Snychro update--new tranny not a rebuild
 

Got a call from the dealer today regarding the 04 MT we have with 35K miles. They pulled the tranny and found not only was the 5th gear synchro gone but at least 3 gears (not synchros) were chewed up badly requiring the whole tranny to be rebuilt. Mazda decided to replace the tranny complete and not do the rebuild--thank god. Car should be back in 2 days.

So, here we have an August 03 build with 35K miles, driven by my wife 95 % of the time and most of that time spent on interstates at 70-75 MPH that needs a new tranny. No gear banging or powershifts.

What is the story on this? Bad QC at Mazda? Bad material from a supplier? Who makes this tranny and how did it go so bad so soon?

Hate to say it, but I think we're all done with this one. I do want to say that this board has provided an incredible amount of info on this car that has been very helpful in dealing with the various problems and recalls.

bummer on the transmission, but at least they're fixing the problem.
I had my transmission replaced after 30,000 because 2nd and 5th gear were also chewed up. I've put 2k on the new transmission and the shifts are SMOOOOOOOTH.

Keep us posted, Good luck.

asian makes the trannys.. i guess they had a bad week... just hit 75k miles on my 04 still smootttthhhhhh as butta..

beers :beer:

that trans aint new for the rx8.....its been around. so any probs ur having cant really be "omg this car sucks" problem.....

mine shifts like total shit and its at 28k and the 3-2 downshift grinds like a boitch!!!!!!!!!!!!!

im afraid to call it in and they make me tear it down to see the prob and they make me rebuild it....eeeeek no thanks......

yea, i had to get my tranny switched out a while ago as well. my 3rd to 4th gear kept grinding at 5000+ rpms. technician said it was a synchro problem after showing me how to shift without using the clutch.

if you guys have Royal Purple in the tranmission, flush it out BEFORE you take it to the dealership.
I'm helping a forum member battle MNAO right now because he put RP and the new manuals clearly state GL-4 fluids. (not GL-5. RP is both 4 & 5)

Just save yourselves the headache is all I"m saying

I have been saying this for some time now - you want a GL-4 ONLY fluid for the trans - even though Mazda called for a combo fluid (mistake if you ask me).

These GL-4/GL-5 combo fluids still have too many Extreme Pressure (EP) and Limited Slip (LS) additives so they can be used in diffs as well that are really hard on the Syncros and all the softer metals that a used in trans (brass, etc.).

Many people still don't understand that GL-5 is a diff spec and GL-4 is a trans spec. GL-5 is not a more modern, better spec, but a different one for a different purpose. Some manufacturers have developed these combo fluids for ease of selling one fluid for multiple purposes, but this causes tradeoffs and compromises in design as these two applications have different needs that work against the other.

I love BG Syncroshift II, as it is GL-4 only, and is working superbly in my trans. Redline also makes a couple of great GL-4s as well as Amsoil, but stay away from the combo fluids.

the 04 and 05 manuals state that GL-4 OR GL-5 are acceptable for the RX-8 but I'm being told that the 06 and 07 manuals no longer list GL-5.
(I haven't confirmed this yet since my manual is for my 05)

Just in case anyone was wondering....Redline MT-90 is a GL-4.

Go with Redline MT-90 or MTL if you must have a sythetic in your box.

MTL "This 70W80 GL-4 Gear Oil (SAE 5W30/10W30 engine oil viscosity) is designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting."

MT-90 "This is a 75W90 GL-4 Gear Oil that's slightly heavier than MTL. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting."

+1 for Redline.

I'll be going in soon. :(

As soon as I get some much needed paperwork from Abbid. :)

I wouldn't recommend MTL unless you baby shift, it's not heavy enough to provide durability under stress

just so you know, i believe it was in '02 maybe '01 year model when the miata had the 6 speed trans added(which btw is basically the same trans thats in the rx8) that they had issues with "hard to shift" and "tough to get in gear" complaints. mazda had us draining the factory fluid and adding redline synthetic. no more probs after that.

Redline 75W90NS and 75W140NS are options too, the "NS" designation means no slip additives like what comes in the standard gear oil

I think it is Stealth that mixes MTL and MT-90 in a 50/50 mix so that adequate protection is there with a little thinner fluid for smoother shifting.

Of course, I would not do this if you are tracking/auto-x'ing your car, but for normal street use, should work well.

how much was the new tranny? i'm tryin to sell my 8 and no one wants it because of the problem with 2nd gear

Had my tranny replaced at 7k miles. Had it in before i ever got 1k miles on it and told them my third to fourth shift at over 7500rpm was grinding. They kept it a couple days and finally said they couldn't re-create the problem. at about 4k miles second started grinding (upshifting and downshifting) I let it continue getting worse until i couldn't stand it anymore. that way i knew they could "recreate the problem". They didn't even bother trying to fix it, just ordered me a new one.

Odd part was that when i got my car it had a little over 100 miles on it from test drives. the original transmission NEVER felt even REMOTELY close to the way the tranny they just put in feels smooth wise.

It's MazdaManiac

I ran the 75W140NS before changing to Shockproof Heavy, it always shifted smooth cold or not

My 2006 transmission shifts like a drunk falling down steps... awkwardly! It's been this way since Day One. I thought perhaps it would "wear in" and smooth out as it got older, but with nearly 13k miles on the car now, it's no better. Was going to try Motul 300 75w/90 in it and see if it helps...

TeamRX8-What's the weight of the Shockproof Heavy?

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New tranny in
 

Feels great--better than the original when new.
Saw the invoice that was prepared for the value of the repair--$3400; since ours was covered under warranty i just paid for an oil change but I'm glad it wasn't on coming out of my wallet.
Again, thanks for all of the help.

Glad to hear it all worked out for you.

Abbid, I'm PMing you.