[Terry M. Hunt]

When I bought my ’65 GTO, l discovered it had a ’62 vintage Borg Warner 4 speed in it. Decided to rebuild it and use while car was being restored, with an eye toward eventually locating a date coded Muncie for the car. This B-W trans never operated well, but I figured it was just because it was so old and had been abused to the point that the rebuild still left it with a lot of slop internally. Three issues were experienced. First, trans would not shift into first after car came to a complete stop. Sometimes, I could get it into first by pushing really hard on the shifter, but there was obviously some serious binding going on. Other times¸ I could get it into first when stopped by moving the shifter back and forth a few times from first to second to first until it would finally go into first. Other times after I stopped at a light, I could not get the trans to shift into any gear and had to shut off the engine, shift into first, and restart the engine. It was almost like the shifter was hung up in neutral. The workaround has been to always remember to shift into first before the car comes to a complete stop. Second issue was that about half the time I would try shifting into reverse after stopping, I would get a crunch. This was true even if I waited 2-3 seconds before trying to shift into reverse and moved the shifter very slowly toward reverse. I would hear a growl and feel a vibration in the shifter that told me to stop trying to get the trans into reverse. Third issue was that sometimes after shifting into reverse and then trying to go back to first¸ it felt like two of the shift rods were binding against each other, and I had to pull really hard to get the shifter to move out of reverse. While all this was going on with the B-W in the 65, I noticed the Muncie in my ’64 GTO was giving a little crunch when shifting into third. I decided to have it rebuilt by a different guy (Randy) than the guy who did the BW. While I was at it, I replaced the clutch and release bearing in the ’64 with the identical Center Force parts that had been installed in the ’65 earlier. I set the clutch adjustment on the ’64 according to the chassis manual and the car drives and shifts like a dream. Now back to the ’65. I tracked down a correct Muncie and had Randy rebuild it. Installed it last August behind the identical Center Force clutch and release bearing used in the ’64 and set the clutch adjustment the same way. Now the Muncie in the ‘65 is displaying all the issues outlined above that the B-W did. At this point, I’m thinking this is really a clutch adjustment issue, not a problem with the trans, since I’m getting the same problems with two different transmissions. My guess was that my initial setting according to the chassis manual (backed off 3 ½ turns) was just not providing enough release on the ‘65. So I turned the clutch push rod back toward the fork 1 ½ turns and did a test drive. Same issues occur. Made a second adjustment by turning the push rod toward the fork one additional turn. Same issues, maybe even a little worse. I still have free play in the pedal at the top, and the engagement occurs 2-3 inches off the floor. Once I get the car going¸ there are no obvious problems upshifting or downshifting as long as the car is moving. I have watched the clutch linkage move through its entire range of motion several times from below the car. Don’t see any problems. Have done the same for the shifter and see no problems. Shifter was rebuilt by Hurst and alignment pin fits into the shifter with no resistance at all with the shifter in neutral. Shift arms and rods are all new. Pivot ball in bell housing is new. Fork was used, but showed no excess wear. If my initial clutch setting was not providing enough release, how come turning the push rod out of the swivel back toward the fork doesn’t seem to be adding any more release? Looking for ideas on how to solve this. It’s really lousing up the driving experience on this car for me.

[johnta1]

Well, I would say it's a combo problem?


I think the shifter linkage isn't just right and the clutch linkage isn't just right.

[Terry M. Hunt]

Well, I guess I can't argue with that logic, but I was hoping for some specific ideas, suggestions as to what else to research, test, etc. to get this corrected.

[johnta1]

Well, if it shifts OK with the engine off, it would be the clutch setup/adjustment.
If it doesn't shift OK with the engine off, it's probably the shifter adjustment or tranny internals.

Is it a diaphragm pressure plate?
The throw out bearing has to match the type of pressure plate.

I don't think you answered if it was a new problem/install or just started doing it on a running installation.

The shifter fork studs/bolts where the arms attach, should have no play.
The shifter itself should have a hole on it to check adjustments with.
(put 1/4" rod in it then the arms should slide right on tranny attachment points)

There is also a spec, when the clutch is pushed in should be a certain space between disc and flywheel.

