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I'm replacing a slipping clutch and fell down the rabbit hole of 'might as well do this too' which included replacing 5th gear synchro (it wasn't even grinding!), the associated spring at the end of tranny (and seal), replacing the 2 bearings (main and countershaft), sourcing and making the tools (puller with extended arms, pipe for hammering in), learning how the shift rods work, finding the right split roll pin replacements, applying / redoing gasket sealant everywhere, etc.
Now, I'm just about to assemble everything, I thought it was only the rear oil seal that was taken care of while doing this job, but found that "rear stationary gear o-ring" is also possibly replaced.
PIcs attached are of the seal and with the seal removed. Upon removing the rear seal, a bit of oil did begin to drip, but maybe that is normal without the seal in?
Question:
Since I'm already this far, is replacing the, "rear stationary gear o-ring" recommended? Just remove those 6 bolts and it's right there? Or some other special tools and/or techniques to watch out for?
Thank you!
Ed Yes, I will be redoing oil pan gasket with brace and motor mounts. But after this is complete, almost did add that to the 'might as well' list!
Rear oil seal Seal removed pic of clutch kit and some replacement parts/tools
That little bit of oil is normal.
I’d just do the real main seal and leave the ‘O’ ring.
Geez you really did go to town with parts…even got the ‘Mazda’ SST bearing puller and an install tool. Looks like a pretty comprehensive re-do of things. The only thing I don’t see is the rear transmission seal.
Since it’s already off anyway, are you having the FW resurfaced with that new clutch kit?
IMO oil pan sealing is hard to do properly with the engine in the car. If it’s not leaking I wouldn’t mess with it. Honestly even if it’s just sweating, personally I’d leave it unless it started leaving puddles or the engine had to come out.
O ring is 0813-10-555A, its easy to do, you just need to be careful not to rotate the engine with the gear out, the gear locates the rotor
I have heard of stories of people removing the rear gear with the engine in the car and the rotor moved out of time. Once that happens you have to pull the engine apart.
If it's not leaking I would leave the O-ring as is. IMHO that's just a can of worms to fix something that isn't broken.
"If it's not leaking I would leave the O-ring as is."
YES.
also... when removing the rear seal most use a flat bladed screw driver and hammer. if you do it this way be very careful not to score the surface that seals the bearing. this often happens and even the smallest scratch can cause a small leak. do examine the bearing surface and if it is scored i recommend a very small amount of HondaBond be applied to just the damaged area.
That little bit of oil is normal.
I’d just do the real main seal and leave the ‘O’ ring.
Geez you really did go to town with parts…even got the ‘Mazda’ SST bearing puller and an install tool. Looks like a pretty comprehensive re-do of things. The only thing I don’t see is the rear transmission seal.
Since it’s already off anyway, are you having the FW resurfaced with that new clutch kit?
lol! yeah, and as much as i tried, never had all the parts together at the start. It's been order parts on a Monday, receive a few days later. Work on car Saturday, find out need a new part, order on Monday and repeat! This 'rear stationary gear o-ring' was the next in that sequence, after 6 or so weeks of this i'm less interested in going down this path another week. Putting together the bearing puller & having Home Depot chop up a 10ft pipe was an ordeal!
The clutch kit comes with FW, you can somewhat see it in the pic, here is another pic with the kit apart, FW is behind the clutch discs.
-Ed
Clutch kit w/FW separated Scattered pic of tools & parts for the 5th gear synchro, rear transmission oil seal is on the bottom in this pic.
old & new 5th gear synchros Home Depot chopping up 10ft pipe pipe into 20in segments, then threading both ends! This was about an hour!
"If it's not leaking I would leave the O-ring as is."
YES.
also... when removing the rear seal most use a flat bladed screw driver and hammer. if you do it this way be very careful not to score the surface that seals the bearing. this often happens and even the smallest scratch can cause a small leak. do examine the bearing surface and if it is scored i recommend a very small amount of HondaBond be applied to just the damaged area.
H. Coleman, thanks for the tip on being careful to score the surface. j9fd3s, thanks for the part number of the o-ring, finding part numbers between the Mazda parts guy and the shop parts manual is also an ordeal, so this is helpful!
Great, thanks everyone sounds like i will skip this o-ring and can start putting everything back together! Oh yeah, while tranny down, another 'might as well' took place and grabbed the Banzai Diff & Transmission braces, ugh.
If it makes you feel better I’m fighting the “while you’re in there” urge as we speak…only on my antique car. Having pulled the radiator for a leak I bought new radiator hoses, a t-stat and of course, coolant. With the radiator out and easy access I’m now debating whether I should replace the water pump. It’s not leaking but the gaskets have some reputation for failure.
At any rate, regrets to adding to your parts list but that rear trans seal is really cheap and takes less that 5 minutes to R & R. And since you’re disturbing it by pulling the driveshaft snout in and out, it’s probably a good idea.
Rear transmission seal….no special tools. I just place the old seal on the new one and tap it in evenly.
On the contrarian side, here, professionally, you'd struggle to find a workshop that wouldn't replace the O ring when doing the seal.
