hey i was reading some threads about changing your car from TBI to carburation and so forth, so i put in a 1406 carb 1201 intake hei distributor, fuel regulator, open element, so i'm going through the list of things you hafta do they say... and it says if you have auto tranny, you must lock up torque converter or something crazy like that... anyone know what the heck any of that means. ?? like are they right? must i do this and how do i do it... i'm pretty lost... i could handle all that other stuff but this is outta my league..


nathan vetter

 

I have a 2500 stall 10" non-lockup converter in my '89 Formula 350. No problems.

You do need to do a couple of mods to the internals of the trans and a minimum 16,000 GVW trans cooler to be able to run one with out frying it on the highway.

The advantage is around 18-20lbs off the crank for quicker revving and more power transfer to the driveshaft, but a little less gas mileage on the highway.

I have been told a lockup converter can help at the strip by locking and carrying through the traps in 3rd gear.

 

I take it you have an 4L60E transmission where the computer used to control Torque Convertor lockup? Aftermarket vendors have a manual Torque Convertor lockup assembly that operates on fluid pressure only. Any competant Tranny shop should be able to install one of these.

700R4's and 4L60's will run very, very hot in 4th gear without the Convertor locked. GM in it's infinite wisdom diverts some of the fluid internally to reduce pumping loss ( and increase fuel milage ).

As formula8!! said...you can modify the trnny's to work with a non-lockup convertor...but the manual Lockup valve might be an easier fix for you.

A big cooler, as mentioned, is a worthwhile investment for ANY Auto Transmission. Two things will make slush boxes live longer. Clean fluid...and cool fluid.

 

According to his sig his car is a 1991. The 4L60E was not used in the f-body until 1994. The fact that the computer controls the lockup does not make it a 4L60E. The "E" refers to computer controlled shifting, not converter locking.

 

i think the computer does control your lock up but you shouldnt have to worry about because your computer is still in tact and operating.

 

I believe the computer looks at TPS setting for lockup. So if you switch to carb you need a kit. Bunch of companies make the kits, TCI, B&M, Painless..... I'm planning on using a toggle switch just so I can throw it going down the highway or interstate. I do most of my driving in the country so I'm off and on the brakes all the time so lockup doesn't really effect me until I get out in the wide open areas.

 

where exactly would the throttle postioning sensor be on a throttle body car?

 

It should be on side of the TB. I'm only use to TPI's there on the passenger side TB. TPS is a throttle position sensor. Just tells the computer how far the blades are open. A converter should disenage while under WOT or braking. WOT would put a strain on convertor and might even burn it out if it went long enough getting abused. Braking it disenages for emergency stops we can all agree that a car should stop faster with converter slipping not locked up the transmission. Of course it doesn't lock up in 1st gear so it doesn't consider braking then.

Link to TPS sensor position on TBI board

 

My apologies. I don't think I was clear enough. Yes the computer does control the converter lockup. I just meant that he doesn't have a 4L60E. He has a 4L60. The 4L60E has a computer that controls the actual shifts as well as the converter lockup. The 4L60 only has computer controlled lockup, and not shifting.

 

so my post about the computer controlling is correct...?? is that what you mean or is there a TPS to deal with....


because nathan2003 has been driving his car and the tranny has been lockin up or he would surely notice that wouldnt he?

 

I'm not sure of all the parameters the ECM uses to decide if/when to lock up the converter. I'm sure the TPS must be involved, as well as the VSS, as that would make sense, but I'm just guessing.

 

If the rest of the wiring infrastructure from your TBI setup is still in place, you should be able to wire a switch into the ALDL connector to force the computer to enable the lockup... Pins A & F I believe... Yeah.. Here's the link: https://www.thirdgen.org/newdesign/t...ueswitch.shtml

I would probably integrate it into the brake switch as well to be safe (so it unlocks if you hit the brakes).

That's what I did before I rewired my lockup setup...

PS: The computer uses TPS and VSS input and a minimum engine temperature to determine whether conditions are proper for lock-up..

 

wow, this stuff is like greek to me... i'm sure glad other people know whats going on and understand it all... strokedtpi ... thinks hes my mechanic and he understands a bit more then me so he can retranslate all this to me... haha... but ya so if i'm going to be pulling my tranny out what do or could i do to it or do i have nothing to worry about... because my overrun clutches (burnt), input sprag (broken), and overrun hub (broken) at least thats what some of you thought in an earlier post i had so if i'm going to be havin this tranny out is there anything i should change or could change since its going to be out....




nathan vetter

 

haha oh vetsky im just sayin i dont really knwo what you need to do for sure becuae if your tranny wasnt lockin up at all i think it would be like slipping pretty major when you just try and take off...

 

hey vetter have you noticed any difference in rpm at different speeds than before you changed over to the carb....
for example when you are goin liek 60 or so the rpm it used to sit at in overdrive when you had tbi....is that any different than now?

 

ok swan... heres my scoop on the shiznak... or at least what my somewhat mechanic side of me is thinkin...

seems like the tranny is makin harder shifts inbetween sometimes but it really does seem like its not shiftin right but i'm not for sure... this is the first time i've had the cam in like 4 weeks... but ya... and like going down the highway now at 60 it seems or well i'm pretty sure that it is running higher rpm or whatever... is that what you were askin ?? right...

and ya for sure i noticed that the car doesn't brake near as good like it freakin won't slow down much that well but once its almost to a stop or so like 10 mph or so then it like stops like it should like its noticeably different... so ya if you can figure that out and understand what i'm sayin...



nathan vetter

 

what exactly did you do to rewire your lockup---i think the idea with the ALDL connector would be a little hard on his tranny because he does a lot of in town and highway driving simultaneously.....maybe this is wrong but from the link thats what i understood.

 

He could just switch it when he goes on the highway. I think theres another post somewhere on the forum about how you can rewire the transmission so it will automatically lockup when it hits 4 th gear. try doing a search

 

right but wouldnt drivability and gas mileage still be lost if one were to drive around town and it wasnt lockin up...

 

if i just dropped the tranny could i do something then instead of having to wire in switches and all that bull crap. i want to put in a **** kit... corvette servo.. . over run hub clutches... that sound reasonable or does it sound kinda like i'm an idiot.....

also the car brakes are really hard, like won't stop, car shifts hard on some gears like just dont' seem right and it does run higher RPM.....



nathan vetter

 

Sounds like you messed up your throttle valve cable system when you did the swap to carb... Make sure your cable maintains the same geometry as the original tbi setup and that it is adjusted correctly.

As far as not having to hook up switches, there's not much you can do to make it lock up without some wiring. The only way I could think of would be putting some of the '82-'86 mechanical lockup valving in the valve body (where there is an aluminum plug in anything past I think about '86).. It's been a while since I have dealt with the early model 700r4's so I don't remember all of the details.. I would just devise a wiring/switch solution that best fits your needs (lockup in 4th only, lockup in 3rd or 4th, etc)...

 

could anyone explain to me on how i can go about this wiring crap i need to do... i know you said depending on my setup how i need to wire it but,, how do i determine my setup, like honestly i know jack crap when it comes to transmissions and so forth, i can't even act like i know something because i don't, so if you could kinda step by step me on this or if anyone could i would appreciate your help and time..




nathan vetter