1993C4LT1

I've been doing research on the ZF6 because I've been wanting to get a 6spd C4. I do have a few question and concerns.

Are parts hard to find for it?

If I ever need a rebuild, it seems like Bill B is the only person who will do it the best?

And the rebuild will be at least 3 grand?

Are the ZF's like an auto in that, if you flush them and they have more than 70k miles, it could start shifting bad?

What is the difference between using a dual mass and single mass flywheel?

What are some signs the ZF6 is in bad shape?

Might come up with some other questions

Kevova

If changing fluid causes problem either the wrong fluid was installed or it was already broken. Dual Mass was to reduce vibration and noise. They will rattle in neutral. zfdoc.com for parts and more info.

zr1fred

Parts can be hard to find, and are expensive when you do find them. There are a lot of places that can work on them (in larger towns), chose carefully though. ZFdoc here in Phoenix is probably one of the best, and has been around a long time. Figure at least 3k PLUS R&R. Good rule of thumb, if you have concerns, don't buy it. Its definitely NOT a do it yourself transmission.

1993C4LT1

That kind of worries me on buying a 6spd lol

SJW

There is absolutely no reason to fear buying or owning a ZF-equipped C4. In fact, I'd argue (and plenty of others would agree) that the ZF C4s were the best of the breed.

The ZF is a very nice gearbox, and quite durable. Just make sure the one you buy has no problems when you buy it, and you're very unlikely to have any trouble so long as you follow these three basic rules:

1. Change the gear lube at the intervals ZFDoc recommends, and use a lube that he recommends.

2. Don't try to shift gears if the clutch isn't fully disengaging (this will quickly kill synchronizers).

3. Don't do anything else that would constitute outright abuse.

I wouldn't own a C4 that had any other transmission in it.

Live well,

SJW

pologreen1

A old vendor here was selling me the COMPLETE conversion for $800 on a pallet. 100% complete including computer, etc...

A local place here said there are tons of changes to the zf, they would charge 1200- 1500 to rebuild a used one if I did it.

I'm happy now with gears and a stall. Stall is key. My 2800 yank stall made the car pull like a freight train, the it wanted to rip loose in the cam band.

Now I have a 4k stall and it's more happy with it, but the car does not pull as hard, it will just blow the tires off period even at highway+ speeds when stepped down.

1993C4LT1

Polo, I thought your C4 was stick? Thanks for the info SJW.

pologreen1

2 mustangs were stick, 2 vettes auto. I parked this one for 8 years due to the auto factor, but now I'm happy with it. It's rather old school now so I still have to put it in N sometimes etc and I made a custom shifter so it feels like a fun car now.

1993C4LT1

May ask why you had to park it for 8 years? From what I've read, it seems like the ZF will last longer(with both trans in stock form) if you like to get on it, and I like to get on it. But hey man, glad your car is back on the road

pologreen1

Disappointment with the car. Did not care to do anything with it. Always knew what I wanted, but the economy and times said the car is not worth anything and stupid to put money in to a 90 vette.

I eventually had a bite on CL that turned out to be a member here and we did not make a deal, so I offered him money to get it going to give to wife or sell, and get a viper or whatever. Then a complete rebuild of the car later it is better than expected. Glad I did not make it stick as much as I craved it. I listened to Bjankuski here and he has had automatic and done them right. It's a blast when done right. I now look back and laugh. And I laugh at the guys with the stock cars calling mine a girls car. I like it a lot. If you plan to make power auto is a blast. I can DRIVE the car way better like this. If it was stick and I might put a blower on it yet I would have to go auto anyway, or get the t56 mag or what ever anyways. If it was stick I would not like driving it as much the way the car was built in the end anyways.

For me the zf is not the best even if I went stick. My trans is built to match my motor at 750hp. My motor can make 1200 with n20, but the trans won't.

The zf is expensive overall to deal with.

Fine for stock or somewhat modified but they are not made to handle big hp thought the black tag can do ok.

Mine is auto, BUT completely fresh almost finished build. More not listed. Now carbed, but still computer controlled too on fans, TC, etc...



