Bad transmission whine and bearing questions
 

After a 4 year battle, I finally got my turbo swap running well. Its putting down 350-400 at the wheels, for reference. I was driving it on a freshly paved, deserted stretch of highway a few days ago and decided to punch it in 5th gear. I got (rapidly) up to about 140/7000 RPM and immediately afterwards I noticed a very loud mechanical whine. It is very noticeable in 1-3 and present in 5th, but not 4th. It is so loud that it can be heard noticeably over my bridgeported engine, even when accelerating.

From searching, I didn't find much info but it sounds like the bearings are bad. My question is which ones? I looked at the parts manual and there are quite a few of them! I'm trying to get an idea at what I'm looking at. Is there any way get an idea without pulling the transmission apart? I don't have a lot of money right now, and if I have to get $300 in parts I'm going to wait until I save up some money so its not sitting taken apart so long I forget where everything goes.

Also: while I have it apart, are there any other things I should check? It theoretically was rebuilt about 5k miles ago so it shifts smoothly.
Also, also: is there anything I should beef up to handle high horsepower? I'm anticipating 500+ RWHP in the next year.

Buying parts without knowing exactly what let go is silly. If your set on fixing it and not buying a replacement trans I would open it up and find out exactly what went wrong before throwing parts at it.
If your looking to beef up the trans you might want to look into straight cut gears but those kinds of upgrades get real expensive real fast.
What transmission are you using?

I'm definitely not going to buy parts until I pull it apart. I was just wondering if there was any way to get a ballpark idea of what I'm looking at based on the symptoms. I definitely do not believe in throwing parts at the car! In searching, I've found that you can also cryo-treat the gears (jrat did this, for example) but I'll have to look into it more.

As for the transmission, it is a J-spec transmission (I think s5), which is why I want to rebuild it. This is built as a track car so the tall 5th gear not only isn't necessary, but hurts performance on the track. Its basically like putting Miata gears in an NA - when shifting into 5th, its still nicely in the power band. On top of all this, there aren't any nearby TII transmissions and shipping them gets pretty expensive.

As for the actual rebuild process, I can figure out pretty much anything as long as there is decent documentation and you don't need any super-expensive tools. From skimming the FSM it looks like a bit of a PITA and pretty time-consuming with a lot of parts, but something I can manage. I'm saving up for a single turbo swap because my bridgeported engine is totally overwhelming my hybrid turbo, so I've got the time to mess with it.

My old s5 trans did the same for about a year. It would always whine under heavy throttle except in 4th and about a month and a half ago something broke... i bout another transmission and it ended up being an s4 trans which i've heard are a little beefier. when i drained my gear dope in my old trans it had chunks of metal that looked like they came off of the gear teeth. If i was you i'd change the gear dope and look at it to see how much metal it has in it. it might not fix the problem but it might help. :)

I'm going to be pulling the motor and transmission next week, so I'll see what it looks like at that point. The fluid is Redline MT-90 that isn't very old, so I doubt replacing it would fix much. Its going to be down for a couple months while I upgrade to a T-70 turbo and V-mount, so I'll work on the transmission then.

Can this problem be caused by a single bad bearing? I'm guessing that since one went bad its a good idea to replace all of them, correct?

Yes and yes.

If it isn't whining in fourth, then it is the thrust bearing on the intermediate shaft. When in 4th gear, there is no torque running through the intermediate shaft thus, there is no "thrust" to load up the bearing.

Looking around online, I found this: Manual Transmissions by Unit Code: RX7 & RX8 series: Manual Transmission Parts - Online
Do you think its worth getting these? It's a very significant savings over Mazda. It looks like they use Nachi and NSK bearings, which look like pretty good brands from searching the internet.

I've been on that page before and am wondering the same. Anyone used them before?

Yes, NSK and Nachi are excellent bearings.

those bearing kits are ok, Mazda supplies NSK bearings.

however, Mazda switched the thrust bearing to a roller, and generally the aftermarket kits come with a double row ball unit. the double row ball is vastly inferior to the roller.

also Mazda went through some updates with sealed vs open bearings, and the aftermarket is usually behind here too, although it doesn't matter too much.

building the transmission is a big job, but it is doable. make sure you have plenty of time, and space and stuff.

I accidentally shock loaded my transmission 2,000 miles after it got rebuilt (long story, but it was an accident).

In my thread about my throwout bearing, in the video I posted you can here the whine of the ball bearing thrust bearing that has whined like that ever since for the last 4 years.

the 1st gens all came with the double row ball bearing, and they get noisy really fast, but it will hang in there a while, so between the time its annoying and the trans falls apart can be like 50k

Mine isn't annoying yet, just evident.

I was talking to Chris Ott at RP one day and he brought up the whiny trans, and I told him what happened and that it only had 2,000 miles on it when it started. He told me that the trans shop probably used the old style bearings and that he uses the mazda roller thrust bearing. D'OH!

I got a quote from him on rebuilding the transmission again and he only charges slightly more than that mom and pop trans shop does. D'OH! again.

What did he quote, if you don't mind me asking? I come to Dallas a couple times a month on business so its easy to get there.

This was 4-5 years ago but I believe he said $2,300 but that also included a new clutch and pressure plate.

Wow.... Thats the reason I do everything myself!

I fucking hate rebuilding transmissions. I did it twice in college, Toyota front wheel drive ones, and then also when i was a teenager, I rebuilt my buddies 1965 mustang automatic transmission. All 3 where automatic. Maybe a manual is easier, but after the third I was like "I am never doing this again unless my life depends on it".

Yeah, it doesn't exactly look enjoyable.... Unfortunately I'm broke, and the car has already been sitting way too long just saving up for the parts. Either way, I'm going to keep it as-is for now. I don't drive it much so it should be fine until spring, by which time I should have everything ready for my turbo swap and I can just do everything at once.

I have thrust bearing whine in my trans and it has lasted 5 years now (knock on wood!!!). I saw your race videos, and that likely caused it, lol. Really though, it should hold up as long as you change the fluid more frequently to get rid of any junk that might be floating around.

Here are some links on rebuilding a 3rg gen transmission, same as a 2nd gen.

http://www.wrex-racing.com/docs/fd/T...isassembly.PDF

http://www.wrex-racing.com/docs/fd/T...ction_Misc.PDF

http://www.wrex-racing.com/docs/fd/T...Reassembly.PDF

Clutch mechanism is not however, just wanted to point that out.