Swapping out a 4+3
Race Director
Joined: Feb 1999
Posts: 12,772
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From: Indianapolis IN
Re: Swapping out a 4+3 (B387)
I'm in the process,
the straight forward approach is the ZF6, it can be bought from GM for $1800 + shipping. You can get the rest of the parts from a salvage yard or as a package. You need Clutch Slave, Clutch Master ( sort of) , clutch fork, bellhousing, output yoke, and shifter from a ZF model year, 89-93
http://hometown.aol.com/corvettez51r...age/index.html
I am, sure others will chime in!
the straight forward approach is the ZF6, it can be bought from GM for $1800 + shipping. You can get the rest of the parts from a salvage yard or as a package. You need Clutch Slave, Clutch Master ( sort of) , clutch fork, bellhousing, output yoke, and shifter from a ZF model year, 89-93
http://hometown.aol.com/corvettez51r...age/index.html
I am, sure others will chime in!
Thread Starter
Advanced
Joined: Jun 2004
Posts: 78
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From: Olympia wa
Re: Swapping out a 4+3 (ld85)
ld85. Ok, keep me posted how it goes. Any idea what a working 4+3 would be worth if I wanted to sell this one? The only problem I have had is 2nd gear occassionally pops out on decel. The car has 137000 miles, but mechanically seems in great shape. I just bought this car as kind of a winter project, so I'm exploring all of the things I might like to do to it. Appreciate the input.
B387
B387
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Joined: May 2004
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From: St. Charles IL.
Re: Swapping out a 4+3 (B387)
4+3 worth $600.00 to this 4 speed guy named Darrell but I can't find his card right now. The richmond 6 speed is the easiest swap. bolt it to your clutch and bellhousing and throw it in. I have been researching this myself to do this month. It is supposed to work well with the 3:07 rear end. :flag 
Race Director
Joined: Feb 1999
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From: Indianapolis IN
Re: Swapping out a 4+3 (DaveAnd)
The richmond 6 speed is the easiest swap. bolt it to your clutch and bellhousing and throw it in. I have been researching this myself to do this month. It is supposed to work well with the 3:07 rear end. :flag
If you dont mind having a 5th gear 1:1 instead of a 4th gear 1:1
Thread Starter
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Joined: Jun 2004
Posts: 78
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From: Olympia wa
Re: Swapping out a 4+3 (ld85)
id85 Thanks for the info. I visited the web, and found it most informative. Do you know of anyplace I could get some pics of the tunnel surgery and reconstruction? It does sound kind of daunting.
Thanks for the help
B387
Thanks for the help
B387
Thread Starter
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Joined: Jun 2004
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From: Olympia wa
Re: Swapping out a 4+3 (DaveAnd)
Thanks for the reply. I checked the richmond site, and found the instructions for the swap. It seems to save a lot of parts and fabrication of the tunnel, but its a little more expensive on the front end. $3,200 was the price I found for the 6spd. It might still be worth it to go this way. What are you going to do?
B387
B387
Race Director
Joined: Feb 1999
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From: Indianapolis IN
Re: Swapping out a 4+3 (B387)
Sent email pics from http://www.zfdoc.com
BTW I pciekd up my ZF today from http://www.vette2vette.com ,very very nice people!
BTW I pciekd up my ZF today from http://www.vette2vette.com ,very very nice people!
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Burning Brakes
Joined: Nov 2001
Posts: 1,189
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From: Austin TX
Re: Swapping out a 4+3 (ld85)
If you dont mind having a 5th gear 1:1 instead of a 4th gear 1:1
with a 3.28 first, 1:1 5th, and .76 overdrive 6th is a great combination for
a 3.07 rear. I trap in the quarter in 4th gear which works out to a 3.81
final drive ratio, and turn about 2300 at 70 mph on the highway in 6th.
Dan
Race Director
Joined: Feb 1999
Posts: 12,772
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From: Indianapolis IN
Re: Swapping out a 4+3 (danno85)
If you dont mind having a 5th gear 1:1 instead of a 4th gear 1:1 With a 3.07 rear gear this works out really well. The Richmond 6 speed
with a 3.28 first, 1:1 5th, and .76 overdrive 6th is a great combination for
a 3.07 rear. I trap in the quarter in 4th gear which works out to a 3.81
final drive ratio, and turn about 2300 at 70 mph on the highway in 6th.
Dan
[Modified by ld85, 11:12 PM 7/2/2004]
Tech Contributor
Joined: Jun 2004
Posts: 20,905
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Re: Swapping out a 4+3 (B387)
B387,
I put the Richmond 6 spd in mine about four years ago. Other than minor surgery to cut out the original tunnel "shifter box", it was pretty straight forward. The latest Summit catalog shows a $2900 (with shifter) price tag. It might be a few bucks higher to get the modified tailhousing, I don't remember. Back then I was under the impression that installing a ZF6 box would be more expensive, and require several other changes to the car/clutch/drivetrain. And as far as the 1:1 fifth gear, who cares? The car and tires only know the total torque multiplication of the trans and differential. Mix and match the gears to get whatever you want. Unless you feel the need to worry about secondary or third order issues (driveshaft torque limitations or rear axle ratio selection limitations), it's merely an RPM/vehicle speed issue.
Good luck,
Mike
I put the Richmond 6 spd in mine about four years ago. Other than minor surgery to cut out the original tunnel "shifter box", it was pretty straight forward. The latest Summit catalog shows a $2900 (with shifter) price tag. It might be a few bucks higher to get the modified tailhousing, I don't remember. Back then I was under the impression that installing a ZF6 box would be more expensive, and require several other changes to the car/clutch/drivetrain. And as far as the 1:1 fifth gear, who cares? The car and tires only know the total torque multiplication of the trans and differential. Mix and match the gears to get whatever you want. Unless you feel the need to worry about secondary or third order issues (driveshaft torque limitations or rear axle ratio selection limitations), it's merely an RPM/vehicle speed issue.
Good luck,
Mike
Race Director
Joined: Feb 1999
Posts: 12,772
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From: Indianapolis IN
Re: Swapping out a 4+3 (69427)
B387,
And as far as the 1:1 fifth gear, who cares?
Good luck,
Mike
And as far as the 1:1 fifth gear, who cares?
Good luck,
Mike
Since my car started out with a 4+3 I liked having a true over speed, and 2-OD's are plenty for highway speed, the RO6 has a short first gear, I thought.I agree either tranny will suffice.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Re: Swapping out a 4+3 (ld85)
Id85,
I'll confess I haven't spent much time thinking about the two shifts versus three shifts in the quarter mile, as all my playtime is on roadcourses ('84 Z51 single turbo 355 w/ROD6). At the time I ordered the gear box Richmond offered customer selected gear ratios in the box. I did a bunch of rpm vs speed calculations and then picked (from the gear charts) the ratios I wanted. At the end of the day, just drop it in sixth gear, and it's a cruising machine. All in all I'm happy. Big improvement over the 4+3.
I'll confess I haven't spent much time thinking about the two shifts versus three shifts in the quarter mile, as all my playtime is on roadcourses ('84 Z51 single turbo 355 w/ROD6). At the time I ordered the gear box Richmond offered customer selected gear ratios in the box. I did a bunch of rpm vs speed calculations and then picked (from the gear charts) the ratios I wanted. At the end of the day, just drop it in sixth gear, and it's a cruising machine. All in all I'm happy. Big improvement over the 4+3.