813KR$

The thicker the oil, the better. It is as if the synchros need the thick oil in order to grab?

Charles R. Hill

iTrader: (7)

The challenge for modern transmission fluids which are to be used in modern transmissions is that they need to balance the concepts of lubricity and friction because the bearings, gears, and synchros each have different needs for proper function, and they all work at cross-purposes.

In other words, thicker is not always better. Having a "clinging" property in your fluid is not always advantageous, either.

RX-865

mine does this when i shift into 4th at high rpms occassionally (7500rpm-redline). Its not a crunch or a grind. Its more of a scrape sound, but still not a pretty sound

cidvicious831

same with me but its on the 4th and it feels like a grind, but if i shift in really slow it goes in smoother.

RX-865

same with me, when I shift slower into 4th it doesnt make any sound at all and is smooth, but if I shift hard it makes the scraping sound.

813KR$

Im not saying theoretically the thicker the better, Im saying from my experience the transmission loves the thick azz Lucas.

155,000 mile and counting

I probably have the loudest whinning grinding trans around, until the the Lucas experience. in 6th gear with regular 90 wt gear lube, the trany whines so bad it truly gets annoying!


CHARLES, what would be the weak link when using too thick of oil? Something I could keep my eye on?

WTBRotary!

iTrader: (6)

Think about it logically bro, in your transmission as well as in your engine, there are certain clearances... the smaller the clearances the more thin your oil needs to be to lube though clearances/ gaps... if your oil is too thick you rob those small clearances of oil which in turn makes put more metal to metal contact/ wear on those parts... Thicker oil isn't always better.

Nemesis8

iTrader: (3)

I thought there was a new 1-2 shift fork part number? Isn't the 2nd gear syncro and crown the problem?

TeamRX8

iTrader: (25)

There was, back many years ago, it's the standard part now

I went back to Heavy Shockproof Redline. It's the only oil I haven't blown up on yet and they blow during the hard 1-2 shift shock. I still don't recommend it for street cars. It will need to be changed too often.

813KR$

You guys keep on grinding, and I will smoothly shift into 160,000 miles on the original trans, with my thick *** lucas

cidvicious831

i hate you!^

nelson08

i have a 2004 mt with 58,000 and i am already on my second transmission and its starting to grind in second again. Does anyone have any experience with changing the shift fork and having success?? There has to be some way to fix this that isnt oil. I dont know about you guys but something has to be wrong if all gears arent grinding with this oil. all the gears and syncros are probably engineered with similar clearances and that would make me think everything should wear evenly.

I also heard about the possibility of running braided steel lines. Which sort of makes sense because my tranny tends to grind more when warm and being warm could cause the lines to balloon ...???? but still the question is why does it only happen in second gear???? if it was the lines it should happen in all gears right?????


So, im leaning toward the possibility of a new shift fork because that is the one part that could change the way a gear engages depending on what gear is chosen. thus causing 2nd gear to go out. either that or a flaw in part of the 2nd gear and syncro..... anyway Thanks for any insight that anyone has on this issue this problem is really getting annoying

scremn8

cross my fingers. i bought my 04 in 04
and i just had the oil changed after 70000 miles
and still no grinding, a lot of it has to do with how you
shift

kdoiron08

iTrader: (6)

alrite, had an 04 and would only grind in 2nd gear...it kept getting worse, i changed the oil to lucas..still grinded in 2nd...bought a new(used tranny) istalled and its still was grinding...so i bought a new slave cylinder. Problem solved>>>>turns out i ddnt need that tranny after all...the part is only bout 85 dollars new from phoenix friction....hope this helps.

kdoiron08

iTrader: (6)

oh btw braided clutch line soesnt help the problem either...though it does stiffen the clutch a bit..

Soravia

The MT I had was crapped out on multiple synchros at 3rd and 4th. I was at 100,097 miles but the dealer fixed it for free and gave me an Auto Mazda 3i.

I'm only speculating here but the cat near the transmission makes so much heat on RX-8, like sitting on top of a stove, WHILE the car has AirCon running. I think even with heat shields, that much heat would crap out the transmission oil.

I will be taking out the cat for a resonator on my next RX-8. (Maybe relocate it?)

RedLine9x

Yeah I had problems with 2nd gear too as well as reverse. Yesterday a buddy of mine and I changed out the tranny fluid...there was a lot of gunk in it...so we cleaned it out and replaced the fluid with 75W 90 royal purple tranny fluid and WOW did it make a difference. Minimal grinding at worse now and much smoother shifts and a little more get-up, especially at low rpm's (not that there is much <6.5k, but noticeable and nice for city driving)

SPHINX144

i will be getting amsoil 75w-90 for the transmission as I get the occasional grind when i shift from 3rd to 4th gear. I'll let you guys know if I notice a difference.

SPHINX144

well following everyone's consensus on the the best transmission oil for our cars, I I bought red line 75w 90 in order to solve the grinding issue I experienced at high rpms in the gears stated above.
Needless to say, I'm a testament to the the high quality of redline. The grinding I was experiencing entirely disappeared and my transmission feels smooth and effortless. I completely recommend this product to those experiencing the same problem as I did-- and I suggest taking this approach before investing money on more expensive potential solutions.

I need to clarify that the change won't be instantaneous after you change the oil, but rather it will take a couple of hundred miles--more or less--to fully appreciate the improvements.

Spirograph

Update: I've put 6k miles on since posting this. It scraped in 2nd a couple of times more for the first couple of weeks, and since then I haven't had any problems. It still has trouble getting into reverse, but I can avoid grinding by first shifting into 3rd, and I now can tell by feel the minute difference in feel when the gear isn't going to stay locked in reverse when I give it gas, so I'll run it through 1st and 3rd again a time or two until I know that it will stick. The fluid is probably still dirty from the remnants of the old fluid so I'm going to do another fluid change soon. This time I'm thinking about skipping the Amsoil MTF synchromesh 10w30 fluid, and using solely the Amsoil MTG (Soravia has a good theory about heat from the cat), hopefully it won't be too notchy. I'm also installing a synchrosaver (shift stop) to theoretically help protect the synchros from overshifting, and an AFE short shifter to get a better feel for what's going on with the gears.

Has anyone besides kdoiron08 had their 2nd and reverse grinding fixed with a new slave cylinder?