Alright, i just finished my 4th gen dash swap, and i'm running an earlier model car (w/ the cable speedo) my prob is, the cable speedo uses the "optical sensor" on the speedo cable to send a signal to the computer, allowing the car to know how fast it's traveling. Because of the new dash not having provisions for this, my car won't lockup the Torque Convertor. Essentially, i need some help in findng how to wire up the optical sensor so that it'll tell the computer how fast the car's moving, but more importantly, what damage will be done to the transmission if the torque convertor doesn't lock up? I've heard that the tranny's run hotter in this situation, but how much hotter? How damaging is it to the transmission etc? If anyone has any answers to question number one, thanks in advance....but the later ones i'm really needing.

 

i know someone out there has an idea as to what happens when a TC won't lock up....ttt

 

If you have swapped to a dash that uses an electric speedo then you should use a VSS sensor on the transmission. If you do a search you will find all the info needed for what has to be done to use a 4'th gen dash electronics. If I remember correctly the 4'th gen dash uses a different pulses then the 3'rd gen VSS so you need to get a conversion box.

 

sorry, my questin might have been mis-inturpreted...i know what needs to be done on a dash swap, done research , ontop of research, and have pages and pages of notes, (i should do the same thing everyone else says about it, and write up a tech article...but like most others, i'm too lazy) There's a thought to fixing the speedo issues w/o using a later model VSS setup and gear swap too, hopefully it'llwork, it involves the optical sensor which is a 2000 ppm signal, and then a conversion box to change it to a 4000 ppm signal for the dash, should work....hopefully, either way i'll need the box. I'm simply wondering what happens when the TC doesn't lock? Does the fluid actually get hotter? Does it cause pre-mature transmission failure? what about cars w/o locking TC's , older automatic transmissions like dynaglides (didn't think they had a locking torque convertor) or what about convertors w/o an electronic control, will they work fine w/o locking? As far as my researach goes, some say it'll harm them, some say it won't...but both sides agree that the reason for the locking torque convertor is to save gas millage, and if thats the biggest trouble,then i won't be afraid to drive my car, just penny up at the tank.

 

One of the ways in which locking torque converters save fuel is by allowing the use of numerically low gear ratios. When the torque converter doesn't lock, the constant slippage in the torque converter results in more heat. If you're cruising above the stall speed, say with 3.73 gears, the slippage is minimal so it's not all that bad. If the car had say 2.56 gears though for better mileage, it could easily be cruising below it's stall speed, which means slippage in the converter will be much greater and the heat will be much higher.

 

Get a VSS for 86-92 firebird. The speedo gears on that still need to be setup to match your tire size & gear ratio. Wire that up to the buffer box that has input from VSS, 2002 output to ECM, and 4004 output to instrument cluster. See

https://www.thirdgen.org/techbb2/sho...hreadid=247892

for info on buffer box. Someone around here has an article on doing the 86-92 `bird gauges swap into an 82-85. That'll tell you how to wire up the buffer box.

The 4th gen speedo uses the same exact signal as the 86-92 bird speedo.

700-R4's are not happy and burn up if you don't have TCC function, or if the trans. isn't modified for non-lockup.

Getting a box to convert 2002 to 4004 is IMO, a waste of time when you can use all factory parts and be done with this project and get lockup

summary: wire your car like a later third gen bird with regards to vss, wiring, buffer, and use your 4th gen speedo. done. Don't run your 700 without lockup.

the end
-Matthew

 

I forgot to mention too that running without lockup in pretty much any O/D transmission is a bad idea.

 

to everyone, thanks a mililon on the help....

basic idea, don't run w/o the TCC being functional, now, for slow...around town cruising (say a coupel blocks, i'd assume it'd be ok, as the TCC wouldn't lock anyway, so, i'll keep it off the highway, and away from long drives)

Also, i'll be hitting up the bone yards in search of a VSS and buffer box, guess i'll have to work on re-wiring, hate that, but sacrifices must be made.

jmd, you seem to know a lot on the subject, so there's a good chance i might call on your wisdom again...

Thanks again to everyone, i'll return if i encounter more probs.

