Torque converter lock-up not working for drag racing FIXED!!

  • Thread starter @BurnoutsandRotorblades
  • Start date
@BurnoutsandRotorblades

@BurnoutsandRotorblades

Greasemonkey
Apr 9, 2017
122
43
Las Vegas, Nevada
with that kind of power if your trans was slipping whatsoever you would have toasted it long ago IMO
That is the kind of thought process I was using. Anyone else think it's not the trans, or have any insight why it shouldn't be ruled out. Also, trans fluid is full and bright red, not burnt.
 
pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
25,626
113
Kitchener, Ontario
could it be that under hard acceleration the transmission oil is low at the filter and not being picked up. I sort of remember a friend who worked on GNs that were used at the drag strip and I think he mentioned he adds 1/2 quart to the transmission so there is always oil for the pump.
 
lilbowtie

lilbowtie

Comic Book Super Hero
Jan 7, 2006
2,670
113
Canton Mi
With the fluid being red and not burnt I'd be looking at the converter. As Hoffa65 said with that much slippage you would have burnt clutches. Was the converter always this way when you got it back ?? I can't believe a converter could have that much slip without something broken. I'd be having a conversation with the converter builder. You ask about converter manufactures, there are a lot of good ones out there. It depends on what level you want to take it to. FTI builds a converter specifically to my cars specs and has been great on service. I have used Greg Slack and Abruzzi which I still do.
 
@BurnoutsandRotorblades

@BurnoutsandRotorblades

Greasemonkey
Apr 9, 2017
122
43
Las Vegas, Nevada
The problems

At the track the speed and rpm don't line up. 4th gear at WOT, and I'm passing the traps in the 70's for MPH.

For some reason, the converter doesn't stay locked up on the highway in fourth at WOT. By that I mean RPM climbs without a corresponding increase in speed.

I have a B&M torque converter lockup controller. I thought it might be to blame. While driving I disengaged it and re-engaged it and the converter locked up. Could have been that or the solenoid in the converter but I couldn't get it to repeat that. However, the converter still slipped at hight power settings in high gear.

So here is the fix.

I swapped the converter for an FTI 9.5" model. It is a triple disc lockup with a 3800 stall. Putting in a 700R4 that has the weight of a dying sun with no trans jack while on your back in Las Vegas summer heat is miserable. It has me looking at inexpensive car lifts. There aren't any.

I did a trans-filter kit while I was there and the inside of the pan was spotless clean. The pan magnet had more junk on it than i would have liked to see but nothing concerning.

the new converter can lockup in any gear with the B&M controller and at WOT if it locks up in the powerband it will chirp the tires at speed. Likewise if it locks up low, the engine doesn't have enough power to overcome it and it'll bog hard.

I took it out for some testing the other night. I put the shifter in D (not OD) set the converter lockup to come on at 65 mph. My speedometer only goes up to 85 mph but I blew past that with plenty of rpm to spare. I don't know what that'll mean on the track but the butt dyno considered it a big improvement.

Now to take it to the track and see what it puts down for numbers. If all this works it might be time for a bigger pulley on the blower and some less conservative timing.

But first I have a newly discovered problem. I run out of fuel after too long in boost. A boost referenced regulator is on the way.
 
Last edited:
@BurnoutsandRotorblades

@BurnoutsandRotorblades

Greasemonkey
Apr 9, 2017
122
43
Las Vegas, Nevada
So, a bunch of stuff went in to this fix

1. converter lockup controller had a loose connection

I had the B&M Lock-up controller dangling under the dash. Even though the green light was on the converter was still slipping. If I was in 3rd gear, it wasn't a huge deal but I'll get to that next.

2. I was using 4th gear

I'm retarded about drag racing. I didn't know using overdrive at WOT was a bad idea. Turns out, my trans can't handle it. it slips in 4th at WOT, but other than that, it does just fine. So, this will be a costly mistake later, but for now i'm just ignoring it and only using 3rd at WOT and using the converter lockup like a 4th gear.

3. converter was still slipping

The stock converter was loosened up and stalled around 3300, which worked ok, aside from being generally inefficient. The lockup clutch however, was not designed to take the abuse of nearly 500ft/lb of torque that my little SBC was dishing out. So, it was time for an upgrade. After doing the math and looking at the dyno sheets, I ordered one that with a stall 700 rpm below my peak torque. Honestly, it's about 1000 rpm below my peak torque but I wanted some room for the engine to rev out and I wanted to retain some street manners. So I picked a 3800 stall triple disc converter from FTI. It is working great coupled with not using overdrive and having a good connection with the lockup controller.

watch the video to see the results:

My beater wagon achievers Drag Racing GLORY!! . . .at least in my eyes. . . | #FamilyBurnoutWagon EP16

 

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