My steering started to get sloppy and I noticed (fortunately) that the nut was coming loose on my Corvair offset pinion arm. I've read that this should be torqued to 200 ft/lbs. Should there be a lock washer on this? Should it be drilled and wired? Really freaked me out that it almost came off.
Pinion arm Nut question
- Thread starter Speccobra
- Start date
choppedtop
Well-Known Member
Don't know about the Corvair box, but my Vega has a lock washer. I don't think mine is torqued that much, but all I could put on it with a large box end. Never has loosened as of yet.
Lee
Lee
Hotrod46
Member
If you're using an aftermarket pitman arm, you might want to check the internal splines. I think is was Donsrods that had a problem with an arm from Speedway. The splines wore out and the arm got loose.
BTW - Every pitman arm I've ever looked at either had a lockwasher or a locknut.
BTW - Every pitman arm I've ever looked at either had a lockwasher or a locknut.
Screaming Metal
Active Member
What HR46 said! While the cars (Stock that are driven) on the road 100 of thousands of miles have a pitman arm with a castellated not that enploys a cotter pin to lock the said pitman arm.The least you can do is to use a lockwasher, possibly a locknut.
A little dab of the appropriate Hi-Strength locktit or thread locker will insure that the sucker never comes undone....
A little dab of the appropriate Hi-Strength locktit or thread locker will insure that the sucker never comes undone....
Lee_in_KC
Active Member
OK, here's my result. Nut had previously been torqued with a socket and 12" ratchet. Just now I torqued it with the same socket (1-1/8") and a 24" breaker bar. Here's how much movement I got...
Arm is now tight again. I don't remember for sure where I got this arm... probably from Speedway in early 2006.
Edit: Not sure why those pix posted upside-down!
Arm is now tight again. I don't remember for sure where I got this arm... probably from Speedway in early 2006.
Edit: Not sure why those pix posted upside-down!
Swampdog
Active Member
In aviation, helicopters specifically, we do not use an spring type lock washers on flight critical parts. Aero space engineers say lock washers actually aid in the fastener losing torque. We use high grade washer and some kind of locking devise on the nut. Some fasteners are still safety wired but that is being replaced by cable ties.
We use Inspectors Anti-Sabotage Markers on all critical parts especially fluid lines. We refer to it as torque seal. It is a lacquer based paint in a small tube. Its advantage is that it is easily removed for maintenance.
It does take good maintenance practices to keep the used torque seal out of filters and fuel control systems.
With that being said I don't have anything torque sealed on my T Bucket, I use Loctite on hard to get to fasteners like fly wheel bolts and engine mount bolts. But we have the advantage to pull over and fix things on car that we don't on helicopters. I need to rethink the steering and brakes though.
Swampdog FAA Certificated A&P/IA since 1969
We use Inspectors Anti-Sabotage Markers on all critical parts especially fluid lines. We refer to it as torque seal. It is a lacquer based paint in a small tube. Its advantage is that it is easily removed for maintenance.
It does take good maintenance practices to keep the used torque seal out of filters and fuel control systems.
With that being said I don't have anything torque sealed on my T Bucket, I use Loctite on hard to get to fasteners like fly wheel bolts and engine mount bolts. But we have the advantage to pull over and fix things on car that we don't on helicopters. I need to rethink the steering and brakes though.
Swampdog FAA Certificated A&P/IA since 1969
Off Subject to SD-- I put pinto brake rotors and calipers on my brothers plane when he first got it. It was supposedly just FAA inspected. Went like that until the next inspection time. Inspector asked what the hell kind of brakes those were and grounded the plane. Expensive brakes on a plane even if something else is better or just as good. Next, the air box fell off the carb and I made an aluminum one for it with a fire screen on it. He laughed again and failed the plane for its last inspection before my brother got rid of the money hog. Did you know that you can buy a nice plane cheaper than you can a brand new car? But the upkeep and maintenance is very expensive, just ask SD .
