How to Remove Rotor Gear?
 

When I took my 13B PP race engine apart two days ago, I found that the 20B front stationary gear had lost several teeth, and that a couple of half teeth were chewed up in the rotor gear. I have a lot of machine work put into this rotor, and I want to reuse it. How can I remove the rotor gear and change it with a good one? How do you remove the 12 double spring pins (little spring pin inside bigger spring pin? Is it possible to change rotor gears with one from the same year, or is there some kind of special rotor to gear matching done by the factory, something that cannot be replaced?

My buddy Dave Jones gets his PP rotors from Darrel Drummond, and Dave says that Darrel says that once a rotor gear is removed from a rotor, the rotor will never grip a replacement gear that tight again, and that is why they always snap ring the rotor gears when they put in hardened gears.

I still don't know how to get those roll pins out :(

thread them with a tap , then slide hammer them out , works for me. RON

The PP engine is already gone? :(

I hear the same for the exhaust sleeve roll pins. Tap then slide hammer. Dunno how that works for a rotor gear, or if its wise to remove and replace sorry. Maybe a call to RB will answer your questions.

need some help with this.
any ideas where I can buy new replacement pins to press in the rotor

call clr motorsports

Do you know the cause for the teeth on the s/gear and rotor getting chewed up? I got a 13B from Japan with the same issue, bu never could figure the cause. I also have a beautiful rotor with damaged teeth that I would like to salvage

If the rotor gear pins are as hard as the exhaust roll pins, best way to remove 'em is clean the inside out, and use a mig welder to build up from the center out, until it is hot and you have enough metal to get some vice grips on. If it breaks off, repeat.

^^this works well for the exhaust roll pins not sure about the rotors though

ok, so removing seems to be doable, now on need to find new pins to add in the gear after the slot for the c-clip has been lathed in

doesn't work with rotors, the pins are down inside the inner oil seal bore and it is impossible to get a bead welded to them down there. the exhaust pins also have the benefit of being bedded in aluminum which does not stick when welded.

best bet is to drill out the center of the pins slightly to tap them for screws to get something to lock onto and hammer or pry them out with.

The roll pins (yes, that's all they are) are standard metric roll pins (yes, they are hard, spring temper). The outer are 6mm and the inner are, IIRC, 2mm (maybe three, I forget). Here are some pics of my method and tools. The last is the pin puller. Some of the pins come out with the gear, the others stay in the rotor so the you need to pull them.

The pics are of a junk rotor I use for experimenting and test machining. It's been welded on (just to see if I could), machined on to find mistakes in my program, and generally, used as a guinea pig.

I made the tools myself.

Probably true (about them not gripping as much). I pursued the removal so I could snap ring them myself.

You're just not a good enough welder then. :)

Good hardware you got there :)

i suppose not, considering you need a bead about 1/2" tall in order to get it close enough for something to grab onto it with. even if you are that good it's more effort than worth with high likelihood of possibly screwing up the good gear.

your tool is an idea i had thought about but how do the gear teeth fare after pressing on them? the teeth edge still contact the whole stat gear so imperfections can be critical.

the really old rotors actually had the pin holes go all the way into the oil passage so they could be run through.

No issues. The three piece set up I used was 4140 and CRS off fall I grabbed at work. There is no mark what so ever on the gear. I know the tool looks extremely simple and is rusted from laying in the garage but it works like a champ.

I gauge pinned under the gear (a drill bit or other known sized devise will work), subtracted .005",and made that the flange. I calipered the minor dia of the gear, subtracted a bit (don't remember exactly how much) and spun it up on the lathe. Made a simple scale drawing to take a guess at how much to take out of the center and went to the saw. The standing piece on the driving plug fills in that gap and keeps the tool from deflecting too much under use.


Check out my post in this thread for welding.

https://www.rx7club.com/fabrication-250/welding-859946/

On a 12A rotor it (the nice tool) won't work by the looks of it..

https://cimg1.ibsrv.net/gimg/www.rx7...c64c30c0fa.jpg
https://cimg2.ibsrv.net/gimg/www.rx7...38789bfed3.jpg
late update from my side. I had to remove a gear from a 13B PP engine because the inner oil control ring cracked for u known reason and got eaten by the gear .

to get a broken gewr out is easy. Tack a big washer on it and press out. To get a good gear out of a bad rotor I pressure the gear out and hogged out the gear bore big enough so the good gear can confortably pressed out. This takes around 10 min a lathe. To get the sping pins out I just used a 6mm rod and tig welded it to the pins, then use slide hammer and you can easily pull them out.

then find some 6x30 or 6x32 mm spring pins. The inner ones can be re-used from the broken rotor where the gear is stolen from because all pins come out with the gear if you remove enough material, or new 3mm ones can be sourced.

To get the new pins in is pretty easy with a 1/4' driver. The gear itself falls in.

I did also clearance the gear and the ring area on the oppsite by 0.03mm to bring the total rotor clearance slightly over 0.2mm. I just did it on a lathe and the results is blistering. Measured at 6 places the width of the rotor is within 0.01mm