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Sure it can be the input shaft bearing but the main point is that they say it's normal and that the transmission will last forever with that noise that will be only an acustic disease. I want to be sure about this.
I’m not familiar with what’s “normal” in an RX8… this is the FD RX7 forum after all. But it does not sound “normal” to me. Or more precisely it’s not a “ normal “ sound on an FD, which has a similar transmission. Additionally I doubt they’d have sold as many cars as they did if that was a “normal” sound.
And since I have personally experienced a bad input shaft bearing on my FD, and stupidly ignored it until it was almost too late, I posted warnings earlier in the thread.
Nobody can wave an internet wand over your car and diagnose it so you can “be sure”. So to me the main point is it’s your call whether to deal with it…or not.
But when you say "it's too late".....what was the damage produced by the seized input shaft bearing? Does it locked the gearbox with heavy damage to the trasmission?
I'm asking because if you search in these Rx7 forums also someone told that he went foward 230.000miles with that noise and the gearbox is still running!
I don't want to rebuild the gearbox if this is only a noise problem!
Also i changed the oil in the gearbox with Mos2 additive and the noise (probably input shaft bearing) was reduced by 70%.
But when you say "it's too late".....what was the damage produced by the seized input shaft bearing? Does it locked the gearbox with heavy damage to the trasmission?
I'm asking because if you search in these Rx7 forums also someone told that he went foward 230.000miles with that noise and the gearbox is still running!
I don't want to rebuild the gearbox if this is only a noise problem!
Also i changed the oil in the gearbox with Mos2 additive and the noise (probably input shaft bearing) was reduced by 70%.
The input shaft bearing inspection/replacement doesn't take a trans rebuild. It only requires the removal of the trans, and the bearing, to do this and not having to take it apart.
If you let the bearing noise go to long it scores the shaft and you have to buy a new shaft.
I bought a used trans with some bearing noise once I put it in and when taken apart for rebuild it needed a new shaft even though it worked fine.
The cost of the shaft plus rebuild was about the price of a brand new transmission so I bought new.
Mazda recently lowered the price of USDM spec (tall 5th) FD transmission. Its around $2,000 w/ shipping from Japan with racer's discount.
But what i don't understand is: i see photos of the input shaft bearing and the bearing seems like a sealed one (with a cover over the *****)......but inside the trasmsission there are also needle roller bearings. I put new fluid with Mos2 anti friction additive (Liqui Moly) and the noise in neutral reduced a lot. If the noise is caused by the sealed input shaft bearing new oil or additive can't heal it because the oil or the additive won't pass through the cover! So i think that the noise can be produced by the roller needle bearings not the input shaft one.
Also the strange thing is: i have no noise with gear engaged and the car in motion. I have read that it is because with the gear engaged the small "free play" beetween bearings shaft and gears is reduced to 0.
Ah just for knowledge: my car isn't a FD but a FC Convertibile Turbo 2 (almost same transmission of the FD, very similar but older)
On my FD transmission it was the needle bearings on the back of the input shaft that went bad and destroyed the snout of the mainshaft.
On the FC make sure to check the bushing in the transmission crossmember.
If that bushing deteriorates and the washer in the center can contact the crossmember it will transmit a loud transmission noise into the car. That will make a perfectly fine transmissiin sound like it has bad bearings.
Another small journey with the 7.........just 6km where i used manual transmission heavily........after i changed gearbox oil with "ENI ROTRA 80W90" + BARDHAL T&D ADDITIVE + WYNN'S H.P.L.S TRANSMISSION TREATMENT + 50g LIQUI MOLY MOS2! A magic "cauldron". Noise is now reduced by 90%.......and it's not placebo effect........transmission is now almost silent like a charm! I'm 100% sure that regarding my gearbox needle shaft bearings are worn and not input shaf bearing.....that for what i explained before: input shaft bearing has seals and ***** separated from transmission oil/additives......needle "roller" shaft bearings are "submerged" by transmission oil!
04-06-24, 12:24 PM