Lots of things it could be, need to know what is happening with it.

[geeteeohguy]

You didn't mention the flywheel. If the flywheel has been resurfaced too much (too deep of a cut) the clutch plate springs could be hanging up on the flywheel bolts, because the flange area is now not deep enough for clearance. All of the issues described for the '65 indicate that the clutch is not disengaging fully, before and after the trans/clutch change, so I would look really hard at the flywheel measurements. Looking at the whole problem from an overview standpoint, the clutch is not disengaging when you need it to.

[Terry M. Hunt]

I did have the flywheel resurfaced, but don't recall measuring the thickness afterward to see if it was still within some minimum spec. I haven't checked the chassis manual to see if it lists such a spec. Does anybody know what it is? All these issues began as soon as I started driving the car after the drive train and B-W trans rebuild. I have no previous driving impressions to compare this to as the car was not running when we rescued it from the junkyard. The drive train rebuild included a new clutch pressure plate, disc, and release bearing and a new pilot bearing and clutch pivot ball. All the shifting issues take place with the engine running/driving the car. With the engine off, the trans shifts smoothly into all gears. I'm tending to think the clutch is the problem, and appreciate the responses regarding other aspects of the clutch to check into. Anybody else have any additional ideas?

[Terry M. Hunt]

Went online to the Center Force site and printed their Clutch Diagnosis Guide . Also reread all the printed material included with the clutch when I bought it, and will be calling the Centerforce tech line once I get everything disassembled again. At this point, all signs point to what geeteeohguy mentioned in his post. I seem to recall replacing the flywheel bolts with a set that had heads much thicker(taller) than those that I found when disassembling
the clutch. This may wind up being the source of my problem, but a flywheel that is too thin may also be a contributing factor. One of the handouts included from Centerforce addresses Chevy v8 applications specifically and describes a method of measuring the flywheel:
" To determine whether the flywheel is at stock thickness or is manufactured/surfaced below specification, the flywheel will need to be measured. To perform this, measure from the friction surface to the crankshaft flange mating surface(through the center of the flywheel works best). The stock dimension is approximately .950. If the flywheel thickness is significantly below the factory specification, the clutch disc springs may contact the flywheel bolts resulting in improper release and possible damage and failure."

Of course, I plan to make this measurement on my flywheel when I get it off, but don't know what spec to compare it to in order to decide if it has become too thin. Is the .950 spec mentioned in this Centerforce literature applicable or is it something different? I plan to ask their tech rep or course, but still wondering if anybody else knows what the stock thickness of a '65 flywheel is or what the minimum thickness is.

[BertMac]

A couple of things that come to my mind.

1.wrong fork or throwout bearing...is the back side of the fork hitting the bellhousing when pedal is depressed?
2. thick bolts on the flywheel....when you ease off the clutch can you hear a scraping noise for just a second?
3. do you have the clutch disc in backwards? springs to flywheel
4. look for trash, bolts springs inside the pressure plate. a stray nut spring or bolt there will cause what you are describing. this has happened to me a few times from clutch failure where the springs come out of the clutch and lodges behind pressure plate
5.making the rod longer should give you more clutch, but if you are 2 or more inchs off the floor before it engages then you dont need more lenghth on the rod
6. good pilot bushing?

take it out and drive it shift thru the gears without using the clutch. if it shifts smooth up and down theu the gears then your tranny and linkage isnt the prob..of course upshifting and downshifting without a clutch is kinda a learned art but that will anser the tranny and linkage side of the problem

[Txbobcat]

I had a similar problem on a 95 chevy truck. It took a while to figure that when the you engaged the clutch the crankshaft would move forward not letting the clutch do its job. The answer was a new shortblock.

[ron cozzo]

I'll put in another vote for thick flywheel bolts. When I put my 64 together we used ARP flywheel bolts on the Hayes flywheel. The heads were too thick and the springs on the clutch disk would rub the bolt heads. Never could completely disengage. Changed to Mr. Gasket bolts and no more issues.

