# 1970 GTO 400CI M20 4 speed issues help needed



## Ken D (May 31, 2020)

I recently pulled my engine and had it rebuilt. While I had the engine out I replaced the clutch and throw out bearing. I have the car all back together. I have only used it for about 30 miles. Yesterday the car developed an inconstant problem when coming to a stop with the clutch pedal fully pressed. The car starts to shake as it the clutch is not engaged fully. It was difficult to pull the shifter out of gear and when I did the vibration stopped. I was able to restart the car and the issue seemed to go away stopping at lights with no issue. When I reached my home to park in the garage it did it again. This morning when I went to start the car the starter did not crank at all as if it was locked. I pulled the shifter out of reverse and the car fired up and still seemed to move slightly as if it was still in reverse.
Any suggestions of what could be wrong would be greatly appreciated.
Thanks Ken


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## PontiacJim (Dec 29, 2012)

Not enough information to diagnose the problem.

Right off it sounds like the clutch is not fully disengaging.

Was the clutch working before you pulled the engine.
Same clutch/pressure plate/throw out bearing that was in it when you pulled the engine?
Same linkages? Did you replace anything?
Same shifter? Did you replace anything? Did you line up the shifter throws?
Where does the pedal grab when you let out the clutch? Near the floor, couple inches up, 1/2 pedal travel, near the top?

If you used the same clutch set-up that came out and it worked fine, sounds like an adjustment per the Service Manual.

If new clutch set-up, sounds like wrong throw-out bearing. Too short, and the pedal is close to the floor to get it to release. Pedal should be about 4" off the floor when you release the clutch. Get the correct longer throw-out bearing. You cannot adjust the clutch linkage enough to get the pedal to work if you have the wrong short throw-out bearing.

Clutch fork has slipped off the pivot ball in the bellhousing or throw-out bearing collar. Grab the fork and make sure it is not flopping around. It should be angled forward towards the front of the car and just about hitting the bell. It should not be pushed/angled back to the rear of the car.

Align the shifter throws using a drill the correct size in the alignment hole found on the shifter body per the Service Manual.

Clutch set-up not installed correctly.


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## Ken D (May 31, 2020)

PontiacJim said:


> Not enough information to diagnose the problem.
> 
> Right off it sounds like the clutch is not fully disengaging.
> 
> ...


Hi Jim, The pressure plate / fly wheel was ground by the engine rebuilder, the church and throw out bearing was also replaced that came with McLeod clutch 75117. I will look and try some of your recommendations you provided. Thanks ken


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## Ken D (May 31, 2020)

And yes the old clutch was working fine, same shifter and the throw out bearings looked identical in size


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## PontiacJim (Dec 29, 2012)

My bet is on the wrong throw-out bearing. I bought a McCleod set-up for my car many years ago. They supplied the wrong throw-out bearing. Had to pull the trans and replace the short with the long bearing and I was good. Again, the clutch fork position will indicate this.


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## O52 (Jan 27, 2019)

Clutch guide


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## BLK69JUDGE (Jun 10, 2010)

pedal adjustment first ..like Jim metioned...does the clutch grab around 2/3rds of the way up? diss at 2/3rds to the floor?
creepage is fairly normal in neutral w cold lube
is the flywheel inspection cover back on?
I need a picture of the flywheels ring gear edge..for flywheel thickness
if the pedal is adjusted fairly close.... I think the flywheel was turned
too thin and disc springs are hitting the flywheel bolt heads....
causing the disc to spin and not having complete neutral 
seeing the flywheel edge gives me a clue ... if the bevel is gone
it may be over surfaced and may be the issue...
jack the rear up block the tires ... jack stand the rear...
put it in gear engine off .. takes 2 people 1 in drivers seat....
get under with your headat the tranny and your feet at the drivers rear tire
have them push the clutch down in gear .. spin the tire making the driveshaft and tranny spin ..making the disc spin and motor stationary
you may here the clutch disc springs chatter bouncing over the
flywheel headbolts... mostly if original thick /deep/tall headed bolts were reused...mr gasket makes a shallow headed bolt for the aftermarket thinner non cast flywheels,,, very common issue ... no clearance
I have had this problem on several customer cars


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## Ken D (May 31, 2020)

Adjusted the pedal, as it was grabbing close to the floor. I thought it was resolved as I took it for about about a ten mile ride.
As I got close to home and the car was hotter I started hearing a Loud squeal sounding like a bearing when pressing down the clutch. It would go away under load. Also squeed in neutral really bad with clutch let out. Back in the garage, I wish I could upload the video.


