Clutch Ballfork position & ball stud question.
Thread Starter
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Clutch Ballfork position & ball stud question.
Do these two pictures look like the clutchfork is in the center of the opening? The first picture is the original 1970 M-20 I removed from my Vette. In this picture the ball stud is 1.5 inches:
This picture is the BB I'm working on. It too utilizes stock internals but the question is whether I have the correct ball stud. I'm not sure what size this ball stud is but it looks pretty darn close to me.
Thanks
Len
This picture is the BB I'm working on. It too utilizes stock internals but the question is whether I have the correct ball stud. I'm not sure what size this ball stud is but it looks pretty darn close to me.
Thanks
Len
Instructor
Joined: May 2004
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From: Weaverville NC Sit down, shut up, & hold on!
Well dude i know its in the right position for sure
Your Z bar should be pretty easy too take off the car and check the fit
I did not do that before i dropped my BB in, ( i must really like doing things the hard way, or at least twice) i had put my stud ball on the bell housing, OH YEA, Im stupid! nice looking 621 too, I did not paint mine, stripped the paint off and polished it.
keep em flags flying
Your Z bar should be pretty easy too take off the car and check the fit
I did not do that before i dropped my BB in, ( i must really like doing things the hard way, or at least twice) i had put my stud ball on the bell housing, OH YEA, Im stupid! nice looking 621 too, I did not paint mine, stripped the paint off and polished it.
keep em flags flying
Melting Slicks
Joined: Nov 2003
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From: San Antonio TX
I have a silly question why after all that work and going with an improved Big Block would you put a stock Bell housing on there instead of a scatter shield? Or have you ever seen a flywheel and clutch assembly fly apart?
Team Owner
Joined: Mar 2002
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From: Huntsville AL
Len, the Z-Arm ball stud in the picture in mounted in the wrong hole. It goes forward of the oil pressure hole. With the stock 621 bell housing the SB and BB studs are the same.
The position of the clutch fork in the bell housing looks fine. With the throw out bearing touching the clutch the fork should be in the center with an equal distance on each side (or close to it). The ball stud inside the bell housing is a fixed stud, if you felt you needed more you would have to install a adjustable stud. This is really only required sometimes with aftermarket clutch setups. I'm running a Center Force setup on my 427 with the 621 bell housing with all stock GM Z-Arm/ball stud parts.
Dennis
The position of the clutch fork in the bell housing looks fine. With the throw out bearing touching the clutch the fork should be in the center with an equal distance on each side (or close to it). The ball stud inside the bell housing is a fixed stud, if you felt you needed more you would have to install a adjustable stud. This is really only required sometimes with aftermarket clutch setups. I'm running a Center Force setup on my 427 with the 621 bell housing with all stock GM Z-Arm/ball stud parts.
Dennis
Last edited by Mr D.; Aug 25, 2004 at 06:15 AM.
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Originally Posted by Mr D.
Len, the Z-Arm ball stud in the picture in mounted in the wrong hole. It goes forward of the oil pressure hole. With the stock 621 bell housing the SB and BB studs are the same.
The position of the clutch fork in the bell housing looks fine. With the throw out bearing touching the clutch the fork should be in the center with an equal distance on each side (or close to it). The ball stud inside the bell housing is a fixed stud, if you felt you needed more you would have to install a adjustable stud. This is really only required sometimes with aftermarket clutch setups. I'm running a Center Force setup on my 427 with the 621 bell housing with all stock GM Z-Arm/ball stud parts.
Dennis
The position of the clutch fork in the bell housing looks fine. With the throw out bearing touching the clutch the fork should be in the center with an equal distance on each side (or close to it). The ball stud inside the bell housing is a fixed stud, if you felt you needed more you would have to install a adjustable stud. This is really only required sometimes with aftermarket clutch setups. I'm running a Center Force setup on my 427 with the 621 bell housing with all stock GM Z-Arm/ball stud parts.
Dennis
Your're correct Dennis, I put the Z-bar stud in the wrong hole! Thanks for pointing that out. :o Hopefully I would have caught that when I got to that part. I just didn't want to misplace the stud.
Thanks for explaining the ball stud positioning.
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
Len,
The corect dimension from the block/bellhousing face to the top flat portion of the ball stud is 4-3/4".
There are at least 3 different height GM ball studs out there used on different applications. Plus there is an adjustable ball stud sold aftermarket but I would avoid that if I were you.
-Mark.
The corect dimension from the block/bellhousing face to the top flat portion of the ball stud is 4-3/4".
