I'm a prospective buyer, and as much as I want a manual Vette, I can't afford later year 6-speeds. So the choices are the 4+3 or the Automatic. I would prefer a stick, but I'm not so sure of how reliable/strong these 4+3's are. Anyone have any insight on the strength/power capabilities? Thanks in Advance

 

Anyone? I repeatedly hear people call them "disaster's" of transmissions, but why? Can they hold power, etc?

 

I love my 4+3. Only 53,800 miles on mine, but I've had no problems with it. Here's a website for you to refer to:

4+3 Reference Page

 

If you ask about the 4+3 transmission on this forum you will get 90% replies from people who have never had one and they will tell you how unreliable they are. They go by what someones friend of a cousin of a brother in law heard. I believe that there were only 25% of of the early C4's that had them originally. If you can get documentation of the service history showing that the fluids were changed routinely and that they were operated correctly, these were very good transmissions. Remember that about 75% were automatics and I am sure that there were many problems with them, but it seems that most people just expect to have transmission failure sooner or later with an automatic. When there is a problem with the 4+3 tranny it becomes a disaster of huge proportions according to some of these people. The 4+3 was not the best transmission built but it sure as heck was not the worst either. If you havent guessed by now I have one in my 85 and it gets the job done very well.

 

Ok, thanks. I definitely don't want an automatic, but I can't afford a 6 speed. I like the idea of a 4 speed over a 6 speed.

Any other opinions of the 4+3? Can they take power, etc? If It ever goes, are 6 speeds a fairly reasonable swap?

 

I don't know how much you plan to spend, but there are 6 speed cars out there for less than what some 4+3's will go for. It's not just the age, but mileage and condition. If you shop long enough, you'll find a 6 speed car you can afford.
With that said, yes there are options for swapping a 6 speed into a 4+3 car. Not exactly cheap. . .but can be done.

 

My transmission went out at 80k, lost every gear but 1st, went with no warning just getting on the freeway one day. Had a performance rebuild done on it and it's better than ever. I'm at 108k now and have had no other problems.

 

The Callaway Twin Turbo cars of 1987 & 1988 used the 4+3, so in terms of power capabilities these transmissions could handle a lot of power (562 ft/lbs tq in 1988). As others have pointed ou the key is maintanence, especially the o/d unit.

 

I don't own one because I am a paraplegic, so I have to have an automatic. But before I got hurt, I drove a couple of them, and they are cool as heck. Without using the OD, they are pretty much like driving a Muncie, which are about as good as they get, IMHO. And with the OD, it was fun to drive. Wish my legs worked, I'd have one now.

Rich K

 

When I bought my 85, my OD did not work on the 4+3, I drove it as a 4 speed until reverse went out. This was a problem with the OD and I shopped around and learned as much as I could about the Doug Nash unit. Every year they made upgrades and improvements up until it was discontinued in 88. I found a 88 unit on ebay for 500.00, and it works great. It's like having two separate trannies in your car, one for city and one for highway. The earlier units can be rebuilt and upgraded far cheaper than a 6 speed swap. Search " Doug Nash 4+3" and you will get an overview of what your dealing with.

 

Thanks guys. I'm actually looking into a 1988, so I guess that's the best year. I have to keep it low budget, I found one for ~6 grand. I like the idea of a 4 speed over a 6 speed, I just wondered about these trannys.

I plan on full bolt-ons, eventually head+cam, so I won't be going wild, but I want a strong transmission. I only asked about the 6 speed swap in case the 4+3's were weak.

So if the OD tranny goes out, it will still drive as a regular 4 speed? This is my first manual, as I drive an automatic Audi now, and I'm fairly clueless about this setup.

 

My recommendation is to drive one before you buy, to make sure you will like it. My 88 drives like a dream, shifts smooth as silk with nice clutch take up. It's actually one of the easiest manuals I've ever driven. But make sure you will like driving it before you buy if you're not used to a manual. You will find most people drive their 4+3 like this:

1 - 2 - 3 - 4 - O/D button (in this way it is used like a 5 speed).

I always clutch when turning the O/D on or off and I only use the O/D on the highway. Around town I leave O/D off and use it like a normal 4 speed.

 

3rd OD is like 5th gear and 4th OD is like a 6th gear......and it will kick out of OD if you stomp on it......a really cool passing gear.

 

The cheapest of the 6 speeds will be the '89.

I say keep looking and you'll find a nice coupe for under $8500.

 

I drove a 4+3 once, almost like having a 4 speed mated to a Powerglide! Pretty slick deal, really, but a 6 speed would be preferred, depending on price.

 

I owned an 87 with a 4+3 in it. At first I thought it was really neat but then I started having problems with it. Wouldn't shift automatically or manually. I put a few hundred dollars into repairs and it continued to have problems so I looked into a full rebuild and was put off by the cost. In the end, it was one of the main reasons I sold the 87 and went to a newer model.

 

Wow, this thread is a first. Usually this topic turns into a 4+3 bash fest. All but a couple have been pretty good about a REAL review of the 4+3.

OP, understand that the 4+3 has a lot of Electrical inputs. These sensors of various types tend to be like all 80s designed electro/mechanical Electronics. Once one of these sensors start to act up or go out the O/D will not work.

Many unscrupulous mechanics in the past used this as an opportunity to get a ~$1500 rebuild out of a "sensor" going bad. The best "rumor" is that the O/D is only worth about 30K miles.....then a rebuild is needed. And just like the Many Urban myths the O/D or 4+3 comes with a bad name attached.

The cure for this urban myth is to educate yourself as to how all the Electronic inputs are attached and what the are sensing for the CPU. Once you understand all the inputs and you follow the FSMs clearly outlined trouble shooting guides......you most likely will find a $35 switch has gone bad.

You'll note (after reading threads like this) most of the time the ones claiming that they had to have a rebuild are also the ones that had a mechanic doing all the diagnosing and coincidentally the same mechanic wants to rebuild the O/D unit.

The tell tale sign is reverse gear dropping out. This is a true sign that the O/D is gone....but as pointed out in this thread....that starts to occur at a greater mileage than 30K.

The threads where you find a DIY guy going through the FSM trouble shooting procedures usually find that a Sensor has gone south, they replace the Sensor or Solenoid and move on in life.

Sorry to sound so crass on this subject, but it seems whenever it is touched on, it usually turns into a bunch of guys telling you to get a $5k Doug Nash 6spd......when the car is only worth $5k to begin with not to mention a $35 switch and a Saturday afternoon fixes the issue to begin with.

 

Listen to these guys. They know what they are talking about. With these tactics, you will be fine with the 4+3.