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Old 09-20-2017, 09:13 PM
BMW_X6M BMW_X6M is offline
Join Date: May 2012
Location: Los Angeles Coast
Posts: 66
Default Oversize AN175-20A bolt solution worked for me

My RV-9A has 800 hours now, and made some noise from the front gear when using the toe bar. I found I could rock it back and forth very slightly with the weight off of it. I purchased the oversize bolt and metal lock nut, and it went back in snugly, having to turn an old nut on the bolt to seat it. After final torque with the new nut, I have no more play in the gear.
This is obviously a huge relief and thank you for the creater of this thread. It proved to be valuable information for this non builder.
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Old 08-25-2019, 09:11 PM
boxflyer*B777 boxflyer*B777 is offline
Join Date: Jul 2019
Location: Chandler, AZ
Posts: 11

Is this too much play in my RV9a nose gear leg? The airplane has about 80 hours since new.
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Old 08-25-2019, 09:21 PM
Vlad's Avatar
Vlad Vlad is offline
Join Date: Oct 2008
Location: Utah
Posts: 8,440

Originally Posted by boxflyer*B777 View Post
Is this too much play in my RV9a nose gear leg? The airplane has about 80 hours since new.
It's a lot in my opinion. Check the bolt.
Where is N666BK?

Не имей сто рублей, а имей сто друзей.
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Old 08-25-2019, 10:55 PM
gasman gasman is offline
Join Date: Mar 2007
Location: Sonoma County
Posts: 4,137

Way too much play.... The proper amount is NONE. If the plane has 80 hours on it, the bolt is not properly installed. It may be too short. The shank must pass through the entire outer tube and be exposed by at least 1/16 inch on the nut side. The bolt has a slight taper at the start of the threads, and if that area is still in the wall of the outer tube, it will show play.

Use the next longer bolt and washers under the head and under the nut to allow full shank contact with the nut side of the hole. Do not over torque the nut. It has nothing to do with this play.
VAF #897 Warren Moretti
2020 =VAF= Dues PAID

Last edited by gasman : 03-12-2021 at 12:08 PM.
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Old 08-26-2019, 07:45 AM
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jcarne jcarne is offline
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 1,983

Originally Posted by boxflyer*B777 View Post
Is this too much play in my RV9a nose gear leg? The airplane has about 80 hours since new.
Way too much, if you ever get into one of them wheel shimmy scenarios that bolt it going to take an absolute beating! If you search the forums there are other bolts that people have fixed this with, usually one that is just slightly larger.
Jereme Carne
RV-7A Flying as of 03/2021
Exempt but gladly paying!
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Old 08-26-2019, 05:01 PM
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Malndi Malndi is offline
Join Date: Sep 2014
Location: Sydney Australia
Posts: 133
Default Repair and improve

Originally Posted by boxflyer*B777 View Post
Is this too much play in my RV9a nose gear leg? The airplane has about 80 hours since new.
During the last annual inspection I discovered roughly the same amount of play between the nose leg and engine mount as seen in this video. Further investigation revealed the bottom hole in the engine mount was flogged out. Disappointing given that a snug NAS bolt had been installed to prevent exactly that.

I think part of the problem was that I had the unfortunate experience of having two Aeroclassic tubeless tyres in a row that were out of round and exciting a lot of shimmy. Third time lucky I got a tyre that was round and the shimmy is now resolved. But I digress.

From here, installing a taper pin seemed to offer a solution to the flogged out hole. Using the procedure described on Matronics as a guide, the appropriate parts were ordered from ACS. However, it became apparent that the damage was worse than expected and the hole was too large for the taper pin.

I might have considered a new engine mount at this stage, maybe even a tail wheel conversion, but being on the other side of the world there was now no doubt the repair would involve welding.

To my great relief a master toolmaker offered to repair and improve the engine mount. As (I hope) you can see in these photos, compared to the engine mount tube alone there is now a lot more surface area for the taper pin.

The most difficult part of all this was accepting that the engine needed to come off. It got easier after that.

Short of converting to the new nose wheel arrangement, I think my nose gear is now more robust and I don?t anticipate there being any further issues.
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Old 08-27-2019, 07:28 AM
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grubbat grubbat is offline
Join Date: May 2012
Location: Ga
Posts: 718
Default Nice

I like how that repair was done. More area to support the through bolt and a nice weld to boot. Nice job!

The danger for ?improving? an area such as this is that you could be moving the stress to another unwanted area. I?d recommend you Look at this every 50hr or maybe oil change for the next couple of years. I suspect that you will not have the wear you had before.........but since it is a change, albeit a minor one, won?t hurt to keep an eye on it.

By the way, thanks for sharing!

RV-3 Sold
RV-4 Sold
1968 Twin Comanche - Sold
RV-6a Sold
1965 Comanche 260 - Sold
RV-9 Built and Flying
600A Aerostar - Sold and regretted
2000 Maule MXT-7 Project
1965 Maule M4 Bushwacker projectů till RV-15 shows up
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Old 08-27-2019, 08:36 PM
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Bill Boyd Bill Boyd is offline
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,711
Default I'm going to disagree.

I'm not an engineer, but I did do the nose gear bolt replacement last year at the first sign of slight play (900 hours on turf). I had a rock solid second lease on life when I finished, but just last weekend I started hearing a new groan out of the mount when castering the nose wheel to position the plane in the hangar. I haven't checked with the wheel off the floor yet (need a helper on the tail) but I'm sure the play is back again.

I like the repair pictured above, and in my opinion the factory mount should be made this way ab initio. In fact, I find it irritating that nose wheel mounts ever left the factory the way they do. Too many have worn loose not to get out ahead of this known (or entirely foreseeable) problem.
Bill Boyd

Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
RV-10 - N130YD - 50 hours +
65 years running stock DNA
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Old 04-24-2020, 06:35 PM is offline
Join Date: Feb 2005
Location: Zurich, Switzerland
Posts: 487

anyone done the fix with an upsize -X bolt to get rid of a small wiggle on an -A model recently?
finding inconclusive information...

Is a NAS6605-26X, NAS6605-27X or NAS6605-28X the right length?

thanks for a quick confirmation!
Bernie Daenzer, Alex Lichtensteiger
S/N 72072, Flying!
HB-YMT (Switzerland)

Last edited by : 04-24-2020 at 07:16 PM.
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Old 05-22-2020, 11:11 AM
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johnbright johnbright is offline
Join Date: Aug 2010
Location: Newport News, Va
Posts: 390
Default my tapered pin installation success story

My tapered pin installation success story.
John Bright, RV-6A, N1921R reserved, at FWF
O-360, 8.5:1, vert sump, dual SDS EFI EM-5-F
Z101 as a template, links
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