I think it would be best to keep this in this thread as it has more information n it. The other one I just sent a quick reply to.

But,since were on this topic again-

Let me explain. I got the car from someone in Michigan for very little. The tach works speedometer not. I had someone look at it and he took the vss out of the transmission. He showed it to me, and I saw the pin broken that goes to the connector. Since it has a little leak, I had him come back and he put some putty stuff around it. I think he bent it up taking it out and possibly he lost the gear. Thats how the connector wound up on the exhaust pipe. I took my chances he said he had 25 yeas experience with GM cars.

The connector may or not be too bad to reuse. When I saw iy and pulled it off the exhaust it looked slightly distorted but maybe could be trimmed with a knife and fit.

So, at this point I dont want to dig it out until I have SOMETHING to put back in that wont leak or require some kind of putty around it again.

The gear ratio I havent done yet until I figure out how to gt the back up in the air. All I have is a floor jack and Im not sure if its low enough or where to put it on this car (overly cautious).

I thought in 84 all Automatics came with t he same rear ratio.

For now Im driving it the way it is.

If the converter isnt locking isnt there a switch that can be put on it o control that?

Also, I understand square ave sine wave etc but this 2 pulse 4 pulse thing I never heard of. Wouldnt a square wave be the same as any other?

 

It appears 2 different gears?

http://www.corvetteforum.net/c4/vett...Gearshtm.shtml

 

Once I get the rear ratio verified I will post it here. With all the other things to do it might be next week sometime. Had an o2 sensor changed and I put fresh antifreeze in today. Going down to the 20s tonight in St Louis. Of course that doesnt mean it wont hit 60 in December we have crazy weather.

 

Hello again! Let's try to "short cut" maybe the axle ratio thing. It's not the way I generally do things but it could work maybe. What size tires on the car? Now let's assume that the tach is correct (big assumption) so if you've a GPS drive at 50MPH, 60MPH and 70MPH in 3D gear "NO OVERDRIVE" with a GPS and record the RPM's for those speeds. Maybe do it a couple of times or three and record them. Maybe we can get "close enough".

The car is new to you so there's no assurance that the rear axle ratio hasn't been changed. In my previous post in this thread I wanted to confirm everything before moving on. We could try these numbers and see what the "numbers say"!!!

Buy this part #'d seal from a dealer 15552872 - that's the correct seal for the VSS so that you can remove it and check for the color of the drive gear in the transmission. Check the color OR we could assume it's red and 17 tooth and then guess. You do that and post back and I'll give you some numbers to search for.

I'm checking something else but can't comment yet!

For my friend "MrWillys" - that chart has errors but could generally be accepted. Everything in it needs confirmed.

 

I can try that Thursday and post the results then. I still dont want to take it out because I know its all bent up he tried to straighten it with a hamer again, but I didnt realize he had probably bent it up prying it out.

 

I understand the "reluctance" now - hammers and "crow-bars"!!!

 

I kind of knew at that point I had a worse problem than I had started out with

And Im still learning, a lot of places dont undestand working on a Corvette is a little different than what theyre used to.

Would this work with the right gear?

http://www.ebay.com/itm/Standard-Motor-Products-SC13-Vehicle-Speed-Sensor-/151064205255?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3ACorvette&hash=item232c20d7c7&vxp=mtr

 

[QUOTE=ToniJ1960;1585415492]I kind of knew at that point I had a worse problem than I had started out with

And Im still learning, a lot of places dont undestand working on a Corvette is a little different than what theyre used to.

Would this work with the right gear?

That is NOT a physical match for your car. I'd avoid it for the time being. let's deal with some known fixes after confirming what you do Thursday! 3D gear "no overdrive" for the GPS speeds!

You just haven't stumbled upon the "right shop" shop yet. There's also no need for the Corvette "only" thing either. Someone that will listen and has some interest in what they're doing can do most everything you'll need done - without the "crow-bar & sledge"!

 

The weather was nice when I was there last weekend. I didn't even put on a jacket the whole weekend. I was at the Sheraton Westport for the national NCCC meetings.

That may have been true in 1984. Who knows what's been done to your car since then? It's quite possible that the rear axle ratio has been changed.

If you get the speedometer working that will fix the converter lock problem. The ECM controls the converter lock but it needs to know the speed to do that.

The VSS puts out a sine wave at 4000 pulses per mile. That is divided by two inside the instrument panel and a 2000 pulse per mile square wave is sent from the instrument panel to the ECM. It also goes to the cruise control circuit.

