Rebuilding a 4 + 3

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Apr 21, 2010 | 01:20 AM

Lankhoss

Thread Starter

Racer

Joined: May 2006

Posts: 290

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Rebuilding a 4 + 3

Hello,

I just recently purchased a 1986 Corvette with the manual "4 + 3" transmission, and the overdrive does not work on it. It is looking like the internal seal between the two trannies was leaking, and leaked manual fluid into he automatic section, ruining it.

My friend that owns a shop is saying we should just put a 6 speed in the car. I was curious what the cost difference would be in going those two routes. I am thinking it will be much cheaper to just rebuild my stock tranny, but I am not sure.

Thanks.

Apr 21, 2010 | 02:42 AM

powerpigz-51

Drifting

Joined: May 2006

Posts: 1,428

Likes: 7

From: Chewelah Wa

You can rebuild it, buy a rebuild or pick up a good used one way cheaper and easier than any conversion. I picked up a good used one on Ebay for 500 bucks. I see them sometimes in the "For Sale" section of this forum, though not for awhile. Last time I checked, a rebuilt one was about 1200 bucks. http://www.5speeds.com/nash.htm http://www.skspeed.com/Xmas2009web.pdf

Apr 21, 2010 | 07:53 PM

Lankhoss

Thread Starter

Racer

Joined: May 2006

Posts: 290

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Quote:

Originally Posted by powerpigz-51

There is some great info on that site, thanks for the link!

Apr 21, 2010 | 08:03 PM

Lankhoss

Thread Starter

Racer

Joined: May 2006

Posts: 290

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Took the car to my friend's shop today, by the way. He does not work on Corvettes, and is not familiar with this transmission, however he got under the car to discover there was hardly any fluid in the O/D unit. We put about 2 quarts in, and I took it for a drive. The fluid was POURING out of the car, so we jacked it back up to find that some clamp had rubbed a hole in the metal lines going to the cooler. We quickly threw some rubber hoses on there just so we could get fluid pumped back into the unit, but my friend had an emergency come up and had to leave very quickly.

What was happening the first time we filled it with fluid, was the car would go into O/D, but the SECOND I gave it any gas (regardless of speed or RPM), it would come out of O/D. After putting the hoses on and fixing the leak, on my way home the car just wouldn't even show the O/D light on the dash at all (and didn't go into overdrive).

Jul 2, 2010 | 02:02 PM

tdr1919

Racer

Joined: Sep 2004

Posts: 258

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From: Coram NY

what have you done? repaired/ replaced or converted to a non OD transmission?
Thanks,
Tom

Jul 6, 2010 | 01:51 PM

88BlackZ-51

Race Director

Joined: May 2003

Posts: 10,749

Likes: 41

mine will be forsale in the future. it's an 88 model, and works mint! will be putting in a ZF for the added power of the 421 eventually....

Jul 6, 2010 | 06:22 PM

vetteoz

Safety Car

Joined: Jan 2004

Posts: 3,556

Likes: 13

Quote:

Originally Posted by Lankhoss

What was happening the first time we filled it with fluid, was the car would go into O/D,.

If as you say the O/d worked 1st time ,that would be a reasonable indication that the O/d is good and that you have a problem ( very common with age ) in the control side of operation.
Bad relay / bad connection / wiring , etc
Need to check all connections

Jul 6, 2010 | 07:51 PM

pmihaltian

Slingshot

Joined: Dec 2001

Posts: 3,817

Likes: 24

From: Charlotte NC

Once you get the fluid lines repaired and the unit filled with transmission fluid, the next thing to check it the OD button switch. This is a common failure over time and a cheap fix. Check this out before you charge off and spend money unnecessarily.