Guys,

When I converted to ARAP code from $32 I noticed that the torque converter locks up earlier. It used to be 39 mph and is now 35. I have a 2.77 rear end and the engine revs drop to about 750 rpm and the engine struggles. After increasing the speed to 37 it is not too bad. Is ARAP designed for a higher gear?
Just interested to know what speeds you guys are using. I think the car accelerates better with the TC locking as soon as possible is this correct or is it the other way around.
Finally my TC broke a couple of weeks ago do you think it is something I have done?
Thanks

Simon

88 5.7 tpi

 

Is ARAP designed for a higher gear?

3.07 gear

3.07/2.77*35=38.8

So 39 is probably about right.

I think the car accelerates better with the TC locking as soon as possible is this correct or is it the other way around.

At low throttle with minimal slip locked up is better. At high throttle the TC will provide some gain.

HTH

John

 

The locking speed of the TC is another one of those "personal" preferences. Locking early does help reduce gas mileage.

The biggest problem with the stock TC in these cars is they can't handle too many WOT passes when locked. You really do need a better quality TC to do that. If you are doing a lot of WOT with a locked TC, make sure you replace your tranny fluid on a regular basis.

To further compound the problem, if the TC is not locked, tranny fluid doesn't flow through the cooler (which is kind of opposite of what you would really want - you want fluid flowing through the cooler when the TC isn't locked). It's a GM design issue.

 

Thanks both of you for replying. I think I'll change my lock up speeds to those I had when I used a $32 bin.

I'm amazed about your comment Glenn. I thought things got hotter in the tranny proportional to TC slip and so the cooler should work when the TC is unlocked.
I know guys whose TC doesnt lock and they fit extra coolers because of this. Presumably these are connected in series with the standard cooler and are thus not much use.

Simon

 

Yeah, so was I. Bruce and a few of his friends told me about this problem with 700R4s. Maybe Bruce will see this post and explain it a little more. There is a "modification" you can make to the tranny so some fluid can flow to the cooler when the TC is not locked. But if it isn't done right you will cause even more problems - as you won't have sufficient line pressure.

I've come to the conclusion that the best thing to do is to get a GOOD TC like a PI Vigilante that can handle locking and WOT passes.