hello everyone, i have 85 c4 with a 1987 383 stroker and trans is manual 4+3. i am swaping in the zf 6 speed from a 90 c4. my zf is missing the speed sensor. can someone tell me what sensor i can use for replacement? 85 c4 to 90 zf also do i have to use duel mass flywheel? my present flywheel is ballanced to my 383 engine i can put up with some gear noise

hang on a bit, CC will be here with tons of advice as he has this exact swap......it's only 7:00am here on the West Coast....on a Sunday

Welcome!!!

I can step in here and fill in some immediate blanks.

The speed sensor is gonna he hard to come by... I think they are discontinued, but I don't know for sure. You will need to do something with the internal speed gears, too, but I don't remember what at this time. Central Coaster has all the info needed for this phase of the project.

You can use any flywheel with the ZF. The only reason they did the dual mass, really, was for noise reduction on the ZR box. So don't expect it to be quiet... far from it, especially at idle.

If I could recommend a solution, the RAM system, that uses the hydraulic throw-out bearing, looks like a good fix. Just get their flywheel match balanced to your existing engine balanced flywheel.

Match balancing is a process that mounts the two flywheels on a machine, 180 degrees out. The machine thens spins them up and tells the operator where to add weight on the unbalanced unit. This is a very common practice on the LT1 Corvettes because the DM is also the final say in engine balance. This makes the DM really impractical in a non-LT1 engine... you can get one match balanced, sure, but that's a pricy proposition - expect to pay $1000 for one - IF YOU CAN FIND ONE!!! I got the last one from the mid-west district warehouse... and you can't have it.

Back to hydraulics for a moment, I hope you have the ZF bell housing. I don't think the ZF will fit to the 4+3 bell housing. Central Coaster can confirm this. The hydraulics are not compatible between the ZF and the 4+3.

You will also want to consider upgrading the rear gear ratio. The 3.07 will not do jack with 6th gear! It's a .50:1 overdrive... and is just so tall that you won't be able to use it until over 90 MPH!!! If you have 3.33, that would work, but if you want the best ratio, 3.73 comes highly recommended with the ZF. The stock ratio for the ZF was 3.42. That's what I have in my 92.

Also, there are only a couple of approved oils for the ZF6... The stock GM fill, the BMW/Castrol TWS 10-60 (gotta get it at your local BMW dealer). I hear Amsoil and Royal Purple both make an oil that works really good.

I hope this helps clear up some points.

If you go to a 3.73 rear end, wouldn't 1st become as useless as 6th with a 3.07?

not at all... first is 2.68 on the ZF6... it rocks, yo.

Especially if that 383 breathes any...

ok guys i will deal with rear gears after trans is up and running (373 yea yea) i am a master truck mechanic, not compleetly stupid, i know you hold a hammer by the wood part, but when getting my new zf ready for my install i run into a problem!! how in the hay do you get the leather shift knob off of the stick? i twisted and pulled to no avail. also when i stab the trans should i leave the compleet shifter asembley off trans or just the stick, or none of the above

I assume you are removing the shifter from the ZF6?

If so, that's kinda easy... pop off the 6spd pattern cap from the knob. Under that is a wedge that needs to be pulled/pried out. After that, you can then unscrew the knob. Done.

This is not the EXACT part, but they make one for the ZF:

http://www.msperformanceonline.com/1630016.html

Also, Hurst used to make a shifter for the ZF6... I don't see it on their current catalog.

http://www.dougherbert.com/competitio ... f37f5dd04253c89fe5e855fcd

B&M makes one, too. But I can't find it...

In short, if you are drag racing, the B&M seems the better choice, if you are road racing or street driving mostly, then the Hurst.

I have the Hurst, it really shortens the throws without increasing effort.

It's a might as well whilst in there.

Oh, and I never said you were completely stupid... If I imparted that, sorry. All I was doing was sharing experience and insight.

sorry, not you at all. i was hinting that i may be dumb for not knowing how to remove knob. now that i know about wedge i will be ok. how about trans install. with or without shifter on it

with my stock 3.42 1st get's me to 60mph

So 3.73 should feel great.

