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-   -   What Causes Clutch to Drag. (http://www.clubcobra.com/forums/all-cobra-talk/103014-what-causes-clutch-drag.html)

lovehamr 02-24-2010 02:05 PM

Jim, one thing that hasn't been said for sure, I think in either of these posts, was whether you are using a pilot "bushing" or a pilot "bearing." I say this because my own experience showed that the bearing, though offering less rotational friction, does tend to sit out farther from the crank than the bushing does. I had to have my input shaft machined back a few thou to make everything play nice together.

Steve

Jerry Clayton 02-24-2010 03:34 PM

most of the time when a clutch drags, it is because whoever installed it let the weight of the trans hang on the input shaft of the trans thru the clutch bending the center of the disc--this makes it instant junk and there is no way to fix it except to replace the disc, using the proper alignment splines and long guide studs in the bellhousing to guide the trans exactly down the center without any weight being rested on the input shaft/splines

Tom Kirkham 02-24-2010 03:44 PM

The pressure plate bolts may be loose, or pulling out. This is a more common problem with FE and aluminum flywheels.

jhv48 02-24-2010 03:59 PM

Quote:

Originally Posted by lovehamr (Post 1031641)
Jim, one thing that hasn't been said for sure, I think in either of these posts, was whether you are using a pilot "bushing" or a pilot "bearing." I say this because my own experience showed that the bearing, though offering less rotational friction, does tend to sit out farther from the crank than the bushing does. I had to have my input shaft machined back a few thou to make everything play nice together.

Steve

Thanks for that mental picture. Now I'm worried that they used a GM trans instead of a Ford tranny.

RICK LAKE 02-24-2010 04:21 PM

You have the trans out
 
jhv48 J any chance of getting a first name?? To check the trans for what input shaft you have measure the diameter and the number of splines on it.
Next measure the length of the input shaft to where the pilot bushing is riding. This is from the trans body to where the end of the bushing rides on the input shaft. Next measure the bellhousing from ground to the back of where the trans sits. Last is to put the bell housing on the motor with out the clutch and measure from the face of the bellhousing to the pilot bushing in the crank. Need these 4 numbers to see what the clearances are.%/ Again what bellhousing are you running??? This clutch should n't be worn out in 1,500 miles unless you can't drive a clutch car. I know this is not the problem??:confused:;):rolleyes::) Rick L.

Ibr8k4vetts 02-24-2010 04:31 PM

Quote:

Originally Posted by RICK LAKE (Post 1031679)
jhv48 J any chance of getting a first name??

Do you mean Jim?:confused:

jhv48 02-24-2010 05:06 PM

Whew, the correct trans was used.

And they still think the pilot bearing is the culprit, as they have checked everything else and all parts look and function like new.

Man I hope that's it. Hate to button this thing back up and then have to do it again.

RICK LAKE 02-25-2010 04:05 AM

22 hour await and working you get punchie
 
Ibr8k4vetts I missed it after 22 hours. My bad.:o Rick

CobraEd 02-25-2010 07:46 AM

How does the tip if the input shaft look? Is it scratched or galled? Any blueing?? If there were a pilot bearing problem, you would think there would be some evidence of it on the tip of the input shaft.

.

jhv48 02-25-2010 10:39 AM

The tip has been proclaimed healthy.

I think the bushing is the softer of the two and would expect the damage to show up there first.

carmine 02-25-2010 11:01 AM

Pertaining to the senario that Jerry Clayton has described.
Have you done a test on the disc to see if the center is bent which would cause the dics to wobble when spun true from the imput shaft area.

jhv48 02-25-2010 11:48 AM

Yep, the disc is ok.

jhv48 02-25-2010 02:20 PM

Solution
 
According to the installer.............................

It was the F---ing pilot bushing.

Replaced it, put it all back together with the same parts (that was a big gamble) and they say it drives like new.

I pick it up today. Will let you know if that did it!

Hope this helps any others who experience abnormal grinding in reverse.

CobraEd 02-25-2010 02:39 PM

What about the bushing?? Worn, too small, not in deep enough???

Is it truely a bushing, or a needle bearing type?


.

jhv48 02-25-2010 07:09 PM

Nothing visible on the bushing. But defective somehow.

Just drove the car 60 miles. All is ok for now.

TButtrick 02-28-2010 06:33 AM

wow. never heard of that before but makes sense. i'm a bit surprised it didn't grind into first but then again, reverse is a much lower gear. glad you caught it early and on are your way.

strictlypersonl 02-28-2010 03:55 PM

I hope they checked the bellhousing concentricity when the trans was out. That would be a primary candidate as a cause for a short-lived pilot bearing.

jhv48 02-28-2010 07:35 PM

I'll know in another 1500 miles or so.

jhv48 05-05-2010 11:45 AM

The problem reared its ugly head again in 700 miles.

However, this time it was the slave cylinder installation. They had to put a washer on the tip of the slave rod to keep it from slipping through the shift fork. The washer was just a bit too small and it was pushing through the fork slightly so that the clutch would not completely disengage. Put a larger washer on the end of the rod and the problem went away..........for now!

mdross1 05-06-2010 06:53 AM

My TKO will grind going into reverse,unless the clutch is adjusted properly.My 11" clutch needs to have almost no freeplay.


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