zecc81

So I bought this car knowing it needed a new input shaft bearing and clutch, I take it to a trans shop and they agree. Long story short, the transmission was actually fried (overheated or low on fluid) so I needed another one. The mechanic finds one at a breaker yard and so I opt spend $650 on this trans with 45k miles on it. More or less it has the same sounds: whirring when idling and clutch engaged (input shaft bearing) and harsh whirring in 1st, 2nd, a little bit in 3rd (4th is quiet of course), and inaudible in 5th. They've acknowledged it's bearing noise but also say these are "noisy" transmissions anyway, with straight cut gears in some places. They said the trans had a little bit of water in it and the noise may just be the rust, but that will go away eventually. In the end, they told me if I bought a bearing kit, they would rebuild it at no extra cost because the $650 I spent should have bought me a fully working trans. A bearing kit apparently is going to cost me another $250, and I've already spent a lot of money, so should I wait to see if the noise stops, or get it rebuilt? Any other thoughts on this subject?

Sorry for the lengthy post. I have an '86 N/A.

RotaryRocket88

iTrader: (7)

You should not be able to hear much of anything at all. The "noisy transmission" comment is fairly off-base. The only time I hear anything from transmission is during deceleration. Definitely do not wait to see if the noise stops. Bearing problems won't cure themselves. If you trust the shop, a rebuild for the cost of the bearing kit alone is a good deal. Labor cost on a transmission rebuild would normally be much much more than $250.

Something else to consider is a used NA transmission can be had for around $150. The $650 you paid is excessive, especially if it needs a rebuild anyway.

Aaron Cake

iTrader: (1)

Another thing to remember is that these transmissions are getting old, and many of them are just plain worn out. In my experience, most RX-7 transmissions have a whine to them. Even my friend's new RX-8 is much louder then I would expect.

The wrecking yard is giving you a load of BS though. You should not be hearing a harsh whine in the lower gears.

zecc81

When I first heard the news about my original transmission I called around and got quoted around $900 for a refurbished trans, so where you found one for $150 beats me. I checked on ebay and didn't really find anything worthwhile there. The mechanic then assured me 45k for a trans is "like nothing" and it should be perfect so that's why I bought it from this shop's source for parts. This yard apparently provides a 90 day parts and labor warranty, but refuses to pay the labor costs of rebuilding it, so it's on the shops dollar now. The shop knows they f-ed up, I guess that's why they're offering a rebuild for cheap. I've driven in enough manuals to know this noise is excessive, so I'm definitely going to get it rebuilt.

RotaryRocket88

iTrader: (7)

The classifieds section of this forum. I also sold my old NA transmission (rebuilt w/ 30k on it) for $150. I have a pair of TII transmissions now, and they both cost me around the same amount.

There's a big price difference between "used" and "refurbished/rebuilt".

zecc81

Yes there definitely is, and it looks like I paid too much for a used one that needs to be rebuilt anyway. I'll check out the classifieds from now on.

canonize-ryda

my 86 na tranny makes noise not like grinding but like burrr....... kinda low not very high pitch at all. and does it in 1st 2nd and a litlle in 3rd(barely) but not in 4 or 5. its never gotten worse or gone away. i replaced the clutch after i got it(didnt replace throw out bearing) didnt have the proper tool to remove old one. but ive just dealt with it and im prettymean to it and she handles with no slippage.

RXSpeed16

iTrader: (41)

Are there any other drawbacks to using a transmission with a bad input shaft bearing? Noise is not an issue, but will it damage pilot bearing or anything else?

Aaron Cake

iTrader: (1)

The input shaft bearing is actually fairly easy to replace, if I remember correctly. I think all that is needed is to remove the input shaft cover, then pull of a giant snap ring and slide the bearing out (persuasion may be required).

zecc81

Anyway...back to the original thread, I just got the car back with new bearings in the transmission and it's nice and quiet and smooth now. All whirring and grinding noises have gone away.

zecc81

The trans has been good for a while now but I'm concerned about how much vibration there is when a take it past 5k rpms and shift. Like a high rpm 2nd to 3rd shift feels like I'm grabbing...well, something long and thin that vibrates a lot.

Sgtblue

iTrader: (16)

Do you have a short shifter? Just a thought.......most aftermarket short shift kits don't isolate the shaft (that part that holds the shift ****) in rubber as the OEM shafts are. You will tend to feel more vibration with them. They also tends to transmit more gear noise...especially in the first couple of gears. It can be aggravated by some shift ***** too.
Otherwise look at your drive-train mounts.

zecc81

No it's a stock shifter, although it has been taken off and on and off again during the time the car was in the trans shop. 3rd gear also makes this obnoxious buzzing sound at high rpms. I made sure new shifter bushings we're put in but it didn't help the noise. Mounts would make sense, but it's more of a harmonic vibration like something is out of balance. I'll have to get it checked out.

