DROBECO

ok well i'm pretty sure my car is shifting into 4th without the speedo plugged in but now that you mention it i cant be 100% what rpm should i be at say at 50mph when i'd be in 4th? and i dont know how to strip the magnetic gear off to put the mesh gear on. my TC is also making a ticking noise im not sure what the deal is with that but every problem im having seems to just be going back to the TC.

also what is a IAC? and when i say i feather the throttle i mean i press the break harder and keep my rpm's at like 900. and sometimes the RPM's get squirly when im at idle doing that going up and down it actually did a break stand like that about a week ago and i threw it in N real quick but still got pulled over for because a cop was two cars over i explained what my car was doing and luckily he understood and let me go just said to get it fixed of course haha

sharkbait

I don't know about the early 700R4s, but 1985+ the electric plug only triggers the torque converter lock up. The ECM and speedo don't control gear selection, just converter lock up. Converter lock up means your transmission is function like a manual in the sense that there is no slippage occuring between the motor and trans.

If your tires are stopped with the car in gear, and motor is still running, your converter is not locked. Period.

The IAC, Idle Air Control, is a small valve/motor that controls the air mixture at idle. If it is broken, misadjusted or just gunked up it can cause serious problems at idle. By increasing RPMs via throttle position, you are allowing air to get in past the throttle blades and the IAC becomes less relevant.

50 mph in 4th gear with 3.27 rearend and stock tires = approximately 1500 rpm, 3rd gear at same speed = 2143rpm.

sharkbait

Not sure how your car is configured, but I believe disconnecting your speedo means you have also disconnected your VSS (vehicle speed sensor) which will cause problems with the IAC and could certainly create some of the problems you described. Are you getting any trouble codes?

recordrascal

I haven't the experience to say if you are right or wrong about the converter not locking without the speed sensor plugged in. I can only tell you of my experience with the mystery trans. I have been driving for 7 months including several extended highway trips with the speedo sensor unplugged. I said before all shifts and lock up work but failed to point out that some shifts are at higher speed than normal. 1-2 is an almost uncomfortable 25 mph, 2-3 is at 32 and lock up doesn't come until 60. This causes me some distress on icy roads and costs extra gas around town. As I said before this trans is a complete mystery, I have no idea what it is out of or what has been done to it (possibly a shift kit), But I can tell you without a doubt that my converter locks every time with the speed sensor unplugged but not until 60 mph.

DROBECO

that sounds like the tvc or the "kickdown" cable is not set did you set that when you replaced the tranny?

ok now that does make some sense finally about the speed sensor not being hooked up and messing with the IAC because the car did run great i mean good as new esp being it only has 150k on it. my friends dad also said something about the speed sensor causing those problems being he's a back yard mechanic he probably didnt know the exact reason just knew it would casue those symptoms. so how can i go about repairing this speed sensor problem? and do you think this would cause damage to the TC over time?

sharkbait

Shifting from 3-4 and the converter locking are two different events. The converter lock up is much more subtle than a gear shift. You can get the car into 4th gear without any input from the ECM, but converter lock up needs input from the ECM to engage, or an aftermarket kit that performs a similiar function. The ECM looks for input from a speed sensor before providing a signal to lock the converter. Overdrive is simply a 4th gear within the transmission. Lock up is taking the slippage out of a torque converter. Slippage is what allows you to be stopped with the car in gear and the engine running. The ECM needs to know how fast the car is going so locking up the converter doesn't cause it to stall or stumble. Some people even reprogram their computers to raise the mph where the converter will lock up.

DROBECO

"The ECM needs to know how fast the car is going so locking up the converter doesn't cause it to stall or stumble."

so this would be my issue here? since my speed sensor is unplugged.

recordrascal

I don't know the specs on the trans, I can only tell you of my experience. I own nine Roadmasters, this last one I purchased because it was cheap and because I needed a winter car. All my 92s run 60 mph at 16 hundred rpm with the converter locked. this one does the same. It's easier to keep track of with the factory tach, I can see where it would be harder to track in the later ones. The 94s on up deleted the tach

recordrascal

I was under the impression that a 700r4 was a three speed trans with lockup converter, is that an error on my part?

DROBECO

yeah but you said it was shifting at 25mph from 1-2 is it shift hard? sounds like the kickdown cable, the cable that coneects from tranny to the back of the throttle body bracket there's a little D button you press in and then open the throttle all the way the kickdown cable will ratchet itself out and set at where it's suppose to be. did you do that when you put the tranny in?

sharkbait

No. If it is unplugged, the ECM will not send a signal to lock the converter. However, that will cause problems with the IAC.

