The Cessna 120-140 Association Forum

Reference Continental Overhaul Manual Page 103 Figure 38. Note that studs are specified to have holes for cotter keys, and special "Lock O Seal washers are to be used, and the castle nuts are to be tightened only finger tight.

When we acquired our project airplane in 2012 the installed studs were not drilled, and plain non-locking nuts were used. I do not recall if the Lock O Seal were there or not. I have ordered and received the washers (pretty inexpensive) and the drilled studs ($94 each). Three questions for the "experts" out there:

1. What is the purpose of the Lock O Seal washers?
2. What is the best method of removing the old non-drilled studs without damage?
3. If the old studs won't come out, is there an alternative method for securing the spider?

Looking forward to your advice, as usual.

John

7313 wrote: ↑Mon Oct 26, 2020 11:20 am 1. What is the purpose of the Lock O Seal washers?

Good question. I'm not sure, but I think it's to provide a little cushion or vibration dampening between the engine and the carb. This jives with the "finger tight" requirement. For sure, there's noting to seal.

2. What is the best method of removing the old non-drilled studs without damage?

Don't. If you're set on it, drill the ones that are already there. You can be pretty certain they were put there by Continental...

3. If the old studs won't come out, is there an alternative method for securing the spider?

Drill them, or ditch the lock-o-seals for plain washers and use lockwashers and torqued nuts (or all metal stop nuts.)

Here's a close-out for this topic. I hate it when topics are never competed!

I only made a modest attempt to get the old studs out. It became clear that the risk of breaking one off was not worth any potential gain. I sent the new studs back - $50 return charge. I used the Lock-o-seal washers although I really don't know their purpose. I obtained thin all-metal locknuts for securing the whole assembly, and tried not to overtighten them.

I used a Grainger Stud remover.
i believe the lock-o-seals are to keep from cracking the spider.
The parts manual calls for 4.
Finger tight only.
Cotter Pin.
Charlie Webb