Miata 5 Speed Manual Transmission Repair/Rebuild

By: Dave Kasakitis (average nice guy, tinkerer)

This article provides suggestions and guidance on rebuilding your Miata's 5 speed manual transmission. It isn't a point by point guide to repairing or rebuilding it though. There are several excellent repair manuals that can take you through a total rebuild, complete with pictures and details. The 'instructions' provided here are more advice/opinion, what to watch out for, and hints the repair manual doesn't go into. Like most Miata owners, I'm not a professional mechanic, just a car enthusiast and part-time, week end, shade tree mechanic. I've written this for two reasons. One, as I've indicated, to give you the benefit of my screw-ups/ learnings/ solutions etc. concerning the job and Two (more importantly), to give you an idea of what's involved so that you can decide for yourself if this is a job you want to get involved with.

Unfortunately the one thing I can't tell you, is IF you need to rebuild your tranny. If you're reading this I'm assuming you strongly believe you have to repair/rebuild your tranny. Perhaps you've missed shifts and now the tranny grinds badly. Perhaps you've looked elsewhere for shifting problems, like clutch, etc. and now are convinced you have to get into the tranny. Maybe you've had the car to the dealer or shop and they think your tranny needs work. Unfortunately I just don't have enough experience with trannys to give you a diagnostic guide or flow chart for determining the noises you're hearing are indicative of a tranny repair/rebuild. So this 'article' assumes that you definitely NEED to have the tranny repaired or rebuilt.

I guess the 1st question to ask yourself is 'should I repair/rebuilt the tranny myself or what'? Repairing /rebuilding a Miata tranny isn't an impossible task. Your transmission is not some mysterious contraption. Actually its operation is pretty straight-forward and disassembly, while physically hard isn't that bad. The job is hard as opposed to difficult, and there are some things you should consider before you decide to tear into the job.

1. Degree of TECHNICAL difficulty. I'd guess that repairing/rebuilding a Miata tranny is a 7.5 or 8.5 out of 10 on the technical difficulty scale (maybe some would say a 10 out of 10). In my opinion it's a few good steps up beyond clutch replacement (at maybe 6.5) and timing belt/water pump replacement at maybe 5.0. So while it isn't the most difficult job you should be an accomplished shade tree mechanic. I think if you've done a clutch job, brake job, timing belt/water pump job, you can probably handle this job. If you haven't you might want to ummm… skip this job for now.

2. Degree of PHYSICAL difficulty. Make no mistake about it, your Miata's tranny is bound together with some pretty incredible forces. If you thought pulling the tranny and putting it back in was tough, assuming you did a clutch job, well I have news for you, it's physically tough to get the thing apart and back together. Splitting the cases, pulling bearings, unloosening a few BIG fasteners are all major heavy duty stuff. You will have to direct enormous forces deftly to tear the tranny apart. Fortunately putting it together isn't too bad, just near the end of the job when you have to mate the major pieces do you have to wield some major whoop-a$$.

3. Time. Repairing/rebuilding your tranny is going to take lots of time. You should expect to make several runs to parts dealers before the job is complete and that takes time. Why?

Well for one, you probably won't know what's wrong entirely until you get the thing apart. Two, if you use new components, like bearings, there are clearances that change. The clearances need to be brought back into spec by specially sized thrust washers, or spacers. So as you assemble, you'll measure and then have to run to the dealer to get the correct sized component, unless you are incredibly lucky and all the clearances match up.

Mazda dealers that do this job are certainly set up with a big parts inventory. The mechanic doing the job only has to walk to the parts counter a few times, you'll have to haul out, part in hand to get a replacement. My local Mazda dealer does not do tranny repairs/rebuilds, so I had to have my parts ordered. Unless you are extremely lucky you can count on your Miata being down for 2-3 weeks. I did my job in the winter over several slow, painful months!

4. Cost. If you're doing this job it's probably for 1 or 2 reasons. One, you hope to save big $ over having a shop do it, or Two, you're a tinkerer who loves the challenge of fixing something and are just interested in how it all works. Even doing the work yourself, you'll find that any parts required can get expensive. Bearings, thrust washers, snap rings, circlips, etc. aren't too bad, but things like synchros or gears can add up to hundreds of dollars. And if there's something really amiss like a damaged countershaft, then the cost gets horrendous. I'll give you some hints on parts later on, just be aware that parts can get expensive.

