Hi all,

I have a '68 442 with an M20 4-speed. A few years back I replaced the clutch when I had the engine and trans out for cleaning/painting. I was not having any clutch problems at the time but figured I would replace it while I was in there. I had the flywheel resurfaced and installed a Hays clutch and throwout bearing. I made sure everything was degreased and spotless prior to installation. Since soon after, the clutch has chattered when taking off from a stop and has gotten worse over time (about 2000-3000 miles). It got to the point where the driver's side motor mount bolts in the block started backing out. I pulled the engine and trans again last week to inspect everything and replace the clutch, thinking I probably had some oil on the clutch disc, flywheel, or pressure plate when I installed them. When I separated the engine and trans this time, I noticed oil on the inside of the cover at the bottom of the bellhousing as well as a thin film of oily grime on the inside of the bellhousing and on the outer inch of the flywheel (outside the pressure plate), and some on the front of the trans. This oil doesn't smell like gear oil and the machinist who resurfaced the flywheel said seeing some grime like this wasn't out of the ordinary. There was no obvious oil residue on the pressure plate, clutch disc, or contact surface of the flywheel. It seems like the oil pan gasket is leaking at the back but could oil from the other side of the flywheel work its way around under the clutch disc? Pictures are attached of the parts as I found them last week. Though it chattered on takeoff, the clutch didn't slip at any speed in any gear and everything worked smoothly once I was moving. The engine was not taken apart when I previously replaced the clutch but I did replace the valve cover gaskets and oil pan gasket because they were leaking pretty badly. I'll be replacing them again and looking for the power steering leak which has coated the underside of the engine and trans. I had the flywheel resurfaced last week and the machinist said he took .006" of material off. I have a new McLeod clutch, pressure plate, and throwout bearing I'm about to install. Is there anything obvious (or not obvious) I need to check before I reassemble everything?

 

Is the pilot bearing good?

 

I believe it is. I replaced it when I replaced the clutch last time and used a new, GM part. I didn't remove it this time but I checked it by putting my finger inside and turning it. It turns smoothly through a full rotation.

 

the chattering taking off could be caused by the loose motor mount bolts,not the other way around.if the engine is moving due to the lose bolts it effects the clutch linkage

 

It's probably that Fram oil filter causing the problems....lol

Sorry I couldn't resist.....

The rear main or pan gasket is definitely leaking. It's mot uncommon for the oil to get onto the clutch disc from there...

 

I had my 1967 442 Muncie M21 recently rebuilt by an 83 year old gentleman who has been rebuilding manual transmissions on the side for 46 years. He said he's rebuilt over 4,000.

He told me to put a very very thin film of lithium grease on the front housing surface that the throwout bearing rides on but not to put ANY type of lube on the splined input shaft to

prevent any chance of lube getting transferred to the clutch. Whether intentional or not, your photos definitely show some type of lube on the input shaft which cannot be

helping the situation.

 

What style clutch. Snap pics of both sides of the disc and clutch.
What brand and style of TO bearing? Bought as a matched set?
TO bearing mounted on the fork correctly. Fork pivots OK?
Was the wheel balanced post-machining?
Is the disc installed in the right direction?
What is that red goop on the flywheel bolt holes?

Verify zero run-out in the pilot hole and flywheel. Run the engine and observe.

Post Tip: When posting please break up the post with proper paragraph structure(google).
Not being an *** its just very hard to read that huge block.
Especially when most of us don't have time or eyeball strength for a 10-minute read.

 

Thanks for the responses.

jcdynamic88 – I’m glad you brought that up because I didn’t mention it in the original post. Thinking loose motor mount bolts could be the source of the problem, I checked them a couple months ago and found the mount-to-block bolts on the driver’s side were really loose. I tightened them well (a pain while the engine is in the car) but didn’t notice any improvement when driving. I checked this evening and they're all still tight. I hadn't thought about the clutch linkage moving around as a possible problem but when I pulled the motor this time everything was snug and there was no slop in the bushings, etc.

skekas33 – The clutch instructions (yes, I kept them) say to “lubricate input shaft of transmission lightly with a light grease.” I may have used too much. I hadn’t considered the input shaft slinging oil onto the clutch surface but that’s a good point. With a leaking oil pan gasket there would have been a steady supply of oil. I will follow the advice of your trans guy when I reassemble everything.

 

droldsmorland – lots of good questions, so here goes (hopefully this long post is a bit easier to read )

What style clutch. Snap pics of both sides of the disc and clutch. – diaphragm style. Pics below. I just noticed the dark ring on the inside 1/3 of the friction material in second picture of the disc. Could that be caused by oil contamination?

What brand and style of TO bearing? Bought as a matched set? – Hays stock style, came in the clutch kit.

TO bearing mounted on the fork correctly. Fork pivots OK? The picture of the bellhousing below is a slightly better angle to see the TO bearing installed on the fork as it was when I pulled the bellhousing off the engine. I don't know if you can tell from the pic but I think it was installed correctly, i.e. not wedged between the spring and the fork as I've heard of some people doing. The fork pivots OK but the pivot ball has a small groove worn into the outer edge it so I will replace that while it's apart.

Was the wheel balanced post-machining? I didn’t specifically ask for it to be balanced after machining so unless that’s standard practice, I’ll say it wasn’t.

