NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   Rotary Engine Building and Porting FAQ Section (https://www.nopistons.com/rotary-engine-building-porting-faq-section-85/)
-   -   Replacing Rotor Bearings (https://www.nopistons.com/rotary-engine-building-porting-faq-section-85/replacing-rotor-bearings-55675/)

DJ Rotor 12-13-2005 11:13 AM

I got a local shop to machine some for me, worked well and was cheaper than the Mazda tools.

j9fd3s 12-13-2005 11:31 AM


Originally Posted by banzaitoyota' post='786103' date='Dec 13 2005, 08:52 AM

oh-oh II got MIKEY!!!!!!!!!



Part No.

0000-09-0103

Description

MAIN BEARING PULLER AND INSTALLER

Notes

To install or remove main bearings from stationary gears. #49-0813-235

I cant show the price on mazdacomp due to my racers agreement



On the Comp PArts PAge, scroll down on the first pick menu to "SPECIAL TOOLS"; all the special tools are then shown.



lol, that thing is cheap! $51.10... i cant order it. its a comp part

Mr. Midas 12-13-2005 11:36 AM

Thanks!

R.P.M. 12-13-2005 09:46 PM

I went to the local Mazda dealer today and I can get the rotor bearing tool next day, the warehouse shows 1 in stock....its about $100 Can.

The other tool isn't available in Canada....at least thats what he told me.

1Revvin7 12-20-2005 08:57 PM


Originally Posted by Lynn E. Hanover' post='785737' date='Dec 12 2005, 04:49 PM

The alignment tab serves no poupose. There is no indexing feature that must be maintained.

I grind them off of the bearing.



I have yet to heat a rotor or cool a bearing for installation. Just a film of red Locktite, and a slight chamfer on the bore in the rotor, so it doesn't shave any bearing. You should make up a bearing pusher for main and rotor bearings. The pusher should have a flange so the bearing stops at exactly the right depth. That way a fairly stupid press operator can do it right. In my case that would be me.



If you hose the bearing with a missed shift or whatever. That tab will keep the bearing from spinning for about 1 nanosecond. However that tab can ruin an engine if the bearing is pressed in and the tab is not lined up properly. It will raise a lump in the bearing and make it fail, if you can even get the crank through it.

If that happens to you, just die grind the lump off and go on with your life. It won't hurt a thing.



Lynn E. Hanover



Don't the surface temperatures exceed the temperature limit for locktite?

Lynn E. Hanover 12-21-2005 06:47 AM


Originally Posted by 1Revvin7' post='788507' date='Dec 20 2005, 06:57 PM

Don't the surface temperatures exceed the temperature limit for locktite?





Good point.



The surface of the rotor exposed to the fire runs between 350 and 400 degrees.

(from what Iv'e read). The bearing could not survive anything like that, under load,

so, appearantly the oil cooling is adequate to maintain a far lower temperature around

the bearing bore. We try to stay under 190 oil temp, so the bearing is being supplied

oil at that temperature. If the whole rotor were to get as hot as the surface, the bearing

would loose its crush fit, and all would be lost. But the bearing overlay would be moving off

the interface before that, anyway.



If you press out two used bearings with a manual press, you can tell which one had the Loctite on it.





Lynn E. Hanover

ArmyOfOne 12-26-2005 04:54 AM

Thanks for the tip Lynn.

1Revvin7 12-30-2005 08:59 PM


Originally Posted by Lynn E. Hanover' post='788623' date='Dec 21 2005, 08:47 AM

Good point.



The surface of the rotor exposed to the fire runs between 350 and 400 degrees.

(from what Iv'e read). The bearing could not survive anything like that, under load,

so, appearantly the oil cooling is adequate to maintain a far lower temperature around

the bearing bore. We try to stay under 190 oil temp, so the bearing is being supplied

oil at that temperature. If the whole rotor were to get as hot as the surface, the bearing

would loose its crush fit, and all would be lost. But the bearing overlay would be moving off

the interface before that, anyway.



If you press out two used bearings with a manual press, you can tell which one had the Loctite on it.

Lynn E. Hanover



I am just curious, but I take it you do this as a precaution to help prevent bearings from spinning?

Lynn E. Hanover 12-30-2005 10:52 PM


Originally Posted by 1Revvin7' post='791052' date='Dec 30 2005, 06:59 PM

I am just curious, but I take it you do this as a precaution to help prevent bearings from spinning?





Just as with the magic tab, the locktite will not prevent a bearing from spinning that has welded itself to the crank. If a person were to hone out the bore just a bit, and sand out the bearing ID with some 600 silicone carbide paper in solvent, to get a bit more clearance, then you want to add some help for the lost crush fit.

The loctite also helps make a thermal conductor. Some rotors have dismal machining in the bore ID. As though they were done with dull tooling. The Locktite fills those voids.



If you get the oil too hot, then you are skating on thin ice. The bearing gets bigger at the same rate as the bore of the rotor, but bigger means more clearance off the crank, and some more flow, for less pressure.



The bearing wear surface looses strength quickly with heat. The loaded oil film gets very hot in the wedge.



The oil being sprayed into the rotor is cooler than the wedge oil, so cooling continues.



The only way it is cooled is with the oil,so, if the oil is already too hot, the material on the bearing starts to move away from the loaded zone. If you rebuild you may see some flaking at the edges of the bearing. Also so flakes in the filter paper. You do cut open your filters, right? If you get it hot enough to fail the bearing

it will get hot enough in two nanoseconds to fail the Locktite,and the bearing will spin in the bore.



But I think it helps a little on the heat flow so I keep at it. I also run three Setrab 13 row coolers.





Lynn E. Hanover

R.P.M. 01-12-2006 09:47 PM

When you order a new rotor bearing from Mazda does it come with the locating tab already bent over? You you have to prescicley line up the tab with its groove when pressing it in?

Or is the bearing completly round and then once its pressed in, you just punch over the bearing into its groove?



I've never seen a new bearing un-installed before.


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