[Tom Vaught]

Fastener height might be a possible cause.

I have never used the Pontiac method.

Your 65 Bellhousing should have the "D" shaped opening on the bottom.

I have used that 65 Bell Housing after modifying the Bell Housing cover plate to allow removal of the "D" shaped opening flap under the bell Housing.

I have someone depress the clutch, I install a feeler gage between the pressure plate and the flywheel (usually around .030") and then adjust the linkage to where when the clutch pedal is fully depressed, the feeler gage will fall out.

That way I know I have .030" clearance on clutch release.

No issues with grinding, reverse engagement, etc, EVER.

Tom Vaught

ps I use a modded lakewood shield today.

[geeteeohguy]

I too have run into this with aftermarket flywheel bolts. Went back to the oem bolts with the shallower heads and the problem was solved. The flywheel I was using was a brand new Weber unit.

[Terry M. Hunt]

Appreciate all the input. Ron, I have bought a set of ARP flywheel bolts in anticipation of discovering the ones I have in place now are too tall. Disappointing to learn that even these wound up being too tall in your application. I think I'll order a set of factory bolts also just in case. I recall one of the major suppliers offering a reproduction of these. I only went with the ARP because of their reputation for strength and high quality. No idea where or how the repro flywheel bolts are made. This is one place where looking original is a very distant second to highest quality material and manufacturing methods. I don't want to wind up with the flywheel in my lap some day. I got the car up on the lift last night, so the teardown should commence in the next couple of days. Having nightmares about discovering I need to replace a crank and/or block.

[geeteeohguy]

I would be much more inclined to re-use oem, USA made bolts rather than repro Chinese stuff. Problem is getting a hold of them. Good luck with it, Terry, and let us know what you find. Hoping it's simply the bolt heads.

[Terry M. Hunt]

Problem solved. Flywheel had been resurfaced so much that an adjustable pivot ball was needed to maintain linkage geometry. I posted a long detailed message about how I figured this all out, but the @#*&@@ compter keeps telling me I'm not logged in, security issue or some other crap, so not able to send all the details I wanted to. Special thanks to Roger, the tech rep at Center Force and also OMT.

[Old Man Taylor]

Did you get your pilot bearing/bushing issue resolved to your satisfaction?

[Terry M. Hunt]

OMT, yes I did. Used the Dorman bushing 690023. Since there was some evidence the bearing 7109 that I had been using was not fitting tightly and may have been turning inside the crank bore, I chose not to use another bearing. The bushing was 1.381 thick compared to the bearing at 1.377. I figured if the old bearilng had been turning in the crank, I wanted something installed that would fit beyond (further out of the crank) where any possible wear generated by this bearing had happened. I test fit the bushing about 1/3 of the way into the crank, and it was a nice tight fit. I did have one concern that the additional thickness of the bushing might produce interference with the point on the trans input shaft where the splines bevel down to the tip that fits into the bushing. I installed the bushing and mocked up the bellhousing with no clutch components and measured from the rear face of the bushing to the rear face of the bellhousing. Then I measured from the trans front face to the point where the splines just begin to bevel up on the input shaft. I found I had 1/4 inch of clearance between the bushing and the point where the splines start. So far all is good. Trans shifts easily into first when car comes to a stop and no clashing when shifting to reverse. As I mentioned during our phone conversation, I drive like an old maid school teacher and my cars seldom see the far side of 3000 RPM, so I think I'm going to be okay with the fix I made.
I did pursue the flywheel bolt head issue and Roger told me how to check for a minimum of .060 clearance between the bolt head and any part of the disc hub. I checked 5 different brands of bolts and found all had plenty of clearance, but I decided to use the Mr. Gasket bolts P/n 914 since they had the thinnest heads and offered the most clearance. Probably overkill, but I was determined to eliminate any possible area of interference in the whole clutch system, since I definitely did not want to tear this all apart again. I did congratulate myself many times during this last tear down for forking out the money to buy a 4 post lift about 2 years ago. What a time and labor saver this thing has turned out to be!!!

[Old Man Taylor]

Good job, you will be very happy with the result.