Question: 84 Manual Coupe - Doug Nash 4+3

[AussieCorvetteNut]

Hi Guys,

Well I recently picked up a 1984 Manual Coupe, with the Doug Nash 4+3 combo.
Overdrive doesn't engage at all.

I have ordered a new overdrive relay, it has arrived and is ready for me to collect from the post office.
I am assuming that the Gage fuse in the fuse holder is OK as I have all instrument cluster operation, speedo etc. I ordered and installed a refurbished Instrument Cluster, but had to use parts from the reco unit and my unit, as when the Vette had a right hand drive conversion, the cluster got changed and the wiring harness plugs move from being plugged into the side of the unit, to being plugged into the rear of the unit...lot of soldering done there. :ugh
Last owner said he doesn't recall if the overdrive ever worked in the 11 years he had it...

My decision is to try and find out if the overdrive does actually work or not.
From there I can pull it out and rebuild both the gearbox and the overdrive (I have both rebuild kits) or junk the DNE and opt for an upgrade.

I don't really want to junk the DNE, as I am sort of thinking that my Blue two-tone 84 Coupe with the DNE is low production...cloth trim is also an issue, I can't figure out why the original owner ordered cloth trim.
I would prefer to fix what she came with and enjoy, be a caretaker. Parts are the issue for the DNE system, I cannot find simple parts such as the overdrive rocker switch on the console...rare as rocking horse poo.
Switches on the side of the gearbox also seem to be rare.
Has anyone changed the overdrive console switch for an 1985 selector with the overdrive button on top?

I also need to check the fluid levels in both the gearbox and OD unit.

Appreciate your thoughts.

Cheers

Tony

 

[hcbph]

Tranny upgrade

I can't speak to the DN 4+3 unit, my car had it originally but it was changed out with a Tremec TR3550 5 speed prior to my purchasing it. Here's my eval on it based on a year that I have had the Vette (86 convertible L98). The gear ratio is wider than I'd prefer, especially low. I'd call it too high a ratio difference except for cruising.
As far as I can tell, it looks like other than the actual transmission everything else looks to be oem - bellhousing, slave, driveshaft, shifter location etc. One thing though different is that there is a Dakota Digital signal convertor there to drive the speedometer as it's apparently a different signal between the original and the Tremec unit. The unit works well for the driving style I do (cruising) but if it was planned for drag racing, there would be better ratios IMO than this one.

 

[AussieCorvetteNut]

Thanks for your Tremec info.

I can't speak to the DN 4+3 unit, my car had it originally but it was changed out with a Tremec TR3550 5 speed prior to my purchasing it. Here's my eval on it based on a year that I have had the Vette (86 convertible L98). The gear ratio is wider than I'd prefer, especially low. I'd call it too high a ratio difference except for cruising.
As far as I can tell, it looks like other than the actual transmission everything else looks to be oem - bellhousing, slave, driveshaft, shifter location etc. One thing though different is that there is a Dakota Digital signal convertor there to drive the speedometer as it's apparently a different signal between the original and the Tremec unit. The unit works well for the driving style I do (cruising) but if it was planned for drag racing, there would be better ratios IMO than this one.

This might have to be the option if I can't get the overdrive to work.

We have a 110/kmph speed limit on some of our highways, and at this speed with no overdrive, the tach is reading 2900 rpm, sounds great though.
Even worse when the boy racer comes out and my hat goes on backward...get up to the 120+ mark and she needs the 5th gear.

Cheers

Tony

 

[hcbph]

Misc

1800 rpms at 75 mph in 5th gear. O.D. definitely worth the effort whether it's a 5 speed or using the 4+3 unit.
Good luck getting it going.

 

[AussieCorvetteNut]

1800 rpms at 75 mph in 5th gear. O.D. definitely worth the effort whether it's a 5 speed or using the 4+3 unit.
Good luck getting it going.

Thanks Mate...

Relay arrived today...I am lucky enough to have a Bendpak 4 post hoist and she is on the hoist in the shed. I have a new OD filter, so will drop those in with some fresh tranny fluid.

 

[hcbph]

4+3 od

If you don't already have one, I'd strongly suggest getting a FSM for your car. I know there's a section in there on the O.D. unit. I remember seeing one but didn't need that info because my car no longer has that transmission in it. I believe there's a way to jumper the switch to engage the O.D. which could confirm if it's working or not.

Good luck.

 

[gmhowe]

For my 85 4+ 3:
What I did since I couldn't find the parts for the switch in the gearshift knob was to get a 2 wire rocker switch and bypassed the old stuff altogether and I fastened it to the left had part of the console. Here in Phoenix I run it in OD all the time unless some little rice burner car comes along and wants to play.

 

[AussieCorvetteNut]

1984 Factory Shop Manual

If you don't already have one, I'd strongly suggest getting a FSM for your car. I know there's a section in there on the O.D. unit. I remember seeing one but didn't need that info because my car no longer has that transmission in it. I believe there's a way to jumper the switch to engage the O.D. which could confirm if it's working or not.

Good luck.

