hsukaria

I rebuilt my Fox 74 sometime ago with new bearings and piston rings before learning about the bearing seal removal on the inside. So, my front bearing is sealed (bought from RC Bearings) on both sides. Is that bad enough that I should take it apart and remove the inner seal? I am not using the engine right now anyway.

Cougar429

My Feedback: (3)

I would say that is necessary if you want lube reaching the bearing. The problem here would be if you have to use force for removal. From my perspective the only accessible part from the rear is the inner race that fits against the crank, (rolling element). Any excessive load there, in ANY direction, can deform or damage the balls or race surfaces.

After heating the case, unless it falls out with anything up to a light tap with wood the likelihood is you will ensure the bearing will fail. The amount of damage controls how long that takes. If the fit is tight or gummed up with old oil, (or corrosion) removal may become more difficult. Sometimes a good soak in hot glycol will loosen it up enough without damaging anything, including the seal you want to retain.

NOTE: I find slow heating will help cleaning, but not removal since all pieces warm up uniformly. Best to allow them to return to room temp, (or even cold soak), then a quick external heat source aimed at the bearing area can allow the alloy case to expand before the bearing begins to do the same.

Don't forget to clean an old bearing thoroughly before spinning as abrasives and/or other foreign material stuck between any of the rolling elements can cause the same damage as forcing it out during removal. You should also NEVER spin the bearing up using compressed air as this will allow the elements to contact at high speed without the benefit of lubrication. On that note, during or immediately after reassembly you will want to lube the bearings and any other rotating elements with a good quality oil.

Sport_Pilot

I thought sealed bearings were sealed on both sides with grease for lubrication? Not sure about when their is a seal on just the outside of the front bearing.

Cougar429

My Feedback: (3)

sport pilot, you can pick bearings with single, double or no seals/shields at all.

hsukaria

Well, I went back to the RC Bearings website and looked at the bearing I bought for my Fox 74. It looked exactly like the shielded one rather than the sealed one. So, I guess I got lucky. Had I known more back then, I might have bought the sealed one and removed the inner side seal. But even with the shielded front bearing, I hardly ever see any oil oozing out the front.

1QwkSport2.5r

The bearings I've ordered from RCBearings all had grease in them. With the rpm of these little engines, much of that grease is displaced from centrifugal force and heat. There is sufficient space around rubber or metal shields for oil to reach behind the seals/shields so removing them isn't necessary IMO. The positive and negative pressures within the crankcase is likely enough to force oil into the bearings. It certainly doesn't hurt to remove the inner seal/shield from the front bearing but I don't see it as being necessary. I have yet to have any bearings fail that I personally have replaced and I don't remove seals or shields.

That at is just my limited experience talking so take it for what it is.

blw

My Feedback: (3)

The Evolution TPS 455 has the oil draw groove cut under the carb base hole like you described. The engine was in a crash and I replaced the fragile o ring Evolution uses as the engine was drawing air from someplace. Also, there is a wide shim that fits under the carb and o ring. I didn't really trust that skinny o ring and used a thin layer of RTV to make a gasket under the shim, o ring, and carb assembly. The engine runs fine again. My point in mentioning another brand of engine is that I didn't trust the seal of the thin o ring over the oil groove under the carb. I should have experimented with a thicker o ring.

hsukaria

This is what started the latest round of bearing discussion. Sarpet was not able to run his Fox 25 properly, it would not even quit when carb was closed off. In his case, a sealed bearing on the front helped prevent air from being sucked in. According to what everybody is saying, had the crankshaft to crankcase fit been properly fit, he would have been ok with a shielded bearing instead of needing a sealed bearing. It's all making sense now.

hsukaria

I had a similar experience with an Irvine 40 about 3 years ago. I thought it was time to replace the o-ring under the carb and put a fatter o-ring, thinking it would improve the sealing. Well, it was actually worse and I couldn't kill the engine, even after plugging the intake with my finger. I put the original o-ring seal back and it has worked perfectly ever since. So obviously, that engine did/does not have a leak from the front bearing either.

RichardGee

My Feedback: (156)

http://www.wimp.com/happyfox/

Sport_Pilot

But it isn't advertised as a "sealed" bearing unless it has seals on both sides and packe with grease.

Bigmak1

My Feedback: (5)

Is anybody interested in parts for fox motors, I came across a box from my dad's old hobby shop with parts. Just looked real quick saw some carb part copper head gaskets some other seals. Don't know exactly what is in there

1QwkSport2.5r

I could use some parts... Any piston/liner sets? Maybe shoot a few photos and post em here... Some of us will gobble them up.

blw

My Feedback: (3)

Let's do it this way- maybe Bigmak1 can post pics or a list and we can talk about them. But, we should talk about the buying part via private messages.

50+AirYears

I remember someone stopping at our department with a big oil leak in a diesel engine component. Oil was pumping out a shaft bearing seal. He brought it to us thinking it was our product, till we showed him the difference. The competitor used a plane sealed bearing with flat seals. We used a more expensive seal that used the crankcase pressure to force the seal tighter against the shaft, getting a better seal.We didn't just sea off the races, we sealed the unit.

NoOneFlysAtMyClub

My Feedback: (32)

earlwb,

Thanks for the lineage. I have Eagle III.

