Nosegear creaking

[GAHco]

A couple of things.

A Nylock of any type would work just fine with a light (interference) drive fit.
EXCEPT THAT IT IS ONLY RATED TO 250 DEGREES F.

Over tightening this installation just increases the chance of failure.

The bolt being .0005 larger than the holes (Not hole, holes).

A medium drive fit up to .0015 would work but be a little difficult with steel to steel.

No matter what you replace the AN bolt with, even if its not oversize, the NAS Bolt is better all the way around.

We have a threaded reamer that should work from the top of the nose gear if you can get in there with a nice 90 deg drill. (we have those too). Look at how much is obstructing it and see. Do not over speed the reamer slowly and carefully will get you best results.

We have 4 of the threaded reamers for the first oversize 5/16 Nas bolts in stock, they are M42 Cobalt made to Airbus Spec STD 236 with the exception of the drive style being 1/4-28 instead of the straight shaft for use in drills.
We have the ergular drive ones in regular and long.

Post 17 has some excellent info that should fix things for a long time.
Be advised, if you over ream on this situation you will say more than
Oh schtuff! So be real careful, it is a very good fix, but once things get too large you have very little you can do to repair.

If enough folks want the taper pins I may be able to get them and sell them piece by piece, brand new ones, at this point I don't know what the cost or lead time is.

We have no minimum order, there is a small order fee of $5.00 when order is less than $25.00 (book orders excluded).

[GAHco]

FEI (for everones info)

Excerpt of part of my reply to Scotts PM

I did find some NAS6605-27Y and am waiting to confirm with my supplier as to whether they are still available. I should know this by Monday.

If the NAS6605-27Y's are still available, we would get them in a week to 10 days after confirmation of our order.

So one way or another, sooner or later, you should be able to fix that squeaky nose gear of yours.

[jonbakerok]

Originally Posted by GAHco

A couple of things.

A Nylock of any type would work just fine with a light (interference) drive fit.

Sure it would work, if it wasn't sitting so close to the exhaust stacks. Hi-temp Nylon becomes liquid at 400 degrees. Even at 200, I doubt that it's hard enough to prevent a nut from backing out when it's being shaken by a castoring nosewheel.

My point is that a lot of guys who haven't yet experienced the problem will probably never experience it if they just replace that nylock nut with the correct hardware for a high-temperature application. I did, even after the problem had started, and I haven't had any further movement in four years.

[AlexPeterson]

Originally Posted by Captain Avgas

snipped

I doubt the wear would have been in his original bolt. At 125,000 PSI ultimate tensile strength the steel in the AN bolt would probably be far harder than the steel in the mount.

Well, I can tell you that the AN bolt that was in my plane was clearly worn after a few hundred hours. It took a couple hours to get it out, since there is no good way to tap against it. The gear leg is quite hard.

Originally Posted by chaskuss

The tensile strength of an AN bolt has no bearing on how hard it is.

This is not true, it has a direct correlation - this is precisely how one indirectly determines strength of steel alloys. See section 7 of this treatise:


http://www.calce.umd.edu/general/Fac...rdness_ad_.htm

[GAHco]

Originally Posted by jonbakerok

Sure it would work, if it wasn't sitting so close to the exhaust stacks. Hi-temp Nylon becomes liquid at 400 degrees. Even at 200, I doubt that it's hard enough to prevent a nut from backing out when it's being shaken by a castoring nosewheel.

My point is that a lot of guys who haven't yet experienced the problem will probably never experience it if they just replace that nylock nut with the correct hardware for a high-temperature application. I did, even after the problem had started, and I haven't had any further movement in four years.

Thank you for pointing this out.

Ok I'm only up to just finishing my wings on my six and it its a tail dragger.

With The temps being higher, an AN363-524, MS20365-524C, MS21042-5 or L5, MS21043-5, MS21045-5, MS21046-5, NAS679A5 or -5, all of these should meet both the strength and temperature requirements to do well at holding whatever 5/16 bolt you decide to use for the repair.

I will revise my Nylock Post. (#21)

[mlw450802]

Originally Posted by AlexPeterson

Well, I can tell you that the AN bolt that was in my plane was clearly worn after a few hundred hours. It took a couple hours to get it out, since there is no good way to tap against it. The gear leg is quite hard.



This is not true, it has a direct correlation - this is precisely how one indirectly determines strength of steel alloys. See section 7 of this treatise:


http://www.calce.umd.edu/general/Fac...rdness_ad_.htm

You are right. Also, hardened 4130 will range from 130 to 170 ksi tensile strength. I know it is not the intention of the fabricator to harden up the tubing but the welding process may create hardened zones due to the weld melt quenching too rapidly. A temper bead pass will mitigate some of the hardening but a lot of the welds are single pass and they really could benefit from a tempering heat treatment after the welding is completed. (These may go though that as I have no idea of the actual process used by the fabricator.) My point is simply that the bracket could easily be the same (or greater) hardness/strength as the bolt.