There are at least 3 different height GM ball studs out there used on different applications. Plus there is an adjustable ball stud sold aftermarket but I would avoid that if I were you.
-Mark.
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Originally Posted by stingr69
Len,
The corect dimension from the block/bellhousing face to the top flat portion of the ball stud is 4-3/4".
There are at least 3 different height GM ball studs out there used on different applications. Plus there is an adjustable ball stud sold aftermarket but I would avoid that if I were you.
-Mark.
The corect dimension from the block/bellhousing face to the top flat portion of the ball stud is 4-3/4".
There are at least 3 different height GM ball studs out there used on different applications. Plus there is an adjustable ball stud sold aftermarket but I would avoid that if I were you.
-Mark.
How, exactly do you measure this with the bellhousing in place?
I just measured the stock bellhousing(pic #1 above) & stock stud distance(removed from the block) and came up with 5 inches?? This, with a 1.5 inch ball stud.
Sorry for all the questions.
Last edited by Jughead; Aug 25, 2004 at 09:08 AM.
Le Mans Master
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From: Little Rock AR
Measure it off the car. Just pull the motor out, tear it down and measure. 
If it is off the car you can measure using a straight edge across the opening and a tape measure down to the top of the ball stud. If it is all installed in the car with the fork attached it would be difficult or impossible to measure.
If you have 5", you might have the taller ball stud. There is a short and a tall that are common. I have some old ones out in my old trash stash somewhere. I will look in a little while and see if I have examples of the tall and short.
-Mark.
If it is off the car you can measure using a straight edge across the opening and a tape measure down to the top of the ball stud. If it is all installed in the car with the fork attached it would be difficult or impossible to measure.
If you have 5", you might have the taller ball stud. There is a short and a tall that are common. I have some old ones out in my old trash stash somewhere. I will look in a little while and see if I have examples of the tall and short.
-Mark.
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Thread Starter
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Wonder why this combo worked ok for my SB all those years?
Last edited by Jughead; Aug 25, 2004 at 09:25 AM.
Le Mans Master
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From: Little Rock AR
Originally Posted by Jughead
I think if I have 5" then I'd need a shorter stud?
Wonder why this combo worked ok for my SB all those years?
Wonder why this combo worked ok for my SB all those years?
I have torn down a number of different bellhousings and clutches and seen all kinds of different things in there. Tall bearings, short bearings, egg shaped bearings, flat clutch springs, cone shaped springs, small aluminum bearing retainers, bigger cast iron retainers, bronze bushings, needle bearings. They all work for the most part. 
If your stud is worn, replace it. If you get a choice when you are shopping, buy the 1/4" taller one as it will be correct. The dimension is good to know if you are replacing a GM piece with an "improved" aftermarket blow-proof design that requires a "non-stock" adjustable pivot ball.
-Mark.
Last edited by stingr69; Aug 25, 2004 at 09:35 AM.
Race Director
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From: Living in the Hartland
Always wonder if the fork should NOT start perpendicular to the eng/flywheel, reason being is that the fork travels in a circular motion similar to a clock so my thought is you should try to determine the travel distance and the fork starting point should be 1/2 back from perpendicular so half way through its travel it is perpendicular and when fully engaged it would be same position in the X-axis as it is when it starts. If you start at perp then the fork will bell end up being way to the driver side of the car when fully engaged thus putting more pressure to one sided of the throw out bearing.
OK engineers correct my flawed logic.
OK engineers correct my flawed logic.
Le Mans Master
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From: Little Rock AR
Originally Posted by Fevre
Always wonder if the fork should NOT start perpendicular to the eng/flywheel, reason being is that the fork travels in a circular motion similar to a clock so my thought is you should try to determine the travel distance and the fork starting point should be 1/2 back from perpendicular so half way through its travel it is perpendicular and when fully engaged it would be same position in the X-axis as it is when it starts. If you start at perp then the fork will bell end up being way to the driver side of the car when fully engaged thus putting more pressure to one sided of the throw out bearing.
OK engineers correct my flawed logic.
OK engineers correct my flawed logic.
Len, I believe the 1.5" stud IS the shorter one. I just measured the one I found in my stash and it is the "short" one. The taller one is about 1/4" longer from my memory.
-Mark.
-Mark.
Melting Slicks
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From: St. Charles Mo
CI 5 & 8 Veteran
All, this discussion is bringing back some fond memories 
Dosen't this all depend on which throwout bearing you have? If my memory serves me correctly, there are three different sizes, short medium and tall. the medium is perfered but darn near impossible to find...at least for me. I wound up using the adjustable ball for this reason.