 

ok guys to put to rest the later vss in the early cars. My car a 89 z51 354 gear had a moron replaced the black tag with a blue tag and not change the vss over between the two. So I ended up with the wrong late vss and wrong connector to the vss (early connector). Suprisingly the connector slides in but does not lock.Its a miracle but it stays put. The vss output is read by the 84-89 digital dash. No problem at all. All that needs to be done in this situation is change the connector. Now did I find a early vss on the loose after beating my self to death finding one and a black tag trans later with vss yes. I will install the vss in the blue tag soon as I will not cut my wiring.Black tag is for later down the line. For the guys that dont care put the late vss in for low gear conversions finding a early black vss is to much of a pain.Just change your connector. Or get in line my vss late will be for sale lol.

 

Might be just a couiple nights into the 20s for now you know St Louis weather is so weird.

The reason I wonder about a lockup switch is I am driving it the way it is, and some people say it can damage the transmission in even just a few miles. I did drive the car from South Michigan to St Louis though and I bet it was like this all along more or less (maybe had the gear wasnt bent etc but wasnt hooked up or functioning). The car has a ton of things it needs done.

So maybe if I know its going to take a good time to get the vss issues worked out at least a lock up switch would keep the transmission from taking damage?

And that I can understand, Four thousand pulses of sine wave converted to 2000 square wave would be a divide by 2. Could be just a flip flop, or part of a counter. I would imagine the signal would be squared before the divider, probably, unless the divider has a schmidt trigger or some kind of input signal conditioning internally. I usually used a small signal transistor as a switch to square up signals for digital circuits.

 

It shouldn't hurt anything to drive it as is. The older cars didn't have lockup torque converters and they did just fine. There will be a little more heat generated in the torque converter and your mileage will be slightly less.

I traced out the circuit yesterday and did some tests today. There is a speedometer IC that takes the sine wave and converts it to a square wave (that IC is bad in my cluster -- I got a goesinta but no goesoutta). From there it goes to a flip-flop to do the divide by 2. After that it goes to the ECM and the cruise control.

I don't remember if I posted this earlier or not, but you can check the VSS, wiring and connectors by taking the cluster out and measuring the resistance across pins D11 (VSS signal) and C15 (VSS ground) of the connector. I put straight pins into the connector so I could probe the pins with a DVM. The FSM says the resistance should be between 340 and 500 ohms. I got 435 ohms.

 

Is it a 14 pin DIP? You might try to match the input output power and ground pins up to a schmidt trigger ic. Is the flip flop cmos or ttl? It could be even the output is disabled or not enabled? If all it does is square up the signal maybe do it with an auxilary circuit?

 

The results are in (approximately, my gps responds to mph change pretty slowly and there isnt a great amount of resolution in the tach) .

Thirty MPH was about 1400 rpm, might be 32 at 1400 so 30 would be just below 1400. Forty MPH was about 1800, 50 mph was about 2100 rpm. All in 3rd gear.And I think its missing a little too Just had the plugs changed it was running fine maybe one got fouled it smokes pretty good. One wire is melted through the outside but its not close to anything and theres no light show from it. I moved it off the metal part it was on that melted it.

 

Tire size?

 

50r16

 

According to the cluster schematic on batee.com it's a CD4013. The signal is not coming out of the speedometer IC. I just bought a new one so I'll find out in a few days if that is indeed the problem. Meanwhile I'm driving around without a cluster...

 

Some numbers maybe - for these numbers I used a 255/50-16, a "rolling circumference" and used the diameter of that to arrive at some quick calculations. I did NOT use any of the advertised tire dimensions so if you attempt to compare using on-line calculators the numbers will NOT match.

1400 RPM - 33.8

1800 RPM - 43.45

2100 RPM - 50.79

For those numbers I also used a 3.07 ratio which we could assume to be stock. These numbers for an automatic would also assume 100% converter efficiency. A manual transmission numbers these would be spot on I'd think. Your numbers - I'd say +/- maybe comparable.

I probably should have had you done specific RPM's and done it in reverse but I'm accustomed to correcting speedometer errors or comparing speedometers to a tach signal to a scanner from the ALDL to confirm tach error on the cluster.

I'll be back!

 

I wanted to say thanks for this post.

I'm replacing this seal on my '89 Vette. Couldn't find it at my local parts store, went to the dealer and he said the part I was looking for is 25518664 and is discontinued. Tried a few places and got the same answer.

I found this post and called them up. They had the 15552872 in stock and it appears to be an exact match. I don't know if it's an updated version (it's blue instead of black like the o-ring that was in it) but they had no cross-reference.

Thanks again.

 

The composition of the seal changed a couple times to keep pace with the sealing requirements of later fluids. Sealing compositions have improved.

The seal number you mention is the seal that is used to seal the shaft on an older style speedometer driven gear arrangement. It's an error that's frequently made by some. Use that number and check "Google" or "eBay" for an image of that part number.