4+3/ZF Swap
Thread Starter
Burning Brakes
Joined: Apr 2004
Posts: 792
Likes: 1
From: Stanfield NC
4+3/ZF Swap
The 4+3 is coming out of my track car, an 88, while it is still in good working order and I am putting in a ZF 6 speed form a 89-91 car. I was able to purchase the tranny, bell housing, flywheel, preassure plate, drive shaft, clutch ( will be replaced with new) and all the hydraulics from one source. My question concerns the C beam. Will the C beam from the 4+3 work or do I need the C Beam as well?
All of you who have been down this road before and have suggestions, hints and comments are invited to add your .02. The help would certainly be appreciated.
All of you who have been down this road before and have suggestions, hints and comments are invited to add your .02. The help would certainly be appreciated.
Melting Slicks
Joined: Apr 2000
Posts: 3,490
Likes: 2
From: Oviedo FL
CorvetteZ51Racer did this a couple of years ago and I copied his instructions:
Swapping a ZF 6 speed transmission into a 1984-1988 Corvette involves a lot of work. First and foremost, the shifter accomodations are different between the ZF and 4+3 transmissions.
Making the modifications for the shifter linkage is the most daunting part of the swap. Other than the fiberglass fabrication in the transmission tunnel, no fabrication work needs to be done: everything else is merely parts swapping.
Parts list
-----------
1) ZF 6 speed transmission out of an '89-'96 Corvette w/ bellhousing and shifter
2) Driveshaft from the same (actually, all you need is the output shaft yoke from the ZF driveshaft as the shafts themselves are the same, but they are VERY hard to find separately)
3) For the clutch setup, you have a few options:
a) stock ZF hydraulic clutch system, dual mass flywheel, and stock ZF clutch assembly
b) stock ZF hydraulic clutch system, single mass flywheel, stock ZF clutch assembly, and single mass conversion clutch pivot ball** Note: '85-'88 4+3 flywheels will work just fine. The '84 FW is too thin to use with a ZF-style clutch. Despite the fact that 4+3 clutches are listed as 10.75" clutches and the ZF is 11", it will work.
c) stock 4+3 hydraulic clutch system, single mass flywheel, McLeod p/n 1345 push-type throwout bearing conversion, and 4+3 style clutch.
4) IF your bellhousing is from a '92-'96, you will also need a new starter motor (LT1/4's use mini starter). '89-'91 bellhousings retain the 4+3 style starter motor.
5) If using the ministarter, you will need a longer (54" if memory serves...maybe 60") starter cable.
6) If possible, '89 center console plate. If you can't find one, don't stress, the '84-'88s will fit with a minor modification.
7) Fiberglass cloth, resin, and acetone.
Process
-----------
The first thing is to remove all of the 4+3 related parts. Do not forget to remove the 4+3's OD oil cooler tubes. They can be a major hassle to remove as they are full length hard lines that snake under the motor. If you don't need to save them, you can save yourself a lot of time by simply cutting them off in pieces and pulling them out part by part.
1) Get the car HIGH up on jackstands (the high-rise 3 ton jackstands work well for this).
2) Pull the entire exhaust off up to the manifolds/headers.
3) Remove the driveshaft.
4) Remove OD oil cooler lines, shifter linkage, and wiring.
5) Support the engine AND transmission on SEPARATE jacks or stands.
6) Remove the torque arm/C beam.
7) Disconnect the transmission from the bellhousing and remove from the car.
8) Remove the starter motor.
9) Unbolt bellhousing from the back of the motor and remove.
10) If you choose to reuse the 4+3 flywheel and clutch assembly with the McLeod TO bearing, you can skip ahead to step 16. If you choose to use the ZF style clutch, remove the clutch assembly from the flywheel.
11) If you are using anything other than the stock '85-'88 4+3 flywheel, remove the flywheel and install the new one (unless your rear main seal is leaking...now's a GREAT chance to replace it if it is
12) Install the new clutch assembly.
13) Remove stock 4+3 hydraulic clutch system. You will need to get under the dash to get the linkage between the clutch pedal and clutch master. BE VERY CAREFUL not to drop the spring clip for the pushrod!
14) If you're using the '92-up mini starter, you will need to install a longer battery cable to the starter.
15) Install new hydraulic clutch system. Be sure all who are easily offended are not present, as this step will induce high volumes of expletives (the aforementioned spring clip on the clutch pedal pushrod is a lot of fun to reinstall).
