| Re: 4+3 transmission |
Subject: Re: 4+3 transmission by CentralCoaster on 2008/3/6 3:29:11 Why are you getting rid of the 4+3? Going to a ZF isn't cheap or easy, compared to making what you have work. I really enjoyed my 4+3 until I destroyed it racing on a dead clutch cylinder. Plus the factory programming on your 88 defaults to overdrive on, which is stupid, and can be undone. A ZF6 swap will cost you about $1600 with a used trans, $2200 with new. COMPLETE PARTS LIST FOR 4+3 TO ZF6 CONVERSION: 84-85 Corvettes only: 89-93 black-tag ZF6 & 90-93 ZR1 clutch set or 95-96 blue-tag trans & 95 ZR1 clutch set Standard Flywheel p/n: 6516 from Kragen/PartsAmerica (reusing original flywheel not recommended) 86-88 Corvettes only: 89-93 black-tag ZF6 & 90-93 clutch set or 95-96 blue-tag trans & 95 clutch set Reuse stock flywheel or 89-96 ZF6 (dual mass) flywheel Everyone: 91-96 bellhousing, from salvage yard 89-96 clutch fork and pivot stud, from salvage yard 88-91 starter 89-96 clutch master cylinder 91-96 clutch slave cylinder 91-96 clutch slave hose, from salvage yard 89-96 driveshaft, from salvage yard (or just get the slip yoke and install it on your 85-88 manual driveshaft) TH400 rear seal, Timken #9449 (optional) Backup switch connector, a.k.a. horn connector, AcDelco # PT1357 or Napa # ECHEC11 (5) metric M12 x 45mm transmission bolts, McMaster.com # 92820A650 (6) standard 3/8" x 1-3/4" pressure plate bolts, McMaster.com # 92316A630 17mm allen driver socket attachment (for fill & drain plugs, available at autozone/kragen in a 3-pack) 12mm allen driver socket attachment (for fork pivot stud) 3 quarts of GM 1052931 or Pennzoil Synchromesh from Autozone Sheetmetal, rivets and sealant for patching the trans tunnel, and some extra carpet insulation. Hurst B-4 Shifter Boot p/n 1144580 or OEM 89-96 shifter boot For dealing with salvage yards..., refer to my part number/application guide and make sure you're getting the right stuff: CLICK HERE CorvetteSalvage.com and Vette2vette.com are recommended. Beware of defective parts! The ZF6 replacement throwout bearings are Chinese and prone to failure. Inspect the rear flange carefully before purchase for cracks. If it breaks, the car will be undriveable. CLICK HERE For awhile, many of the slave cylinders were defective from the factory with a backwards seal. This has since been addressed, but check anyways incase you got an old one: CLICK HERE CLICK HERE ALSO Shifter Upgrade: I highly recommend installing a Hurst or B&M shifter before installing the ZF6. They are far superior to the stock shifter but are a bitch to install when the trans is in the car. Gearing and Vehicle Speed Sensor (speedo) The stock 3.07 ring/pinion makes 6th gear unusable under 85mph. I recommend upgrading to a 3.33,3.45, or 3.55 ratio. This will require changing your speedometer gears. CLICK HERE Some background info on the VSS: There are 4 types of VSS's, "large gear" 40-45 teeth, or "small gear" 35-40 teeth, and "early" 84-90, or "late" 91-96. 4+3 owners, just install your old VSS in the ZF6. Automatic owners, you can install your "small gear" VSS upside down in the ZF6 to get proper mesh. Push-type Clutch Options: You can retain your "push type" clutch setup with the ZF6 if you convert to a hydraulic throwout bearing. This gives you a superior clutch setup, and more clutch options, but isn't bolt on. Check with forum member LD85 for more info. Hydraulic throwout bearings are made by McLeod, Howe and Ram. debunking a few myths: My 85 did not require a longer battery cable (+). The stock one is long enough. I had to tweak the end of the cable to fit the ministarter terminals and rerouted it sideways to the positive battery terminal to get extra reach. Do this when the bellhousing and trans are out of the car. The longer ZR-1 pivot stud was NOT used. I used the regular pivot stud tightened down all the way. The fork comes close to the rear of the bellhousing with clutch out, you'll need to slide it onto the pivot stud, put the bellhousing in place, then tighten the stud into the bellhousing.[/QUOTE] |
