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9/19/2018 1:34 AM  #1


Clutch Chatter- a point of reference please

Ladies and Gentlemen- I have a favor to ask. I need a point of reference. If you take your standard transmission Mustang to a level parking lot and, with the engine idling, in first gear, clutch on the floor, and ever so slowly engage the clutch without feeding in more throttle does your clutch engage smoothly or does it chatter like crazy before the car starts to roll? Mine chatters like crazy such that I'm thinking my clutch has oily facings even though it doesn't seem to slip at speed or during upshifts. For comparison, and I realize that it is a completely different animal, my Miata takes off gently with no vibration whatsoever. The Mustang bucks and chatters as I roll off from a stop sign with the proper throttle applied. Just curious what other drivers are experiencing. I searched other forums and found one that was Ford related with a thread related to my question and saw quite a range of responses. Is my situation normal, I don't think so, or does it point to a bad clutch? My car is a 66 FB 347 TKO 600 9" 3.89 gears with only about 9000 miles on the rebuild. Thank you in advance.-Brad
PS-I should add that the clutch actuating mechanism has all been upgraded with roller bearing pivots and heim jointed linkages and adjusted properly with sufficient free play.

 

9/19/2018 4:12 AM  #2


Re: Clutch Chatter- a point of reference please

hello ,  This is the best brief i found :  Clutch chatter is the sudden shudder that occurs when a faulty clutch disk or clutch component is initially engaged. This shudder or vibration may vibrate throughout the entire vehicle. It’s often the result of worn or contaminated clutch components. This chatter is caused by the disc grabbing and releasing the flywheel and pressure plate as the assembly is turning. It happens very quickly as the engine is rotating.

Inspection of manual transmission clutch disc.
Clutch chatter is different than clutch slippage. Clutch chatter occurs when the clutch is first applied and goes away after the clutch has fully engaged. Clutch slippage is the continued spinning of the clutch disk without its full engagement. Faulty dual mass flywheels and worn or over machined flywheels result in clutch slippage. With clutch chatter, the vehicle will shudder and shake, and with clutch slippage, the engine increases in rpm with little change in vehicle speed. If it’s real bad, the vehicle may not even move forward.

Worn or contaminated clutch facings cause clutch chatter and grabbing. Contaminated clutch disk friction material is typically the result of a leaking crankshaft main seal or front transmission seal. Depending on the vehicle, this oil may easily be seen during a visual inspection of the clutch housing.

In my mustang 66 with t5 i had that issue with high temp engine , until i changed the radiator .
With lower temp working engine this chatter has disappear.

As i am not expert , this are my two cents

 

9/19/2018 4:45 AM  #3


Re: Clutch Chatter- a point of reference please

In my experience a leaking rear main seal isn't going to contaminate the clutch disc.  That theory relies on a belief that oil will make a 180 degree turn around the flywheel.  If that's going to happen there has to be a colossal amount of oil leaking past that seal.

A more likely scenario would be oil leaking around the threads of the flywheel bolts.  Those bolts should always be installed with a little silicone on the threads to prevent this.

BUT, oil contamination is not the only reason for clutch chatter.  It can also be caused by poor flywheel machining (sadly somewhat common on overseas made flywheels), or an issue in the pressure plate.

Bottom line, the tranny's coming out and you need to carefully inspect everything and look for hot spots, etc. 

 

9/19/2018 6:45 AM  #4


Re: Clutch Chatter- a point of reference please

Has your car been sitting for a while or regularly driven? I have had chatter show up on my 65 when it has sat all winter but it goes away after a couple of days of normal driving. Normal for me is "every trip is a race" kind of driving.

 

9/19/2018 9:46 AM  #5


Re: Clutch Chatter- a point of reference please

Out of curiosity, what clutch are you running? 

When I first got the car going with the Centerforce, it was a challenge to get it moving without chatter. This was from a brand new clutch that sat in a box for close to 12 years. The clutch disk was new. The flywheels was new also. No contamination on anything during assemble.

The McCleod went in with a new disc and no chatter what so ever. It also came with a recommended brake in procedure to prevent problems in the future. Which was basically drive it like Grandma for 400 to 500 miles.


John  -- 67 Mustang Coupe 390 5 speed
 

9/19/2018 10:44 AM  #6


Re: Clutch Chatter- a point of reference please

Another thought to consider: ignition. While I was still running the factory single point distributor, three speed, and 2.80 rear gear, I thought I had a bad clutch. It would grab and chatter and required lots of engine revving and clutch slippage to get going. I installed a Pertronics conversion and coil then set the timing for 32 degrees all in at 3000rpm and verified the vacuum advance was working. The car ran much better, almost no clutch shudder. The 2.80 rear end kept it from being a rocket ship, but I no longer dreaded driving it in stop light land.

 

9/19/2018 10:56 AM  #7


Re: Clutch Chatter- a point of reference please

My experience is different than all the rest.

I have experienced clutch chatter a lot over the decades.  Thru a number of clutches both stock and after market.  To make a long story short - My clutch chatters when I release it too slowly at start up.  Release it a little faster and the chatter disappears.  The problem is my slow leg.


Original owner - 351w,T-5, 4whl disks, power R&P
 

9/19/2018 11:15 AM  #8


Re: Clutch Chatter- a point of reference please

I agree with everyone; the clutch should not chatter. Mine did for a long time if I babied it. If I launched from the light it did not. Then one winter I decided to change the engine mounts as the old ones were 40ish years old. To my great surprise the clutch never chattered again. 


