OnCam

Hi guys im starting to get a little bit of gear engagement lock out when going into 3rd gear, its 6 speed with 60,000km on it, stock clutch i believe with only very minimal whirr noise from the throwout bearing when disengaged.

So i switched gearbox fluid to full synthetic at 55,000 when i got the car after what was possibly the factory oil fill & since have started to have a small 3rd gear lock out issue when shifting into it, I tried the redline MT-90 & then a mix with 50:50 MT90/MTL & now trying a slightly thinner full syn Penzoil 75w-85 but i keep getting the lock out. It does shift the best out the 3 options.

I believe all was normal till i switched the oil. Using 1.8 Quart as per manual suggests.

As you try to shift into 3rd it sometimes resists for a sec or two but does eventually shift without crunching. It feels as though the clutch is in need of some adjustment or the new synthetic oil is too slippery for the syncros. Mostly when the gearbox is cold to warm it will have this issue. Once hot its better.. still can do it occasionally perhaps 1/4 of the time.

I have given the clutch a bleed with new DOT4 castrol performance fluid just at the nipple by the oil filter but i perhaps need to adjust the rod on the back of the pedal to see if increasing the travel/ rod length a small bit will help, or try bleeding it again.. OR try just a factory fill oil again from Mazda. I have also checked the pedal box to see if i can see any signs of the cracking/bending mount but all looks normal still.
No other problems with gears just 2nd when starting off in the morning for a shift or two but gears are smooth otherwise.

Would be nice to have it shifting positively again without hesitation!!!! as its starting to get frustrating on the amazing rx8 driving experience!

Piper161

Try switching to straight mineral oil no synthetic
Also u can try to deglaze the syncro by very lightly bumping it towards third sitting still with out pushing the clutch. If you are on level ground if the syncro is bad or glazed when you push the shifter toward third gear the car won't move keep lightly bumping the shifter toward third untill the car starts to pull forward if the syncro is still good and just glazed this will fix it if it doesn't you will need to replace the syncro at that point a series 2 trans is a better idea which is what I finally did

9krpmrx8

iTrader: (46)

Odds are your 3rd gear synchro is going. Plenty have used Redline without issue and sometimes fluid changes can improve some conditions but generally the issue with grinding gears or lock out is wear.

My factory trans was pulled at 120k (20,000 boosted) and it worked perfectly fine when pulled (given away for free today actually, to a guy going back to stock) and I never did anything other than regular 30,000 mile changes with OEM only fluid. I just got a 09' trans with 9,000 miles on it and it will only get OEM Mazda fluid as well.

OnCam

thanks man i might pick up some oem fluid, do you have specifics on what its called just so i know the dealer doesnt just give me a substitute..

i think ive got written here: "Ford Motorcraft XT-M5-QS Full Synthetic" but is that correct?

Also does it say that its a 75w-90 weight on it..

ive done a bit of reading on the BRZ/FRS forum as well and they are all having lock out issues with their brand new gearboxes even with all the synthetic oils like redline 75w-90 etc as i did and track guys are pretty much are saying the redline MTL is the way to go even though its thinner than specified apparently meets the durability standards of the stock oil at 100deg or something even though 75w-90 is what is required.

Something also mentioned about all gearboxes being different (tolerances) so one fluid may work for one but not the other.

The redline 75w-90 did work well for maby 2,000kms but couldnt put up with the cold shifting, so tried the 50:50 mix with MTL an that was better but still some lockout, the penzoil 75w85 is a lot better with only a touch of lock out but its pretty good, but im quite fussy.

i may also try the deglazing method but hopefully does not do any further damage.

9krpmrx8

iTrader: (46)

OnCam

awesome thank you!!