sse94

Hi!
I'm new to this forum and I was wondering if someone could help me out with findning an exploded view of the C4 4+3 manual transmission. Since I'm new here, I'm having a hard time finding one!
Thanks!

sse94

Why I'm interested in the exploded view is because I was wondering if I have to "connect" the last three gears to have the car going, or can I just ignore "connecting" them?
I'm sorry if the question is confusing, I'm not that good at english and terms differ from different languages

frank j. moran

I'll try to help you. Are you trying to repair the transmission or are you trying to understand how to drive the car with the 4/3 transmission.

vetteoz

You don't have " 3" last gears.
The gearbox is a BW Super T10 4 speed with a 2 speed O/d attached at the rear so you have a 4 speed trans with overdrive available on 2nd , 3rd and 4th
that give the extra 3 gears

Depending on what the problem is (mechanical or electrical ) causing the O/d unit to not work which I assume is the question you are asking ?
you can possibly still drive it as a 4 speed without using the O/d

Explain what your problem is and we may be able to help you fix it
Electrical problems are common with age and it may only be a faulty relay or bad wiring that is stopping it from working

In the pic you can clearly see the O/d unit attached to the rear of the Super T10 gearbox

c4cruiser

It woud also help to let people know the year of the car. While the 4+3 is pretty much mechanically the same, operation on the OD is different depending on the year. Here's a good link to how the OD operates by model year.

Also, if you intend to do any work on the car or transmission yourself, it would be a very good idea to get a Factory Service Manual (referred to as an "FSM") for your specific year of car. There will be a section in the book that has everything you are looking for, including exploded views and step-by-step instructions for tear-down and reassembly. FSM's can sometimes be found in the C4 Parts For Sale section or on eBay.

1985 Corvette

Check Ebay, as well. I saw someone on there selling 4+3 OD rebuild manuals for $20 a piece. You can still run the car without the OD but last person I talked to who ran it without one said it was screaming at certain speeds. I thought about rebuilding an old 4+3 I had and I REALLY wanted to but the OD section seemed so finicky. There's an old pic floating around here from the "101 projects for your Corvette" that details graph-style with a particular rear gear what speed and rpm 1-4 allowed with and without OD operation.

vetteoz

http://www.corvetteactioncenter.com/...Overdrive+Unit

sse94

Thank you for all the great responses! I recently came home from a vacation, so I haven't been able to respond.
The thing is, I'm building a AC-Cobra replica, which is all Corvette under the hood. I was wondering how you would connect and set up this transmission without the overdrive enabled, in a safe way. Would I need to fill the overdrive unit with oil? And how would one connect and wire correctly for this to work?
Your help is greatly appreciated! And I hope I'm making myself understandable..

sse94

And the transmission model year, I would estimate to be approx 1990

AGENT 86

All you need to do is supply 12v+ to OD solenoid input. On/off switch would work fine, or use with a relay.
Is the motor, computer controlled ?

sse94

The engine has it's own ignition system, so it's not computer controlled. Also does the overdrive unit need a cooling system?

AGENT 86

Yes, the factory cooler is built into rad.

sse94

Thank you so much AGENT 86! You've helped me a lot! One last question though, what oil do I need to use in the manual part of the transmission?
Again, I'm so grateful for the professional help you've given me!

AGENT 86

80W/90 gear oil in trans
ATF in OD unit