Pilot bearing or Input shaft bearing?
 

I have a 'growling' noise when idling in neutral with the clutch out. 'Growling' pitch changes with rpm and goes away completely with the clutch depressed. It seems to be loudest when cold and is noticibly quieter once everything is warmed up.
From searching I understand this is either the pilot bearing or the input shaft bearing. But is there any way to diagnose it beyond that? I figure on pulling the transmission out at the end of this driving season, and changing the pilot bearing doesn't concern me. But I don't have the pullers for that input shaft bearing and would probably have to take it to a transmission shop. I'd rather not go to that expense if isn't necessary. And obviously I don't want to pull the transmission a second time in the event it isn't (just) the pilot.

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I have this same issue . I have the engine out so I'm gonna try the pilot bearing first , and if that doesn't do it . i'll be in the market for a new tranny since from what i've looked it it seems cheaper to swap the trans for a low millage JDM one then it is to rebuild .

My input shaft bearing has been growling for a long time and hasn't gotten worse - pretty much a normal condition. It actually got quieter when I switched from dinosaur to Redline MT90 back in 1999.

I would say input shaft bearing, friend just had same noise, picked up low km JDM tranny, noise gone....

Your cheapest route will more then likely be a low km JDM... Friend paid under $400 for his from a local vendor


J.

Appreciate responses, but I've no intention of sticking a used transmission in the car, especially a JDM version. I just want to know if there's a way to know if it's the pilot or input shaft bearing...either before or after the transmission has been dropped.

If you-all understood how and when each of the two bearings worked, you would know the answer.

When the clutch is engaged, does not matter if the trans is in neutral or in gear, the trans input shaft is locked through the clutch disc to the flywheel. Thus the pilot bearing is not being rotated/used.

One correct answer before me. You have a bad trans input shaft bearing.

Agreed^^ Look for the problem from the input shaft bearing moving into direction of the tranny.

ok so I guess we're in the same bad inputshaft bearing boat. May I ask ? is there no ill effects from having a bad input shaft bearing ? besides the noise ?? wont it get to a point where things just go kaput? :scratch:

'I-all' understand how and when each of those bearings work. And I started out thinking the same thing. But post #11 by degeesaman in this thread https://www.rx7club.com/3rd-generati...-shaft-846512/ threw me some....suggesting it could be either/or. And I know him to be pretty experienced with the transmission. Besides, we all want to hope for the easiest fix.
At any rate I checked with a trusted local shop. He confirmed it, but it doesn't sound like it's going to be as expensive as I thought to replace that bearing with me R & R'ing the transmission myself. Have been considering a Street-lite FW anyway. Maybe this winter is the time.

could a bad input shaft bearing make a bad clunk/chattering noise when accelerating on 1st or reverse?? I need this issue fixd assap and don't know what it is..

I guess "Bad" is a matter of degree - At about 30,000 miles I noticed that the bearing was louder than I would like. I asked the best FD mechanic I knew to listen to it. He said it sounded normal and was not a problem. In the 20,000 miles since then it hasn't failed or even gotten noticeably louder. All bearings make some noise, and they get louder with mileage and use. The transmission still runs and shifts fine. If the noise gets worse or other symptoms develop, I'll just replace the bearing or the transmission.

I don't think that's the input shaft bearing. I had a Triumph TR3A with that problem. That model did not have syncromesh in 1st, and mine was missing a few teeth on one of the gears. Big clunk in 1st and Reverse. I drove it for quite a while until one really cold morning when one of the loose teeth got caught up and jammed the transmission. I replaced it with a full-syncro transmission from a TR4.

Pilot bearings, Clutch pull out bearing, and Input shaft bearing; all have different noises and affects when going bad. Then throw in loose gear bearings.

Ahhh, the ol' FD input shaft bearing....

My input shaft bearing was noisy from the very beginning; when brand spanking new. I took the car to Mazda for warranty service and almost got a new tranny from them until one of the techs noticed that all of the FD's seemed to have the problem....and so they called it normal operation, which in reality, it is--for the FD. Don't know why these particular bearings are so noisy. Still regret not getting a new tranny under warranty (at about 45k miles). Lol.

I replaced my clutch & flywheel in March of 2003. I installed new pilot & throwout bearings. Before I did the job, I had no noise. After installation, I had the noise you are referring to. I still have the same noise, and it has not gotten worse in more than 10 years of driving, which is around 24,000 miles. Although the miles are low, there have been many autocrosses, and a lot of spirited driving. I have no intention of doing anything about it.

this ended up being my input shaft bearing (in case it sounds the same).

^Yep. Same as mine. Thanks for posting for posterity.

Just curious, did you change it yourself or have it done. Costs?

I changed it myself in my garage with jackstands and a floor jack. Took me 12 hours to do on my own, would have been less if I had a helping hand. JDM tranny was around $300

If you plan to fix it, you mine as well rebuild the transmision because the input bearing is the last bearing on the shaft so everything must come apart. I did mine in 2008 and all new bearings and synchros were about $500 from Malloy.

Shortly after I went single turbo and with less than 4K miles on the rebuild stripped 3 or 4 teeth off 3rd gear. In retrospect, the low milage JDM transmission people are suggesting is not a bad idea.

Jack

MIBagentQ, that bearing sounds nasty. Mine is much quieter and only really noticeable if the car is inside a garage.

What is that orange rocker switch on the bottom of your dash for?

It wasn't quiet but the video makes it sound much worse because I was actually using a remote microphone plugged into the camera and the mic was literally sitting on the floor under the tranny (you can see it in the beginning of the video).

rocker switch controls my intercooler and oil cooler fans, I only use those when I'm at the track

Mine seems to quiet alot once wamed up.

If I absolutely was certain of mileage on a jdm trans. that would be one thing. Trouble is... EVERY JDM trans. seems to be low mileage but no guarantees. Since I KNOW how many miles and treatment mine has had, I plan on fixing it. Besides...I like the taller 5th.

Hey Sarge, what ever happened with this. My trans just started making noise and I’m sure this is what it is. Did you just fix it? New tranny? Jdm? Thanks. I know it’s an old thread

Hey Chief,
It was the input shaft bearing. Was pretty much toast. Which IIRC, isn't all that involved to replace by itself. But I ended up having a comprehensive rebuild at the same time...R & R'ing the transmission myself.

Yeah they can get pretty noisy right before they fail.