Here's a new one - clutch problem

[DaddyGlenn]

The subject is a 85.1 NA 944. It is my race car used in NASA TREC endurance races. A few weeks ago, at Mid-Ohio, the clutch pedal started top feel like it was hitting a physical stop. In less than a lap, the pedal would move only an inch or so and I could not disengage the clutch. There was no abnormal sound or other strange behavior.

I wasn't a hydraulic failure of any type and there was nothing wrong with the pedal assemble. Something was preventing the fork from moving the throw out bearing or there was an issue with the clutch pressure plate.

My best guess was that the fork had broken in some way that jammed it and prevented movement. I knew I would have to pull the bell housing off to know for sure. I frikin' hate that job.

Back in the shop, I had the transmission out, the torque tube disconnected and pulled back in a couple hours. Then I spent the next few hours just trying to unbolt the bell housing. It is very tight space to work in.

I finally got the bell housing loose enough to remove the fork. I was anxious to see what broke. I slipped out the fork. It was in perfectly normal condition. Nothing broken, no abnormal wear and the bearings were like new. WTF? Next I got my hand in there to feel the throw out bearing. It, too, was perfectly fine. Had to be the pressure plate, right? But I never heard of one failing in that manner. And it isn't an old clutch, either.

I looked up in the bell housing to see if there was any debris or other signs of failure. This is what I saw.



I feel for all that work just to get to it, it should have been something more spectacular.

And before anyone says anything, It was new hardware, bolt and lock washer, and torqued to spec. I will be adding Loctite to all three bolts.

[kdjones2000]

Not seen that one before. At least it was a "low cost" fix

Maybe not in shop time, tho.

[944 Ecology]

The parts catalog shows those bolts without a lock washer.

Loctite is probably the best approach.

[Monkey Wrench]

a bit of oil on the bolt or in the hole can make the locktite not stick. I dont know if that actually happened but especially in a spot that's so hard to get to , maybe use some acetone and flush out the hole and clean the bolt chasing the threads with a bolt wet with acetone might help, then wipe it all down.

There are also a bunch of different types different types of Loctite.. Loctite is a brand name not a product name, but it's often used in a universal way, just like "skilsaw" is to circular saw.

Sawzall is a milwalkee tool but if you say "sawzall" then people nod and think " reciprocating saw" then hand you a dewalt recirocating saw, or whatever brand is available without any thought to the brand,,

crescent is a brand , but if you say "hand me the crescent wrench" they mean the "adjustable wrench", despite what brand it may happen to be.

by the same train of though. not all "locktite" is equal. it's only a brand that is well recognized as a supplier of a line of several special purpose thread locking adhesives..among other products.

[wwdwgs]

MW,
then - blue locktite.

[DaddyGlenn]

Originally Posted by 944 Ecology

The parts catalog shows those bolts without a lock washer.

Loctite is probably the best approach.

You are correct, just the M7x16 bolts. I will be de-greasing the whole area "replacing" the lock washers with Loctite 242 or 243.

[Monkey Wrench]

I looked at what i had here onhand . 271 thats the red stuff, 290 says "wicking grade" Ive used the blue too.. it says "for small fasteners" 242 qnd 243 are different.

here's a chart showing each "flavor" the stuff is sweet, and poisonous I believe, Its a product where I do wash my hands if I come in contact with.

weird that it never dries in the bottle, only if it's on a bolt, then it does, or as I understand it , "in absence of air"..

it shows 8 different kinds of "blue" I think considering the price it's tempting to carry about 2 kinds.. I'm not trying to micromanage what you should use, I know you know what you are doing. Its just surprising how many there are now

sometimes Ill get new bolts for things and the machine vendor has pre coated the bolts with stuff that does dry. I dont know if it's a locktite product. Might be one of the ones in the list.

When I was younger, I bought a Honda motorcycle and every bolt must have had the red and when unscrewed them they took the treads out along with them. I probably wasn't educated enough to use heat to break it so I got an exercise in retreading, heii coils..

thanks for letting us know what happened, it might prevent another from finding ourselves in the same scenario, what a lot of work.


here is that list

https://www.ellsworth.com/globalassets/literature-library/manufacturer/henkel-loctite/henkel-loctite-selector-guide-threadlocker-properties-chart.pdf

[DaddyGlenn]

Originally Posted by Monkey Wrench

{snip} ...

https://www.ellsworth.com/globalassets/literature-library/manufacturer/henkel-loctite/henkel-loctite-selector-guide-threadlocker-properties-chart.pdf

Love the chart! Thanks for sharing.

[Chalt]

Monkey Wrench, thanks for sharing that. That will be very useful.

[originalowner]

Originally Posted by Monkey Wrench

weird that it never dries in the bottle,

The bottles are semi-permeable to air. Also, the bottles are not full when sold, keeping a reservoir of air available. If you put it in a different bottle, or combine bottles filling one, it will cure in the bottle.