Lock-up with 87 ecm, mechanical speedo

[matt921]

I'm curious as to how this will work. I swapped to the 87 ecm and when I drive I throw a vss code. ok I under stand why I have a mechanical speedometer(it don't work cable issues). So my question is how does my lock up work if I have no reference to speed. Is it locked up by knowing what gear its in like 3rd and 4th. Or is there some way the mechanical speedo sends a signal. The reason I ask this is I don't think i'm getting lock up in 3 4. I tap the breaks and I don't feel or see any difference in rpm on my tach.

 

[pacecarta]

lockup is by mph ,
no cable to speedometer = no vss signal , so the ecm doesnt know the vehicle speed =no lockup

 

[matt921]

No I know that. But I know on the 87 the speedo is electronic. So how does it read having a mechanical drivin speedometer. Is there someway in the mech itself that it translates to the ecm?

 

[v6turbo87]

The 87 speedometer is not electronic it is mechanical and driven by a cable as well. There is a photo optic cell that picks up the rotation in the speedo and spends that signal to the VSS. As was said no rotation means no signal to the VSS.

 

[pacecarta]

you seem to know a lot matt
first you say and i qoute.."I under stand why I have a mechanical speedometer(it don't work cable issues)"
now you say ..and i qoute "But I know on the 87 the speedo is electronic"

the speedo in the 87 isn't electronic ,its mechanical driven by a speedometer cable and at the back of the speedometer is a blade like a lawn mower blade only shiny. and at the back of the speedometer cluster there is an optic sensor that shines a light out and recieves the bounced back light off tat b;ade as it spins driven by the speedo cable (two pulses per revolution) . that signal runs to the vss buffer box by the radio and that buffer sends out a signal to the ecm , the ecm uses that to determine speed and when to engage lockup which is usually about 47mph, the speed it locks at can be varied in a custom chip if desired and with the turbo tweakchip will be disabled in the chip to not lock at WOT

 

[matt921]

I'm not saying I know a lot. if I did wouldn't be posting on here asking this. I know the 87 has the electronic pick up. I'm asking does the 84 have one in the gauge cluster as well, because I never got a vss code with the 84 ecm not having a speedo. Maybe I had a problem with it and the 87 ecm is reading it I don't know. Again there's a reason I'm asking these questions to fix the issues I'm having not to have a knowledge battle.

 

[matt921]

So yes I was wrong about the 87 being mechanic and thinking it was electronic. I though this cause the last 87 I worked on had a electronic display on the dash to show speed. this is why I figured this. There is no need to be rude pacecarta as you can see i'm trying to figure this out. I honestly dislike forums because of this because things get said and people get upset

 

[pacecarta]

you asked i answered , then you tell me something else you know and i take the tme to explain the mechanics ofhow it goes from mechanical to an electronic signal for the ecm and im the dick
im too old to be a dick , facts i can do good

 

[matt921]

cool well thanks. have a good weekend.

 

[matt921]

so let me get this straight. we are taking I'm person I tell you my situation. you tell me one thing and I say no I know but then I'm wrong you correct me then I say another comment asking you the difference. then say oh and explain myself why I thought that then I say why I thought that. I'm the dick. wow funny how the internet changes things

 

[novaderrik]

84-87 used the same gauge cluster with the same speed sensor driven by the same cable...

why doesn't the speedo in this car work? broken cable? just not hooked up?

 

[matt921]

Oh I didn't know that. the one I worked on had this gauge in it. http://www.doubleyoudigital.nl/imgsold/digidash_buickgrnat1.jpg


But my speedo doesn't work cause my drive gear in the trans is bad. So I have to pull the tail off the trans and replace the output shaft gear. I think it got broke some how and keeps breaking drive gears. My speedo would jump up and down like it was getting bound but I hooked a drill up to it on the cable and it work fine an steady.

 

[pacecarta]

well here goes if you take this as being a dick you need to adjust your attitude on how you perceive things
...unless your 84 as built off a carb car your trans should be a BQ 4speed 200-4r
3speed transmissions like th350 th400,th200 have removable tails ..you cant fix the 200-4r speedo drive gear by taking off the tail housing because it doesn't have one , the case is 1 piece
if your trans is a 2004r and the drive gear is busted you would know it because that gear drives the governor gear and that controls the shifts and your trans would be really jerky just like the speedometer
the governer gear drives the driven gear behind the bullet
if the driven is bad its a simple 10mm bolt on the outside , remove bolt pull it out and replace
if the governer drive teeth are bad you need to drop the pan and remove the governor cover and replace it , problem is that gear for 3.42 rear is not easy to get your hand on

http://www.google.com/url?sa=t&rct=...cMNmZUQpCx2Y46hi__M1BWw&bvm=bv.83339334,d.cWc

 

[Wahoo]

I think what you aren't understanding is that some cars have a digital dash, which has numbers like an alarm clock, so one would call it an electronic speedo because it is digital numbers. But it is still mechanical is what everyone is trying to tell you. It still has a cable connected to it.

 

[novaderrik]

well here goes if you take this as being a dick you need to adjust your attitude on how you perceive things
...unless your 84 as built off a carb car your trans should be a BQ 4speed 200-4r
3speed transmissions like th350 th400,th200 have removable tails ..you cant fix the 200-4r speedo drive gear by taking off the tail housing because it doesn't have one , the case is 1 piece
if your trans is a 2004r and the drive gear is busted you would know it because that gear drives the governor gear and that controls the shifts and your trans would be really jerky just like the speedometer
the governer gear drives the driven gear behind the bullet
if the driven is bad its a simple 10mm bolt on the outside , remove bolt pull it out and replace
if the governer drive teeth are bad you need to drop the pan and remove the governor cover and replace it , problem is that gear for 3.42 rear is not easy to get your hand on

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CEIQtwIwAA&url=http://www.youtube.com/watch?v=oVP53P0LGQg&ei=lhy1VJPeHObksASNq4LQAg&usg=AFQjCNGNMB-cMNmZUQpCx2Y46hi__M1BWw&bvm=bv.83339334,d.cWc

the teeth that drive the speedo gear could be stripped even if the gear that spins the governor shaft is bad... it's not too hard to drop the pan and pull the governor out to have a look at it.. the fluid and filter probably needs to be changed anyways..

 

[matt921]

well here goes if you take this as being a dick you need to adjust your attitude on how you perceive things
...unless your 84 as built off a carb car your trans should be a BQ 4speed 200-4r
3speed transmissions like th350 th400,th200 have removable tails ..you cant fix the 200-4r speedo drive gear by taking off the tail housing because it doesn't have one , the case is 1 piece
if your trans is a 2004r and the drive gear is busted you would know it because that gear drives the governor gear and that controls the shifts and your trans would be really jerky just like the speedometer
the governer gear drives the driven gear behind the bullet
if the driven is bad its a simple 10mm bolt on the outside , remove bolt pull it out and replace
if the governer drive teeth are bad you need to drop the pan and remove the governor cover and replace it , problem is that gear for 3.42 rear is not easy to get your hand on

I did not know that about the 200 I didn't really pay tomuch attention to the tail when I was under. But I think it might be in the dash cause I can kinda hear a little bit of noise behind the dash. I'll pull my speedo gear out and see if its ok tomorrow on the lifr. Shifts fine some times when cold it takes a second to go from reverse to drive.