My1st

I'm putting a B&M Megashifter in my 89 and there is a switch on the OEM shifter I beleive is called the overdrive enable switch. At lest thats what I found it to be looking at the FSM.
Does anyone know what has to be done if anything with the two wires that run to it? The B&M does not have this switch. If they are not connected to anything will the overdrive still work?

crowz

As far as I know the only overdrive switch is on the manual shifter. A mega shifter is for an automatic. At least the mega shifter I had was for automatics.

My1st

This is an auto. There is a switch on the OEM shifter I thought was the OD enable switch? If it is not what would it be? It appears it is only ingaged when youy put it into 1, 2, & D.

crowz

My 87 doesn't have a switch so I have no clue. Just the button on top.

If it is an overdrive defeat switch like on my trucks etc you would have to rig up something or get a nos handle for the megashifter if its a momentary switch on the factory shifter.

Does the switch seem to hold down when you use it on the factory shifter or does it just seem to go down and come back up to the same spot?

If it does the the nos/nitrous **** for the megashifter would solve your problem.

crowz

Actually a better way to test is to use a voltmeter set to resistance. Hook the leads to the 2 wires from the switch on the old shifter. Notice if its showing anything on the meter or not. Then push the switch and let go. If the switch shows a short (same as touching the probs together on the meter or it may chime like mine does) only when pushing the switch and doesn't keep showing a short when released (do it twice to make sure) then its a momentary switch and the nos handle will solve your problem for sure.

crowz

Heres the handle Im talking about :



http://www.bmracing.com/products/806...ae-and-metric/

$54

My1st

Here's a picture of the switch I'm talking about.

crowz

Still hunting. I only have the factory service manual for the 87 and it has the park/reverse/neutral switch as one big unit on the side of the shifter. Nothing like what you pictured. So hunting.

crowz

Ok Im showing the switch mine has is used from 86 thru 96.

My1st

Yup, got the big one too. Took it of in order to get the wire harness of it.

crowz

Does the factory shifter have this :

My1st

Yupper

crowz

Ok figured it out.

That's the switch for the ecm to know your in a gear that can have the torque converter locked up.

Let me study on this a second to figure how to get around it.

My1st

Bingo! I remeber reading some place that a resitor is needed but don't remember where I saw it or what resitor is needed.

My1st

Correction not a resistor it was a relay. The B&M came with a relay apparently for the six wires that are in the harnes per the instructions unless two of those wires do not get used and the two for the switch take there place? The instructions are for an 82-92 Camaro so maybe it's different for a corvette being it's not made for our cars?

crowz

Ok heres your options.

This is all guessing that its a normally open switch (I cant find information to know so you will have to test with a meter)

Leave it unplugged - This will make the ecm think your in overdrive all the time. This means it will work like normal in od setting aka 4th gear. So it will engage the torque converter at low speeds like normal.

Short the wires together - This will cause it to wait longer about engaging the torque converter. Thus higher speeds.

Put it on a switch and mount it somewhere. This gives you the ability to have it behave more peppy when you want to fool around and will make the converter lug less around town. Heck you may like the switch even in the normal 4th gear setting.

crowz

To sum it up, its not a big deal for the most part whatever you do with that switch.

Its just changes at what speed the computer locks up the converter.

My1st

Great! Thanks for all the help.

crowz

No prob. I enjoying hunting for stuff.

Plus it may help someone later with the same problem..

One thing I didn't mention was my opinion on the shifter your going with. I don't care them that much.

1. Tricky to mount so it looks right (but does look good if done right)

2. Hard to adjust so they don't bind up. (Seems cable length and routing are key)

3. Short life span if used a good bit. (The one I used in my trans am had to be replaced several times from basically wearing out)

4. Very easy to bend from side to side pushing on them. This shows up after you've had it a bit and is basically the frame area bending where the ratchet part is. Eventually causing it to jam up and or do nothing when you ratchet it.

Best advice I can give on them is to not let anyone else ever drive it once its put in. My wife killed the ones I had. Either making it worse each time she used it or causing me to have to go to some store somewhere and shift it for her when she couldn't get it to shift

Not wanting to rain on your parade just didn't feel right not pointing it out. Again multiple user role seems to be the big thing. When I didn't have other people driving the car it wasn't that much of a problem.

The pro shifters don't look as good that they make but they work a TON better than the megashifter.

My1st

Yes, I've read pro and cons on the Megashifter but anything will be better than the stock shifter. It was getting to the point I could hardly push the button down much less get into gear it was getting really stiff.

Naturally I had to modify the mounts to get it in but I believe I have it where it needs to be to look like it came stock. I'll post a pic when the job is completed. Just have to sort out the wiring which I believe should be smooth sailing now.

As for anyone else driving my car that will never happen. I've had the car for seven years and my wife has yet to even set in it.
My luck she doesn’t want anything to do with it.