Clutch bad. Decisions, decisions
Thread Starter
Racer
Joined: Jun 2009
Posts: 429
Likes: 0
From: Marlborough CT
Clutch bad. Decisions, decisions
Well I had the wonderful suprise the other day driving home from NH. My clutch is bad. It is still drivable, but if I get on it the car just rev's up. My question is while I am doing the clutch I might as well do the ZF6 swap, right? From what I understand the ZF6 is a direct swap, with a little floor cutting for the shifter. I also understand I need a conversion kit, is this correct? My next two days will be dedicated to the search function. A few questions I have are with the ZF6 what type of clutch should I get? Where can I get a conversion Kit if it is needed? What is the difference between Blue tag and Black tag ZF6's? Anything else I should be aware of like speedo problems? Thanks for any help.
Back to the search.....
Back to the search.....
Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
Black tags are the preferred ones, but hard to find. They have a more square-cut gear and are rated for higher hp/tq loads than the blue tags. They changed the cut of the gears after a few years because they got complaints they were too "noisy"...
Le Mans Master
Joined: Mar 2001
Posts: 7,999
Likes: 14
From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
Cruise-In III Veteran
Cruise-In IV Veteran
St. Jude Donor '12
On top of the cost and noise of a ZF your gonna need to go to a single mass flywheel. The dual mass ones are unobtanium.
Depending on the wieght you chosse it will be between "rocks in a can" to "very large rocks in a 55 gal drum" noise with the clutch out in neutral
Depending on the wieght you chosse it will be between "rocks in a can" to "very large rocks in a 55 gal drum" noise with the clutch out in neutral
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,289
From: Central Maryland
The black-tag boxes have a slightly higher input torque rating, but generate more noise than the blue-tag boxes. This is because the blue-tag boxes have a steeper helical angle to their gears. Both are plenty stout, and unless you're planning to feed much more than stock power levels through them, either should hold up just fine.
I recently installed a Spec Stage 2 clutch kit, along with the Spec extra-weight billet steel single-mass flywheel, in my '94 with the blue-tag box, and am very pleased so far with the setup. No rocks-in-a-can noises, silky-smooth clutch engagement, and a Kevlar-faced clutch disc which I'm hoping will hold up just fine behind my stock LT1.
Live well,
SJW
I recently installed a Spec Stage 2 clutch kit, along with the Spec extra-weight billet steel single-mass flywheel, in my '94 with the blue-tag box, and am very pleased so far with the setup. No rocks-in-a-can noises, silky-smooth clutch engagement, and a Kevlar-faced clutch disc which I'm hoping will hold up just fine behind my stock LT1.
Live well,
SJW
Thread Starter
Racer
Joined: Jun 2009
Posts: 429
Likes: 0
From: Marlborough CT
Thanks for the input so far guys. I have seen the posts about excessive noise with the ZF6. The noise doesn't really bother me too much as long as it is not causing damage. Down the road I plan on heads/cam combo and long tube headers, but nothing monstrous. Still digging through all of the threads. There is a lot info on this site.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
Likes: 196
From: folsom california
respectfully disagree. have sec stage 3 plus clutch and their 22 lb billet (light weight) steel flywheel; more like an early 60 muncie truck 4 speed with granny gear and unsynchronized first gear. hardly "rocks in a can".
Melting Slicks
Joined: Apr 2007
Posts: 2,616
Likes: 111
funny how you describe it but yea.......I have had both the blue/black tags in mine.....with an aluminum light weight FW.......if the blue tag is quieter I sure can't tell the difference.......with my engine mods coupled with the aluminum FW, it is one noisy tranny........love it though! don't drive it every day, if I did I would go with a heavier FW as mentioned above; in fact I bought a steel, one piece FW just incase......me and the car are getting older 
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
The black-tag boxes have a slightly higher input torque rating, but generate more noise than the blue-tag boxes. This is because the blue-tag boxes have a steeper helical angle to their gears. Both are plenty stout, and unless you're planning to feed much more than stock power levels through them, either should hold up just fine.
I recently installed a Spec Stage 2 clutch kit, along with the Spec extra-weight billet steel single-mass flywheel, in my '94 with the blue-tag box, and am very pleased so far with the setup. No rocks-in-a-can noises, silky-smooth clutch engagement, and a Kevlar-faced clutch disc which I'm hoping will hold up just fine behind my stock LT1.
Live well,
SJW
I recently installed a Spec Stage 2 clutch kit, along with the Spec extra-weight billet steel single-mass flywheel, in my '94 with the blue-tag box, and am very pleased so far with the setup. No rocks-in-a-can noises, silky-smooth clutch engagement, and a Kevlar-faced clutch disc which I'm hoping will hold up just fine behind my stock LT1.
Live well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,289
From: Central Maryland
funny how you describe it but yea.......I have had both the blue/black tags in mine.....with an aluminum light weight FW.......if the blue tag is quieter I sure can't tell the difference.......with my engine mods coupled with the aluminum FW, it is one noisy tranny........love it though! don't drive it every day, if I did I would go with a heavier FW as mentioned above; in fact I bought a steel, one piece FW just incase......me and the car are getting older So far as I've been able to discern based upon the numerous posts I've read on this and other forums about this subject, it seems that nearly everybody who has used a lightweight flywheel (especially the aluminum SMFs), and/or who has a heavily modified engine (especially one that has a lopey idle quality), has ended up with the can-o'-rocks sound effects as a result of the swap, especially if their box is a black-tag unit.