fluidfloyd
Active Member
Swampdog is dead nuts on not using split ring lock washers on aircraft. I've never seen one on any helicopter I crewed on nor any civilian plane I've done work on. I have helped out building various parts for some of the aerobatic home built biplanes and never saw one called out on any drawings or instruction sheets. I worked about 3 1/2 years for a company that built a lot of oilfield type equipment, cryogenic equipment and other specialty one off projects. Again, no lock washers. All the years I built race cars and specialty components I used aircraft quality fasteners, flat AN washers and lock nuts. Every engineer I dealt with would avoid lock washers every time. All had the same feeling or opinion as to torque values changing over time depending on the load and application. Not a bad rule of thumb to follow. One other note. Not to bad mouth Speedway but we got in a bunch of half height jam nuts for locking down rod end bearings. Over half of them were drilled and threaded at an off angle to the center line bore axis. I can pretty well guess where they were manufactured. As we were only using them for a mock up as we built a car we didn't worry about it. On reassembly it will be all AN, NAS quality fasteners with a paper trail. Even if you use commercial grade 5 or 8 fasteners you owe it to yourself, your passenger and your family to know you have a quality piece holding you together. Just my thoughts on the subject. Stay safe!
George
George
fluidfloyd
Active Member
After thinking about the spline issue that started this discussion I believe I would first determine were the source of manufacturer was for each component. That would be the steering box and the pitman or steering arm. I hate to pick on Speedway but they do sell a lot of off shore parts and that is always suspect to me when it comes to structural or high stressed components. If you do in fact determine the splines are now a loose or sloppy fit then I would suspect soft or low yield material in the steering arm first. The reason I would think that as the most likely part to give up is the ease of manufacturing it. Just blank out a profile and run a broach though it. OEM automotive manufacturers forge such parts for two reasons. Speed and toughness. Blanking it from steel plate is OK as long as you know was the material specs are. If it is built by some guy living on the edge of a rice patty, then I would have to pass on that deal. Also food for thought would be a low strength retaining nut. There are plenty of Grade 2 nuts out there and you would have a hard time figuring it out. With 200 ft/lbs it would be awfully easy to yield or stretch that nut. When it comes to choices in drive lines and suspension you need to buy like your life depends on it. It Does! One more thing. I know a lot of steering boxes are imported. That doesn't mean they are bad or junk. But you do need to inquire and do some research as to problem history with that particular brand or source before you lay down your hard earned cash. I feel that all the sponsors here use the best quality parts they can and I think they all will stand behind what they sell. And if in the end Speccobra finds another reason he has this spline/nut issue then pay no attention to me. I'm just a White Boy lost In The Blues!
George
George
Screaming Metal
Active Member
As a person that can't believe it can be too safe when it comes to speed....The use of QUALITY lockwashers and fasteners is MANDATORY. Whether you use a split lockwasher or a wave washer, match the fastener to the application. A grade 2 nut will not hold hardly any torque. Therefor if you think you have a 5/8 nut that is a #2, try torqueing in the fastener, if its too easy to torque, its too soft or the threads were/are bad.
One other thing, I always stake the nut to the bolt with a chisel or a punch, 1/2 on the nut and 1/2 on the bolt/stud. That, with the appropiate loctite, a good lockwasher or locknut. If you use a locknut or jamnut, skip the staking, its usually not needed.
I prefer to have at least 1/8th sticking thru the nut to stake it. even 1/16th to flush will work. NEVER EVER Use a fastener that doesn't come to at least flush to the edge of the nut....and that is after using a lockwasher....
Using fasteners is a science in itself. Sometimes a flatwasher is called for UNDER the lockwasher.
Know your fasteners!
One other thing, I always stake the nut to the bolt with a chisel or a punch, 1/2 on the nut and 1/2 on the bolt/stud. That, with the appropiate loctite, a good lockwasher or locknut. If you use a locknut or jamnut, skip the staking, its usually not needed.
I prefer to have at least 1/8th sticking thru the nut to stake it. even 1/16th to flush will work. NEVER EVER Use a fastener that doesn't come to at least flush to the edge of the nut....and that is after using a lockwasher....
Using fasteners is a science in itself. Sometimes a flatwasher is called for UNDER the lockwasher.
Know your fasteners!
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