ZF six speed problem
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
BTW;
another option is to move the idle speed up until the noise is minimal....that’s where mine was annoying...w/o the clutch engaged.
I moved my idle speed up to 1,000 RPM which nearly eliminated the “ rocks in a can” sound w/o the clutch engaged...Now, I run a Holley HP ECM making that adjustment much easier.... but with my cam, the idle is smooth...just not as lumpy like it used to be...
another option is to move the idle speed up until the noise is minimal....that’s where mine was annoying...w/o the clutch engaged.
I moved my idle speed up to 1,000 RPM which nearly eliminated the “ rocks in a can” sound w/o the clutch engaged...Now, I run a Holley HP ECM making that adjustment much easier.... but with my cam, the idle is smooth...just not as lumpy like it used to be...
Last edited by TheGreek!; Jun 29, 2018 at 03:26 PM.
Melting Slicks
Joined: Apr 2007
Posts: 2,616
Likes: 111
interesting....well, I am speculating based on my experience. You could have other problems.....let us know what ZF Doc says! He knows more about these trannies than I will ever know!
Race Director
Joined: Sep 2001
Posts: 14,680
Likes: 752
From: NEwhere Ohio
Everyone has focused in on the elements that cause the "ZF RATTLE"....but that is a rattle. Are we sure that's the problem?
I think the problem may be something else. ZF rattle doesn't typically happen when underway/under load. And trans whine should diminish in higher gears....with none in 4th gear. I think it's something else.
I think the problem may be something else. ZF rattle doesn't typically happen when underway/under load. And trans whine should diminish in higher gears....with none in 4th gear. I think it's something else.
yes it would occur on mine under load. Esp in first and if lugging it in too high of a gear up a hill.
the rocks in a can neutral noise is not an issue as thats not how i normally drive the car.
(if im at a drive thru, i turn car off - its loud for other reasons like exhaust)
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
ZF doc called me yesterday and said that he would be here in Tucson tomorrow (which is now today) and asked if I could bring him the car today instead of next week. Of course I said yes and drove out to where he was at to let him drive the car. After he took it for a test drive he said that there is nothing wrong with the trans other than it having the infamous "ZF rattle" that these transmissions are notorious for. He said that his countershaft shim will fix it. He also thinks that I may have a solid clutch disc in it, if so he said to replace it with a sprung disc. I'm really glad that the trans isn't bad, that all I need to do is shim it and possibly have to replace the clutch disc.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
I was going to buy your shim but ZF doc brought a shim kit and a few other ZF things with him and I felt kind of obliged to buy the shim from him since he took time out of his day to meet me and diagnose my trans for free. Sorry about that but I didn't want to say to ZF doc "no thanks, I can get one cheaper somewhere else", it just wouldn't be right to do that to him.
Melting Slicks
Joined: Sep 2003
Posts: 2,270
Likes: 118
From: N. Babylon NY
I was going to buy your shim but ZF doc brought a shim kit and a few other ZF things with him and I felt kind of obliged to buy the shim from him since he took time out of his day to meet me and diagnose my trans for free. Sorry about that but I didn't want to say to ZF doc "no thanks, I can get one cheaper somewhere else", it just wouldn't be right to do that to him.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Melting Slicks
Joined: Apr 2007
Posts: 2,616
Likes: 111
That pretty much went the way I thought. These trannies rarely fail, but often make noise when put behind a single mass FW; especially an aluminum piece like mine and yours!! I mentioned idle in mine since that is the most noticeable to me. But yes, under a load in higher gears you will hear it as well.
You are are one of many, trust me! That thing can rattle like crazy and will not a hurt a thing other than your ears!!
You are are one of many, trust me! That thing can rattle like crazy and will not a hurt a thing other than your ears!!
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
That pretty much went the way I thought. These trannies rarely fail, but often make noise when put behind a single mass FW; especially an aluminum piece like mine and yours!! I mentioned idle in mine since that is the most noticeable to me. But yes, under a load in higher gears you will hear it as well.