*ENGINE*: NEW
_______________________________
-Dart 434 sbc forged
-Diamond pistons
- 3 core radiator, customized to fit in the '90 no surge tank
-New flywheel
-AFR 220 comp ported heads flow the same as 227 shaft heads
-Howards racing cam 296/302, 248/256 @.050 on a 110 LCA with .650 lift
-Howards racing push rods
-Howards racing 1.6 roller rockers
-Dual roller timing chain
-March under drive pulleys
-7quart road race oil pan / removable windage tray
-customized efi converted single plane Motown intake
-custom fuel rail lines
-Kirban racing adjustable fuel pressure regulators and gauges
-Wahlbro 1,000 hp E85, or regular fuel pump
-custom tuned chip
-Procomp adjustable rev limiter
-Custom billet engraved valve covers
-New wires
-New plugs
-New cap and rotor
-Oil cooler
-AC delete custom brackets
- Nascar air cleaner
-Holley 850 hp double pumper

*EXHAUST*:
_______________________________
-Tpis Long Tube headers
-Stainless Steel dual 3" straight pipes
-X pipe
-mufflers
- TPIS 02 sensor Heated (removed)

*DRIVE TRAIN*:
_______________________________
-D44 3.45 gears
-D44 Rear end/ Drive shaft / C beam
- ZF DOC C beam plates
-Shift kit
-built 700r4 to hold 750 hp
-Shift points changed
-B&M Trans cooler
-Derale Power Steering cooler
- TCI 4000 stall
-New MOOG half shaft U joints
- New MOOG drive shaft u joints
-New wheel bearing hubs

*CHASISS*:
_______________________________
-R&D camber brace
-R&D cross frame brace/ camera mount
-R&D sub harness belt/fire extinguisher brackets
-GM X frame brace
-Mitch Piper Custom 8 point rollbar ...not installed
-!2" grant steering wheel, removable

*SUSPENSION*:
_______________________________
-Bilstein sport shocks
-VB&P race springs (stiffer than Z51)
-VB&P 32mm front and 26mm rear sway bars
-New ball joints
-New hubs
-New braided brake hoses
-New drilled / slotted brake rotors
-New brake pads
-Vacuum canister for brakes

*BODY*:
_______________________________
-Race AirDam with brake cooler ducts/tubes
-Greenwood body kit
-4" harwood cowl scoop
- GTO C4 race wing
-Interior dress up / short auto shifter/ custom auto shift ****
-GM Auxiliary Hard Top
-Grand Sport wheels/chrome caps
-new hood strut
-added 2 side hood struts

*DELETED PARTS*:
_______________________________
-A/C system
-A.I.R. system (smog)
-Heater core (un hooked)
-surge tank
-Idler pulley
-Spare Tire / Carrier / jack
-Horns
-Air bag
-Cruise control
-Radio / speakers
*STILL HAVE ALL THESE PARTS*

1993C4LT1

Damn your is badass no doubt. Thanks for sharing the mod list

keep going back and forth between auto and stick

QCVette

For me the 6 speed is just more fun to drive. I like having full control on which gear. I like working through the gears on acceleration, and I like downshifting to engine brake. I had an automatic as a daily driver and although it made for a nice commuter car (100 miles/day), I sold it to get a 6 speed that I enjoyed a lot more. It made me look forward to the commute.

Parts can be expensive, however you can find some good prices if you shop around and are patient. I got a complete setup from a part out '90 that had a brand new dual mass, new Valeo disc and pressure plate with a new INA throwout bearing, and a perfect shifting black tag with shifter all for $650 plus shipping. (I said new on all the flywheel/clutch parts because I could see all the original machining on the friction surface and even the paint lettering on the friction surface of the disc.)

I think my find was much better than most deals, however I see a lot of used low mileage ZF transmissions for under $1000, and there are some deals on dual or single mass flywheels for under $100. Jim at PowerTorque systems can correctly refinish and rebalance the dual mass flywheels.

I have had 4 cars with the ZF and never had a problem with the transmission. Some were low mile, but my '94 was up to 140k miles (I put on about 45k miles). So I think they are pretty durable.

I think it is simply what do you enjoy driving the most unless there is a specific reason for one or the other. My wife has had some knee problems so she needs an automatic, stop and go traffic many prefer the automatic, many drag racers prefer the automatic.

Good luck with your choice.