Gary Zilik - Pine Junction, Colorado - 67 Coupe, 289-4V, T5
 

9/19/2018 12:09 PM  #9


Re: Clutch Chatter- a point of reference please

RV6 wrote:

I agree with everyone; the clutch should not chatter. Mine did for a long time if I babied it. If I launched from the light it did not. Then one winter I decided to change the engine mounts as the old ones were 40ish years old. To my great surprise the clutch never chattered again. 

This was my experience too.  I didn't figure it out until I saw where the air cleaner wing nut dented my hood from the inside out.  New motor mounts... no more chatter.

 

9/19/2018 1:32 PM  #10


Re: Clutch Chatter- a point of reference please

Thank you to all for the responses so far. I purchased my car back in 2012 with most of the modifications that I wanted supposedly done properly. Unfortunately this has not been the case. I have had to literally redo most everything on the car. In fact, I would have to think long and hard to come up with something that I haven't laid a wrench on. I think maybe the headliner was ok. This was not out of ignorance about these cars but more out of the belief that I had something that was about 80% complete and I could just drive and enjoy. I'm not looking for sympathy here just describing reality. I was hoping to get back into the hobby with a car that I could safely modify without a risk of totally devaluing it. I like to tinker and modify things so I felt that the purchase of this 66 fastback would be a logical move since the value of one of my other cars, a 67 Shelby GT350, has gone through the roof. I know that some will say that "It's your car do what you want with it" but I just felt that the mods that I wanted to make would take the Shelby too far from being original. I have a 68 Cougar that I made several suspension mods to back in the mid 70's and the handling was amazing. The Klaus Arning mod should have been done by the factory. I can't make my test with the Cougar because it is an automatic and the Shelby is now in need for a restoration itself so I am appealing to you folks. I read on one of the other forums that a certain amount of chatter seems to be normal depending on the build but I'm not convinced. This is why I was hoping that someone else might do the parking lot test that I described in the original post. As far as the components used by the previous owner, I can't say I'm kind of whistling through the graveyard on some of this. I received a large folder with paperwork with the purchase but there are a few gaps as far as components used. I built the 9" rear with a Wavetrac differential , I sent the TKO600 to Liberty's Gear, originally a Keisler Perfect fit kit, and have rollerized the front suspension and upgraded the brakes. I probably should have pulled the bellhousing off and inspected the clutch while I had the transmission out but I didn't feel I had a clutch problem at the time. The entire car has about 9000 miles on it with various drive line pieces having less than 500 miles on them. I have spent 95% of the time under the car and 5% behind the steering wheel. Hence the frustration.

     Thread Starter
 

9/19/2018 5:53 PM  #11


Re: Clutch Chatter- a point of reference please

Clutch chatter is simply not normal.  If everything is right (flywheel machining, no engine or mount issues, etc.) and it still chatters get a different clutch.  I've had a lot of stick cars and trucks over the years everywhere from mild to wild, and the only time I've ever had clutch chatter was when the clutch wasn't suited to the application.  I put a Spec Stage 2+ in my WRX and it made the car almost undriveable.  I swapped it for an ACT Streetmaster and it was like driving a stock clutch, except it could hold the extra 80HP I was making, and last more that 50k miles (AWD cars are brutal on clutches).

Takeoff technique may make a difference too though.  I tend to leave the line with some authority.  Typically I'll slip it in at about 1,000RPM and go in basically anything I drive. 

Another thing to consider is the trans mount in addition to the engine mounts, and the driveshaft u-join operating angles.  If the angles are off front to rear you could be getting a bind situation that you're mistaking for clutch chatter. 

Its a shame that it seems most places and people who work on these cars just can't or won't do the job right.  We certainly hear it on here a lot, and witness it first hand a lot too.  What I can say is that you've got a great group of guys (and a few gals too) on here that will do their best to help you figure out your issues. 

 

9/19/2018 10:43 PM  #12


Re: Clutch Chatter- a point of reference please

TKO-Thanks for the information everything told has value. I went through a drive line angle problem when I first installed the 9" rear but I now believe that I have it pretty well cured. The housing needed to be shimmed up in the front to match the downward angle of the transmission, at least within a degree and a half or so. The TKO600 that is in the car was installed by the previous owner with the aid of his mechanics. It appeared to function fine with the stock 8" rear and it was only when I installed the 9" that I had problems. It would vibrate horribly at 60 mph and above. I started with 2* shims and finally ended up with 6* or so if I remember correctly. I added 2* at a time until I got the smoothest ride. I can now go over 100 without issue. I even added shims to the transmission mount to get it as high up in the tunnel as possible. The 9" housing appeared to have had the spring pads welded such that if set level the opening for the center section would be 90*. When I compared it to the 8" housing that I was removing it seemed that the 8" was pointing upwards about 4* more so I added the shims to get it close. I will be removing the transmission and bell housing to inspect the clutch and flywheel in a couple of weeks. I will also be verifying the squareness and alignment of the bellhousing. Something that I can't be sure the installers did properly. If I find damaged components they will obviously need to be replaced. The car will probably never be raced on a track. It will be a high performance street machine, basically a weekend corner carver and a toy. I've tried to build it such that it would be considered a step above what Carroll would have produced if he didn't have the bean counters at Ford to deal with. The 347 engine dynoed at 430 hp/430 torque, it will red line at 6200 rpm and as mentioned, the transmission is a TKO 600. The rear gear is a 3.89 wavetrac. What clutch and pressure plate would you recommend based on the details given? As always thank you in advance.-Brad

     Thread Starter
 

9/20/2018 4:39 AM  #13


Re: Clutch Chatter- a point of reference please

The Ford Racing King Cobra clutch is probably up to the task.

Another option is to call Clutch Dynamics and they can make a clutch to suit your specific application.  It sounds expensive, but its not.  They're an old school company, no web ordering, etc.  517-321-7389.  They get rave reviews on all the late model Mustang forums. 

 

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