37 60' foot and was hitting limiter on the 1-2 shift and 2-3 shift. Got the 1-2 shift point fixed but cant seem to pin-point the 2-3 shift issues. Looking for any insight or help here!

 

Since you got the 1-2 shift fixed, what was the RPM drop? You won't see as much as the 2-3, but will give us a good idea of what's happening with the converter.

-Brian

 

It was at 6200 then dropped to 5400 (800rpm drop) then within 2 tenths of a second was back at 6200 again bouncing off the limiter.

When just driving normal, the rpm sat at 2000-2500 and couldn't feel a single shift till it got to 50 mph where it commanded torque converter lockup then it dropped to like 1500 where it normally is for that speed.

 

bump.

 

Brian any thoughts?

 

800 rpm drop on the 1-2 would be more like 1000 rpm on the 2-3. I think the converter is holding efficiently. I would keep working on the tune. Everything sounds spot on so far. Good 60' too on the footbrake. Possibly transmission related? How is the fluid level and smell?

-Brian

 

That's another thing we were leaning towards was transmission related issue now. Fluid level looks good when warmed up and smells fine. Still red and no burnt smell. Transmission guy is a family friend, so will be looking to see if we cant get things squared away with the tune if I can have him open it up and take a look at it. Thanks for all your help Brian!

 

Hm. It seems suspect that the 1-2 shift was fixed in the tune. I don't think I would go into the trans just yet, but I'm not an expert tuner either. Maybe someone else can offer their .02.

-Brian

 

Any buddy else chime in on this?

 

bringing back to attention. any ideas?

 

Some questions that may help others narrow it down for you. At what boost are you launching and what rpm does the conveter flash to? Next how much boost at 2nd gear shift point and at what rpm and mph is the commanded shift? What is the commanded shift rpm and mph 3rd? When it does shift to 3rd what rpm does it drop to, I'm guessing it drops to a little above where it flashes on the line and holds it a little while mph catches up. With the new converter being looser and probably not as efficient at about 6000 rpm where I'm guessing your shift point is by the 6200 rev limiter. This will give a lower mph vs rpm compared to the last tighter converter causing you to hit the limiter while waiting on commanded mph to be bet. With an 800 rpm drop on the on the initial 1-2 shift leads me to think the conveter is coupled up pretty good in first gear and 2nd gear just isnt holding the power.