Throwout Bearing Question

fuzz1957 · Oct 11, 2016

Have a throwout bearing question. Information that should help. Muncie M21 transmission and 10 1/2 inch clutch was made/setup by a Big A auto parts shop. If you have followed some of my build problems, the latest being replacing an aluminum truck bell housing with a correct size "403" aluminum car bell housing so the Muncie transmission flange fits correctly. While doing this, I've found the fork I used GM part No. 340218 had a spring that holds the throwout bearing in place half broken off. (I think it was put in this way by my "mechanic" friend because I painted it with por15 and it was still all painted. I observed him doing the work and thought it was right.) The throwout bearing I took out looks like the thin outside edge is very slightly bent because of the broken spring not keeping the bearing completely square. The TO bearing number is CC-02337 CR that was taken out and I believe it came with my Big A auto parts clutch. Googling the fork number shows it is for a chevy truck vintage 1980 and probably came with the truck bell housing I originally used. It is supposed to be a heavy duty clutch fork. I picked up a new fork GM part No. 14066235 which is the replacement/super seeding number for No. 340218. I want to replace the throwout bearing (don't want to take a chance on old bearing) with a new one. Can't find any real information about what throwout bearing I should use. A 1980 truck throwout bearing by National is No. 614018 at Advance Auto and should fit my No. 14066235 clutch fork. FINALLY - my question to those who are knowledgeable/talented - is that the throwout bearing I should use for my setup and fit the fork and Muncie transmission?

Thanks for reading this long post question and appreciate those who are very willing to help those of us who are doing this for the first time. Hope I have enough information so you can give an answer. Thanks again!

Fuzz

MAGA

Muncieman · Oct 12, 2016

Throw out bearing

There is another part to this equation. Throw out bearings come in different lengths as part of the geometry. For instance a raised finger diaphram pressure plate requires a "short throw out bearing" and a flat fingered diaphram pressure plate requires a long throw out bearing. You also mentioned changing bell housings, be advised that the stud in the bellhousing on which the fork rides comes in different lengths as well as an adjustable one. So be a real mechanic and look at eveything. Don't forget the pilot bearing. Its a must to use a bronze oil-lite bushing because the muncie pilot shaft is not compatible with a roller bearing and will chew up the muncie shaft
Gary

fuzz1957 · Oct 12, 2016

Gary,

First, thanks for your reply and insight.

1. How do I tell if my clutch fingers are flat or raised? Will look tomorrow.
2. I was told the stud in the bellhousing is a short one. Will measure length. It is in very good condition.
3. I do know/remember the pilot bearing is the bronze one.

Will do more research and post back again. Want to do it right this time.

One more thing. When putting the Muncie back in, is there any advice (other than keeping the trans. shaft straight) about sliding the trans. shaft thru the throw out bearing without dislodging it from the fork?

Thanks again, Fuzz

MAGA

Wayne Meuir · Oct 12, 2016

I think that one of the main things to do to set it up is to have the clearance between the TO Bearing and the clutch plate fingers set correctly and the clutch for angle set up properly.

I am going to have to do this shortly and do not know exactly how it is done or what the measurements should be.

I think the clearnace is set by adjusting the ball stud in the bell housing. Not sure if that measurement also gets the fork angle set up correctly.

Watching this thread for advice.

Wayne

Dragsix · Oct 12, 2016

Fuzz, when I was younger, I could lay under the car and roll the stock three speed onto my arms and then hang it all by myself. Youth right! Now, not so much. So when I recently installed my four speed, I made up a pair of pins using long bolts with the heads cut off, and the unthreaded shank end rounded off. Cut a slit in each end for a screwdriver in case you need a little help removing them. Install them in the lower two holes of the bellhousing. Then you and a friend can hoist the trans up onto the pins and thus will have the trans mostly centered while you slide it forward on the pins, which will allow aligning the trans input shaft with the throwout bearing way easier. Once on the bearing, you should be good to go. Just slide the trans forward until it mates with the bellhousing. Then install the upper two bolts for the trans, remove the pins one at a time and install the lower bolts. The other benefit from using the pins is you lessen the risk of damaging or bending the input shaft or front bearing by having the trans hang from the motor by the tip of the input shaft, the weight now being borne by the pins, and if the bellhousing is way off center from the crank center, you will know it, the trans will not easily go in. You still may have to wiggle a little bit with the pins, but if you are doing the install and the trans will not go in on the pins, tells you to check the bellhousing. You may need to dial indicate or get, borrow or rent one or the newer fixtures for centering a bellhousing.

Raised finger diaphragm pressure plate, would use the short throwout bearing.

http://www.ebay.com/itm/McLeod-RACI...Chevy-Pontiac-Olds-/391431617353?hash=item5b23247b49:g:BycAAOSwnH1WYhkA&vxp=mtr

fuzz1957 · Oct 13, 2016

Thanks Dragsix.

I read somewhere about the bolt trick and already have mine ready to go. Just got home and took some pictures and will post them asap.

Fuzz

MAGA

fuzz1957 · Oct 13, 2016

Here are some pictures of clutch and bellhousing stud.

Bellhousing stud viewed from top.

Bellhousing stud measurement. 3/4" or 13/16" high.

Full view of clutch.

View of clutch fingers distance.

Clutch fingers measured. 1 3/8" distance.

Pilot bearing.

Do these pictures help with knowing what throwout bearing I should be using? And what would be the correct throwout bearing?
Is the bellhousing stud correct for my clutch fork?
From these pictures, is there something I should know that hasn't been covered?