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## Ken D (May 31, 2020)

IMG_2042.mov


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## Ken D (May 31, 2020)

Video of nose 1970 Pontiac GTO


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## PontiacJim (Dec 29, 2012)

Hmmm. Sounds like something is hitting or bearing noise.

Did you use a pilot bushing or pilot bearing? If pilot bearing, it may have gone bad on you. I always use a pilot bushing just for this reason as the bearings can go bad or get damaged installing them into the crank if you had to use any hammering to knock it in.

Factory flywheel or aftermarket Hays? As BLK69JUDGE mentioned on the flywheel, I have never had an issue with a factory flywheel, but if you use an aftermarket 11" flywheel, the factory flywheel bolt heads are too tall and will hit the springs on the clutch disc - learned this myself and you can see this in the photo. The center recessed area where you bolt it up to the crank is not as deep as factory. You need to install a thin head flywheel bolt which I think were from ARP. This will position the heads down in the recess and they will not strike the clutch disc springs.

Is it possible the front bearing in the Muncie is bad? Or any other bearings in the trans?


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## Ken D (May 31, 2020)

Hi Jim, thanks for responding. I believe the flywheel is factory. The engine rebuilder installed the new pilot bearing or bushing so It’s unknown if it’s bushing or bearing. It only does this after it gets hot, so I’m leaning towards the pilot bushing / bearing. I had to stop working on the car for today. I plan on pulling it apart next weekend and looking at all of the different possibilities.
Thanks for all of your help and Technical suggestions.
Thanks Ken Dasaro


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## Ken D (May 31, 2020)

BLK69JUDGE said:


> pedal adjustment first ..like Jim metioned...does the clutch grab around 2/3rds of the way up? diss at 2/3rds to the floor?
> creepage is fairly normal in neutral w cold lube
> is the flywheel inspection cover back on?
> I need a picture of the flywheels ring gear edge..for flywheel thickness
> ...


Thanks for the suggestions 
Ken


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## Ken D (May 31, 2020)

Gentlemen 
I reached out to my engine rebuilder and included the details I’m experiencing and the video. He installed a bushing.

(Response from him below)
U have a stock flywheel. We installed a new bushing. It is not a bearing. Your noise is most likely a release bearing. When it gets some heat in it it gives a squeal.the release bearing only contacts the clutch fingers when u push the clutch pedal in.


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## BLK69JUDGE (Jun 10, 2010)

one way or another 
tranny needs to come out ...


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## Ken D (May 31, 2020)

BLK69JUDGE said:


> one way or another
> tranny needs to come out ...


Yep


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## lust4speed (Jul 5, 2019)

As far as the newest problem, I'm just wondering if you have about an inch of free pedal before slack is taken up. If the clutch was adjusted too tight the pressure on the throw-out bearing would be constant and they were not designed for that. Although I would think that a new throw-out bearing would go for many miles before complaining. 

If clutch is released and trans is in neutral or car moving in gear then the pilot bushing/bearing is a non-player since the input shaft is maintaining the same speed as the crank.


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## Ken D (May 31, 2020)

I’m going to pull it apart in a couple of weeks, I did adjust the clutch so the pedal come up four inches before it grabs as Jim recommended, that made it better but did not resolve. I really think I got a defective throw out bearing.


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## integrity6987 (May 10, 2017)

Sorry about these issues, but this is informative - please keep us posted.


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## Ken D (May 31, 2020)

I will let everyone who have been so helpful know the outcome and provide photos


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