-mike

[GAHco]

If this is a new installation, and you have not drilled this hole to Vans Recommendations, then you may want to get the following items and do it the best way possible the first time.

We have the threaded reamer PPRT-.3105 and The Close Tolerance Higher Strength Bolt that matches the grip length of the AN5-20A called out.

If you already have reamers that its the hole size you want .3105"

The Standard diameter part # is NAS6605-27

For this important issue,

We have changed our package qty on these from 5 to two.

Orders placed over the Webstore that exceed $75.00 are eligible for free UPS ground shipping in the US.

So stop that Nose Gear from squeaking while it is still easy to get to.

hopefully you wont have to hear from it again.

If you need the Oversize, read the previous posts.

[chaskuss]

Quote:
Originally Posted by chaskuss

The tensile strength of an AN bolt has no bearing on how hard it is.



This is not true, it has a direct correlation - this is precisely how one indirectly determines strength of steel alloys. See section 7 of this treatise:


http://www.calce.umd.edu/general/Fa...ardness_ad_.htm
__________________
Alex Peterson
RV6A N66AP 800+ hours
Maple Grove, MN


Alex,
I stand corrected. Great link you provided. I meant that one should not ASSume that because the tensile strength of an AN bolt is higher than an industrial bolt or automotive bolt, than you can assume it has a greater surface hardness. Since AN bolts are intended to be ductile (so they stretch, rather than fail catostrophically) they may well be softer on the surface than certain automotive heat treated bolts.
The bolt's alloy & any heat treating also factor's into both it's strength and surface hardness.
Charlie Kuss

[Scott Will]

Today with the help of a good friend I fixed the nose gear creaking problem. I used a 1st oversize threaded reamer that fit on a 90 deg drill to clean up the enlarged hole in the engine mount. We debated about doing it as an assembly or individually. Because we couldn't guarantee that the parts would stay lined up and hold everything in place properly, we did the mount and gear leg separately. After that we put the bolt in the freezer for 25 minutes or so. Then I proceeded to install the NAS6605-28X from the inside, just like the original bolt. It took some tapping with the hammer and eventually rivet gun to get the bolt in there but it went right in. Nice and tight fit.

The original bolt measured .3065" diameter! And I guess I used a regular 5/16 drill to dril it originally. The current setup has essentially no tolerance.

The only huccup is that the only bolt I could find was a -28X length. That is a little too long becuase it took 5 washers to get the nut on properly (1 under head and 4 under nut). I know this is more than the 3 washer rule however the bolt is loaded primarily in shear. And the bolt isn't coming out becuase it took some force to get it in there. Maybe if I find a -26 bolt I can replace it someday. But for now my gear is working great.

Thanks to Tom @ GAHco for theirexcellent service and tools.

[GAHco]

Originally Posted by Scott Will

Today with the help of a good friend I fixed the nose gear creaking problem. I used a 1st oversize threaded reamer that fit on a 90 deg drill to clean up the enlarged hole in the engine mount. We debated about doing it as an assembly or individually. Because we couldn't guarantee that the parts would stay lined up and hold everything in place properly, we did the mount and gear leg separately. After that we put the bolt in the freezer for 25 minutes or so. Then I proceeded to install the NAS6605-28X from the inside, just like the original bolt. It took some tapping with the hammer and eventually rivet gun to get the bolt in there but it went right in. Nice and tight fit.

The original bolt measured .3065" diameter! And I guess I used a regular 5/16 drill to dril it originally. The current setup has essentially no tolerance.

The only huccup is that the only bolt I could find was a -28X length. That is a little too long becuase it took 5 washers to get the nut on properly (1 under head and 4 under nut). I know this is more than the 3 washer rule however the bolt is loaded primarily in shear. And the bolt isn't coming out becuase it took some force to get it in there. Maybe if I find a -26 bolt I can replace it someday. But for now my gear is working great.

Thanks to Tom @ GAHco for theirexcellent service and tools.

Thanks for the compliment Scott, we will be looking for the shorter bolts based on your input.

I will post what I find.

I have a feeling that many people will need to do this repair on their Nose Wheel RV's.

You may want to offer your used once reamer for sale, 20 years from now if you have to get a bigger bolt that one wont help anymore anyway.

Maybe you could donate it to your local EAA chapter and get a deduction for it, after all you will receive no other benefit from that reamer, unless the mains are held in the same way. If thats the case you may want to just keep it.

Everyone else reading this, don't forget if you have a good gear hole and just need a better, closer tolerance bolt, we have the NAS 6605 in standard diameters too.