The Stovebolt Site Forums The Shop Area Driveline Clutch Confusion

Hi Guys!

I've been reading lots of old posts on clutch replacement/sizing and have ended up confusing myself.

But first, the vital stats: My truck is a 1953 3100. It currently has a replacement 235 engine and original transmission/bellhousing/torque tube. The truck is being converted to 12v electrical system. The 235 that's currently in the truck is dead and will be replaced by a running 235 from a donor 1961 Impala. The Impala's 235 was setup with a cast iron powerglide transmission.

In preparation for running the 12v starter and the manual transmission, I recently purchased a flywheel with the correct ring gear. The flywheel part number is 3705410. Before purchasing the replacement flywheel, I tried doing my research here, and determined that part number was usable on my truck.

Now my confusion...what clutch size will fit within the original, 1953 bellhousing? I've read that 10 3/4" clutches were available in 1953, but will the combo of the 3705410 flywheel + 10 3/4" clutch fit or should I use a different size clutch?

In going to websites like rock auto, it becomes even more confusing since they sell 10.4" clutches, not 10.75". Does this make a difference? Will the bolt patterns match up to those on the flywheel? I can't afford to buy multiple sets of clutches trying to figure it all out. I need a little stick and rudder here to get back on my desired flightpath.... Thanks in advance!

Any of the clutch assemblies sizes will work with a 1953 truck clutch housing. You just have buy the correct size/assembly for the flywheel.

Buy an entire clutch assembly (all parts in a "kit").
This way, they will all match.
- clutch disc
- pressure plate
- throw-out/release bearing
- pilot bushing
- plastic clutch alignment tool

There were different diameter clutch-disc/pressure plates. You have to find one that matches the attachment holes in your 12v ring gear fly wheel. Good luck with on-line listings, because, as you have found, they have interesting ways of measuring diameters.

Also, you need matching parts because the clutch release-bearing height must match the pressure plate height (there were two height combinations).

I try to get a local parts supplier to order a set with all the parts. Ask them to determine what set you need. I have even brought in my flywheel, so they take responsibility for getting the correct assembly. This way, if it is not correct for your flywheel, they are more likely to refund/replace/reorder.

Check your flywheel for check-marks and glazing. A good parts place, like a big NAPA store, will turn/surface the flywheel for $20-$50.

Regarding the pilot bushing - let's hope someone posts info on any oddities related to a Poweglide crankshaft end (where the pilot bushing is installed).

3705410 is a 10" clutch flywheel

http://chevy.oldcarmanualproject.com/1929_57chevyparts/57cmpc0147.htm

A heavy duty clutch. Relatively uncommon.

The more common 9.5" & 11" clutch assemblies will obviously not work with that flywheel.

Tim,

Thanks for the information! So a 10" clutch kit will do. I have access to all of the major flaps in my area and I can definitely take the flywheel with me when I order. I bought the flywheel off of ebay, taking a leap of faith. My normal mechanic recommended an "old timer" to do the machine work on the flywheel. I contacted the gentleman and he was pleased to be able to work on some of the old parts again. He did a wonderful job machining my flywheel. Some time ago I had asked some questions here about reviving the old engine. At the time, I think the consensus was that powerglide or not, the crank should be able to accommodate the pilot bushing. I guess time will tell !

OK, good, Mike

Nice looking flywheel. Nurture a relationship with that guy.

Come back here and report on the finale.

Also, report back here on the pilot bushing in a Powerglide flywheel. That info will help someone in the future (and, keep me from posting bs).

Good luck with installing the clutch assembly and connecting/adjusting the torque-tube fittings. It is not formidable, but can be confusing "the first time out".

I thought I would take a pic of the back of the crank shaft. Hopefully, you all can tell if it will accept a pilot bushing or not. If the pic isn't good enough to tell, let me know and I'll try again.

Looks good for a pilot bushing. Get the ID, see if corresponds to available bushings.

Ed

If the hole ends up to be too small, someone manufacturers one which will fit it (if it is the same ID as what is in a 1953 235 with Powerglide transmission).

As Carl said, there is one made for that application. Your oldest guys at your local FLAPS can probably help you out. Use calipers to measure the outside diameter of the hole and then measure the tranny shaft.🛠

The image on the left, below, might be the pilot bushing that supposedly allows a 235 Powerglide crankshaft work with a manual transmission forward shaft.

That part number, 690-034, is the same for the same-purpose Dorman bushing?
https://www.dormanproducts.com/p-18310-690-034.aspx

Supposedly, the National bushing PB-656-HD serves the same purpose? (second image from the left).

I'm resurrecting an old post to provide an update on what finally happened.

It took me 2 years to get to the point of actually installing the heavy duty flywheel. The actual installation was easy. It fit onto the crank perfectly and bolted easily. Adding the new clutch was fiddly, but I managed. The issue came when I tried to install the clutch release fork. It would not fit between the stud and the new clutch cover. No matter how I tried to wiggle it past, it would not fit. So I went to the engine that I had recently removed from the truck and looked at the clearance between the stud and clutch cover there. There was a significant amount of additional space on the old engine.

I tried to measure the thickness of both flywheels and it appears that the heavy duty flywheel is much thicker than the regular one. On the order of about a 1/2" thicker. So now it seems as though I'm going to have to remove the clutch and heavy duty flywheel and go to the original one, after getting it resurfaced and replacing the ring gear with a 12V ring gear to match my starter.

