FDZero

iTrader: (10)

(sorry if this is a duplicate post, getting error messages)

Hey all,

Just recently picked up a '93 FD about a month and half ago. Didn't really start driving it until about 2 weeks now. At the time of test drive, getting into 5th gear was fine but needed extra budge. I figure it was a 5th gear syncro needing to be replaced in near future. Later, the car would grind sometimes going into 5th gear so I try to avoid going into 5th gear at all until I can set a time to check the the syncro.

Well, whoop-ti-do, today on the way to work while attempting to shift to 5th (I avoid when all possible), the 5th gear syncro, I believe has broken. I can hear the piece rattling in the drivetrain I believe. The noise noise doesn't get louder, it just "spins" faster the higher the rev. However, the noise is absent if I'm in neutral.

So my question is, is this in fact the 5th gear syncro I believe that has broken (or a part of) or is it something else? Any info would be appreicated. I'll continue my search in the forum for any related stories. Thanks. Tim

seven samurai

I would say yes I'm not A rotary guru like men on this site but I have had the same problem. One easy way to get around still is to shift early or allow your rpm to drop lower when you shift into 5th and it should get in with no problem or no grinding you just lose that punch cause fifth gear has to climb back up. drove around for like two months like that until i saved enough to get it fixed

FDZero

iTrader: (10)

I'll sit down and check it out and do some more research. This 3day weekend coming up should help out though not sure if I can square it away. May need some parts I have to order. Does anyone else have similar problems at the moment or in the past?

I'll hit the search engine some more. Tim

FDZero

iTrader: (10)

To clarify, the believed-to-be-broken-piece-of-5th-gear-syncro makes sounds in all gears but not neutral. The piece spins faster as I get in a higher gear/rpm...so for now, I'll just have to stay in lower rpm and praying between now and time fixed, piece doesn't damage internal drivetrain. Unfortunately it's my only ride...just rid of my SUV (!).

TwinTriangles

My 5th gear syncro just went out this spring too. Grinds everytime I shift to 5th. It used to only do it now and then and if you shifted just perfect, now it doesnt matter it just grinds every time...

impactwrench

Mine has been going for about a year. It was grinding going from 4th to 5th. I found that I could live with it by hesitating four a couple seconds after pushing the clutch in, before moving the shifter to fifth. That still works, but over the last weekend, getting into reverse, is a hit or miss, and from what I've read here, is also a symptom of that synchro. I met Ray Crowe from Malloy Mazda at the Rotary Revolution and he told me the replacement parts are less than $75. I will be calling my old friend Ray after this weekends club meet

rlee429

iTrader: (25)

my 5th gear grinds as well, but only when i shift to 5th really fast or when i shift at 80mph, so now i just shift really slow to 5th and it works fine. But second gear is a bit clunky, is it the syncro's too?

FDZero

iTrader: (10)

Sounds like everyone is having sync problems all in May. Hahaha. Mine did shift into 5th just before it went out earlier today. Well, I guess learning from me, replace it when you have a chance right away. My 5th gear just gave in and now I got a piece of it rattling in the drivetrain (...) when engaged in any gear except neutral (of course). How risky do you guys think driving it just to work in low RPMs until able to fix?

impactwrench

Loose parts in an enclosed area with lots of gears can't be a good thing. $75 now versus lots after you destroy the whole trans. Maybe you get lucky, maybe not

FDZero

iTrader: (10)

Yah, I can't risk it. I'll ring them shortly. Thanks.

cesarx7

iTrader: (1)

My transmission also has a broken synchro. It always grinds when I put it in 5th gear. But if I just blip on the throttle while the clutch is depressed right before I slip it into 5th gear, it doesn't grind. People on the highway look at me crazy cuz they'll think I'm revving my engine at them, but that's better than possibly damaging my transmission any further.

SHPNOUT

iTrader: (3)

It could block out reverse as well as it continues to fail........That is what I am dealing with.

Master_Ly

Hey man, I was thinking about it some more tonight. I would definitely try not to drive, if anything, at high RPMs or just not at all. If if you stay no higher then 4th gear and avoid trying 5th completely, your RPM may keep climbing just to keep the car with the traffic flow. That piece of synchro disconnected then it potentially could bounce around between the gears more as the RPM rises or get caught up in between the teeths and ruin them.

Master_Ly

In addition, my car had a TSB on our double synchros due to it grinding 2nd gear. This was happening because the synchro was not matching up the gears and at the same speed so it would grind like crazy. It wouldn't do it if I was over 4G in RPM or if I let it drop, shift, and then bring the RPM back up; similar to what others are saying in this thread as a work around. If the synchro is near 100% fail, it's going to most likely grind regardless. Synchros, any parts of the car for that matter, will most likely go out eventually due to daily use and aging (can't say the same for mine since it was straight up messed up, ). Fortunately, TSBs are covered regardless warranty exists or not so if so many people experience this then maybe there is a TSB for the FDs.

