Throwout bearing failure

[Brendan Sellers]

Hello all,

I have a 1966 Belvedere II, 273, 3spd manual. The old throwout bearing failed on a Sachs clutch, so I put a new clutch and throwout bearing in, from McLeod. Well, this bearing is failing after 300 mi. This clutch was SO jumpy, so I removed the return spring inside the cab. The pedal still returned fully, so I left it off. I don't think the release fork was riding on the bearing all the time.

When you press the clutch pedal down you can hear the bearing squeaking. The pedal feels rough as you depress and release it. I removed the inspection cover and it appears that the pressure plate fingers don't align correctly with the throwout bearing. I guess that's due to the bearing pivoting on the release fork.

You can feel a slight shaking in the pedal when the release fork contacts the throwout bearing - I assume that's because of the bearing pivoting. I rotated the engine thinking the pressure plate fingers got bent, but they appear straight.

I know I have to pull the trans again to remove the bearing, but what should I look for this time? Pilot bearing on the trans? Also, should the clutch rod that goes from the clutch pedal to the bar mounted on the frame be bent? Mine is crooked where it passes through the floor / firewall.

https://www.youtube.com/watch?v=D4hrQg9Q7g8

 

[Daves69]

As I understand the over center spring is removed for the diaphragm style plate.

I think I'd take a hard look at the fit of the release bearing on the trans bearing retainer. Also look at the fork pivot and make sure it's not bent inward possibly causing off center pressure on the plate fingers.

If your pedal rod mates flat with the torque shaft and pedal posts, and you're not popping the retainers off, I'd say your good there.

 

[bm02tj]

If and when you replace the clutch make sure you suck it down evenly so not to warp cover
a lot of clutch issues are caused by tightening one bolt at a time instead of the slow way a little on each till down

 

[Brendan Sellers]

Glad to hear that the spring should be removed. That over center spring was way too huge.

NAPA shows two release bearings, both are mated to the cast iron piece the throwout arm contacts. They differ in that one is self-centering - the picture shows a taper to the bearing face.

I'll have to look at the release fork upon disassembly. Bummer to pull it all apart again! Thanks for your input, Daves69. How can I check for the input shaft bearing failure? There is no appreciable noise difference when the clutch is depressed and shifting from neutral to a gear. As I understand, that is a test for input shaft bearing failure.

 

[Daves69]

I'm not real familiar with the diaphragm clutch sets. Need some experience to help here.

Not losing gear lube and no noise is a good sign. I'd say the bearing is probably fine.
But is that tube part of the bearing retainer worn out and biasing the release bearing force outward? Is the fit too loose?

Don't forget the fork pivot condition.

Inspect the pilot bushing in the crank while apart. MP recommends wheel bearing grease for lubrication on the bushing.
Also make sure your disc hasn't gotten stray lubricant on it.

Oh, don't scrap that spring!! It just may come in handy some day.

 

[Brendan Sellers]

Haha I am certainly keeping that spring. Currently it hangs on the wall @ my bench @ work.

I should remove the pilot bushing retainer & inspect the bearing, right? RTV it closed & proceed?

 

[Garys1969RR]

I had the same prob on a 383 Roadrunner. Finally figured out that the bearing was contacting the clutch release fingers all the time. So the bearing was always spinning, wearing it out.

 

[wannadrag]

You still need a spring from the pivot arm to keep the throwout from contact when not engaged.

 

[Brendan Sellers]

Perhaps I had insufficient throwout bearing freeplay. Well, the trans removal should be quicker this time! Hahaha.

The spring on the release fork is still present for that reason. The clutch pedal return spring had to go, though. It was almost impossible to drive the car with it on. It must not be calibrated for a modern pressure plate.

 

[Daves69]

........................I should remove the pilot bushing retainer & inspect the bearing, right? RTV it closed & proceed?

The "pilot bushing" I'm referring to in post 5 is in the back of the crankshaft. A bushing here was standard. There is a needle bearing option these days that can be used instead of the bushing. They control the front of the transmission input shaft.

The input shaft bearing is under the bearing retainer that the clutch release bearing (throw out bearing) ride on. No leak or noise likely fine.

The link below has a couple pictures in post 7.

One clearly shows a bent pivot that evidently was causing the fork to slip off the release bearing spring clip.

Another shows the release bearing on the retainer. Looks like minimal clearance between the two.

http://www.forabodiesonly.com/mopar/showthread.php?t=322117

 

[Brendan Sellers]

Fantastic, thank you for clearing that up. When I first did the clutch I decided against touching the rear main seal. I presume, if I change the pilot bushing to a needle bearing, I'll have to get a new rear main seal as well, correct? Can I change all this without dropping the oil pan?

 

[Daves69]

Fantastic, thank you for clearing that up. When I first did the clutch I decided against touching the rear main seal. I presume, if I change the pilot bushing to a needle bearing, I'll have to get a new rear main seal as well, correct? Can I change all this without dropping the oil pan?

I can't say for sure your crank end will accept the needle bearing. Check the diameter first against Brewer's dimension....

http://brewersperformance.com/products.asp?cat=32

Is there a need to go to the needle bearing pilot? Like the bushing is worn out or the trans input shaft nose has been shortened.
Installing one does not require rear seal replacement. I you are not leaking engine oil out the rear crankshaft seal there's no need to replace it.

 

[Brendan Sellers]

The needle bearing sounded like a nice upgrade. I'm curious to check the condition of that bushing now. I didn't even know about it before! I suppose I'll pry (with caution) on the flywheel to see if it has axial play. To change the bushing I guess it's easy with the flywheel off?

 

[Daves69]

Shouldn't need to remove a flywheel to inspect or even replace the bushing. Replacing one is not just a cake walk if you've never done it before.

 

[bm02tj]

with the proper puller it is easy I have loaned mine lots so hope some one close to you has one

 

[mopar 3 B]

Pack it with wheel bearing grease install a thight fitting dowel and hit with big hammer. Should pop rock right out. Basic hydraulics.

 

[Brendan Sellers]

Awesome tips guys, thank you all so much. I guess if the flywheel doesn't rock up and down, I'll just leave it on! I am curious to see if that's the source of some nasty clutch chatter that happens ...

NAPA has two throwout bearings available. One has tapered edges, "self-centering." Any advantage with a stock McLeod clutch? Think that might help with the chatter? I have an old F150 with a lot of play in the differential, and that doesn't chatter like this during parking maneuvers, heh.

 

[coloradodave]

Did you have the flywheel surfaced when you replaced the clutch? The flywheel facing condition has a lot to do with whether or not a clutch engages smoothly or 'chatters'. When you have it apart post a couple of pictures of the flywheel.

 

[Brendan Sellers]

Good point, I did not. I assumed it was good because the car has 37k on it.

Which bearing do you think I should go with, tapered or regular?