Considering my signature at the bottom, do I need a lock up switch , am I hurting anything w/ the way I have things right now. The tranny is stock.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

 

Yes to both. With tall gears in OD your cruise RPM is probably right around or even below the stall speed of your unlocked converter. The slippage will produce a lot of heat which will damage the transmission.

 

Putting one in would definatly help fuel economy but it shouldnt damage anything by not locking up

 

Check out the topic called "vacuum questions on carb & trannie", it's on the carb board (got locked though, you'll see why). Towards the bottom, The ODB gives a very good explanation of why you need your lockup functioning.


------------------
DR Stevens
1984 Trans Am 305HO L69
sucks gas, hauls ***
1991 Firebird 305 LO3
for days when I need a/c

 

You mentioned slippage, which can lead to the tranny heating up, my car has been running really hot in traffic w/ a 160 thermostat. I just put in a 2 row aluminum radiator, it has seemed to help a lot but the other day it was 90* here and after a while it did start to heat up. Could this be a factor.

------------------
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

 

The main concern seems to be that you need a TC while in OD, is this right? Ever since I got my car when it was a 305 the OD has never worked. Does this mean I don't need a TC lock up switch?

------------------
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

 

You've got a 700R4, right? Allegedly, OD is "4th gear". Without OD, you're only running three gears if this is the case. If the car isn't shifting into OD, you're probably running about 3,000rpms when you're going 55mph. Yeah, she'll run a little hot!

I read a post awhile back on another TCC topic and it was stated that the lockup is supposed to engage towards the end of third gear as well as most of OD/4th. This is where my tranny knowledge gets a little foggy, but I know that OD doesn't engage the same way as 1,2,& 3.

(Someone care to jog my memory or add anything?)


------------------
DR Stevens
1984 Trans Am 305HO L69
sucks gas, hauls ***
1991 Firebird 305 LO3
for days when I need a/c

 

Actually the rpm subject. I was always told that the TC locked up at 70, so if you have 2:73 gears for instance which I have, then going 70 in 3rd gear I would be at 2730 rpm's. At least this is what I was told and it seems about right. How much do TC sell for and does anyone recommend one, but I don't have a lot of money to work with.

------------------
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER
EDELBROCK 600CFM CARB.
KN AIRFILTER
UNDERDRIVE PULLEY
ACCEL HEI DISTRIBUTOR
2:73 GEARS

 

Torque converter lockup in all mid-to-later 3rd gen 700r4s occurs only in 4th and is controlled by the computer. It's not really MPH dependant, more or less it's throttle angle dependant.

Some trucks/blazers that have 700r4s lock up in 3rd&4th.

 

Actually, the torque converter is locked up by the ECM in third and fourth gears. Under "normal" acceleration, the sequence of events is:

1-2 shift
2-3 shift
Lockup
3-4 shift

I have confirmed this; I have a torque converter lockup LED.

At WOT (wide open throttle), the torque converter will not lock up and most transmissions are set up not to go into overdrive at WOT.

Installing a manual lockup switch will not damage anything as long as you don't lock up at WOT. Premature failure will result. There is only one aftermarket converter that is designed to be locked up at WOT. It is the multi-disc (3 or 5) 9.5" Vigilante.



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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Paxton (6-psig): 12.57 @ 111 mph.
Paxton (6-psig) & 50-hp nitrous: 12.04 @ 114 mph.
ATI D1SC (10-psig): ?

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.