Install with shifter on it, but knob removed. With the rear end up on 6-ton jackstands I can roll the ZF+shifter into place on my $50 Harbor Frieght trans jack. You can use the speedo sensor (vss) from your 4+3, but you'll want a different driven gear for accuracy. I believe I had to install the vss rotated 180 degrees (upside down) for it to mesh with the smaller drive gear. Check my link in the Tech Library for speedo gear selection. I have the rest of the list on an old thread somewhere with part numbers, try searching for threads with "bellhousing" in it and my username. I'm sitting in an airport now but I'll check in later with that info.

I READ ON ANOTHER FORUM ABOUT SHIMMING THE BELL HOUSING. WHATS THAT ALL ABOUT? IS THAT FOR USING MY 4+3 CLUTCH AND 87 FLY WHEEL? AND IF I USE McLEOD HYD. TOB I WONT HAVE TO SHIM. IS THAT RITE???

Quote:

yea, as brian c said, shifter on, knob off.

I am in the midst of this sorta myself... be on the look out for a thread from me shortly.

ok i am trying to do this install rite. today i bought a 91 zr 1 clutch, pressure plate, cl. master and slave, i also got the duel mass fw as i didnt want the gear noise, now for my question. my engine is a 87 383 internal ballanced that calls for netural ballance FW. SO DO I HAVE TO GET THE D. M. FW BALLANCED? or is it already netural

ok i am trying to do this install rite. today i bought a 91 zr 1 clutch, pressure plate, cl. master and slave, i also got the duel mass fw as i didnt want the gear noise, now for my question. my engine is a 87 383 internal ballanced that calls for netural ballance FW. SO DO I HAVE TO GET THE D. M. FW BALLANCED? or is it already netural

It is not neutral balanced, it will need to be.

And I am not sure if the ZR1 DMFW will work...

wheeh!!! just called vettes to vettes, its not zr1 duel mass.it came out of 94 c4 w/6 speed. thanks for keeping me on my toes

That flywheel won't work.

I wouldn't suggest reusing your stock one either. Get an aftermarket replacement that has a full face or it won't play well with the 11" clutch.

It's on here along with the rest of the parts list. It should not need any balancing, just line up the dowel hole on the crank to be safe. The clutch pressure plates can also have a painted spot, line this up with the painted spot on the pressure plate you're removing. But if the paint spot is long gone, then don't worry about it, you won't notice a difference.

...............
....................
...........


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 (recommend cast iron unit)

91-96 clutch slave cylinder (recommend cast iron unit)

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 (good idea to replace if installing a used trans)

Backup switch connector, a.k.a. horn connector, AcDelco # PT1357 or Napa # ECHEC11

(5) metric M12 x 45mm transmission bolts, McMaster.com # 92820A650
(hard to find at local hardware store)

(6) standard 3/8" x 1-3/4" pressure plate bolts, McMaster.com # 92316A630
(hard to find at local hardware store)

17mm allen driver socket attachment (for fill & drain plugs, available at autozone/kragen in a 3-pack, hard to find at local hardware store)

12mm allen driver socket attachment (for fork pivot stud, Hard to find at local hardware store)

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:

SEE PIC ATTACHED BELOW

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.

Attach file:

---

  clutchpartslist.gif (24.83 KB)

i started removing my 4+3 shifter, what is the cable for?? has 3 rods plus a cable

That is that cable that goes to the ignition.....the one that makes you put it in reverse to get the key out.

ok, thanks dont need it with the zf. dont work anyway, key come out in any gear lol

Check the backup light switch is working before you put trans in car.
PITA to get atehen installed

i did ck b.u. switch. it is working

Quote:

Yeah, pretty lame feature. Previous owner on mine disconnected it too. I think I just coiled it up and shoved it behind the stereo.

CENTRALCOASTER says duel mass fw wont work. why not??? my 383 is 1987 block

Quote:
But you state;

"my engine is internal balanced "
'87+ 1 pce seal engines are ext balance at rear from factory ,which is what DM flywheel is. You no longer have the stock balance arangement

In order to neutral balance a DM your have to get the cast weights machined off risking cutting into the hollow part that contains the dampening fluid.
Read
http://forums.corvetteforum.com/c4-te ... ywheel-is-oozing-oil.html

That is why when modifing a engine you retain the stock balance configuration because you can walk into any shop and get a correct balance flywheel of the shelf (if you can find a new DM these days)

http://forums.corvetteforum.com/c4-te ... ass-flywheel-article.html

But you can add metal back to the DM, right? But I don't see the point... they weigh enough as it is!!!