Yeah, I picked one up on eBay and had it and the electrical troubleshooting manual sent over together. These manuals are great, I had one for my L81 Coupe around 7 years ago.

Specific for that one year and have more than the other manuals.

I can't remember seeing the jumper switch, but will have another look.
I know Corvette Central had a section in their Tech Pages, on a similar switch.

Will check it out.

 

[AussieCorvetteNut]

Rocker Switch

For my 85 4+ 3:
What I did since I couldn't find the parts for the switch in the gearshift knob was to get a 2 wire rocker switch and bypassed the old stuff altogether and I fastened it to the left had part of the console. Here in Phoenix I run it in OD all the time unless some little rice burner car comes along and wants to play.

I thought about doing something similar, but then thought maybe I could adapt a later model gear lever and its switch, I think it is on the top of the gear stick in the later C4's.
That way I could leave the rocker switch there for looks, but engage OD they way the later 84's and 85's and up do.

Has anyone done this?

I am going to Autobarn this arvo, so will see if they have any electrical component cleaner.
I don't think the rocker switch is broken, I haven't tested it yet.



Tony

 

[AussieCorvetteNut]

I thought about doing something similar, but then thought maybe I could adapt a later model gear lever and its switch, I think it is on the top of the gear stick in the later C4's.
That way I could leave the rocker switch there for looks, but engage OD they way the later 84's and 85's and up do.

Has anyone done this?

I am going to Autobarn this arvo, so will see if they have any electrical component cleaner.
I don't think the rocker switch is broken, I haven't tested it yet.



Tony

An update from this arvo.

Checked the relay connection and it is bad as the wires are coming away from the clips that connect to the relay...they need to be cleaned and re-soldered.
I managed to ground the circuit and the 'Overdrive Engaged' light came on on the dash. I then tested the rocker switch, and it is working fine, turn the light on and off as it is supposed too.

I think the old relay is ok, but I have a spare just in case.

I think there is a ground issue in the circuit though, as the circuit is not reliable, it seems to be ok, but then no power at all.
I think it may be in the wiring harness that serves the gearbox switches.
I did notice that the wiring and connections to the gearbox were brittle from age and oils.

I didn't win the battle, but have advanced the troops a little so to speak, the rocker switch on the console is good, and the circuit does work.

If I can get it reliable, I can take the pan off, replace the filter and refill with tranny fluid.

A bit of wiring repair around the relay first.

Now back to eBay to see if I can find the wiring bits I need.

 

[m1super90]

1984 4+3 issues

I've had my '84 since, well, 1984 and know it like the back of my hand. Let me know if you have any questions. For instance, you can make your O/D straight manual operation by jamming closed the relay in front of the firewall.

Right now I need to change the O/D switch on the shifter console. These were made with the leads riveted to the base of the switch with a connector at the other end. I can replace it with a generic rocker but would like to get the original if it isn't $50. Any ideas?

 

[AussieCorvetteNut]

The Rocker Switch is as rare as an honest politician

I've had my '84 since, well, 1984 and know it like the back of my hand. Let me know if you have any questions. For instance, you can make your O/D straight manual operation by jamming closed the relay in front of the firewall.

Right now I need to change the O/D switch on the shifter console. These were made with the leads riveted to the base of the switch with a connector at the other end. I can replace it with a generic rocker but would like to get the original if it isn't $50. Any ideas?

I have been searching eBay and the other sites for an original O/D rocker switch, they are very rare and hard to find. Late 84 and 85+ use a different set up, with the O/D button on the gear stick.
I guess you might be able to find one at the Corvette grave yards...I called a guy here in Australia who had just wrecked two 84's and asked him if he had an O/D oil pan and the bolts, he said that he only had complete gearboxes...I aksed if he had any OD bits...I got Nup.

I am lucky that my switch is working, tested it the other day and it is fine...phew!

AC Delco make a fuel pump relay connector that suits the O/D relay, the relay is the same for AC, fuel pump and OD. I purchased two of them and two spare relays from RockAuto and they arrived via DHL in 4 days!...yep 4 days from the USA to Australia...I can't get Ecklers, Corvette Central, Zip, Mid America to ship that fast.
Anyway these have 5 grey wires leading into the connector (yeah not colour matching the original wiring harness), but a better repair job than soldering 30 year old wires and connections...thank you AC Delco!



Tony

 

[AussieCorvetteNut]

Looks like this didn't fix the issue

I have been searching eBay and the other sites for an original O/D rocker switch, they are very rare and hard to find. Late 84 and 85+ use a different set up, with the O/D button on the gear stick.
I guess you might be able to find one at the Corvette grave yards...I called a guy here in Australia who had just wrecked two 84's and asked him if he had an O/D oil pan and the bolts, he said that he only had complete gearboxes...I aksed if he had any OD bits...I got Nup.

I am lucky that my switch is working, tested it the other day and it is fine...phew!