Even if the engine is in the car? I can see replacing the stat gear O-ring if the engine is out and oriented vertically on an engine stand, so there would be practically zero risk of rotating the rotor/E-shaft when the stat gear comes out. With the engine in the car & horizontal, I wouldn't risk messing with it if it wasn't leaking.
Makes sense for a shop that’s concerned with a revenue stream and they’ve done that job a hundred plus times. But for us DIY’ers it makes little sense unless it’s leaking. And afaik that ‘O’ ring has few issues, so the risk out weighs the benefit.
About 12 years ago I swapped my RX-7's engine with a JDM pullout but neglected to swap out the rear main seal on the new-to-me engine. Shortly after that I removed the transmission and flywheel to replace the leaky rear main seal on the new-to-me engine, and a co-worker who knew about rotaries suggested to also swap the stationary gear o-ring. I wouldn't have been brave enough to try removing the rear stationary gear myself, but he did it for me and he made it look really easy. I might try it if you can find a video of someone else doing the procedure to see what it should be like.
About 12 years ago I swapped my RX-7's engine with a JDM pullout but neglected to swap out the rear main seal on the new-to-me engine. Shortly after that I removed the transmission and flywheel to replace the leaky rear main seal on the new-to-me engine, and a co-worker who knew about rotaries suggested to also swap the stationary gear o-ring. I wouldn't have been brave enough to try removing the rear stationary gear myself, but he did it for me and he made it look really easy. I might try it if you can find a video of someone else doing the procedure to see what it should be like.
Thanks for the insight!
Now i'm conflicted I just finished the 5th gear synchro repair...the unknown (opening up tranny) was intimidating, but turned out pretty straight forward with notes here on the forum and a local rotor-head i was texting for questions (Tom, don't think he is here). Searched YouTube, no videos on stationary gear o-ring, then spent additional time watching too many other RX-7 videos, these rabbit holes are everywhere!
It sounds like replacing the stationary gear o-ring could be straight forward like the 5th gear synchro...just have to be careful to not rotate anything. Interestingly a 1st gen thread on this just began earlier this month: https://www.rx7club.com/1st-generati...-gear-1155615/
Looks like @my1strotary did get it done though, nice job! I'm leaning towards placing the rear stationary gear o-ring on hold for another day, it appears this is the DIY'ers route vs. Pro shop/experienced mechanic. Hmm, i'm planning on redoing oil pan gasket...I could pickup an engine hoist and stand with the rotary engine adapter. Then like Pete_89T2 suggests, I can flip the engine vertically on its side and have at it for both the rear stationary gear o-ring and oil pan (already received new OEM one). Yeah, sounds like a fun project to put off for another day!
Those O-rings typically last the life of the engine. Most times IMHO if they leak it's either bad luck, an engine that ran too hot, or an engine that was rebuilt and they neglected to change it or damaged the O-ring on install.
I refuse to do an oil pan re-seal in the car. MAYBE with a lift and one of those engine braces. I'd rather pull the engine and do it on an engine stand. I've done that before - pulled it on a Saturday and re-sealed and re-installed on a Sunday. But I've done a LOT of engine in and out and I've gotten relatively quick at it. Also the good thing is you don't have to break down the WHOLE engine, you can leave the wiring harness on, intake manifolds, water pump, all that stuff.
If you do it, get a NEW oil pan and possibly an oil pan brace. Most oil pans are bent from people prying them off to re-seal them.
Regardless, finish your current project, get the car on the road, do that at a later time.
Those O-rings typically last the life of the engine. Most times IMHO if they leak it's either bad luck, an engine that ran too hot, or an engine that was rebuilt and they neglected to change it or damaged the O-ring on install.
I refuse to do an oil pan re-seal in the car. MAYBE with a lift and one of those engine braces. I'd rather pull the engine and do it on an engine stand. I've done that before - pulled it on a Saturday and re-sealed and re-installed on a Sunday. But I've done a LOT of engine in and out and I've gotten relatively quick at it. Also the good thing is you don't have to break down the WHOLE engine, you can leave the wiring harness on, intake manifolds, water pump, all that stuff.
If you do it, get a NEW oil pan and possibly an oil pan brace. Most oil pans are bent from people prying them off to re-seal them.
Regardless, finish your current project, get the car on the road, do that at a later time.
Dale
this is totally off topic, but when we had to reseal a miata oil pan at the dealership, they would usually condemn something else too (clutch, timing belt) if you did that then pulling the engine was actually faster than doing it in the car. plus the miata is harder to work on than the Rx7. its way simpler, but getting to stuff is harder (FWD engine in a RWD car)
02-28-22, 01:03 AM
I just finished the 5th gear synchro repair...the unknown (opening up tranny) was intimidating, but turned out pretty straight forward with notes here on the forum and a local rotor-head i was texting for questions (Tom, don't think he is here). Searched YouTube, no videos on stationary gear o-ring, then spent additional time watching too many other RX-7 videos, these rabbit holes are everywhere! 