Also be aware that you'll probably have to buy some tools too, which is the next item I'd like to address.

5. Tools. You're going to need some specialized tools to tear into the tranny. Some you can buy, borrow, or maybe rent. Some you will need to FABRICATE. This is not a 'set of wrenches and sockets' job. I'll provide a list of tools later in this 'article' but for now understand you're going to have to rent, or borrow, or buy,- AND fabricate some tools.

6. Workplace/work bench. You're going to need a place to do this job, a garage, a shed, some work area. This is not a job where you can plunk a tranny down on the ground and work away at it like you can some other jobs. You should have a good, spacious workbench in a clean, well lit environment. Think about it, many other jobs don't need this kind of space or work area. Heck for the most part your Miata IS the workplace. You pull junk off and put replacement stuff on.

7. Help/advice. This is one repair/rebuild area that many people don't have expertise in. Even our own forum has just a few people that have been through the job. That's not to say your dealer and people on the net won't try to help, it's just that most can't help. Even my local Mazda dealer does not do tranny repairs/rebuilds. They find that Miata trannys are pretty indestructible, so any work they do is warranty work and for that they swap brand new trannys into customer cars to nearly eliminate any possible complaint about work not addressing the problem or not being done right. So even your dealer may not be able to help you out if you have questions.

What are your options? Well, assuming you are convinced that you have a tranny problem and perhaps other people (like your dealer) have confirmed the tranny needs work, you have options:

1. Have the dealer or a shop repair it. Duh. Yes, it's expensive but you'll probably get some kind of basic warranty even if is only for a few months and a few thousand miles. Plus you'll save the down time and the need to purchase tools that you might only use once. Or maybe you can cut a deal with your dealer or shop and do some of the work yourself. Ask how much you could save by pulling the tranny, delivering it to the dealer so they can repair it, and reinstalling it yourself. Maybe you can save a hundred dollars or so.

2. Get a tranny from a salvage yard. If your tranny is 'bad' or needs repair you can probably get a low mileage tranny from a salvage yard pronto. I came across a posting that someone got a used tranny for $250. I've heard that even salvage yard trannys come with a basic warranty like 3 months or 3,000 miles. You can easily spend that in tools and a few replacement parts. Plus pulling the old tranny and putting one in is going to be a whole lot easier than tearing your old one apart. And also, (I think) any year Miata tranny fits any year Miata. So I'd tend to recommend this route, unless you really want to tear into the tranny!

3. Bite the bullet and repair it yourself. (For the adventurous and determined!)

4. Sell the car at a fair price to someone, letting them know the tranny needs work, and buy a new Miata! OK maybe not, but we can dream can't we?

Required Tools:

OK, let's assume you're still considering this job. You'll need the usual assortment of sockets, ratchets, breaker bar(s), torque wrench, pliers, screwdrivers, etc. Let's look at the other required tools and what they'll be used for.