This might help.... Make sure to read the full pdf file.

http://jaguarsthatrun.com/Pages/Spee...er.html#anchor

http://jaguarsthatrun.com/V8-chapter...ed-Sensors.pdf

sharkbait

Yes. There is a GM three speed with a lock up converter, I think it is some version of the TH350. The 700R4 is 4 forward gears plus a locking converter.

recordrascal

Damn! Perhaps none of my nine cars work right!

sharkbait

Some very informative reading on the 700R4:
http://www.transmissioncenter.net/700r4.htm

DROBECO

ok i have a better understanding now. so im still stuck i'm not sure what to do here since the speed sensor on the replacement tranny is different from my stock speed sensor, when i plug it in the speedo jumps to 110 as soon as i start the car.

recordrascal

That's exactly where I was at. I checked out the speedometer site that was sent to me but if they had something to remedy the situation I didn't recognize it.

DROBECO

damn.. i guess i could do 2 things rebuild the stock tranny and put it back or rip out the ecm and carb it... but even still im not sure how the tranny would work without those sensors

DROBECO

so what did you end up doing or are you still dealing with it like me?

sharkbait

Do you have pictures of both? The TBI and pre 1990 TPI units use 2 pulse sensors and the later TPI units used 4 pulse. Not sure how your car is configured, but I pulled an electronic sender out of my tailshaft and swapped out the mechanical one from my original trans no problem. I have an aftermarket VSS that attaches between the housing and the cable. First one listed on below link: http://jaguarsthatrun.com/Pages/Spee...er.html#anchor

DROBECO

no but i can describe, the stock one was a red mesh gear a gear on the sensor that goes into the tail shaft and a gear on the actual tail shaft the replacement tranny had the magnetic metal gear. the tranny came from an s10 350 swapped i had to put my stock tailshaft on for the track arm bracket and swapped the magnetic sensor over with it so atleast the sensors would match up. my car is a 91 TBI 305

DROBECO

and im still not sure if that will help me because im under the impression that my ECM is set up to read the stock tailshaft speed sensor and by me putting a new tranny with a different speed sensor gear on the tailshaft my ECM can't read it.

recordrascal

The people who sold me the car also gave me the old trans, the origional gear from that was green but the magnetic sensor that I removed from the transmission they installed had no gear on it at all, it was some sort of proximity sensor. To answer your question, Yes, I am still dealing with it because even if as some say it would do no damage I would still love to have the improved gas mileage plus my speedometer and cruise control. Also if you follow the links that sharkbait posted there are several systems that would be off line without the sensor. At 27.5 miles per gallon I can only wonder what kind of mileage I would get if my converter was locking.

hellz_wings

iTrader: (2)

The ECM does read the speed sensor, that is how it determines when the torque convertor locks up.

You have to choose the right amount of driven gears in the tailshaft based on your rear-end gear ratio, and match it. There are calculators on the internet that calculate how many teeth you need, someone posted a link for that site transmission center or whatever it's called, that's where I got my stuff and it worked like a charm.

The other thing is that people seem un-sure about is that a 700R4 has 4 gears PLUS a lockup. So it's as if the tranny shifts into 4 gears, and then once the ECM detects you've reached a preset speed (depends on the LV8 as well, so that it doesn't lock up if you're flooring it for example) then it will lockup and you will gain MPG because you will be at a lot lower RPMs than if you were in 4th and NOT locked up.

I know this because I went through hell to figure this out last summer. I rebuilt the tranny but didn't have the right driven gear to match my 3.73 rear-end ratio so I left it unplugged. Then as I was driving at almost 4000RPMS on the highway, going like 95MPH and i knew it wasn't right, even though I have 3.73's which makes the engine spin higher. So I did some research and found that the tranny should rev ALOT less in overdrive and that the ECM uses the VSS to decide when the TQ converter locks up.

So, I also read that driving for a long period of time with the TQ converter not locking up in 4th, will build up heat and potentially damage or wear out your tranny faster. Thankfully I had a freshly professionally built one and it didn't show any sign of wear or damage.

The gears are cheap, and so is the speedo cable if you are missing it. I suggest you buy the right gears and housing and whatever you're missing and fix it up, car drives soooo much better with it!

DROBECO

yeah i'm going to have to do some figuring because i have 4:11's now my next question is how to i take that gear off the tail shaft and i still feel there is a missing link because i have the stock tranny still in my garage with stock gear on it. so i guess my base question is if i swap the gears off the tailshaft and plug the speed sensor in will this stop my stlling problem?

hellz_wings

iTrader: (2)

I don't know if it will fix the stalling problem, but having this disconnected is a problem and you should fix it either way. So, it might fix the stalling problem, or it might not.