 

hey everyone, know this might sound like a ghetto rigged fix, but it's just a Q for a temporary job (i'm not the type who enjoys having things "half assed" anyway. If for the sake of highway driving, i wired a switch into my ALDL connector to lock up the torque convertor, would this allow me to have it funcitoning, (as long as i remember to turn the thing off as i go back to street driving?) it might work as a temp fix until i can scavenge all the parts i'll need to finish the job. Are there downsides to this? i need good honest answers, however...not really a "just do it right" cause...that's how it'll be done...right.

 

That'll work fine. I wouldn't worry too much about forgetting to unlock it when you're driving in town. If it's still locked up in second you'll know it right away.

 

Yes, lock it up @ "cruise & 4th gear" speeds and you'll be cool. Obviously more of a hassle while driving than just throwing in the aftermarket one that locks up at a given speed, but lockup is lockup.

 

interesting... so if one were to put a switch on these ALDL pins, and lock the torque converter manually... can you do some real damage here?

What happens if you are in first, and you lock the torque converter? Will the tranny try to shift into 2nd and cause internal pains in the tranny, or will it know its locked and not even try, (like having the shifter in "1st gear"?

Does the same apply to overdrive? If I connected these two pins via a switch, while driving on the highway, would this prevent downshifts going up hills etc??

Does anyone know how to tell if your torque converter is actually locked up or not? I would presume as soon as you reach 2nd gear it would lock up if you are accelerating slowly enough... but I don't know...

 

The signal pressure to apply the TCC comes from the second gear clutch circuit, so the transmission can't lock the TCC in first. The operation of the TCC is completely independent from the hydraulic shifting systems. The transmission will happily shift up and down all day with the TCC locked.

 

the engine would not stall when the gear shifts down into 3rd?

or from 2nd into 3rd?

 

No, why would it?

 

I guess I thought it would in a standard when you upshift too early and the engine bogs and starts to choke...

having the tcc enabled is like not using the clutch on a standard, right?

 

Question: If your torque converter is not locking, can you just drive it in third? Just to prevent damage until the lock up is repaired? You're still at 1:1, rpms will be a little higher but shouldn't be too much, especially if you have a low rearend. The overrun clutch may cause some annoyance but is there something else I'm missing? Just a thought.

 

It still would if it was shifting early, but having the TCC locked makes no change to the way it shifts.

 

You can still drive it in 4th if you want, just avoid cruising in 4th for long periods of time.

 

so if you leave the tcc locked all the time, would that simply hinder your acceleration or what exactly would happen?

 

The TCC will lock as soon as the car shifts into 2nd, which will cause it to bog and feel sluggish. The more cam and stall you have the worse it is.

 

could there ever be forseeable benefit to manually locking the tcc? Or is the computer pre-programmed to have the highest fuel economy?

 

I'd be inclined to leave it alone. Some people say that manually locking the TCC gives them better acceleration at the top end, but the clutch itself is a tiny little thing not designed to be used during cruising, not to handle the full torque of the engine under WOT.

 

hrm good idea...

 

wow, talk about a post from the past, didn't even know that anyone had been looking at it. Well, runnig locked up all the time would probably cause some problems, you're acceleration will be horrible with the converter engaged, you might be able to floor it to get good response, however, i've never done this, won't do this, etc, as i need my car to live as long as possible, adn this just seems like a bad idea since it's not what itwas designed to do.

Also, i hooked up the lockupswitch about two-three months ago now (just before i went back to college) and, fuel economy went through the roof. I drive a little v6, was thinking that i was getting average fuel consumption 22-24 mpg , sometimes as low as 19, but always in that range. i made the change, got the switch locking at highway speeds, and boom. Low to mid 30's on the mpg every trip. Have my roommate pissed at me, cause his saturn barely does that, and his ford fairlane (66 351 car) well, you can guess what that toy does. right now, he hates the aerodynamics of the thirdgen.

 

uh did you just say that on your thirdgen v6 you got 30mph because you made a switch that connected the upper left and upper right pins on the ALDL?

I get (normally) 19 highway and 16 city..... I have gotten 21 before on the way to the coast, keeping my engine at almost exactly 2,000 rpm the entire way, but that was literally the most conservative way I could have possibly driven, hands down, and I only got 21...

maybe my tcc doesn't ever lock up?