Tony

Cougar429

My Feedback: (3)

Bigmak1, a list or pics with possible dimensions would help us decide. Can always use bit for existing or future projects.

fredvon4

BigMak1 I am looking for any Fox 36 Mark IV(4), VI(6), or Mark 7 parts...pistons, liners, back doors, bearings, cranks head buttons...if the box o parts has any combat engine parts I am interested

av8tor1977

My Feedback: (6)

I did a search and didn't come up with what I need, and I can't search through 3393 posts one by one to find it, so maybe someone can help? My brother has a troublesome Fox .40 custom with the aluminum spinner and a square bore mount carb. I need to see pictures of the old and new design head button to determine which his has. Can anyone point me to a post, or provide pics to help me identify his??

I am pretty experienced with engines, and have had a lot of Fox engines, so really all I need is to know which head button this one has to continue to sort it out for my brother. Too bad the Fox website doesn't have the pics, and the web archive for www.flitelinesolutions.com doesn't have the pics either.....

Thanks in advance!
AV8TOR

Cougar429

My Feedback: (3)

av8tor1977, I posted a while ago regarding mods to the heads. Cannot remember if I did the same to the 40, but I redid both my 50's and with the Eagle IV 60's I fabbed some new buttons out of 7075 alloy and milled them to different chamber shapes to evaluate the best performance, (I have some 1/4-32 plug taps in my engine rebuild tools). I accomplished this by using an old, short thread glow plug threaded into the button, (to prevent extending into the chamber) and then the plug was clamped into a cordless drill. I ran the chamber side against two different end mills; one was a rounded Ball End to do most of the material removal and the other one was a radius edge flat end mill to do some "Tweaking" on one or two of the new buttons. The ball end really was all that was required as even sandpaper can be used to remove any sharp angle changes at the outer edge of where the ball end mill did the cutting. IT IS CRITICAL not to touch the outer edge where it fits into the sleeve.

This was required to prevent detonation at the 10-15% nitro fuel I run throughout the fleet of 2 and 4-strokes. Fox were the only ones that exhibited this issue, likely due to the fact they were originally designed for low or no nitro content fuel.

NOTE: When one of my 60's was returned from service with pair of new heads, (another for the second Eagle IV) they looked remarkably similar to the one I did on the left.

If you PM me with your EMail I can send you the text file with pics of what mods are done to the heads. The same rules should apply to all.

p.s. One additional mod that I, (and I believe so far only hsukaria has posted something similar) have accomplished makes a world of difference. The only complaint I ever had with Fox engines was their rather loud mufflers. By fabbing this adapter for my pair of 50BB's, of which one is shown here, (and something similar for the Eagle IV's) I was able to fit larger mufflers that did not affect performance, but brought the exhaust volume down in line with the rest of the fleet. The most time consuming effort in fabbing the adapters was profiling the ports to fit the engine outlet on one side and the muffler inlet on the other. Lots of marking and filing.

I understand that most may not have access to tooling as I do, but profiling the head button should be possible with file, sandpaper and patience, perhaps using the same glow plug-in-drill concept to provide rotation.

1QwkSport2.5r

Cougar429 - any chance you have a link to the posts with your designs and the end results? I'm in the process of getting some new heads made for my Fox 1.20 twin cylinder engine that came out of the box set up to run 25% nitro. I am not running a 2oz+/min engine on 25% nitro. So the trumpet shaped heads have to go. I was advised to make new heads using a 5/8" dia. chamber, .200 squish band width with a 7-12º squish angle and .012-.015 piston/head clearance. 10% nitro is the max, likely only going to use 5% nitro and 20% castor for the lube. I will at some point either make or obtain some head shims as I'm sure I'll have to adjust the heads to fine tune it. I will be making 3-4 sets of buttons with each set being different and one set having been tapped to use Nelson plugs.

Any help you or anyone else can share would be great! Thanks!

Cougar429

My Feedback: (3)

Unfortunately I can't remember where I originally got the file and cannot directly copy the pics from a Word document to a post.

Think the original source was from flightlinesolutions. Here are links to both the 40, 50 and 74 mod pages. The 50 and 74 have some info on profiling the chambers with i think the 50, (middle link) being the best:

http://www.fayettevillercclub.com/id59.html

http://www.fayettevillercclub.com/id68.html

http://www.fayettevillercclub.com/id70.html

There are also good additional links with info on carbs and other mods.

1QwkSport2.5r

I've read through a lot of the Flightline Solutions projects and information. Unfortunately they just use Eagle IV production heads on the Fox 1.20. Based on information I've gotten in regard to the Fox 1.20 specifically, They still aren't the ideal head for the Fox twin cylinder engine thus making completely new ones if one has the ability is the way to do it. I'll re-read those links though, thanks for posting them.

1QwkSport2.5r

Alright Club Foxers. I am going through the process of making new head buttons and a custom exhaust for my Fox 1.20 twin cylinder engine. In the process of tuning and dialing in the engine, I'm going to test the old butterfly carbs and also want to get my hands on a pair of MK X carbs or the newest Fox Carburetors for the .60 engines. This isn't for performances sake but more for testing and tuning for the best reliability and tractability.

Is there anyone that has a pair of Fox MK X ( B model with .312" choke) or the new 2-Needle carbs they are willing to part with?

Turqui

My Feedback: (139)

Hi there; i recentrly got for my collection a used fox 120 twin; i need to find a set of mufflre; any ideas or sugestions for a cheap set?
Thanks.