Also, the IAC valve is critical to idle quality. I replaced mine and it runs perfectly now. You can also remove yours and clean it as it may have gunk built up on it preventing it from functioning properly.

I also adjusted the Throttle position sensor (TPS) as well to 0.54 volts (turning the screw on the driver's side of the throttle body).

All these things affect idle and could affect the stalling. When my speedo cable was unplugged i never stalled so I doubt that it is causing your stalling problem.

DROBECO

well thats the best news ive heard all month cause i was also told that the speed sensor has something to do with the IAC and stalling but if you say it didnt stall for you then thats good to hear. now i did notice today that my trans isnt shifting into 4th gear... and my TC is making a ticking noise

hellz_wings

iTrader: (2)

The IAC just keeps some air coming in the engine so the engine does not stall. Do you know what year your 700R4 is from? If it's pre 85 then you will overheat it if driving without speedo cable connected.. If it's 85 and up you can run it without the speedo cable without damage(I just read this on the transmission center site).

If your trans is not shifting in to 4th gear then you may have another problem...

DROBECO

unfortunately i don't know the history of this tranny it came out of a junk yard from an s10 350 swap. now as for the sensor i took a pic im not sure where my IAC is as well as my stock speed sensor i got my gear off my stock 700 tranny tailshaft so tomorrow im going to put my stock speed sensor back on so my system will be able to read it. i took a pic of it too, here what im working with.


and i think this is where my IAC is tell me if im wrong.

DROBECO

i did some research and i think the sensor on the left is the IAC correct? well i unplugged that one and my car immediately idled high at start up. so i dont think it's necessarily bad but yes it may be gunked up. tomorrow im going to take it off and clean it, any good suggestions? also when i unplugged the sensor on the right nothing seem to change im not sure what sensor that is, i plugged it back in after i started the car of course.

hellz_wings

iTrader: (2)

Damn. For some reason I thought you had a TPI engine! What engine is that?

And if that tranny is from an S10, then you're probably going to have issues making it work with a third gen. They say not to mix and match between different car or truck models.

DROBECO

its a 7004r out of a camaro that was used on an s10 350 swap. my camaro is a 305 TBI

recordrascal

]

recordrascal

I am fairly sure that the Throttle Valve Cable is adjusted properly because when the trans is cold it shifts flawlessly, after it warms up the shifts are high. Very puzzled about that.


So many questions were raised that I finally consulted a transmission shop, one of my problems from the start according to their 700r4 expert was flakes from the clutches jamming the throttle valve causing it to act different every time it's driven. This makes it hard to adjust the tv cable properly. The expert says that this happens a lot when a used trans is installed due to bumping and tipping, this stirs up any particles in the fluid, a problem that he said usually cures itself over time as the particles settle out or are trapped in the filter.
If I wanted, he could install a return spring on the tv (they don't put one on in the factory) in fact All my problems could be fixed, including the speedometer/ tail shaft issue for $560. I opted to ignore the issue and drive it as it is because in the spring I plan on changing over to a 5 speed stick shift and $500 in upgrades on a
$200 used trans would be in my view a waste of good cash.

DROBECO

ok so VSS is fixed. car is indeed still stalling, now as for the IAC being the culprit, would it cause the car to idle high as well?

hellz_wings

iTrader: (2)

I don't know about TBI, but I know that on TPI (fuel injected) the idle air control valve can cause a high RPM issue and a low RPM issue as well. My recommendation is to clean it and make sure there is no gunk on it causing it to not function properly, or better yet if you are willing to pay for a new one then that will determine if this is the problem or not..

vangogh4560

7 years no lockup and still kickin BUT very small amount of expressway driving

andre1dre

Okay, let me get this straight. If i swap my TPI system for a carb, then i need a lockup switch?

MSRed91Camaro

iTrader: (2)

saving info

Krisgarrett34

I agree, had my computer rip out and had a carb put on without a lock up kit tranny blew within a few miles now it wont go past 1st gear. Take it from me get the lock up kit 700r4's are designed for lock up take dont install the tcc and you'll be sorry.

John in RI

iTrader: (167)

Bad logic,......

"Post hoc ergo propter hoc,... "

http://en.wikipedia.org/wiki/Post_hoc_ergo_propter_hoc


You are so right - and you are so wrong !! To first state that the dead TC story was a direct report of your experience was exactly what these boards are perfect for......Shared experience ( based on facts) are always the best way to learn expected outcomes.

