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4+3 trans questions

c3guy

Member
Joined
Apr 9, 2004
Messages
12
Location
Toronto c3 addict
Corvette
72 targa blue cpe, 85,89
Hello all,This is my first time posting a thread on here, or anywhere for that matter, so please bear with me. I have always been amazed at the knowledge base on here, and would appreciate any help that can be offered. I am the proud owner of an all original 85 4+3 car that has a few problems. In a nutshell the trans pops out of second gear, and the dash occasionally goes a little berserk and then is almost black now, but I can see that there is still some activity.
Not having the budget at the moment to install Tremecs and ZF's and all that, I am wondering what the best approach is for the trans. I have found a "rebuilt" repainted? maybe, 4+3 from an 84 car at a reasonable price, being parted out. But as I have read there are extra switches on the trans as opposed to the 85. Can this 84 be used? What would you recommend for a clutch which will be replaced at the same time? I understand that there are several grounds for the dash problem, and could use a few detailed pointers in locating them as all the segments were lit properly before the lightshow. Again, all the assistance from guys whohave been down this path before me is very much welcomed and appreciated. Thanks gentlemen, and have a Happy Safe Easter.
p.s. I am not on here every day, so if it takes me a few days to respond, again, please be patient
 
I would remove the trans assy, split the gearbox and the OD then repair the gearbox because it sounds like the four-speed (basically, an upgraded Warner Super T10) needs to be overhauled.

As far as retrofitting the complete assembly out of an 84, I'd be careful with that idea. The Doug Nash 4+3 was a work in progress and there can be significant differences from model year to model year with the overdrives.
 
I would remove the trans assy, split the gearbox and the OD then repair the gearbox because it sounds like the four-speed (basically, an upgraded Warner Super T10) needs to be overhauled.

As far as retrofitting the complete assembly out of an 84, I'd be careful with that idea. The Doug Nash 4+3 was a work in progress and there can be significant differences from model year to model year with the overdrives.

Thanks Hib, I kind of had that feeling as well, but may still buy the 84 unit as I believe the 4 speed Super T-10 part is similar, and may be a good parts source as well. Do you recommend anybody for a gasket kit, or for parts, or just general good knowledge and good diagnostic skills?
 
I can't help with the trans but someone will see the question and respond...

But, the digital dash....I have dealt with and it may be internal. The digital dash had such a great reception when it appeared for the first time in the new '84 vette. It would have probably survived and remained an option if the harsh suspension and the other vibrations had'nt of soured the taste of repair/relacement. Back in the late 80's, that digital dash was worth around $5000 to replace...I bought a used one for $1500 from a wreck back in 89.
What happens typically is that the main circuit board is standing on edge, vertical when mounted,. and this board has MANY things mounted to it, one item being a pretty good size plug-in thats soldered into the circuit board backside with everything else. The constant pounding and the weight of this part eventually break the solder connections. They crack, and things start to happen with the display, and as the crack gets worse so does the display. Typically the Lites flash, and go dark. The 2 turn signal arrows both lite up, and the blue hi-beam indicator lite stays on. I cannot count how many dash's I have seen fail in the exact same way.
Good news is that its an easy fix. If caught early you can do it yourself with a little patience and a steady hand and some mild skill with a soldering iron. The break can usually be seen or where the plug-in contact pins are loose, so you will be able to see the damage. I have repaired my current dash twice now. There are lots of places that do an exchange also. Average rate is about $300-$500 now, and that will get you a rebuilt unit, exchanged with your old one.

The other possible explainations for the dash darkness are grounds as you already know, and sometimes the headlite switch dimmer control. There is a collection of ground wires under the car that mount to the trans bellhousing. Others are scattered all over, under the hood and inside the dash or inside the cabin hidden by trim panels. Pretty much anywhere there is a harness section there will be a ground wire to the frame.
If the dimmer operates the other interior lights then that can be ruled out, and that leaves grounds both internal and external. My bet would be internal. The main plug on the display is also part of the board and that is soldered to a zillion paths with one long, never ending ground loop that circles the entire board. That could be cracked. You also have a series of power sources with fusable links that all connect behind the battery. Look at those to be sure that the power to the dash is not loose. Since the display is not part of control, the car will run just fine without the display being functional. Hope this helps.
 
Welcome to the boards c3guy. :w


I combine your two threads. It is my experience that having one thread will yield better results, and the posters that reply will be able to keep track of responses. Good Luck.
 
Thanks to all of you that have popped in so far Hib, boomdriver, vetteboy and vetteoz. Boomdriver that is exactly what went on with the dash, high beam indicator and all. The weather has been stunning here in Toronto,and after the consumption of massive quantities of turkey tomorrow I am going to play with the dash first. The trans will have to wait a couple of weeks, until I get the one from the 84 in my hands. Do you guys have any suggestions on the best places to buy overhul, and gasket kits for the 4+3? Is there anybody you have dealt with in the past that you feel is better than the others? Thanks to all for helping me wth my first thread!
I have had a serious corvette addiction since '68 and have always enjoyed the people who share my craving for this drug of choice.
 
Only one place for 4+3 parts and service.
Talk to Brian at SK Speed
SK Speed - Peformance Auto Parts and Racing Accessories

I just had the manual trans "rebuilt" on my car and replaced the overdrive with an exchange unit from SK Speed. I wanted to keep the car stock but considered and researched other options such as the Tremec or Richmond.

SK has a waiting list of several weeks, so you may want to get your name on the list if you're interested.

Here's a link with some more details - it started out as a question about the rear seal :) http://www.corvetteactioncenter.com...-forum/120462-rear-main-seal-info-87-b2k.html

Good luck.
 
Doug Nash 4+3

I just had the manual trans "rebuilt" on my car and replaced the overdrive with an exchange unit from SK Speed. I wanted to keep the car stock but considered and researched other options such as the Tremec or Richmond.
These guys took over from Paul Cangliosi in Boca Raton. It's been a few years since I spoke with them, but was positively impressed. Paul redid the unit for my modified '84 and a local guy rebuilt the T-10 section.

My stock engine had caused near-invisible stress cracks in many gears and wear through of the case hardening, particularly 2nd gear. I am unsure that the '84 unit will do you much good at all. That money may serve you better through a rebuild of yours by a specialist.

While you'll find few fans here (many naysayers) of the 4+3, Pauls' website, Corvette 4 + 3 Overdrives has sections that you will find of interest, including a Q&A part where he says they believe the Doug Nash is superior to the ZF, for stated reasons. Others are not fans of the Ritchie as a retrofit.

I recommend using the search of this forum to find the numerous threads on this topic and calling SK. Paul was, and SK were personable and available for questions and expertise, without BS.
:w
 

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