The other issue was the pilot bushing fitting into an original powerglide equipped engine. I did buy the recommended bushing. When test fitting the bushing, I found that the one that came in the clutch kit was a better fit to the transmission input shaft than the extra one that I bought. So I went with that one. It was an extremely tight fit when installing it into the crank, but it did eventually seat all the way.

I'll add some pics of the clearances between the stud and clutch cover and one of the pilot bushing after installation. The clearance pics are kinda hard to see, but better than nothing. In the pilot bushing pic, I had not yet removed the old powerglide flexplate when I took the pic.

Would you have more wiggle room with the clutch fork if you removed the ball from the bell housing? Just spitballing here.

Carl,

What I was thinking of trying is to remove 5 of the 6 bolts that hold the clutch cover in place and loosen the 6th bolt. With the loose bolt positioned at 12:00, I could swing the clutch cover and friction disk to the side and make enough room to install the clutch fork.

What worries me is if I do that, will I have enough room to properly install the release bearing (throwout bearing)? Since it appears that the extra thickness of the heavy duty flywheel is eating up so much space, will the release bearing essentially be engaged all of the time?

I really have nothing to lose mocking this up, since I have to remove the clutch cover anyways. I'll just take a few minutes and see how everything lines up. If it does not appear to be workable, I'll remove the clutch assembly and heavy duty flywheel and move to the flywheel that is in the engine that came with the truck. I might try activating the old 6V starter that's on that engine and see if it works. If it does, then I'll likely just stick with that starter since it already pairs with that flywheel. All I would need to have done is to have the flywheel resurfaced and buy the correct clutch assembly. If I end up going with that flywheel, I'll post in the parts for sale section to sell the heavy duty flywheel. Surely someone could use it....

UPDATE:

I did the mock up today by removing 5 of the 6 bolts on the clutch cover and loosening the 6th bolt, which was at the 12:00 position. That allowed me to swing the clutch cover and disk to the passenger side of the engine and gave me just enough wiggle room to get the clutch fork into position on the stud. Once it was seated on the stud, the clutch cover could be correctly positioned and the remaining bolts installed. I then did a test fit of the throwout bearing. The only way that I could get the throwout bearing to seat in the clutch fork was to "snug it up" against the clutch cover fingers.

DISCLAIMER: I have no experience in this. None. I do not know what is right and what is wrong. I'm learning all of this as I go along and this is new territory for me. So I'm counting on someone to help me learn. Is it acceptable to have constant contact between the throwout bearing and the clutch cover fingers? If so, how do you tell if it is too much pressure? If it is unacceptable to have constant contact, then party over for this flywheel.

Thanks is advance for helping me to learn.

It’s definitely not alright to have the throwout bearing riding on the clutch fingers. The bearing is designed to totally disengage from the clutch fingers. That would surely wear out the throwout bearing prematurely and more than likely cause the bearing to make noise.

Phil,

Thanks for letting me know. I guessed that would be the case, but needed someone who knew to confirm what I was thinking. I'll disassemble everything next weekend and likely post an ad in the parts for sale section. I've got a really nice, heavy duty flywheel that will be going on sale! Too bad it couldn't fit in my 53, I should have been more diligent about verifying the part number before I bought it. Lesson learned.

That is the same reason not to sit at a red light with the clutch pedal in, put in neutral and let the pedal out.

Ed

Hi Everyone,

Final update to close out the thread. I removed the original 1953 flywheel from the dead engine that was in the truck when I bought it. I found a local machine shop and had it cleaned and resurfaced (pic below). I bought the correct 9" clutch from the nearby flaps and it all went together easily. The clutch fork and throwout bearing all have plenty of clearance to fully disengage when not in use (pic below). Bottom line, using the 1953 specific parts is what I needed to do. Using alternate parts, that may or may not work wasted my time and money. Lesson learned. The last pic is the fully assembled replacement engine and transmission ready for installation into the truck. Hoping to do that this weekend!

The replacement engine is one that I salvaged from a local junkyard and is from a 1961 Impala. It was originally set up for the cast iron powerglide transmission. It runs well on the test stand, although it does smoke a little until it warms up.

Mike,

This has been a long post, so this question might not be necessary (sorry): I think you posted that this engine came from a Powerglide-equipped car? Does it still have the hydraulic lifters (they were standard equipment in all non-Corvette 235s)?

Tim,

Yes, it still has the hydraulic lifters. When it runs, it sounds like a car engine. Meaning no clicking. The drawback in using a car engine is that I'll have to drill the holes for the front motor mount and have to attach the bolts from the bottom instead of how it is normally done. If I ever rebuild this engine, I'll get the front motor mount installed the normal way. For now, I just need the truck to move in and out of the garage on its own, so that I can work on it in the driveway (more space and less likelihood of welding sparks burning down my house...!)

Good, Mike

Have installed the water pump relocation plate on your 1961 235 in your 1953 truck?

Tim,

No, I didn't do the water pump relocation. I'm planning on using an electric fan, so the location of the water pump wasn't a issue for me. Now, given my previous statement about alternate parts...maybe I should rethink that decision?!?