16) Install ZF bellhousing. If you are using a ZF style clutch, make sure the clutch fork is engaged with both the pivot stud AND the TO bearing before bolting bellhousing in place.
17) Install clutch slave cylinder. The pivot ball has an adjustable depth. Refer to the GM service manual for setting the pivot stud depth.
18) Ok...here's the LLLOOONNNNGGGG step. Time to go upstairs and do the transmission tunnel mods:
a) Remove both seats
b) Remove center console and transmission tunnel trim pieces to expose top and sides of the transmission tunnel
c) Remove entire shifter mechanism and bracketry from tunnel recess
d) Cut out recess from transmission tunnel. You will want to cut just wide of the edges of the recess. On the side of the recess towards the back of the car, you will end up cutting the fiberglass back to the joint with the steel floorpan.
e) Using a grinder or high speed rotary sander, you need to cut a ledge into the fiberglass....you're basically creating two tiers in the surface of the fiberglass. If possible, do this on both the inside and the underside of the tunnel.
f) take some fine mesh mechanics cloth (wire mesh) and mold it to create a smooth shape to the tunnel...you're trying to bring the tunnel back out flush with the rest of the piece.
g) I used a HOT batch of fiberglass resin to "glue" the mesh in place. Once the mesh is firmly in place, you want to apply 2-3 layers of fiberglass cloth on both sides of the wire mesh. I used 8oz cloth.
h) once the fiberglass patch is installed and cured, you want to mark the shifter hole location and cut it out. I used an angle grinder to cut the hole out.
19) Once the fiberglass patch is taken care of, the center console plate needs to be addressed. If you're reusing the '84-'88 plate, some of the plastic needs to be trimmed underneath the plate on the support structure to clear the rubber shifter boot.
20) If you're using the ZF style clutch, skip to step 22. For the McLeod TO bearing, you will need to make a -3 AN (or is it 4? Instructions included with the bearing specify the size) hose to run from the TO bearing all the way up to the clutch master cylinder.
21) Using the McLeod instructions as a guideline, remove the input shaft housing on the transmission, and bolt the TO bearing in it's place. Be sure that the bleeder hose is on top when the bearing is installed.
22) Install the transmission, making sure to carefully snake the AN hydraulic hose for the McLeod TO bearing through the slave cylinder hole in the bellhousing.
23) Install the shifter assembly.
24) Install the torque arm/C beam
25) Install the driveshaft
26) Install the starter motor.
27) Install the exhaust system
28) Reassemble interior
29) NOW GO DRIVE IT!!!
Mike
Swapping a ZF 6 speed transmission into a 1984-1988 Corvette involves a lot of work. First and foremost, the shifter accomodations are different between the ZF and 4+3 transmissions.
Making the modifications for the shifter linkage is the most daunting part of the swap. Other than the fiberglass fabrication in the transmission tunnel, no fabrication work needs to be done: everything else is merely parts swapping.
Parts list
-----------
1) ZF 6 speed transmission out of an '89-'96 Corvette w/ bellhousing and shifter
2) Driveshaft from the same (actually, all you need is the output shaft yoke from the ZF driveshaft as the shafts themselves are the same, but they are VERY hard to find separately)
3) For the clutch setup, you have a few options:
a) stock ZF hydraulic clutch system, dual mass flywheel, and stock ZF clutch assembly
b) stock ZF hydraulic clutch system, single mass flywheel, stock ZF clutch assembly, and single mass conversion clutch pivot ball** Note: '85-'88 4+3 flywheels will work just fine. The '84 FW is too thin to use with a ZF-style clutch. Despite the fact that 4+3 clutches are listed as 10.75" clutches and the ZF is 11", it will work.
c) stock 4+3 hydraulic clutch system, single mass flywheel, McLeod p/n 1345 push-type throwout bearing conversion, and 4+3 style clutch.
4) IF your bellhousing is from a '92-'96, you will also need a new starter motor (LT1/4's use mini starter). '89-'91 bellhousings retain the 4+3 style starter motor.
5) If using the ministarter, you will need a longer (54" if memory serves...maybe 60") starter cable.
6) If possible, '89 center console plate. If you can't find one, don't stress, the '84-'88s will fit with a minor modification.
7) Fiberglass cloth, resin, and acetone.
Process
-----------
The first thing is to remove all of the 4+3 related parts. Do not forget to remove the 4+3's OD oil cooler tubes. They can be a major hassle to remove as they are full length hard lines that snake under the motor. If you don't need to save them, you can save yourself a lot of time by simply cutting them off in pieces and pulling them out part by part.