AC Delco make a fuel pump relay connector that suits the O/D relay, the relay is the same for AC, fuel pump and OD. I purchased two of them and two spare relays from RockAuto and they arrived via DHL in 4 days!...yep 4 days from the USA to Australia...I can't get Ecklers, Corvette Central, Zip, Mid America to ship that fast.
Anyway these have 5 grey wires leading into the connector (yeah not colour matching the original wiring harness), but a better repair job than soldering 30 year old wires and connections...thank you AC Delco!



Tony

I put the new relay connector and relay in.
When looking at the connector and the wiring diagram for the connection, with the terminals ABCDE, terminal C and E are earth. My circuit tester shows red and green colours, when I earth the tester and touch circuit terminals C and E, the tester shows red and when I bridge terminals C and A, it displays green. I cannot get the 'overdrive engaged' dash light to come on at all. They last time I tried, it came on when I selected 4th gear, ignition on and provided an alternate earth

i thought I may have soldered the connector incorrectly, but I did one at a time.

i had her up on the hoist today, I replaced the spade terminal on the overdrive connector on the transmission...still no light or OD engaged.

I am confused, I had the overdrive light on the dash and the rocker switch controlling it, but can't duplicate this again.

Any thoughts where I may have gone wrong?

The fuse is ok, I wouldn't have C and E power from the ignition if it wasn't.

Frustrated, but hopefully getting closer.


Cheers

Tony

 

[AussieCorvetteNut]

Mmmm still not working.

I put the new relay connector and relay in.
When looking at the connector and the wiring diagram for the connection, with the terminals ABCDE, terminal C and E are earth. My circuit tester shows red and green colours, when I earth the tester and touch circuit terminals C and E, the tester shows red and when I bridge terminals C and A, it displays green. I cannot get the 'overdrive engaged' dash light to come on at all. They last time I tried, it came on when I selected 4th gear, ignition on and provided an alternate earth

i thought I may have soldered the connector incorrectly, but I did one at a time.

Tony

Double checked the soldering job and original wire colours against the circuits ABCDE.
went over it a few times, I am sure it is correct.

Not sure if there should be some sort of a signal coming from the ECM, the wiring troubleshooting manual says it sends a signal.

i thought I may replace the Pollak gear switches, finding them might be interesting.

any thoughts?????

 

[AussieCorvetteNut]

OK, I found Pollak, but they won't ship to Australia.

Ithought I may replace the Pollak gear switches, finding them might be interesting.

I did a search and found POLLAK Ball Switches, but POLLAK won't ship to Australia...ad
They did say to contact NARVA here in Australia, but NARVA won't match the part to the car, especially a Chev Corvette. They also are the wholesaler, so I would need to find a retailer here, I can get the part out of the USA for about half what these guys will charge.

I have narrowed the search down to:

(1) another CAC thread which says POLLAK 21-482-P can be altered to suit the Delphi Weather Pack Terminals on the wiring harness...not real keen on altering the part unless it is a last resort.

(2) Parts 21-462-P, 21-495-P (both CLOSED) and 21-370-P (OPEN) that use Packard/ Delphi Weather Pack 12015792

(3) Parts 21-444-P, 21-538-P (both CLOSED) that use Packard/ Delphi Weather Pack 12103784

(4) Part 21-465-P (OPEN) that uses Packard/ Delphi Weather Pack 12052644

I am pretty sure that the correct Packard/ Delphi pin is 12015792, but I need someone to confirm if they know.

Does anyone know if this is correct???

ASE Supply Outlet Store ship internationally, so all I have to do is match what I have to what they sell and we will be able to replace these ball switches anyway, in the process of elimination of fixing the OD circuits.

Does anyone know if GM14057528 back up switch (which is discontinued) would be the same as any of the POLLAK parts above?

I do think that one of these switches is the source of the grounding issue (or lack of grounding)...well I hope so, I am running out of ideas.

Appreciate your help,



Tony

 

[AussieCorvetteNut]

....aaahhhh crap!

I did a search and found POLLAK Ball Switches, but POLLAK won't ship to Australia...ad
They did say to contact NARVA here in Australia, but NARVA won't match the part to the car, especially a Chev Corvette. They also are the wholesaler, so I would need to find a retailer here, I can get the part out of the USA for about half what these guys will charge.

I have narrowed the search down to:

(1) another CAC thread which says POLLAK 21-482-P can be altered to suit the Delphi Weather Pack Terminals on the wiring harness...not real keen on altering the part unless it is a last resort.

(2) Parts 21-462-P, 21-495-P (both CLOSED) and 21-370-P (OPEN) that use Packard/ Delphi Weather Pack 12015792

(3) Parts 21-444-P, 21-538-P (both CLOSED) that use Packard/ Delphi Weather Pack 12103784

(4) Part 21-465-P (OPEN) that uses Packard/ Delphi Weather Pack 12052644

I am pretty sure that the correct Packard/ Delphi pin is 12015792, but I need someone to confirm if they know.

I checked the Vette this afternoon and the POLLAK switches are opposite to what I listed above, the switches are female and the Delphi/ Packard connectors are male...

If I can confirm that the POLLAK switches can be used, I thought I might just change the Delphi/ Packard connectors to male...


What do you guys suggest?