Thanks,

Fuzz

MAGA

Dragsix · Oct 13, 2016

Hard to tell but looks like a standard pressure plate so would be the long bearing. Do you know what brand pressure plate that is? Remember where you got it?

Mike

fuzz1957 · Oct 13, 2016

Mike,

Thanks for reply.
Bought the setup from a Big A auto parts store 8-9 years ago. The guy I dealt with said he made his own. He asked me how much foot pressure I wanted when engaging the clutch - stiff - medium - or weak. I told him medium. It isn't a name brand. Big A is out of business now in that town and I don't know if this guy is even still around. He was an older gearhead 8-9 years ago. Plus, I've moved 60 miles away. When you say I need the long bearing, is the one I found at Advance Auto - National bearing No. 614018 (in my original post above) the right one to use (a long bearing) and fit my Muncie transmission correctly?

Thanks, Fuzz

MAGA

Dragsix · Oct 13, 2016

I hate to say this but you may end up having to engage in a little trial and error.

Generally, the pressure plates that have a good bit of pressure have diaphragm fingers that stick up a pretty good amount so to speak. In other words, the fingers on these pressure plates extend out further then a standard pressure plate so need a shorter throwout bearing in order to make sure there is sufficient clearance between the fingers of the pressure plate and the bearing when the clutch is fully out and engaged (so the bearing is not constantly spinning on the trans snout, and at the same time allow the clutch plate to disengage with the appropriate clearance between the clutch and pressure plate/flywheel.

So my old Schiefer pressure plate is 2800 lbs and has extended fingers so I use the short throwout bearing (it was originally a higher poundage but I was racing the car when I bought it decades ago so I had it rebuilt to a slightly lower and thus easier on my left leg specification). just as an aside, I just recently had both my vintage and decades old clutch and pressure plate rebuilt at H&R Clutch in Bensalem PA if anyone is interested. They built those pressure plates, as well as the Schiefer clutches, for George Hurst after he bought Schiefer. They rebuild clutches and pressure plates, including high performance stuff. They told me a lot of what is being sold today is offshore junk steel and that the best units are the older USA manufactured units and that those units can be rebuilt to like new performance. They rebuilt mine, works absolutely perfectly, including at the drag strip at the nationals this past august.

The more standard pressure pressure plates have flatter fingers. Looking at your photos, I don't think what you have is a high performance pressure plate. Because the fingers look to be a good bit flatter, that unit would use the long throwout bearing, at least from what I can see. I am not sure what the National number is for a long bearing but there are really only two for the chevy, long or short. So I would ask to see both long and short to confirm. I used a national short this time around but did not write the number down.

Of course the other alternative, and I am not one to just spend money wily nily, is to simply upgrade the whole thing since you have it all apart. New med level performance pressure plate (or have what you have checked out and rebuilt to a mid level performance specification if necessary), face the flywheel and have it balanced with the pressure plate, new mid level performance clutch plate and a matching bearing. Then its done, all fresh and new.

fuzz1957 · Oct 14, 2016

Did some more measuring today. I've got a clutch fork that is exactly the same as what I took out. It is new. I replaced the throwout bearing with a new one that is the same. It is a "short" throwout bearing. I mocked up the bellhousing with fork/bearing installed.

Leveled the bellhousing on my work bench and also leveled the throwout bearing (attached properly to fork) so they would be parallel to each other and the way the Throwout bearing would ride on the transmission shaft in the bellhousing. The distance from the bellhousing where it mounts against the block to the top of the throwout bearing is 4 1/4 inches.

Measured the parallel distance from the back of block where bellhousing mounts to the front edge of pressure plate circle. That distance was 4 inches.

Measured the distance from the top of fingers to edge of pressure plate circle (where I measured to above) where throwout bearing goes thru. It is right at 3/32 of an inch.

So, with these measurements this is how I believe everything should go together.

With the clutch fork/throwout bearing installed in the bellhousing - bellhousing installed on the block - putting the shaft of transmission thru throwout bearing and transmission installed to bellhousing - that should leave 1/4 of an inch + 3/32 of an inch (11/32 of an inch total distance) between the throwout bearing and the pressure plate fingers. (4 1/4 inches minus 4 inches + 3/32 of an inch = 11/32 of an inch)

Am I figuring this correctly as far as the geometry goes?

Is 11/32 (just over 1/4 inch) too much distance between throwout bearing and clutch fingers?
Will this work without any problems with these distances?

Thanks, Fuzz

MAGA

Muncieman · Oct 22, 2016

Throw out bearing

Dragsix said:
Hard to tell but looks like a standard pressure plate so would be the long bearing. Do you know what brand pressure plate that is? Remember where you got it?

Mike

Hi Mike that pressure plate appears to have raised finger which means it would require the short throw out bearing. then the fflat finger takes the long right?

Gary

Dragsix · Oct 23, 2016

Yep, raised finger takes the short, flat fingers take the long.

fuzz1957 · Oct 23, 2016

Thanks to those who have posted here and tried to help. Much appreciated.

Update on my trials and tribulations.

The "403" bellhousing I bought didn't fit. Counted the teeth on flywheel and it's 168. 403 only fits a 153 tooth flywheel. Should have done that before getting the 403. I'm learning. Soooo, bought a 57 stock bellhousing. Only problem is it doesn't have the lower inspection cover or inspection shield. Posted in WTB for them, and so far no success. Hoping to get it back together pretty soon so I can move it from a non heated part of my garage to the heated part before it gets cold and snowy.

Thanks, Fuzz

MAGA

Throwout Bearing Question

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