1) Get the car HIGH up on jackstands (the high-rise 3 ton jackstands work well for this).
2) Pull the entire exhaust off up to the manifolds/headers.
3) Remove the driveshaft.
4) Remove OD oil cooler lines, shifter linkage, and wiring.
5) Support the engine AND transmission on SEPARATE jacks or stands.
6) Remove the torque arm/C beam.
7) Disconnect the transmission from the bellhousing and remove from the car.
8) Remove the starter motor.
9) Unbolt bellhousing from the back of the motor and remove.
10) If you choose to reuse the 4+3 flywheel and clutch assembly with the McLeod TO bearing, you can skip ahead to step 16. If you choose to use the ZF style clutch, remove the clutch assembly from the flywheel.
11) If you are using anything other than the stock '85-'88 4+3 flywheel, remove the flywheel and install the new one (unless your rear main seal is leaking...now's a GREAT chance to replace it if it is
12) Install the new clutch assembly.
13) Remove stock 4+3 hydraulic clutch system. You will need to get under the dash to get the linkage between the clutch pedal and clutch master. BE VERY CAREFUL not to drop the spring clip for the pushrod!
14) If you're using the '92-up mini starter, you will need to install a longer battery cable to the starter.
15) Install new hydraulic clutch system. Be sure all who are easily offended are not present, as this step will induce high volumes of expletives (the aforementioned spring clip on the clutch pedal pushrod is a lot of fun to reinstall).
16) Install ZF bellhousing. If you are using a ZF style clutch, make sure the clutch fork is engaged with both the pivot stud AND the TO bearing before bolting bellhousing in place.
17) Install clutch slave cylinder. The pivot ball has an adjustable depth. Refer to the GM service manual for setting the pivot stud depth.
18) Ok...here's the LLLOOONNNNGGGG step. Time to go upstairs and do the transmission tunnel mods:
a) Remove both seats
b) Remove center console and transmission tunnel trim pieces to expose top and sides of the transmission tunnel
c) Remove entire shifter mechanism and bracketry from tunnel recess
d) Cut out recess from transmission tunnel. You will want to cut just wide of the edges of the recess. On the side of the recess towards the back of the car, you will end up cutting the fiberglass back to the joint with the steel floorpan.
e) Using a grinder or high speed rotary sander, you need to cut a ledge into the fiberglass....you're basically creating two tiers in the surface of the fiberglass. If possible, do this on both the inside and the underside of the tunnel.
f) take some fine mesh mechanics cloth (wire mesh) and mold it to create a smooth shape to the tunnel...you're trying to bring the tunnel back out flush with the rest of the piece.
g) I used a HOT batch of fiberglass resin to "glue" the mesh in place. Once the mesh is firmly in place, you want to apply 2-3 layers of fiberglass cloth on both sides of the wire mesh. I used 8oz cloth.
h) once the fiberglass patch is installed and cured, you want to mark the shifter hole location and cut it out. I used an angle grinder to cut the hole out.
19) Once the fiberglass patch is taken care of, the center console plate needs to be addressed. If you're reusing the '84-'88 plate, some of the plastic needs to be trimmed underneath the plate on the support structure to clear the rubber shifter boot.
20) If you're using the ZF style clutch, skip to step 22. For the McLeod TO bearing, you will need to make a -3 AN (or is it 4? Instructions included with the bearing specify the size) hose to run from the TO bearing all the way up to the clutch master cylinder.
21) Using the McLeod instructions as a guideline, remove the input shaft housing on the transmission, and bolt the TO bearing in it's place. Be sure that the bleeder hose is on top when the bearing is installed.
22) Install the transmission, making sure to carefully snake the AN hydraulic hose for the McLeod TO bearing through the slave cylinder hole in the bellhousing.
23) Install the shifter assembly.
24) Install the torque arm/C beam
25) Install the driveshaft
26) Install the starter motor.
27) Install the exhaust system
28) Reassemble interior
29) NOW GO DRIVE IT!!!
Mike
Thread Starter
Burning Brakes
Joined: Apr 2004
Posts: 792
Likes: 1
From: Stanfield NC
Very Nice. Thanks! Nothing is mentioned about the c-beam. Any idea if mine will work or not? Seems that will be the last step in the installation and I would hate to get that close and find I didn't have the parts I needed.
