TonyD89

iTrader: (10)

First, I just want to say Hello. I've been a member for a little while and posted a few times, but now it's time to get down to business!
Here's my deal. Sometime back, my father ran across a used RX7 through a guy at work. It is a '89 GTU auto with a locked motor and an exceptionally rust-free body. We bought it for $500. Upon disassembly we discovered the apex seals were to blame. We purchased two new rotor housings and a rebuild kit from Atkins. We also purchased a manual trans, ECU, drive shaft, pedals, and a LSD from Mazda Recycling.
We were about to re-assemble the motor last summer when a friend called me with a line on a '91 TII. Bought it sight unseen for $300. It has a dead rear rotor. We want to put the TII goodies in the '89.
After being on this site, I no longer want to put in a "stock" motor.



So' finally here is my questions:


I would like to groove my stock stationary gears and window my new bearings like RB does. How deep and wide should I make the groove. It also appears the groove is "set back" from the groove in the bearing . I'm guessing for strength.

I am also open for suggestions concerning the e-shaft. Should I remove the ball and spring and add the carb jets like is done to the pre '89s. The info I have been able to find is specific to pre '89.

iceblue

What on gods earth would make you consider hacking at the rotor or any part of the roating assembly on your own? That stuff has to be done right and balanced.

The Eshaft mods are good, do them.

Send your rotors off and pay the money if you think you need that. But I doubt you do.

TonyD89

iTrader: (10)

I'm talking about the stationary gears. These can be purchases. Just trying to save a little money!

I should mention that I work in a machine shop and have access to lots of machinary. I' been in the trade for 16yrs i think I can figure out how to put a groove on the inside of a diameter.

Aaron Cake

iTrader: (1)

The groove for the windowed bearing is to be made as wide as the oil groove in the bearing, and about 1.5MM deep. If you go too deep you seriously impact the strength of the gear.

As for the oil jet mods, it's generally not recommended for an engine that is not going to see a lot of high RPM activity. Unless the car will be spending a lot of time on the track it's not worth it.

For the record, all pre '86 13B shafts were made without the oil thermostat.

Wait a sec...we're talking about two different things.

The first are the oil jets that spray the rotors. They've been the same basically forever. The Weber jet mod basically entails replacing the ball and spring assembly behind them with a #20 (or was it #40?) Weber air jet. This allows higher oil flow to the cooling spray and thus better rotor cooling.

The thermal pellet mod replaces the oil thermostat in the front of the shaft. This thermostat is designed to limit oil spray to the rotors to allow the engine to warm faster. It does this by bypassing oil out the front of the shaft. There's a really good discussion on the pros and cons of this mod in the archives.

TonyD89

iTrader: (10)

I have git the Atkins thermal pellet. I am concerned about impacting strength. I have looked at many a pic and the groove seems to be moved back from the gear and even back from the groove in the bearing. I assume for strength.

I read a thread, I think it was BlueTII, where they modded their own bearing.

Thanks for the info Aaron.



Edit: when I mean "back" I'm comparing the relationship of the groove to the oil hole. Though "set back" they would overlap in a cross- section.

TonyD89

iTrader: (10)

I've read the archive on the thermal pellet. NZ seemed to be against it. This wil most definitly be a summer car. I think I will use the Atkins pellet.

My question on the oil jets is exactly what you stated. If I was going for hp would extra cooling of the rotors be of benifit? I'm thinking so. Change my mind if you disagree. I'm an open minded person.

iceblue

You are talking about milling the rotors for weight reduction are you not?

+1 for me about the pellet I think it is a good idea. IMO stoping oil flow to heat up the motor quicker was just a stupid idea to begin with.

TonyD89

iTrader: (10)

I was going to save milling rotors for athread another time. But, it is something I have been considering. It would take alot of sweet talking with the programers in NC but I think I get get it done.

I have already sweet talked the CMM operator into beeping a rotor and the 6-port housing port configurations so I can generate CAD files and NC programs. Just because I could. Don't know if I'll use the info yet.

Aaron Cake

iTrader: (1)

My thought is that it's one less thing to fail....Of course they almost never fail anyway, so it's a bit of a toss up.

Yes, if you plan on making big power then go for it. But really no point otherwise. Keep in mind that this mod can lower oil pressure at low RPMs a little. Some have reported drastic differences, others none at all. On the car that I did this too (silverrotor's engine) there was no change at all.

I had mine done at a local machine shop. They just turned the gears on the lathe and it took all of 10 minutes or so. My grooves are 1.5MM deep and are in fact set back slightly from the bearing groove as you suggest. If I was doing it again I would go slightly wider on my groove to just encourage more flow but I'm sure it will be fine as it is.

The e-shaft thermostat DOES NOT stop oil flow to heat up the engine. It just lowers oil pressure in the e-shaft to prevent the oil jets from spraying as much. All the important areas (bearings) still see ample oil flow as the engine warms up. It's a non-issue.

TonyD89

iTrader: (10)

300-300+ HP is the goal.

pistonsuk

I would highly reccomend NOT machining on the stationary gears. I have read in some SAE papers that the rigidity of this is very important in regards to freqencies excited by the rotor-gear interface. Just pick up a set of used S6 stationary gears, these are already grooved.

Mazda diverted the rotor cooling oil at low temps to aid in fuel atomization and reduced emmisions/quicker warm up.

Justin