Just a thought, would a bad throughout bearing cause the input shaft to have more tolerance than it should, and cause it to vibrate?

Sgtblue

iTrader: (16)

I doubt it. I've had bad throw-out bearings. They were noisey, but mostly when the clutch was depressed. And it never caused vibration. The T O bearing isn't designed to keep the shaft in alignment.
Pilot bearings on the other hand...if really bad will be noisey and might allow shaft vibration as it's function would be to keep things aligned and supported.

RotaryRocket88

iTrader: (7)

An RPM-related vibration can be an issue with a belt-driven accessory. I have had a water pump with a bad bearing cause a strong vibration at 4-5k RPM, but it would get smoother towards redline. Swapped the pump (which was new) and the problem went away. The air pump, P/S and A/C can all be tested by simply removing the belts temporarily.

zecc81

Ok, so it's probably not that but I'll keep it in mind.


As far as the vibration goes, the car itself doesn't vibrate, just the shifter when I grab it for another gear. It seems to build up with rpms with a small amount of vibration at low rpms and progressively more with higher rpms, like something is just a little off balance within the trans and is accentuated with the rapid spinning.

Now I will say this... my rx7 is the oldest manual car I've ever driven, and the only rwd manual car I've ever driven (significance being the shifter is directly connected to the trans and inevitably there will be some vibration) so it's quite possible I'm overreacting, I just don't have anything to compare it to.

Venturer

"not like grinding but like burrr....... kinda low not very high pitch at all. and does it in 1st 2nd and a litlle in 3rd(barely) but not in 4 or 5. its never gotten worse or gone away."

EXACTLY SAME BEHAVIOUR: FC S5 TII Vert MY1990! "BURRR" SOUND NOT GRINDING!

The noise never gotten worse since 2016 when i bought the car!

Also with clutch engaged (foot "off" from the pedal) i see that rpm hand goes down a little imperceptibly then goes up to normal idle.

Do you think that driving indefinitely with this noise will not damage the gearbox or the transmission? Can i live with that without damage.

Hope for few comments

Thank you!

Sgtblue

iTrader: (16)

Neither the throw-out or the input shaft bearing will heal itself. Either one, if making noise, should be dealt with.
I’ve seen TO bearings kind of disintegrate and be a mess. It can also strand you on the side of the road.
A bad input shaft bearing will get louder and eventually gall the input shaft, leading to expensive transmission repairs.

Venturer

I have the noise only with clutch engaged (transmission engaged) not with the pedal depressed (transmission disengaged) so the problem are the bearing inside the gearbox, the clutch TO bearing is ok (no noise with foot on pedal).

I hear low "burrrr" sound in neutral 1st,2nd very very low on 3thd and no noise on 4th and 5th!

I think there are bearings worn inside gearbox Input Shaft or others! I changed the transmission fluid with Valvoline 75W90, noise is the same but shifting is a lot smoother, no problems shifting gears up and down, works like a cham!

The problem is only the noise........."brrr" sound in neutral. When the car is moving the noise is almost absent

I'm asking you if i can keep the gearbox with this noise with no worries driving the car.

Thank you

Sgtblue

iTrader: (16)

No. The sound is the symptom. The bearing will continue to deteriorate and eventually gall/damage the input shaft. If that happens the input shaft will have to be replaced. And that is a much more expensive repair. Fix it.

BLUE TII

iTrader: (9)

I had this issue with my 1st NA FC sfter a transmission rebuild.

Turns out the transmission shop just didnt replace the blown out transmission center mount so it was metal on metal.

The shop re-rebuilt the transmission,but noise was still there.

I replaced that bushing and transmission noises went away...

Sgtblue

iTrader: (16)

I really doubt that’s his issue. The gradual loss of noise in the higher gears also, in my experience, points toward the input shaft bearing.

BLUE TII

iTrader: (9)

The decrease in noise in higher gears as OP described is also just how the transmission sounds though and quite noticeable when amplified through ditect metal on metal contact with the chassis amplifying the noise.

I also put a solid metal on metal transmission brace on my FD and it brought on the same transmission noises.

Check the simple easy to check stuff 1st.

Sgtblue

iTrader: (16)

Don’t look for an excuse to ignore it. Fix it.

Venturer

Just for update this thread

Look at this video, hear the sound and read comments below: it's a RX8 not 7 but transmission is almost the same.......same behaviour same burring sound.......everyone say it's normal for every rx8.........they say it's a normal gear engagement sound in neutral!

https://www.reddit.com/r/RX8/comment...ral/?rdt=37482