MG Shock Disc Change

[cliffy]

I thought I'd start a new thread after seeing the one below being so old.

Doing the MG discs is rather easy without any fancy tooling involved. I just jack the airplane up high enough to put 2 2X6 (3 inches high) boards under each wheel and lower it down (allow for wheel movement when the load goes down) ( I use a tail weight on my D model to jack it up), This gives me enough headroom to sit comfortably in the wheel well. I remove the cross bolt and collar They are usually loose with worn discs, if not, a little pressure on the wing tip will give enough compression to get the parts off. Then I remove the brake assembly, remove the nuts on the 2 large "knee" bolts, then I jack up that side off of the boards, remove the tire and wheel, then remove the boards so the knee can flex down and remove the pucks by taking the lower assembly off of the upper gear by removing the 2 large bolts. You can inspect and relube these bolts and bushings at this time. REMEMBER, the bolts only capture the bushing so the bushing rotates inside the main gear tubing, Nothing rotates on the bolts. The OD of the bushing takes all the rotational wear. They slide out real easy and should be a smooth slide fit. If they wobble you need more work there.  Remember which way the bolts were orientated. Same with the disc assembly bolt. 

Clean and inspect the steel parts, repaint, slide new pucks on and reassemble in reverse order from above. Put the boards back under the wheel/tire assembly and lower onto the boards (again, allowing for aft movement of tire as it loads) you may have to hold the tire wheel assembly up as you lower them down on the boards to keep things in place, have someone lean carefully on the wing tip to help compress the new discs, put the collar on the correct way and slide the cross bolt in. Use some sticky goo like Seallube on your finger tip if you are having difficulty getting the shear nut in place to tighten on the cross bolt. There should be a screwdriver slot in the head of the cross bolt to hold it while tightening it and starting the nut. Remember, if you replace the nut it has to be a shear nut and not a regular nut. The cross bolt is in shear only not tension. It is much easier to work on the cross bolt if it is put in from inboard to outboard and not the reverse.

It does take an A&P though to sign it off. IN Australia you can't jack more than one wheel off the ground at a time unless you are an A&P there. Just a little tidbit of useless information up here. :-)

Even the first time you can probably do both sides in 4 or 5 hours tops. Longer if you bead blast and paint the lower gear leg like I do. 

Hope this helps someone. 

 

[Raptor05121]

Excellent! I think I'll be doing mine this year and having everything powdercoated. Have you done the nose wheel yet?

[cliffy]

Yup. I used a hydraulic press on those discs as I had the entire gear out. I would think twice about powder coating the gear. With the shock loading on the gear it may crackle because its so hard. I've seen that happen.

[brndiar]

Where  can I order new disc for my M20C ?  Price? Thanks. 

 

[carusoam]

On 8/16/2019 at 11:01 AM, brndiar said:

Where  can I order new disc for my M20C ?  Price? Thanks. 

 

There is a secret pass key to be used when looking for these rubber toroids...

they are about 0.1AMU each, and 11 total... 4,4,3...

The lowest cost place may have a really long delivery time...

https://mooneyspace.com/search/?q=Donuts

Best regards,

-a-

[Hank]

Ummmmm, donuts!! Donut Hole, Panama City . . . . C'mon, Mooney Summit!

Sorry for the derail, but I'm ready.  

[cliffy]

MMMMMMM doughnuts!      Homer Simpson

[vorlon1]

On 7/21/2019 at 9:55 PM, cliffy said:

I thought I'd start a new thread after seeing the one below being so old.

Doing the MG discs is rather easy without any fancy tooling involved. I just jack the airplane up high enough to put 2 2X6 (3 inches high) boards under each wheel and lower it down (allow for wheel movement when the load goes down) ( I use a tail weight on my D model to jack it up), This gives me enough headroom to sit comfortably in the wheel well. I remove the cross bolt and collar They are usually loose with worn discs, if not, a little pressure on the wing tip will give enough compression to get the parts off. Then I remove the brake assembly, remove the nuts on the 2 large "knee" bolts, then I jack up that side off of the boards, remove the tire and wheel, then remove the boards so the knee can flex down and remove the pucks by taking the lower assembly off of the upper gear by removing the 2 large bolts. You can inspect and relube these bolts and bushings at this time. REMEMBER, the bolts only capture the bushing so the bushing rotates inside the main gear tubing, Nothing rotates on the bolts. The OD of the bushing takes all the rotational wear. They slide out real easy and should be a smooth slide fit. If they wobble you need more work there.  Remember which way the bolts were orientated. Same with the disc assembly bolt. 

Clean and inspect the steel parts, repaint, slide new pucks on and reassemble in reverse order from above. Put the boards back under the wheel/tire assembly and lower onto the boards (again, allowing for aft movement of tire as it loads) you may have to hold the tire wheel assembly up as you lower them down on the boards to keep things in place, have someone lean carefully on the wing tip to help compress the new discs, put the collar on the correct way and slide the cross bolt in. Use some sticky goo like Seallube on your finger tip if you are having difficulty getting the shear nut in place to tighten on the cross bolt. There should be a screwdriver slot in the head of the cross bolt to hold it while tightening it and starting the nut. Remember, if you replace the nut it has to be a shear nut and not a regular nut. The cross bolt is in shear only not tension. It is much easier to work on the cross bolt if it is put in from inboard to outboard and not the reverse.

It does take an A&P though to sign it off. IN Australia you can't jack more than one wheel off the ground at a time unless you are an A&P there. Just a little tidbit of useless information up here. :-)

Even the first time you can probably do both sides in 4 or 5 hours tops. Longer if you bead blast and paint the lower gear leg like I do. 

Hope this helps someone. 

 

Very good description. Did you take some pictures?