When I do my build, I am going to get a RAM setup with the hydraulic throwout bearing.

http://www.ramclutches.com/Specialty%20products/C4_Conversion.htm

Quote:

You are going to be taking weight off a DM to make it neutral

http://forums.corvetteforum.com/1569152833-post6.html

Quote:

You will need to bring it to the machine shop and have them cut the weight off the side. I forget what the back of the DMFW looks like, but if it's a normal casting it will have an obvious cast in (and slightly machined) weight that can be removed on the mill. Expect to pay about $100 to make it neutral (no counterweight).

Internally balanced simply means the the counterweights of the crank offset the weight of the pistons.

Internally balancing is nicer on the main bearings, but I don't like doing it to motors that are OE spec to be externally balanced (i.e, your 87) because you end up with an oddball that you have to remember is neutral balanced. Just a preference of mine.

Then again, I'm breaking my own rule by internally balancing my 412, since the 400 block should be externally balanced.


-- Joe

Quote:

In theory, you could weld a bar of tungsten to the other side of the counterweight making it neutral too. That would probably end up being a $300 balance job though ;)

-- Joe

agreed.

Quote:

Ok, I missed that part. See my list again. The DM flywheel WILL bolt up, but looks like everyone recommends getting it neutral balanced. GM used the flywheels to balance the back end of the motor from the factory. So unless it was there when you had your 383 balanced, you might want to take that flywheel in.

i see what you meen. i may have to get it welded to add weight. i bought eng. short block w/ internal bal. and i bouhgt duel mass from vette2vette so i will have to make it work. didnt know it had fluid, thought just had springs. bolt in zf!!! i am getting a HEAD ACHE..

There's other flywheels out there that will work, but they'll be noisy.

just wanted to take a moment to thank everyone for taking the time and for all the great info, (priceless) starting the swap this weekend, and probley finish next weekend. P.S. just mite need some more help

Quote:

Joe , I don't see the physical difference.

From the factory; a "internal " balance 2 pce seal engine has the counterweight on the crank (considered to be a internal part) even though the weight is external to the engine.

With a factory "external" balance 1 pce seal engine because of the redesign to fit the new seal , a smaller weight was placed on the flexplate / flywheel.

As both setups place the weight are behind the rear main bearing , what are the load differences on the engine?

hm... I agree. What difference?

If, for example, a NASCAR motor is (the old motor was street sourced) based on an externally balanced crank all of a sudden gets a different crank and rotating mass that is now internally balanced, why doesn't it blow up?

From my perspective, a internally balanced motor has to be better because the weight is right (distributed?) all away across the crank. The rods and pistons are the same weight and the crank counter weights get drilled or mass added to bring the mass into balance.

It's why an F1 engine can spin to 19000 RPM... it's why a NASCAR motor can spin to 9800 RPM... or a drag big block all the way up to 11000 RPM.

And we are aiming at 7500 RPM, tops. Now, I would LOVE to build a smallblock that would spin to 8500 RPM. That would just be cool. But the $$$ is staggering. As an aside, Ferrari does offer a 6 litre V12 hits 8400 RPM. Mind boggling.

I guess the debate is if the crank is balanced across the mass or just balanced at the rear of the motor... That, I would guess, could make a difference.

Quote:

Are you saying the flange where the flywheel bolts up is where the balancing is done? I don't remember seeing any machine marks in mine.

when eng. is internially balanced the fly wheel has to be neutral, no counter weight

Quote:

Exactly , but to my mind that counterweight is still behind the rear main bearing; on an old 2 pce crank it is a big weight close to the crank centerline as part of the crank flange.

[IMG]http://i171.photobucket.com/albums/u309/vetteoz/SA110_26.gif[/IMG]

In a 1 pce crank ,the weight is in the same location relative to the bearing ;
only a smaller one is used further from the crank centerline (weight on flexplate )

[IMG]http://i171.photobucket.com/albums/u309/vetteoz/SA110_2_3A.gif[/IMG]
[IMG]http://i171.photobucket.com/albums/u309/vetteoz/flexplate.gif[/IMG]

My 383 is factory 1 pce "ext" balance at rear but because of the lightweight internal components ,weight was removed from the flexplate weight

I guess I am missing something regarding balance, too...

i didnt want trans noise, thats why i went with duel mass fw and sent it out for nutural balancing. cornell ind.in troy, mi. said thay could it, no problem