Recently, the shift to overdrive became disabled on my 1986 black coupe and it requied me to drive home with flashers ablaze and RPM around 3000. Folks tell me the overdrive "automatic" part of my 4+3 transmission is kaput and that to rebuild the transmission considering that defect, it could cost up to $3500.

Question 1: Is $3500 reasonable (or what one would expect)?

Question 2: If I am going to pay that much for a 4+3, is it possible (or logical) to buy a 6 speed and put it into a 1986 Coupe? If so what would the fare be for that proposition?

Inkyvette

 

Before donig ANY of that...check the Overdrive Relay. They go out and OD won't engage. Also check the switch on the shift **** to see if its defective.

 

If your OD is kaput, you can replace it. Ecklers (or is it MidAmerica?) has rebuilt units ready to ship. I replaced mine that way. As a matter of fact, I'm assembling the tranny to the OD right now. (See, you have a 4 speed transmission mated to a OVERDRIVE unit, that gives you 4 plus 3 speeds)
:D I have actually converted mined to a Richmond 6 speed and was very unhappy with the gear hum. The Richmond has "straight" cut gears; very strong, but noisy. Lots of money and sweat later....I'm installing the sweeet 4+3 BACK into the car. If I break it, then I will have it rebuilt. 'Nuff said. :smash:

 

1st: It could be a much simpler problem that could be solved with some troubleshooting.

2nd: A rebuilt Overdrive unit is $1200.

 

Can you describe how it went kaput and do you get the O/D ligh?
They usually don'd fail without prior warning like slippage in reverse or plenty of noise from planetary gears. I would strongly sugest to check electrical. suspected item would be:
-stick switch or its wiring or even the switch actuator rod.
-1st gear switch
-fuse

If electrical checks ok then I would check the ATF level, Solenoid, internal wiring etc.
What you dont want is to replace costly unit just to learn that a wire was loose. Alsi it is bit of work too.
good luck

 

Good suggestions.
No 1st gear switch on the '86 though.
This is important, because on the '86 if the O/D light does not come on, it is an electrical problem. If it does light, it could still be the solenoid, pressure switch, or wiring, but is most likely mechanical/hydraulic.
True, but the O/D should work without the switch or any of its components. Under normal driving conditions the ECM will command the O/D on when shifting into 2nd. No use of the switch is required. I would troubleshoot the O/D first, then work on the manual engagement if necessary. Start car, allow temp to rise above 122°F, drive normally (no more than 1/2 throttle)shift into 2nd and tell us what the O/D light does. If it comes on, get under there and check your O/D fluid level. Many that see trouble free use out of their O/Ds change the fluid and filter every 3K miles. The level should be checked at least monthly. If the O/D light doesn't come on, swap your Fuel Pump Relay with your O/D relay. They are right next to each other and are the same part. If the relay is the problem, with it in the FP position, you may notice an extended crank before she'll restart, but the Oil Pressure Switch should close as soon as you build up some pressure during cranking and she'll fire right up. Then try the test again. If you did notice an extended crank after swapping relays, it will probably work now.
That 122°F thing I mentioned earlier is important too. The ECM will not allow O/D engagement below that temp, so if your CTS were bad (the one at thr front of the intake that feeds temp info to the ECM), and the ECM was not seeing the temp get over 122°F it wouldn't energize the relay. Don't be fooled by the guage reading, its source is a different temp sensor.

We need to know the status of your O/D light before anything else though.

Sorry for being long winded, but I was trying to be thorough.

 

Thanks for all the suggestions, They give me a much better source than what I've gotten before (RE: the guy who kept the car for 5 weeks and said he'd decided he wouldn't even try fixing it unless I opted for an approval to pay 'cause "it might go as high as $3500").

Here's how it came about. It was working fine for the first hour on a 2 hour Friday afternoon drive from Atlanta to Macon. I was "exercizing" my acceleration capabilities a little as I was being pestered :rolleyes: by a late model Mustang. I passed him and swung back into the right hand lane and I was unnerved that the transmission didn't "automatically" slip back into O/D when I throttled back, and the RPMs stayed way up. I tried to force it back in with the gear shift O/D switch thinking that that was source of the problem, but there was little reaction to that attempt.

