Roger Lee Posted January 1, 2013 Report Share Posted January 1, 2013 Hi All, Many are starting to get to the 600 hr. (100LL users) or the 1000 hr. (91 oct. users) gearbox removal and inspection and is usually time to re-shim. Just a reminder on gearbox removal. I have a Remos in the shop with oil all over the engine and belly of the plane. The owner thought it was the oil pump housing. That's fairly rare and it is more likely the gearbox seal. I pulled the gearbox and found some sort of sealer I couldn't identify. I was hard and brittle, exactly what you don't want in a close tolerance high vibration service. The real eye popper was all the gouge marks on the gearbox hosing seal face and the crankcase side of the gearbox. The logbook said the mechanic that removed the gearbox last did it "IAW" (in accordance with) the Rotax maint. manual. Evidently that was stretching the truth. He had pried off the gearbox. Here was another case of a mechanic failing to read and ask questions and educate before performing a task he had never performed. These gearbox's MUST be pulled off and then use the proper flexible high vibration resistant sealant to re-seal the metal to metal surface. If you do not attend a Rotax school then you are bound to cause problems sooner or later working on a Rotax, especially if you then fail to get educated by reading the manual and asking questions from someone who has performed the task before. I hope I was able to smooth out the gouges with some 600 grit and hope the proper Loctite sealant will hold the seal. If not a new gearbox is in this Remos's future. Always ask if your mechanic has performed a specific task and if not make sure they read and call and experienced mechanic that has performed that task. It's in your's and his best interest, time and money wise. Maybe even travel a little farther for a specific rarely done task to get it done. Here is a picture of a poor man's gearbox puller. It is inexpensive to make and works very well. If you rarely pull a gearbox you may not want to spend a bunch of money on a fancier puller. Link to comment Share on other sites More sharing options...
Jeremy MacGregor Posted January 10, 2013 Report Share Posted January 10, 2013 Just a reminder for you guys getting close to your gearbox inspections that JM Aero Service is fully set up to handle all your gearbox needs. You can have your local Maint. Rated mechanic remove the gearbox and send it in to me or if they're Heavy Maintence rated you can have them handle the gearbox disassembly and send in just the clutch. If your on the west coast your also welcome to fly in for a 1 stop shop. Call 209-481-5881 for a quote. I've been thru close to 100 gearboxes and about 40 clutches over the last 5 years and know them like the back of my hand. Also happy to just give advise to you or your mechanic if needed! Link to comment Share on other sites More sharing options...
Runtoeat Posted April 7, 2014 Report Share Posted April 7, 2014 Hi Roger. Found this previous thread and wanted to review your "poor man's gearbox puller" picture but it is no longer here. Can you please repost the picture and also provide the name for the proper sealer to use for the gearbox? Link to comment Share on other sites More sharing options...
Roger Lee Posted April 7, 2014 Author Report Share Posted April 7, 2014 Here is a picture of an inexpensive and easy to build gearbox puller. It is made from 1" angle iron. You will need to get something to put in the flat end hole as a slide hammer. All the parts and angle iron come from Ace Aviation. All that needs to be is a rod with threads on each end or an all thread rod and a nut on each end with a weight that slides.A slide hammer device pulls the gearbox right off. Put some towels under the bottom lip as it will spill a small amount of oil and it is better to keep it out of the radiator. You should use Loctite 598 (US market) 5910 (European market) Permatex "The Right Stuff" will work also, but not recognized by Rotax. Pretty much the same stuff as 598. There is a right and wrong way to apply this and probably 95% of the people apply too much. ABSOLUTELY do no pry on this gearbox case. You can buy a gearbox puller from CPS for around $80. This homemade one works as well for about $20. Homemade Gearbox puller1.pdf Link to comment Share on other sites More sharing options...
Runtoeat Posted April 7, 2014 Report Share Posted April 7, 2014 Hi Roger. Thanks for reposting. Is the main idea here to get the angle with hole past the prop flange so one gets a more "on center" application of force from the slam puller? Also, can you provide some words of wisdom as to the "proper" application of the sealer? I'm assuming a very thin coat of this? Link to comment Share on other sites More sharing options...
Tom Baker Posted April 7, 2014 Report Share Posted April 7, 2014 Loctite 648 will also work for sealer. With the 648 I put on a thin coat and then stipple it with a foam brush for a nice even thin coat. You can also use a foam roller. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 7, 2014 Author Report Share Posted April 7, 2014 Hi Dick, Yes the arm length and angles get you past the flange. Buy 2 8mm bolts to screw the puller onto the gearbox housing.You clean the metal edges of the gearbox housing on the engine side and the box side with some lacquer thinner and scotchbrite. Clean the alignment pins too. Then wipe everything clean. Apply a very very thin film of 598 to both surfaces and then push the gearbox back in place with your hands. RTV silicone is cured by the humidity in the air so if you live in a humid climate you have 15 minutes at best to slide the box back in place. That shouldn't be a problem, but don't apply the 598 until you are ready to mount it back up and don't let it sit out and start curing. Link to comment Share on other sites More sharing options...
