Which will give better et raiseing force lockup or lowering it.

 

Some people are bothered by the lock/unlock behavior that can happen in certain driving situations so they have the TCC lockup point raised.

I happen to like the stock lockup behavior so haven't touched that operation. If I find it transitioning too much in certain situations I simply do a manual down shift into a lower gear.

 

Mine doesn't lock up at WOT. At least not at speeds below 100 mph. I HAVE heard of people wiring a manual switch on the TCC to force the lock up for drag racing. I don't recall a consensus on the results.

RACE ON!!!

 

Can someone explain to me what exactly this means and how do I tell when mine locks up. Thanks

 

ALDL pin "F" (on my OBD-I setup) is the TCC lockup monitor pin. If you ground that pin to pin "A" you force the TCC to lockup in any gear above 1st.

In theory locking the TC eliminates TC slippage; with the TC output shaft at the same RPM as the input shaft the A4 will be shifting at lower engine RPM. I was told by a tranny expert (Patt Barrett at Level-10) that having the TC locked after launch would give best 1/4 mile performance, though it could be tough on the stock TC during upshifts.

I have a TCC lockup switch and monitor LED on the IROC and didn't see any real change in trap speeds, but haven't tried it with the Vette yet.

 

Did it lock in either car at WOT, before the switch?

RACE ON!!!

 

My understanding is that the TCC should never be locked at WOT as the clutch linings are only capable of transmitting a limited amount of torque. Every GM chip I have looked at unlocks it at WOT for this reason, or so I have been lead to believe......

 

OK in the constant table in the 1f file for the 85 there is a force lockup parameter mine is set at 109mph and under wot that is where it locks
at, reason for ? I saw somewhere on this forum where a Vette was dynoed with the converter locked and unlocked and it showed that with it locked it had about a 20 HP gain.

 

It will improve your ET. My 14sec. camaro was consistantly 2 10ths faster with the lockup activated. However, the wear on the converter and the transmission, seems to be much greater. Good little mod for the track though.

 

Neither car had TCC lockup at WOT on the highwar or on the strip, but I've not had either much over 100mph at WOT.

I never had the IROC on a dyno but the Vette has been on there twice.

The 1st time on the dyno was with the stock A4 and TC and no note was made of TCC lockup through the 145mph pull.

The 2nd time on the dyno was after the A4 had been rebuild with a shift kit and a 2,000rpm TC. After a copla attempts to run the pull the dyno operator asked me to sit in the car to check if there were a problem with the shifter. It turned out that in 3rd gear the TCC locked up on a WOT pull with such force at about 120 mph that he thought it was shifting into OD though the shifter was in the D position.

I didn't figure out what had happened until after the car was off the dyno so didn't catch how much the RPM dropped. The TCC lockup was indeed very abrupt and felt just like an upshift with the new shift kit. The tranny builder said he had installing a modified GN TC so maybe it has a sturdier TCC than in the stock Vette TC since there was no notice of TCC lockup with the old TC. BTW, in both cases the stock CalPac was in the ECM.

Now that we are discussing this topic I'm remembering how hard that TCC lockup felt on the dyno and think it may be worth the effort to install a lockup switch this winter for testing when the strip opens next spring.

 

65Z01,
Thanks for the details. U can easily see why the dyno would look better, locked up. The slippage wastes hp and turns it into heat. The track MAY be a different story, depending on the specific rpms attained and the power available at those rpms. It looks like it is worthy of checking out.

RACE ON!!!

 

The governor is driven by the A4 output shaft so locking the TCC would lower the engine RPM at which WOT shifting occurs. Assuming about 4% slippage, if I lock my TCC in 2nd the 2-3 shift point would drop from 5,700rpm to 5,400rpm.

According to Drag2000 drag strip simulator, reducing TC slippage from 4% to 1% and lowering my 2-3 shift point RPM as stated would lower my ET by a little better than .1sec and raise trap speed by 2mph.

If this works per theory, it could have some use in bracket racing, sort of like a mini-shot of NOS. OK, so now designing a temp TCC lockup switch with LED is my new winter project.

 

Mine shifts when I move the lever. Usually about 6000 rpm. The TCC lock up won't affect MY shift points, unless I decide to shift sooner. Worth playing with.

RACE ON!!!

 

It won't effect your shift points, since you shift by the tach. But it should bring a higher MPH in each gear (except 1st) which should bring better 1/4 mile results.

So, yes, it does look like it's worth some experimentation.