Is the disc installed in the right direction? I’d like to think I followed the directions which say to have the sprung center hub facing away from the flywheel but I didn’t check for that when I took it apart.

What is that red goop on the flywheel bolt holes? It’s paint from the pressure plate that stuck to the flywheel when I removed the clutch assembly.

Verify zero run-out in the pilot hole and flywheel. Run the engine and observe. I’ll have to wait until the engine is back in the car but I will check this.


On the subject of pictures, the ones in my posts seem a bit large. I thought the forum software might scale them down but it looks like it doesn't. Let me know if I should resize them so they each don’t fill up the whole screen.

 

There is paint on your flywheel bolts that match the scrapes on the springs of the clutch disc. I think you need to find out what the clearance is between them when they are bolted together. The flywheel may have been resurfaced too many times and is now too thin allowing contact between the bolts and the springs. Or the springs in the clutch disc may be larger than factory and causing the contact. That may be the reason your clutch disc is not wearing on the inner portion (the darker color around the inner portion of the friction surface) as much as the outer. That would certainly cause chattering when engaging the clutch. Just a thought.

 

Good catch! I noticed the stuff on the flywheel bolts when I was replying to droldsmorland last night but was focused on the big paint chips under the pressure plate bolts and convinced myself that's what he was asking about. I totally missed the chipped paint on the springs. I think you're right which could mean I had the clutch disc installed backwards. I'll take a closer look at everything this evening and measure the assembled clearance then post what I find.

 

Is there more wear (shine) on the 6 o'clock to 12 o'clock ? Was that side mated to the 2 o'clock to 4 o'clock side on the flywheel ?

[/QUOTE]
Just wondering if the lighting is fooling me.

 

Just wondering if the lighting is fooling me.[/QUOTE]
It's the lighting.

 

I measured the flywheel and there is .240 inch between the surface of the flywheel and the top of the bolts. From the surface of the friction material on the clutch disc to the top of the springs is .150 inch which leaves .090 clearance between the flywheel bolt heads and the springs on the clutch disc when installed. I don't think there is any way I had the clutch disc installed backward because when I stacked everything up on the flywheel that way the pressure plate was so far from the flywheel the bolts wouldn't reach to pull it all together. I noticed when I stacked everything up to check that even more paint chipped off the springs so the paint that's missing from the clutch springs and residue that's on the flywheel bolts could be where I tried putting the clutch disc in that direction when I first installed the clutch years ago. That was the first time I had ever replaced a clutch so there was probably some trial and error involved.

I also looked closer at the dark ring around the inner 1/3 of the friction material. There is residue that is slippery/sticky like cooked oil or grease which seems like it would be consistent with oil being flung off the input shaft onto the clutch.

OLDSter Ralph - I don't know what type of machine was used to resurface the flywheel last time but the machinist who resurfaced it this time gave it a good look when I took it in and didn't notice anything concerning. As for the light/dark areas on the flywheel and pressure plate, it's just the lighting and reflections of stuff in the background.

I pulled the oil pan off last night and it looks like the gasket was just slowing down the flow of oil out of the pan rather than preventing it. Unless there are any final ideas I'm going to replace the oil pan gasket, clean everything up, and install the new clutch (making sure everything is spotless before assembling).

Thanks for all the questions & suggestions.

 

It could be your pictures. It appears that your flywheel and pressure plate have hot spots. Those spots will cause your clutch to chatter. Any spots on the surfaces will cause issues. I doubt it’s the pilot bearing, I doubt that it’s your motor mounts. In all cases, I would recommend changing your clutch. I have used Hays many times with no issues.

This is what I would check:
check the input shaft of trans, how are the splines? How does the disc fit? A worn input shaft can make a clutch chatter.

Also, see if anyone can surface your flywheel on a lath instead of the traditional flywheel surfacing machine.

Hope this helps.

 

Hi,
I had a similar problem of the springs and flywheel bolts with my car. Someone machined down the flywheel way to far. Are the edges of the flywheel still beveled? My solution was a new PRW flywheel and Ram muscle car clutch kit. It’s worked great for last 10 years.

 

The only way to properly resurface a flywheel is to have it blanchard ground. This will produce a truly flat surface regardless of hot spots and will result in a unique pattern that I do not see on your flywheel. If your machine shop does not have this equipment, take the flywheel to another shop that does.

 

If you look closely at the flywheel, it does appear to be resurfaced on a "rotary surface grinder". While its a rotary surface grinder, it doesn't appear to be a Blanchard grinder. The Blanchard grinders are much more rigid and can produce a cross hatch pattern. The rotary surface grinder will produce an acceptable surface. The pressure plate surface appears to have been ground on a larger rotary surface grinder in batches.
Blanchard grinders are considered the "Cadillac" of rotary surface grinders and most shops can't afford one. They are extremely rigid and can be larger...... up to about 144" (12' across) tables.

 

The Vette clutch got the Blanchard treatment.

 

Old thread, yes, I know but maybe someone can shed some light here.
Every clutch I have ever installed has dowel pins. My McLoed does not have provisions for this nor any shoulder bolts or sleeves. Do I just use grade 8 bolts to secure the clutch to the flywheel?

It's a PRW flywheel

Thanks,
Dan