You are SO wrong to then state your opinion on why the TC failed. Did you see the tranny shop pour milk into the TC ?? Did you see the TC fall 4' off their shelf before it was re-installed ? Did you see the TC internals before it was re-mounted on the input shaft ? Did you see that little washer fall off the workbench and right into the TC ?? I'm sure none of those things happened - but they are all just as likely to have cause the TC to fail as not plugging in a lock-up system.

My experience tells me that a TC lock-up is NOT critical to the 700R4. From what I've learned by listening to the pro's is that when lock-up is removed the 83 is the most prone to overheating, the 84-86 was better, and the V/B 87+ was the best for dealing with the removal of the TC function. I've personally re-built an 83Z, re-used the original 83 700R4 WITHOUT lock-up for many miles without any problems. ( The 83Z/tranny had 218 thousand original miles on it and when it was first re-installed it did not shift into 4th until it's second test ride. ) I then re-installed vacuum operated TCC lock-up on it's replacement Carb motor and the TC worked perfectly again. I've also run several other ThirdGens I've re-built without lock-up; never had the TC fail in any of those cars either.


"Post hoc ergo propter hoc,... "

Good to learn and understand this fallacy as early in life as possible !!

Steve30

So I'm curious what effect 4.10s would have on the equation. Forgive my ignorance, but will it even attempt to lockup at the high rpms encountered with such steep rear end gearing? When I bought my 84 Z, I had to throw in a junkyard 700r4. I never even thought about the need for a lockup kit in the absence of an ECM (again, showing my ignorance). Hell, I wasn't even aware of such an issue until poking around here. I've had no issues. But I surely will eventually. Just wondering if gearing changes anything.

Apeiron

Numerically higher gears mean a higher cruising engine speed on the highway which may be well above the stall speed of the converter.

TreeFiddy

This thread died over a year ago, but I'll agree with John. The lockup only operates at highway speeds, so the only damage you're going to do without it is with a lot of sustained long-distance driving. I ran mine without lockup for years, while only doing around-town driving, and have sustained no ill effects after 10 yrs.

Your tranny damage was likely caused by bad tv cable adjustment.

novaderrik

just gonna add my experience with the lock up torque converter in 700r4 transmissions:

i swapped a 700r4 out of a 92 Caprice into my 74 Monte Carlo and wired up the lockup converter. drive it like that for 2 years and about 10,000 miles without a problem, but i think the 2.73 gears and 28" tall tires in a 4200 pound car caused the car to lug down the road because i actually lost mpg's compared to the stock TH350.

my 86 Camaro has the stock 700r4 out of an 84 Z28 in it. the lockup doesn't work for reasons that i'm too lazy to figure out- it's all properly wired but pops the fuse immediately when it tries to lockup, i think the solenoid is shot. i have put almost 10,000 miles on it since i got the car running in May- including a road trip that took me from west central MN to Corpus Christi, TX via St Louis, MO and Memphis, TN in June. that's just over 3900 miles in 8 days without a single problem, and the little vortec headed carbureted L69 305 averaged 24mpg on the trip with 3.42 gears and without the benefit of the lockup converter.

vetteoz

iTrader: (13)

There is documentation around that says the early (pre'87?) T700 only had full fluid flow to the cooler when in lockup
which might account for the "overheat and cook your trans if TCC not working" stories?

Gsoleski

Anyone else with an 84 run theirs on the freeway with no lock up? I spin 2500rpm at 60mph with 3.73's.

hellz_wings

iTrader: (2)

I was running no lockup.. Was spinning way too quickly and I fixed it. That's just because my speedo gears were busted and it never really went into overdrive. I would drive at like 80mph at almost 4000rpm or so.. Scary.. Now it's fixed and at 60MPH i'm at a healthy 2000RPM.

Apeiron

Speedo gears have nothing at all to do with it going into overdrive.

hellz_wings

iTrader: (2)

That's odd.. I had this problem when my speedo gears were busted and my speedometer did not work at all.. Then when I fixed the speedo gears (installing the correct toothed gears) the speedo worked once again and my car actually went into overdrive.. I feel that 4th gear has like a 2nd overdrive of some kind, like it goes into overdrive, and then when it hits a certain MPH it goes into the highway fuel mode.. But before it goes into highway fuel mode, is that what you guys call TC lockup?

TheMonster

1983 here, I've had mine as a daily driver for 3 years, guy before me had drove the camaro into the ground for a few years himself with no lockup. Yet it's still going strong!

Also, i forgot about this thread, and all the misinformation.