4+3 OD Switch

[88Z51]

Well, I did a search but couldn't find it. I know I read here where someone used a different console mounted OD switch for the 4+3. A $3. Radio Shack switch instead of the expensive (and perhaps not even available GM OE switch).
My OD seems to work fine, all connectors are connected at the trans., but I cannot manually control the OD lockout via the button on the shifter. I have tried "adjusting" the T rod under the cap on the shift knob. It makes no difference. I still cannot manually lockout the OD. Anyway, does anybody know what switch to use (a part number would be great) so I can get this working properly?

Thanks,

Greg.

 

[JonM]

61F 752 '85 Style (On/Off) ~$7.64
61F 753 '86 Style (momentary) ~$10.79

Newark Electronics - http://www.newark.com/

 

[88Z51]

Well I guess this explains why pushing the button, adjusting the T-fitting did nothing. I just took the console apart. The switch is missing! Called the dealer. $108.10 my cost for the switch! Good grief........ JonM, thanks for the part numbers. I took a look at the one for the 86 (According to the dealer, the switch is the same from 1986 to 1988) on the Newark site. It looks like it should work. My concern is where you can click for a Full Size Image on their site. It looks HUGE. Like way too large to fit in the shifter (?). Is this just the way it appears on the site? Also, is the switch a direct fit or will I need to do something with the connectors?
Thanks for the help everyone. I really appreciate it.

Greg.

 

[JonM]

It should work...everyone I know uses it. Newark are the people that made the original.

 

[88Z51]

The switch is about an inch and a half long. very small. Make sure when you order it that it comes with the spring that returns the button to the up position.

Lem

Since I don't have the original switch to compare, does this mean I do not use the original spring (which seems to me would push the switch plunger down)? Or do I just need a spring to push the plunger up with the Newark switch?

It should work...everyone I know uses it. Newark are the people that made the original.

Cool. That is a MUCH nicer price too!!
Thanks again,

Greg.

 

[Top]

Is the old harness still in the console? See if the old switch is in there somewhere. It may have just worked lose from the shifter and fell into the console. You might get lucky. If not you are going to need to get some type of connector or splice direct into the harness.

Good Luck!!

 

[RonJ]

61F 752 '85 Style (On/Off) ~$7.64
61F 753 '86 Style (momentary) ~$10.79

Newark Electronics - [url="http://www.newark.com/"]http://www.newark.com/[/url]

So Jon, you are saying that in a 1985, a simple toggle switch on the console or dash that is either opened or closed will do the job?

My car is an 85 with the switch in the knob. The plastic button on top is broken, one of the four sets of clips under it is broken. Mushy to use.

Anyone know where I could get a good button?

Ron ...

 

[JonM]

Ron...I do not know the setup for the 85 and beyond...I know my 84 has a simple on/off rocker switch on the console.

 

[scorp508]

Greg,

The part #s Jon gave you are correct. The switch you get from Newark is IDENTICAL to the one in all 86-88 4+3 corvettes minus the harness. I've bought these before from Newark for my '87.

The harness you can solder onto the new switch. It is really simple. Then you also have to use some hot glue on the terminals to cover the solders up. If you don't do this the constant movement on the wires will rbeak the solders.

Good luck!

-brian

 

[88Z51]

Thanks to everyone! I picked up the Newark switch -it did take a bit of adapting, but it did fit in the shifter. I just came back from a test drive. The OD now works like it should! :cool Now I just have one more question. In the owners manual where it talks about the OD switch, it says you may turn the OD off for additional engine braking, etc. It then says to "Be sure to turn the overdrive back on immediately afterward" So now my question is, is it ok to leave the OD off? I would prefer to drive the car like a conventional four speed. But the statement in the owners manual has me concerned. Am I going to cause damage to the OD unit if I lock it out for long periods of driving?

Thanks again,

Greg.

 

[RonJ]

I think that you have to treat the O/D like a fifth gear.

With the O/D off, shift up through the gears, once in fourth, clutch in, hit O/D, clutch out. Just the opposite when you want to gear down back to fourth with no O/D. The unit should last forever if used easily. 172,000 on my 85, original O/D to the best of my knowledge.

Not only that, I don't like the ratio drop from 1st gear to 2ndO/D. In normal driving, it kind of lugs away in 2ndO/D.

And that's my .05 cents .....

 

[jernst]

o/d switch - Radio Shack part number

Hi Greg,

I see this post is really old but in case you never got an answer, I can help. Radio Shack has a direct replacement switch which is a lot cheaper than the GM one. The part number is 275-1555A. In my case, the wires had broken off the switch AND the switch had broken.

John Ernst
67 Lotus Europa 4 Speed 1.47 litre
97 Plymouth Neon 5 Speed 2.0 litre
85 Corvette 7 speed 5.7 litre
98 Dodge Neon Auto 2.0 litre
85 Champion Telstar Auto 7.5 litre
jce1@ns.sympatico.ca

Well, I did a search but couldn't find it. I know I read here where someone used a different console mounted OD switch for the 4+3. A $3. Radio Shack switch instead of the expensive (and perhaps not even available GM OE switch).
My OD seems to work fine, all connectors are connected at the trans., but I cannot manually control the OD lockout via the button on the shifter. I have tried "adjusting" the T rod under the cap on the shift knob. It makes no difference. I still cannot manually lockout the OD. Anyway, does anybody know what switch to use (a part number would be great) so I can get this working properly?

Thanks,

Greg.

 

[WhalePirot]

Unload the O/D clutches for maximum life

I either use the clutch or unload the drivetrain while engaging/disengaging the O/D, but have never found a reason to not fully use the "+3" feature. I alternate, depending upon driving conditions, between a normal 1-2 shift, a 1-3 shift or a 1-2+O/D shift.

The O/D is a tough unit, perhaps more able to take abuse than the manual section, but I don't 'beat' my machine. My O/D was rebuilt and toughened at 105k, but had no problems which dictated the rebuild. We found many small cracks on the 1,2,3 and 4 gears, though.

 

[Jersey-vinny]

I always use the clutch when going into or out of the overdrive.
Clutches- Cheap (relatively)
Transmissions-Expensive
VINNY