Runtoeat Posted April 7, 2014 Report Share Posted April 7, 2014 Thanks Roger. Thanks also for talking to me today on the phone. Tom, why do you use the 648 and not the 598? Interesting that you use a foam brush to spread and prepare the 648. A fiend who's a very experienced aircraft mechanic says he uses Loctite 515 when he rebuilds Lycoming engines. He swears this is the stuff I should use for sealing the my gearbox to the engine. This conversation started due to my recently rebuilt gearbox weaping oil from the gearbox/engine joint after being reinstalled. My mechanic used the recommended 598It will have to be removed and resealed. . Arggghhhh, why do these seemingly simple things become so complicated? Link to comment Share on other sites More sharing options...
Tom Baker Posted April 7, 2014 Report Share Posted April 7, 2014 Back in 2007 I had to remove and reinstall a gearbox because of the SB on the gears. 648 is what Lockwood told me to use, in fact they sent a small tube of it along. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 8, 2014 Author Report Share Posted April 8, 2014 Loctite 648 was only supposed to be used on the gear retention nut. I'm not sure why anyone would suggest 648 on the gearbox flange surface. I can't imagine what that may be like to remove later. The Heavy maint. manual has stipulated (still does in the current revision pages) 5910 or 574 or their equivalent as of recent years. European Loctite 5910 equivalent is Loctite 598. I don't think anyone uses 574 any more. I have had to re-seal at least a dozen gearboxes from people that let a mechanic use the wrong sealer and it started leaking. They basically paid twice for one job. Good for my pocketbook, not so good for their's. The only reason it was complicated because it was done wrong the first time around. On using sealers I would stick with what is recommended by Rotax. Just think Dick you could have been on a cross country in the middle of no where and started spewing all that oil and or burned up an engine if it had been a long leg. If something like this happens Rotax will jump all over this type of thing during the engine investigation. It's just as easy to use the right stuff as the wrong stuff. This is what I get in my shop a lot. An owner pays someone to do a job the wrong way. then they have to pay a second time to do it the right way. Would have been far cheaper just to do it the right way first and less time consuming. By the way there is a new lube that Rotax is now using in the gearbox and on other parts. It is KLUEBER ISOFLEX TOPAS NB 52. It isn't cheap through Spruce, but can be purchased direct from one place in the US. Link to comment Share on other sites More sharing options...
Runtoeat Posted April 8, 2014 Report Share Posted April 8, 2014 Hi Roger. I hear what you're saying and value your opinion on this. Based on what you say and becuase it's what Rotax recommends, I'll have my mechanic give it another try to seal my gearbox with the Locktite 598. Looking at this sealer though, it appears to be nothing more than RTV or regular black silicone rubber sealant. It even says "silicone sealer" on the tube. I'm really wondering why something like Loctite 515 isn't a better sealant? My friend owns 8 to ten Bell 47's and rebulds these and owns and rebuilds old Stinsons. He's rebuilt many many Franklins and Lycomings. He uses 515 to seal the engine cases and says this is a sticky sealant, similar to Halomar, and it is impervious to petroleum solvents. My experience with silicone is that it turns to jelly when exposed to petroleum products. Just wondering out loud here. Just doesn't seem correct to use a silicone sealer in this application but you've convinced me to give it another try. Link to comment Share on other sites More sharing options...
Tom Baker Posted April 8, 2014 Report Share Posted April 8, 2014 Roger, I'll go back ans check the number again, butwhat I used was an anerobic sealant. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 8, 2014 Author Report Share Posted April 8, 2014 598 is what car Mfg's use to seal high vibration area transmissions. Rotax didn't just pull this product out of a hat to use. They must have had a reason. Gearboxes sealed with 598 don't leak when done properly. Link to comment Share on other sites More sharing options...
Tom Baker Posted April 8, 2014 Report Share Posted April 8, 2014 My apologies, I looked at the wrong package on the self. I must have been in a hurry. The product I used to seal the gearbox was Loctite 518. I also have a bottle of the other. Other than switching the numbers everyting I said before still applies. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 8, 2014 Author Report Share Posted April 8, 2014 Over the last year or two they quit using 518. 574 is acceptable, but 5910 or 598 is the preferred. p.s. If you guys have oddball Rotax questions that we don't always have the super secret answer to send them to me and when I go back to Nassau in May I'll ask Rotax then. I'm sure sometimes product changing comes with many years experience after enough owners use something Rotax finds a better way. Link to comment Share on other sites More sharing options...
FredG Posted April 8, 2014 Report Share Posted April 8, 2014 From the Loctite 598TM Technical Data Sheet (December 2008) PRODUCT DESCRIPTION LOCTITE® 598™ cures on exposure to moisture in the air to form a tough, flexible, silicone rubber gasket. This product resists aging, weathering and thermal cycling without hardening, shrinking or cracking. Typical applications include oil pans, transmission pans, valve covers, valves and guides, timing gear covers, and differential covers. This product is typically used in applications with an operating range of -54 °C to 260 °C. TYPICAL ENVIRONMENTAL RESISTANCE The product retains effective properties in contact with automotive fluids, such as motor oil, transmission fluids, alcohol and antifreeze solutions. NOTE: Not recommended for parts in contact with gasoline. Link to comment Share on other sites More sharing options...
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