You are are one of many, trust me! That thing can rattle like crazy and will not a hurt a thing other than your ears!!
You are are one of many, trust me! That thing can rattle like crazy and will not a hurt a thing other than your ears!!
Last edited by TheGreek!; Jul 2, 2018 at 12:51 PM.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Update:
Over the course of the last week I replaced the Fidanza aluminum flywheel with a stock dual mass flywheel and installed the countershaft shim kit from ZFdoc (and also installed a new pilot bearing, clutch disc, pressure plate, and throwout bearing) and the noise is gone! It's nice and quiet now, the trans no longer sounds like it's coming apart inside. The car has just been sitting in the garage ever since I bought it because I didn't want to drive it with that God awful noise, now I can finally start enjoying the car at last.
Over the course of the last week I replaced the Fidanza aluminum flywheel with a stock dual mass flywheel and installed the countershaft shim kit from ZFdoc (and also installed a new pilot bearing, clutch disc, pressure plate, and throwout bearing) and the noise is gone! It's nice and quiet now, the trans no longer sounds like it's coming apart inside. The car has just been sitting in the garage ever since I bought it because I didn't want to drive it with that God awful noise, now I can finally start enjoying the car at last.
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Update:
Over the course of the last week I replaced the Fidanza aluminum flywheel with a stock dual mass flywheel and installed the countershaft shim kit from ZFdoc (and also installed a new pilot bearing, clutch disc, pressure plate, and throwout bearing) and the noise is gone! It's nice and quiet now, the trans no longer sounds like it's coming apart inside. The car has just been sitting in the garage ever since I bought it because I didn't want to drive it with that God awful noise, now I can finally start enjoying the car at last.
Over the course of the last week I replaced the Fidanza aluminum flywheel with a stock dual mass flywheel and installed the countershaft shim kit from ZFdoc (and also installed a new pilot bearing, clutch disc, pressure plate, and throwout bearing) and the noise is gone! It's nice and quiet now, the trans no longer sounds like it's coming apart inside. The car has just been sitting in the garage ever since I bought it because I didn't want to drive it with that God awful noise, now I can finally start enjoying the car at last.
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
I'm glad the noise is gone too. It sucked just seeing the car sitting in the garage and not being driven because of the trans noise. It's a '96 Collector Edition with an LT-4 engine, I wanted to drive it but just couldn't with it making that horrible racket. Now that the noise is gone I've driven the car more in the last few days than I have since I bought the car, I'm finally enjoying the car at last!
Racer
Joined: Jul 2003
Posts: 492
Likes: 16
From: IL
I'm glad the noise is gone too. It sucked just seeing the car sitting in the garage and not being driven because of the trans noise. It's a '96 Collector Edition with an LT-4 engine, I wanted to drive it but just couldn't with it making that horrible racket. Now that the noise is gone I've driven the car more in the last few days than I have since I bought the car, I'm finally enjoying the car at last!
Instructor
Joined: Feb 2007
Posts: 132
Likes: 3
From: CRYSTAL RIVER FL.
ZF Tranny
About 20 years ago just after a picked up a '92 LT1 I bought a brand new ZF 6 speed from a Chevy dealer who was going out of business. Had six in stock and selling for $600.00. With 150k on the clock I thought what a deal. It's a "blue" label and the original is a "black" label. What's the difference? Any way, now that I'm retired, have a lift. a tranny jack, and lots of time, and not knowing how old or the condition of the clutch and FW I'm going to swap it out. It has always had a grinding sound at idle with the clutch out. Just a little pressure on the clutch and it goes away. Always assumed it's the throw out bearing? Also the rear main seal leaks.
Reading these posts I'm not sure what to do about which clutch and fly wheel to use. It's got 175k on it now. Occational driver. Was thinking use a SMF and sprung disc?
TIA, Dave.
Reading these posts I'm not sure what to do about which clutch and fly wheel to use. It's got 175k on it now. Occational driver. Was thinking use a SMF and sprung disc?
TIA, Dave.