Phauss

iTrader: (3)

Hey there, I recently came across some trouble with my transmission (170k on the odometer.) I started from a stop sign in 1st and as I took my foot off the clutch, there was a snap and then the engine spun freely. I tried to start off in 2nd, but to no effect. I babied the shifter out of second gear and into third, which didn't seem to be affected. Power went to the wheels in third, and about 10 feet into my attempt to make it home, there were a lot of clunking noises and I promptly pulled over and called for a tow truck.

I know the transmission will need to be pulled in order to fix it, which isn't an issue because I need to change the main seal on the engine anyways. But I don't know if I should have the transmission either rebuilt or replaced. The car is an 86 N/A, and from searching these forums, that was a bad year for transmissions.

So my questions are:
-If I were to rebuild the transmission, where can I get a decent kit? I see a few kits on these forums mentioned, but most links are dead. Are the ebay rebuild kits any good?
-I have found a few different explanations to my problem, and I think I've narrowed it down to either bad syncros (the transmission has been noisy since I had it) or a bent/broken 1/2 shift fork. If the shift fork is bad, where can I find a replacement? I use the Mazdatrix site religiously for parts, but they don't have anything in the way of transmission internals.
-I would love to put a TII drivetrain on the car, but it's cost prohibitive for me right now. Would an S5 N/A transmission be any better than an S4?

I'm a little cautious about replacing the transmission with something from a salvage yard, since I would likely get something with as many miles or more than what I have right now. I'm leaning towards the rebuild, but a rebuilt/remanufactured transmission would be nice too. Any advice you have is appreciated.

P.S. - If I don't respond right away, it's probably because I fell asleep on the keyboard. This "research" thing can be tiring this late at night, haha!

arghx

iTrader: (3)

Here's the problem. After something actually breaks, it's way more expensive to fix and the parts are harder to find. It's the difference between rebuilding a weak engine and rebuilding a blown engine.

Phauss

iTrader: (3)

Yeah, I'm definitely afraid of some thing irrepairable in the transmission if I were to attempt a rebuild. It would be a lot of wasted time and money. But then what about a salvage yard transmission? Would it be worth it to change syncros and bearings for peace of mind? I hear about people who go through those like it's going out of style.

Bumping for some answers. :/

j9fd3s

iTrader: (3)

if the syncro's are bad, then it would grind when you shift it. if it was a bent/broken shift fork then you probably would not be able to get it into one of the gear pairs (1-2, 3-4, and 5-r). the forks are available from the dealership they are around $35. mazdatrix used to list transmission stuff, but it gets complex, they could certainly order it if you asked nicely though.

the noise in 1st,2nd,3rd, and 5th is the bearings. on an 86, they are all ball bearings, and its possible for them to wear to the point where the ***** fall out, and then the shafts are no longer in alignment.

to fix yours, you'd have to pull it from the car, and then pull it apart and see what is broken.

Phauss

iTrader: (3)

I didn't notice the noise in any gear higher than 2nd since the engine noise would overpower the transmission noise at higher speeds. There was a mechanical whine coming from the transmission in parking lots that was really noticeable. It sounded like crap. It used to grind a little going from 1st to 2nd, but at the time I just blamed my lack of experience and bad shifting for that. As it is right now, it's difficult to get into or out of 1st and 2nd while the car is in the driveway, so it could be both bad syncros and a bad shift fork.

That's good info about the bearing wear, I haven't seen it mentioned before. The ebay rebuild kits are a set of bearings and syncros. Do you know if they're any good? Here's a link to a kit: http://cgi.ebay.com/ebaymotors/Mazda...item27b434084f

On the note of rebuild kits, how do I know what kind of front countershaft bearing I have? 20.5mm double-ball or 15mm single-ball?

j9fd3s

iTrader: (3)

the synchro's only work when the trans is moving, but other than that its really hard to say whats wrong without pulling it apart.

the ebay kits are fine, the OEM bearings are better, but really are you going to drive it another 170k?

i'm not sure how to tell which bearing you have without measuring, if you look it up in the factory catalog, they only list one part number, so its weird that the aftermarket has two. since the trans comes out, budget a clutch and trans mounts too

misterstyx69

iTrader: (142)

I am not a Transmission guy,but it sounds like your Clutch plate took a dump.
Post up with what you find Ok?..I'd like to know how you made out.

Phauss

iTrader: (3)

I'm probably going to end up getting the OEM bearings just to feel better about it. I have the car at the reputable trans shop in town and we're going to disassemble the gearbox to see what needs to be done. It will be nice to rebuild it because the car will need to drive long distances very soon and it has to be up for the job. I will be leaving for the navy soon which will take me across the country and I want to keep the car around for a while. Who knows, maybe another 170k is in its future. (I think I already know where my paycheck is going, haha!)

Thanks again for the help and info. From this point on it's all about what we find inside the transmission.

Phauss

iTrader: (3)

Can do! Hopefully I'll find out tomorrow.

Phauss

iTrader: (3)

I just got a call back from the shop. It turns out the 1st and 2nd gear syncro assembly is destroyed and both the 1/2 and 3/4 shift forks are toast. So far it's looking like $380 in parts, which isn't so bad.

I recently replaced the clutch and resurfaced the flywheel about 500 miles ago because I needed to replace my pilot and throwout bearing, so I went for a new clutch while I was at it. When I took out the old clutch, the throwout bearing was shot the pilot bearing rollers were ground to dust, the clutch was beginning to come apart at the edges, and there were hot spots on the flywheel. The bushings on the shifter were near non-existent, so I replaced those too. I can't help but think that whoever owned the car before me drove it into the ground. I'm guilty of being a bit racey sometimes, but I don't think I've ever really driven it that hard.

rx7w/yaw

iTrader: (1)

Just for piece of mind the oem shifter bushings seem to be bad all the time in s4s that I know of. Two trannys and there was only a chunk left of the bottom of both of them. My tranny went out a couple weeks ago(bad bearings) and I just got a junkyard replacement and ordered a shifter bushing from atkins. Total cost $200. Went with a junkyard tranny because im not a tranny guy and I drove home on 4th gear(the only one that worked) but I figured it was toast and be easier and cheaper to swap out. $380 in parts and knowing everything is fresh would have been wiser fer sure!

2_3D_SC

Usually if the trans works in 4th gear only you broke the cluster gear.
If you can't get into any gear, it's probably a shift fork.
If it grinds shifting from one gear to the next, it's either clutch or synchro time

j9fd3s

iTrader: (3)

clutches are wear parts....

Violent Gravy

Phauss, did you ever find out what bearing size was needed for your trans? im kinda in the same delema ish. i have an 88 SE and the trans is crappen out on me, but i have an extra NA trans to swap into it, but id like to rebuild it myself (currently attending UTI) and start off with a fresh trans vs its current ??? condition one.

ive been hunting around for some help on the counterweight bearing size, but no one has an exact answer for which one it is. even looking at sister vehicles with the same guts in the trans's is no luck (Miata's and B2000's, 626's ect).