I've replaced about 4 O/D switches in the car's life and it has about 120,000 miles on it, so I'm fairly familiar with how a failing one "feels" and I was sure that that was not the problem. During the ride home (at 50 mph and flashers on) the O/D light on the instrument panel was on at times and off others, but when the light came on there was no gentle PRM down shift that I'm used to seeing and feeling. Since then I have not driven it much, but when I take it out just to do a slow (max 45 mph) trip around the block, I've gotten the same indication; the light is intermittant and seemily bears no relationship to the gear the transmission is in.

Hope that helps.

 

Another tidbit some people do not realize for 86-88. Overdrive will NOT automatically reengage after letting off of the throttle unless you are in 4th gear. If you are in say 3/OD and nail the gas and it shifts out of OD it will not automatically go back into OD until you are in 4th and under I think 75% throttle or hit 103mph. You should still be able to turn it back on with the switch though. :)

 

You can be as long winded as you want, Ray. I really appreciate your help.

Thanks.

 

I'm assuming here that you are referring to the O/D On/Off switch in the shifter.
Just for grinlets, have a very close look at the O/D relay. There are two mounted on bracketry near the firewall just onboard of the brake booster. Look at the wires running into the relay. Over time the insulation on these wires tends to recede leaving exposed wire at the terminals. This can cause all kinds of headaches, so if the insulation has shrunk back, either tape the wires up or use the paint on insulation, but sort this out. If it isn't your problem now it will be a problem later. Do the Fuel Pump Relay while your there if it is suffering from the same malady.

At this point we need to go with what we know. When the light is on, O/D is not. We'll work the intermittant later if need be. On the '86 the relay feeds the light and the solenoid. If the light is lighting, the ECM is commanding O/D and the relay is energizing. You need to check the fluid level. I would go ahead and do a fluid/filter change. While you're down there you could check the wiring. You'll see where the Dark Green wire goes to a connector on the side of the case. On the inside of the case with the pan off you'll see where this wire enters. You'll see the little round cylinder with the two spade lugs. This is the pressure switch and his job is to break the 12v to the solenoid in the event the fluid pressure drops below about 60psi. One lug attaches to the wire coming in through the case, the other attaches to the O/D Solenoid. These are the only two components with wires attached so you shouldn't have any problems identifying them. With car off, you don't even the keys for this test, using a fused jumper wire (I have one of those cigarette lighter inserts on one end with about 5 feet of wire and an ECM male pin at the other), connect from the battery + terminal (or cigarette lighter in my case) to the ALDL pin F. Pin F is on the top row last pin on the left. This will route 12v through the NC contacts of the O/D relay and will light the O/D light and should put 12v on the Pressure Switch lug that runs through the case. Measure for 12v from this lug to ground to test the wiring from the Relay to the O/D. You can then jump the two lugs of the Pressure Switch to see if the Solenoid energizes. You'll hear it click. Assuming all this is good, install a new filter, replace the pan and fill with ATF. Report back your findings.

 

A bit off topic. What are the gear ratios in the 4+3? And is there a certain sequence that the OD and normal gears work?
Thanks. :seeya

 

Just got an 86 from someone who had no idea what there was overdrive, replaced relay, light comes on but intermittent O/D engagement. You've been dead on so far though so I'm going to hope new fluids/filter fixes it right up! Thank you I love this trans!

 

I don't know if this will help you or not. I have an 86 that originally had a 4+3 in it. Prior to my purchasing it, a PO had the transmission changed out for a Tremec TR3550 5 speed. Far as I can tell, it was a 100% bolt-in tranny replacement only. Looks like the bellhousing, slave cylinder and anything external is still the original pieces. Can't speak to the clutch as I've not seen the insides of it. The only original item I noted not used is the trans cooler on the radiator, those lines were cut and capped. There is a Dakota Digital SGI-5 rev. C convertor in the line for the speedometer to convert the signal from the tranny to work with a Atari speedometer assembly.

It works and I'm happy with it.