· Shop manual - I used Rod's Miata Enthusiasts Manual. Get a repair manual, read it ahead of time, follow it closely, but not blindly. Although there aren't THAT many parts, there are some incredibly small ones, plus shims, and thrust washers, etc. and mixing one up or losing one can render your tranny completely useless. · Workbench - Like I said above you'll need a big, clean, well lit work area and workbench. · Vise with jaw protectors (must have tool) - You're going to need a 3-4" minimum vice. Rod's manual assumes you have one mounted on your work bench. I didn't, but was able to use it anyway and finagle my way through the job. · Bearing puller - You'll need a fairly large bearing puller, something with in the 3-6" range. · Hub puller - Strictly speaking you don't need this, but if you don't, you'll have to fabricate something in its place. (See tools to fabricate below). · Snap ring pliers (a "must have" tool. Don't consider doing the job without this tool) - Snap ring pliers work on snap rings (duh). These are different from circlips as a snap ring is like a flat washer with a cut in it, but it's made of tough spring steel. · Circlip pliers (highly recommended) - There's a circlip or two you have to take off so have circlip pliers that can expand. Use a circlip plier and chances are any circlip will come right off with no trouble. Use a screwdriver to push or wedge it off and chances are it will fling off into oblivion, traveling into the furthest reaches of your garage, into the most inaccessible area, never ever to be seen again. Circlips that fling off like this are lost to this world and wind up in a parallel universe. So they guy (or gal) on the 'other' side winds ups with an extra circlip while you wind up cussing! · Big hammer - Actually a regular 16 oz. claw hammer will work. · Drifts - Have a variety of drifts, small to large. (A drift is a round chisel). You'll definitely need a 4mm drift. This is another "must have" tool. It is used to drive roll pins out of shift forks and shift selector arms. · Blocks of wood - Sometimes you have to pound on things, or prop things up, or use wood in interesting and novel ways. Several short sections of 2x4 will work fine. · Feeler gauges (or depth gauge) - You'll need feeler gauges to measure down to just a few thousandths of an inch (and a straight edge too). · Eye protection - Some of the things you're going to be cranking on can fling free or chip off, etc. so have eye protection. (I was using a drift and chipped a piece of metal off whatever I was hammering and a piece shot out and stung me in the face. Thereafter I used eye protection.) · Bench grinder - Used to fabricate tools that I'll tell you about shortly. · Ability to fabricate tools - You can't buy this tool. You need to be creative.

Tools to Fabricate:

I had to fabricate the following tools. I've made up the 'names' because I don't know that they might be called, but I'll tell you what they're used for.

1. Thin chisel and pry. There are two large bolts, one on the countershaft and one on the main shaft that have flanges on them. The shafts have cutouts in them like key slots. The bolts are torqued and the bolt flanges are punched down into the key slots as a means of locking the bolts. To free the bolts you need to pry up the flange from out of the key slot. My repair manual said to use screwdrivers. I did. I bent one small screwdriver. I broke two larger ones (and good ones too!). Then I decided to fabricate tools for this job.

I purchased a thin chisel then set about grinding it to fit into the key slot. I guess I went from 1/4" to about 4mm (I couldn't find an 1/8" chisel). This allowed me to point the chisel into the key slot and hammer away, pushing the deformed bolt flange up and out of the key slot. I couldn't quite free the flange all the way so I took one of the broken screwdrivers and made a spoon shape out of it. The back end of the 'spoon' fit at the base of the key slot and acted as a leverage point and the upper edge pushed the flange metal up as I cranked down. Perhaps you'll have better luck than me with a screwdriver or finding a very narrow chisel.

2. Long reach bearing puller. Note: this is one tool you can purchase but it's a Mazda specific tool. I don't know the price, but it has to be expensive. One of the bearings you have to pull off to get to the gears and synchros on the main shaft is located about midpoint of the shaft, so you need to reach about 18" down the shaft to pull the bearing. Follow Rod's manual and purchase two 24" sections of 1 1/2" angle iron. You disassemble your bearing puller and use the lengths of angle iron to extend the reach of the puller. You'll need some nuts, bolts, and washers too but look at the manual and it will be clear what you'll need.

3. Tranny 'case' splitter. The front of the tranny is also the bell housing. The input shaft pokes through into the bell housing area, through the front snout of the tranny on which the throw out bearing rides. After you remove the snout and remove a snap ring, you have to push the input shaft (and entire gear train) out the back of the bell housing. Rod's manual recommended a hub puller, but I couldn't locate the correct style, so I decided to build something instead.

I used a piece of 2x4 (on edge) and three 1/2" diameter bolts. The 2x4 spanned the bell housing and was bolted there with 4" long, 1/2" diameter bolts/washers/nuts. You span the bell housing, attaching it at two edges so that the input shaft is in line with the two bolt holes. In other words, if you drew a line between two tranny mounting holes, the input shaft is in line and in between them.

