Thorp Air Command - T18.net

I have had my thorp for 15 years and noticed the 0-290D 125 hp has begun to sag a tad, time for new mounts. problem is I cant identify them there is no numbers on them and dont know which mount I have. I am not the builder, searching the web and aircraft spruce has not helped, they look like lord mounts but there is no listing for the 0-290. I have included pictures for those of you out there who may have some knowledge of what I need maybe even a good place to pick them up or know who may have a set.As far as replacement goes is it possible to replace them without removing the engine totally any comments will be appreciated.

Thanks, Lance

Lance - I know that's not a dynafocal mount, but those mounts look curiously like the set I just put on my dynafocal 0-320

https://www.aircraftspruce.com/catalog/ ... afocal.php

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

thanks Fraser Im sure someone will recognize it appreciate the return.

Thanks Lance

That is a conical mount, I have never seen Lords on a conical mount, but obviously I have learned somthing here. There are usually machined shoulder type washers used here, I have only machined up one set and that was for Deans plane they are lathed out of t-3 bar stock. Dean, Ira, can you guys shed some light on this, I can't remember what the Rubber element was that was used along with the washers........( IM old). Dan

I don't think that's a conical mount.
My T-18 'Feisty' has the same arrangement.
O-290G mount ears are just drilled thru. It looks to me like those mount ears have not been bored out to the conical mount dimension. Some rubber biscuit, as yet unidentified is used. I have an other O-290G case that has been crudely bored to take the conical rubber pieces. (the 'training engine')
I would like to know what it is, as 'Feisty' needs a set too. Yours look to have more sag, and less cracks than mine, but the same parts & arrangement, like they were built to the same plans.
I didn't get plans when I bought 'Feisty' maybe some one with plans will look in theirs and find out.
Bruce F has a set of plans, an O-290G on his T-18, and has recently removed & installed his engine. How 'bout it Bruce?
Your lower picture shows a silver washer between the welded mount and the aluminum plate, I would guess added as a spacer to lift the front of the engine. Possibly to correct some sag in the rubber elements?
It would be nice to find it's a reasonably price auto part. That wouldn't be a suprise, considering the enginuity of J.T.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

The O290G did not have the cone machined in the mount ear just a 7/16" hole for the bolt and thus JT spec the dynafocal Lord mount for the isolation damper. If the rubber is not cracked or deteriorating I would rotate them 180 deg to remove the sag, else the following is copy from the thread "how to hang an engine" by Lee W

<copy>
This seems to be a recurring topic, there are several options for sandwich mounts the cheapest is the "homebuilders mounts"

http://www.aircraftspruce.com/catalog/e ... ndwich.php

Rumor has it that these are simply the mounts that Lycoming ships their motors with ... regardless they seem to work fine for me.

As John pointed out, (max) torque values are not unique to application each bolt size (in this case AN7) has it's specified torque value (in this case 450-500 in lbs). That being said and I know I've gotten in trouble for this in the past ... I prefer to use the "comfortably snug rule".

I recently pulled N51863's motor and while I was at it I decided to change out the Lord mounts, I agree Frase .. there is no easy way! It requires patience, muscle and a lot of cussing!

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Lee Walton
Houston, TX
N51863,N118LW (under construction)
KDWH
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Note the Aircraft Spruce parts referenced above is what I use several years ago when I replaced my mounts and are the parts as called out on the plans.

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Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Yikes! a set of Part # 08-03500 is about $450!
Phraze' PN #08-03600 is $200 less, but a bit stiffer for acro?

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Scott Emery
EAA Chapter 326
T-18 N18TE

This what I think I know. Drawing 479 specs Lord J7401-3 which is no longer available, I believe the replacement is J7402-5 and cost about $86.00 ea.

I originally purchased the more expensive mounts, then ordered the ones I referenced and shipped the other more expensive ones back.
Ideally, the torque values of an AN bolt (are supposed to) result in the nut bottoming at the end of the threads/beginning of the shank.

FYI - When you start putting spacers into the setup to counter sag, the bolt length changes...YMMV.

I broke 2 nails while re-hanging my engine.....my manicurist say Ho Lee Fook!!

My thoughts on stiffness are these - I want stiff mounts (?)....ahem.....OK...anyway.... Higher durometer neoprene rubber (like the marketing department calls those ones I got for acro) should work great for any application. The harder the rubber the better, IMHO.

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Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

I believe that "ideally" you should never have the nut "bottom out" at the end of the threads... how would you know you're there without damaging threads? Ideally about a washer thickness of threads should be left. Sorry for nit-picking, Frase... I know you know that. Can't help myself.

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Thanks one and all for the info. This is what the forum is all about. As Bill pointed out lord mount J7402-5 at 173.75 as opposed to 08-03500 at 449.00 is the way to go money wise , why the 200+ difference? Is one that much better? Are they the same dimensions or quality, I don't mind paying the difference if the worth is there. As far as complete engine removal as opposed to using an overhead come along to take the weight off and changing them which I would prefer, any thoughts?

Thanks Lance

Lance - clearly the smart and easiest thing to do is to remove and replace one at a time. In my case, the mounts were total trash and the new ones would just not fit - a cherry picker worked for one bolt, but then the next one would not fit no matter how hard I tried....so off it came and I started from scratch, and having to make a "bullet" out of some aluminum rod to hammer the effing sh....?...ahem...uh.... gently guide the last bolt through.

John - right you are of course, I think it was an old wives tale from a browbeaten umpire and part time aircraft mechanic....perhaps stated more accurately.....if you exceed the recommended torque value of a "properly sized" AN bolt with properly sized washer, you risk bottoming out the threads and possibly damaging them, which may in turn potentially decrease the structural integrity of the aircraft, resulting in potential injury and possible loss of life.....>:D

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

Fraser, I guess your saying try one at a time and if that doesn't work pull it, that's what I was thinking the easiest road first. It's a lot more fun flying it then working on it.

lance

Eggzackly!

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

I have a 290 and replaced mine years back. I'm pretty sure the 08-03600 are the ones I used. They are dynafocal mounts, but all mount in a flat plane relative to one another so are real easy to change. Just take weight off engine with hoist, remove bolts and change them. If you have a little slack in the cables, might not have to undo anything. As they sag over time, I have put a couple washers under the bottom ones to shim it up. I'll check to verify the model when I get home on Wednesday.

Bernie Fried
N18XS