Conversely, those I've heard from who have swapped in heavy SMFs (especially the Spec extra-weight billet steel SMF behind a stock LTx engine, myself included), have had either very little gear rattle or none at all, especially if theirs is a blue-tag box. I hear no rattle in my '94, blue-tag, stock LT1 car.
Live well,
SJW
Last edited by SJW; May 15, 2011 at 02:43 PM.
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,289
From: Central Maryland
I ordered the clutch kit and SMF directly from Spec, via telephone. 800-828-4379.
I was very impressed with the quality of the items I received from Spec, and I'll be the first to admit that I'm not easily impressed.
Live well,
SJW
Race Director
Joined: Sep 2001
Posts: 14,685
Likes: 753
From: NEwhere Ohio
Noise is not an issue. The key is to run a sprung hub clutch which stage 3+ is. Other than slight rattle at wot or if you lug it up a hilll in too high of a gear, there's no issues w excessive noise
I did have a spec stage 2 fail on me (center broke out of it), but stage 3+ is the way to go.
Race Director
Joined: Sep 2001
Posts: 14,685
Likes: 753
From: NEwhere Ohio
I too am running spec stage 3+ w fidanza aluminum flywheel.
Noise is not an issue. The key is to run a sprung hub clutch which stage 3+ is. Other than slight rattle at wot or if you lug it up a hilll in too high of a gear, there's no issues w excessive noise
I did have a spec stage 2 fail on me (center broke out of it), but stage 3+ is the way to go.
Noise is not an issue. The key is to run a sprung hub clutch which stage 3+ is. Other than slight rattle at wot or if you lug it up a hilll in too high of a gear, there's no issues w excessive noise
I did have a spec stage 2 fail on me (center broke out of it), but stage 3+ is the way to go.
You may want to consider reusing your original, depending on the slop in the new throwout bearing.
Be sure to compare them!
Depending how **** you are, you may consider getting your flywheel and clutch disk balanced at a local machine shop.
Finally, it wouldn't hurt to bleed your clutch slave (follow zfdoc's procedures) while you are thinking about clutch.
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,289
From: Central Maryland
Considering that we're not talking about made-in-china parts from Autozone here, I must agree. I thought the price was excellent, given what all was included. I can't say whether or not they'll still offer that price today.
Live well,
SJW
Live well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,289
From: Central Maryland
I too am running spec stage 3+ w fidanza aluminum flywheel.
Noise is not an issue. The key is to run a sprung hub clutch which stage 3+ is. Other than slight rattle at wot or if you lug it up a hilll in too high of a gear, there's no issues w excessive noise
I did have a spec stage 2 fail on me (center broke out of it), but stage 3+ is the way to go.
Noise is not an issue. The key is to run a sprung hub clutch which stage 3+ is. Other than slight rattle at wot or if you lug it up a hilll in too high of a gear, there's no issues w excessive noise
I did have a spec stage 2 fail on me (center broke out of it), but stage 3+ is the way to go.
Live well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,374
Likes: 2,289
From: Central Maryland
I forgot to add, keep your original throwout bearing. The new acdelco ones are made in china and real sloppy.
You may want to consider reusing your original, depending on the slop in the new throwout bearing.
Be sure to compare them!
Depending how **** you are, you may consider getting your flywheel and clutch disk balanced at a local machine shop.
Finally, it wouldn't hurt to bleed your clutch slave (follow zfdoc's procedures) while you are thinking about clutch.
You may want to consider reusing your original, depending on the slop in the new throwout bearing.
Be sure to compare them!
Depending how **** you are, you may consider getting your flywheel and clutch disk balanced at a local machine shop.
Finally, it wouldn't hurt to bleed your clutch slave (follow zfdoc's procedures) while you are thinking about clutch.
I'm more **** than nearly any mechanic you'll ever meet, and I did carry my old DMF and the new Spec extra-weight steel SMF up to the House of Balance to have them match-balanced, just to make sure that I didn't have any vibration issues after this thing was all back together. I was pleased when I picked them up, and saw that they only took a tiny divot out of the new SMF to make it match perfectly. Given how little material they removed, I'm quite confident that I'd have had no vibration issues if I'd skipped the trip to the balance shop. It looks like Spec did a very nice job of getting the offset weight just right on mine. I'm pleased to be able to report that this engine is silky-smooth all the way to redline now.
Live well,
SJW
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
I paid $794.20 for the Spec Stage 2 clutch kit, and extra-weight billet steel SMF. This is less than the price of a new DMF alone, back when they were still available, which of course, is no longer the case. This package included the SMF, clutch disc and pressure plate, new FW bolts, new pressure-plate bolts, new release bearing, cheapie plastic clutch alignment tool, and a sintered-bronze pilot bushing that I opted to not use (I bought a replacement OEM roller pilot bearing from a Chevy dealer, and used that instead, just as a matter of personal preference).
I ordered the clutch kit and SMF directly from Spec, via telephone. 800-828-4379.
I was very impressed with the quality of the items I received from Spec, and I'll be the first to admit that I'm not easily impressed.
Live well,
SJW
I ordered the clutch kit and SMF directly from Spec, via telephone. 800-828-4379.
I was very impressed with the quality of the items I received from Spec, and I'll be the first to admit that I'm not easily impressed.
Live well,
SJW