Bullshark
Dosen't this all depend on which throwout bearing you have? If my memory serves me correctly, there are three different sizes, short medium and tall. the medium is perfered but darn near impossible to find...at least for me. I wound up using the adjustable ball for this reason.Bullshark
Last edited by Bullshark; Aug 25, 2004 at 10:08 AM.
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
It's just too bad the archives aren't working properly. I'm getting posts back to 7-2-2004 then nothing again until 8-12-2001???
Those dimensions,without corresponding numbers, don't match up to what is available:
CLUTCH FORK STUDS
3729000 — Stud Ball
13/16–16 x 1.48" overall length.
3790556 — Stud Ball
13/16–16 x 1.78" overall length.
Those dimensions,without corresponding numbers, don't match up to what is available:
CLUTCH FORK STUDS
3729000 — Stud Ball
13/16–16 x 1.48" overall length.
3790556 — Stud Ball
13/16–16 x 1.78" overall length.
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
OK - I put the vernier caliper to mine and I get 1.48" so I definately have the "short" one in my junk pile.
Len, you probably have the short one too. The longer one is still available so I guess you need the longer P/N 3790556 — Stud Ball
13/16–16 x 1.78" overall length. If it was all together and working properly, I would buy the long one and install it the next time you have the tranny out for something.
-Mark.
Len, you probably have the short one too. The longer one is still available so I guess you need the longer P/N 3790556 — Stud Ball
13/16–16 x 1.78" overall length. If it was all together and working properly, I would buy the long one and install it the next time you have the tranny out for something.
-Mark.
Thread Starter
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Originally Posted by stingr69
OK - I put the vernier caliper to mine and I get 1.48" so I definately have the "short" one in my junk pile.
Len, you probably have the short one too. The longer one is still available so I guess you need the longer P/N 3790556 — Stud Ball
13/16–16 x 1.78" overall length. If it was all together and working properly, I would buy the long one and install it the next time you have the tranny out for something.
-Mark.
Len, you probably have the short one too. The longer one is still available so I guess you need the longer P/N 3790556 — Stud Ball
13/16–16 x 1.78" overall length. If it was all together and working properly, I would buy the long one and install it the next time you have the tranny out for something.
-Mark.
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Ok, I got some ball studs. In this picture on the left is my original from my '70 Vette, in the middle is what I think is the taller #3790556 stud, and on the right I have no clue what that one is. It has coarse threads and I don't know where it came from.
Here's the two in question. The one on the right is the taller one but I think it's worn down a bit.... The tip of the stud looks like it worn unevenly too. The very tip of the stud is slanted. I ordered a new taller one & see how that compares.
Here's the two in question. The one on the right is the taller one but I think it's worn down a bit.... The tip of the stud looks like it worn unevenly too. The very tip of the stud is slanted. I ordered a new taller one & see how that compares.
Last edited by Jughead; Aug 25, 2004 at 09:30 PM.
Melting Slicks
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From: St. Charles Mo
CI 5 & 8 Veteran
What size throwout bearing??
Len, What size throwout bearing were/are you using....both old and new?? I had the stock ball which I believe to be the same size as your old stock ball and had this bearing ....measuring ~1.5" in my stock 70-454. It is what I refered to as the medium size.
When I pulled the engine for Project RamJet 502 I could only find what I refer to as the short bearing......don't have one to take a pic of, but it is obviously shorter than the one pictured. I had to go to a longer ball...so I opted for the adjustable type. I have used them on a couple of the cars and have not had a problem, nor heard of anyone around here having one. I adjusted it longer by eye before I mounted the transmission on and before dropping the engine/tranny assembly in. It works great. There is a tall throwout bearing but I think it is for trucks!
Bullshark
When I pulled the engine for Project RamJet 502 I could only find what I refer to as the short bearing......don't have one to take a pic of, but it is obviously shorter than the one pictured. I had to go to a longer ball...so I opted for the adjustable type. I have used them on a couple of the cars and have not had a problem, nor heard of anyone around here having one. I adjusted it longer by eye before I mounted the transmission on and before dropping the engine/tranny assembly in. It works great. There is a tall throwout bearing but I think it is for trucks!
Bullshark
Last edited by Bullshark; Aug 25, 2004 at 10:38 PM.
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
1.5 is the measurement of the one in my 34 year old Vette. I'll need to dissasemble the bellhosuing again for the new one but I think it's about the same size.