I don't know if the FDs have double synchros but over time the grinding will just knock it loose and it could cause it to not engage the gear at all (this would lead me to believe the synchro has failed completey), which could lead to more problem.

BANNOR

I just developed a 5 gear syncro problem also. Its not bad but it is consistent. I had the tranny and diff fluid changed with NEO hoping it would help but it didn't. It definitely helped with the other gears. (shifts smoother).

I am trying to hold off on getting it fixed since I don't just want the 5th gear fixed. I am not a transmission expert so once its dropped I would like to have everything checked out and replaced if needed. I am also contemplating a LW flywheel and inspecting the clutch and replacing if needed. I think it would be better to do this all at once.

I would like to do this sooner but the money tree is bare at the moment. Plus it looks like I am going to have to get some exhaust issues next. (one of the stock muffler tips just fell off due to rust and wear) OH well I wanted the dual racing beats anyway. Luckily this is not my daily driver.

FDZero

iTrader: (10)

For now, I will have to remove the piece rattling around. Called off work today to get to it...

Master_Ly

Also, the synchro could possibly not have disconnected but still fail completely. As the RPM rises, it would rattle like crazy and possibly until it does comes loose completely.

quicksilver_rx7

Add me to the list. 5th sync. is going. Grinds if shifting fast into 5th. Not so bad if I take it slow.

FDZero

iTrader: (10)

...my ride is out of commission for now until I get things straightened out.

David Beale

The typical failure mode for the 3/5th syncro hub is the 5th syncro cracks (often when a 2-3 gear shift is missed). It then "lives" with poor operation until it finally completely falls off (one more crack more than 45 deg from the first). The syncro is brass and often will break into small pieces. If any of these gets between gear teeth it will destroy the transmission by wedging and bending shafts or jamming the gearset and possibly breaking teeth. I've seen a car come to a screeching halt with a jammed transmission. Depressing the clutch will not release it, of course.

I suspect a majority of surviving 3rd gen RX-7s have a cracked or worn 5th gear syncro. I know mine does ;-). I haven't heard of many jamming the transmission though. There must be enough clearance below.

DamonB

If they really are brass as you say then the gears of the tranny will happily grind the synchro into little bits without failing themselves. Heck, I had a Fiat transaxle once that ground up all the hardened steel needle bearings from one of its axles into mush and powder and it didn't care

Montego

iTrader: (1)

my 2nd gear synchro just started grinding when I shift at WOT.

Master_Ly

That's true it could grind it up into dust literally but it wouldn't help with the life expectancy of the tranny or performance of the vehicle with all that stuff floating in and out of the gears and throughout the tranny. Maybe thorough flush temporarily help to buy some time for the full repair but you might as well as address the missing synchro at the same time too, if can, since it's going to be open.

DamonB

Agreed. It's never advisable to have metal pieces flying around inside the transmission but if the synchro were to completely come apart it would most likely not be instantly fatal as was previously said.

dgeesaman

iTrader: (7)

Efinizero, it would seem your synchro is shot but maybe a piece is rattling around in the 5/r housing against the 5th/rev clutch hub assy. You'll end up grinding the synchro pieces and probably not damage the other gears, but personally I suggest getting it checked out asap. You probably also damaged your 5th clutch sleeve, but fortunately that's only a $40 part in addition to the $20 synchro.

For folks who's 5th shift grinds but the other gears are fine, use double-clutching to get into 5th - normally this is a safe workaround when 5th synchro is damaged. Efinizero - it's worth a try to see if it avoids a grind in 5th. The good news is that any tranny shop is equally qualified to work on the FD transmission, although rotary shops are much more likely to have experience with this particular gearbox. Doing 5th synchro is only an hour of work once the tranny is lowered, so for some people it makes sense to double-clutch 5th until they're ready to get a new clutch installed and 5th synchro fixed at the same time.

I fully rebuilt my tranny, and it was a lot of work. If that's your direction, it seems now these low-mileage JDM trannys are a simpler option, where you can rebuild your original later if you wish. The JDM tranny also gets you newer internals (different 5th ratio, updated 2nd synchros, updated select spindle). Any shop or decent DIY person can perform the tranny swap, and the car is on the road almost immediately, but the condition of these JDMs unknown until it's installed.

In case you're interested in rebuilding your manual tranny, I did a writeup on it and the tools I made/bought for the task: www.davidgeesaman.com

Dave