Hey Guys,

Yesterday I was driving with the stereo off for once and noticed a pretty loud whine from my transmission in 3, 4 and 5th gear. My first though is oh crap is this the dreaded input shaft bearing problem?

My 4th Gen was built in Jan of '99 and has just over 80K on it so it's kind of in the window. But I was wondering, if Nissan have been making this car for close to 5 years, was the input shaft bearing ever superseded to rectify the problem from the factory before it began? Nissan by this point I'm sure were well aware of it.

Anyone know?

 

nissan doesn't make the transmissions, aichi-kikai does. they've been making this transmission for a helluvalot longer than 5 years btw, it's the same trans as in the 3rd gen, in older sentras, stanzas, etc.

anyways it's not a design issue that needed to be "resolved" it was just a labor/time issue. the bearing they use is just fine and will last hundreds of thousands of miles if they use the proper shim behind it. they were saving time during manufacturing by just not bothering to measure properly to find out what shims needed to be in it (probably saves them a half hour or hour per trans times millions of transmissions a year times whatever they are paying their employees - millions of dollars a year in savings plus the fact that they will be able to make and sell more transmissions if they skimp on them. tons of money we're talking about here).

the bearings fail when the cars are out of warranty so nissan doesn't care, no reason to spend more money and make themselves less money.

in short, no, no resolution because they have no business reason to.

 

^wow, so THATS why these bearings do so much damage, because of a freaking shim and 30minutes...smh. thats ridiculous!

 

Damn! That's as comprehensive an answer as I could have wished for.

Thanks for the insight!!

 

Well, after a chat with Dave B. prior to reading Nealoc187's answer I figured my first step would be to get new trans lube in there, cross my fingers and hope it solves the problem. Replacing the transmission fluid has been on my to do list for a months, as I didn't know if it's EVER been changed it was well beyond time if still original. Luckily, I found some Redline MT-90 locally yesterday and threw it in there last night.

Just an FYI Dave said there is a upgraded fluid for the 350Z transmissions that we should be using in the A32 and that standard fluid dealers use and sell is just Pennzoil crap with a Nissan part number!

Part Number for it is 999MP-MTS00P Cost: $12.50 QT (Which is what I paid for the MT-90)

Dave said not to be surprised if the parts guy wasn't even aware of it but "this is is what you should be running in your 4th gen - NOT the standard dealer stuff" So I thought I'd pass it on to y'all.

 

999MP-MTF00P is gl4 fluid that you need in your 4th gen trans... 999-MP-MTS-00P is for cvt transmissions.

 

Yea, my friends input shaft went on his 5 speed lasted him about 10k ill say then the clutch disc exploded

 

Thanks for the correction Greddy, guess I misheard him.

 

Would it be possible for a transmission rebuilder to spend a little extra time to get the right shim behind the ISB when doing a rebuild or can that not be changed?

 

Since the FSM has a procedure for determining shim thickness and gives part numbers, I think rebuilders should be doing it.

 

This is good info since my input shaft bearing is making noise and will be rebuilt in January!

 

the shims seem to be on perpetual back order from nissan according to what I've heard. it supposedly takes forever to get them (I've never ordered one but I did rebuild a trans for someone who tried to order them himself before I was tasked with rebuilding it).

I would be willing to bet that most trans shops like AAMCO and what not do not reshim them, but I could be wrong. As long as it lasts longer than whatever their warranty period is (30 days, 90 days whatever) they don't care if it fails again 5-10 years down the line. more money for them when they get to charge $1500 to rebuild it for you again.

Everything I build is shimmed properly when I'm done with it. I have access to a huge number of shims from other makes and models and all you need is the proper diameter shim for whichever bearing you're shimming and then he proper thickness as determined from your measurements and the FSM chart (and maybe a little know-how if the trans is going to be seeing racing duty so you know on what end of the spectrum to shim for different types of bearings).

 

Thank u for this info. Very valuable! Is there any documented information to support this? It would be very useful when filing a small claims law suit. Thanks!

 

Thanks for the info. 999MP-MTF00P is 75w-85. Not as common as 90 weight. Any comments?

Dr J

 

supposed to change the fluid every 30k

 

Part of the issue that's never mentioned was the transmission wasn't designed for the use 95% of us .orgers do with it. It was designed as a street car transmission for a sedan with 160hp, not something street-raced constantly with 200+hp and raised rev limiters.

It's the same reason those 30,000-mile tires on our cars only last 10,000 miles.

That said, I've opened about 8 Maxima transmissions and found all of them to be shipped reasonably well on the main shaft and output shaft.
The input shaft uses ball bearings, so it shouldn't necessarily NEED to be shimmed according to theory. I have been wondering if it wouldn't be a good idea to convert the input shaft bearings to tapered roller bearings and shim the shaft to see how it would work.