The 3rd bolt is also 1/2" in diameter, threaded it's entire length, and was about 6" long with nut and washer. You drill three holes 1/2", in line, matching up them up with the bolt holes and input shaft. I used my bench grinder to put a blunt point on the 6" bolt so it would meet up with the input shaft's concave bevel. You feed the 6" bolt through it's hole and follow it with a washer and nut, leaving very little of the bolt protruding. Next you attach the 2x4 to the tranny bell housing with the 4" bolts, washers and nuts. The small protruding 'point' of the 6" bolt mates to the input shaft.

Now all you have to do is use a wrench to hold the nut on the 6" bolt to keep it from turning and then crank on the bolt's head. As the bolt is driven forward it pushes against the input shaft. I had to twist really hard and also tapped the bolt between twists, but it worked. Why do you stand the 2x4 on its edge? That's simple, the 1st time I did this I used the flat part of the 2x4 against the bell housing and the pressure of pushing against the input shaft broke the 2x4! Stand the 2x4 on edge and it will take more abuse. Mine creaked and groaned but eventually worked, pushing the input shaft out of the bell housing. Crude, but it works. Hints/Suggestions:

Following are some hints that I thought I'd pass along to anyone considering this job. I'm assuming that if you're reading this, you're still seriously considering doing this job.

1. You're going to have to get your car pretty high in the air and work underneath it, so remember, safety first. You're going to be wrenching, pulling, pushing, etc. so make sure your car is secure. (I use a primary holding device, like jack stands, but then always use a 'backup' device like wheels/rims under the car or big blocks of wood should any failure occur from the primary device). It doesn't happen much but every now and then a car falls off its stands.

2. Check on Miata.net for instructions on doing a clutch replacement job. Even though you're not replacing your clutch you have to do all the work you'd do for a clutch replacement other than actually replacing your clutch. So basically you pull your tranny, repair/rebuild it, (or slap a used unit in its place), then replace the tranny and button everything up you disassembled to get access to the tranny.

3. Try to avoid disassembling the main shaft anymore than you have to. If the synchros aren't worn or gears aren't chipped, etc., let it all in place. (you can check for worn synchros by measuring the clearance between the back of the synchro and the front of the pinion teeth). I think the factory spec is 0.059" and my 90,000 mile tranny had synchros within a few thousandths of the factory spec for being brand new. Consult the manual.

4. Once you have the unit disassembled down to the "naked transmission", take as many wear measurements as you can. The naked transmission consists of the input shaft connected to the main shaft, with counter shaft, with all shift forks and rods in place. Rod's manual has you tear EVERYTHING down, then start to put it together to do measurements. You might find that by temporarily skipping the complete tear down, you can go to the re-assembly where Rod's shows you the measurement steps. This may pin point a problem area. If not you'll probably have to tear the entire unit down.

5. If you are replacing the center carrier bearing, the bearing located in the very center section of the tranny, consider the following. The center carrier is a thin section only about 1 1/2" wide and holds the entire tranny 'guts'!. Anyway there's a bearing in there, along with one or more thickness shims. The manual indicates that you drift the old bearing out, then drift a new one in its place, and then measure to see how far, if any, the bearing sits above the flat aluminum face of the carrier. You are supposed to have between 0 - 0.004" clearance at most where the bearing sits "proud" (above the face of the carrier). The bearing's top edge MUST NOT sit DOWN into the carrier at all.

I did what the manual indicated and then had problems. When I replaced this bearing I thought to be really good I'd make my clearance 0.000" exactly, which I thought was "perfect". Not so. Upon final assembly when I put the tranny back together the gear train was not protruding through the bell housing far enough to get the snap ring on its groove. Guess how much? Yep, by the exact amount I removed the shims to get 0.000" clearance. My recommendation; and this is strictly MY OPINION, before you drift the old bearing out, measure it's clearance above the carrier face. Then when you put the new bearing in, make sure you have that same clearance.

6. Know how the parts are oriented. Some parts look like they are symmetric but they aren't. Be sure to note the orientation when you disassemble them. For example, the shift forks are NOT symmetric. They 'face' a certain way. Same thing with the 'clutch hubs'. Use an indelible marker on the part after you wipe the oil off of it and mark it accordingly. (don't ask me why I'm making this suggestion).

7. Keep 'like' parts together. Use plastic bags, sealed, and marked with indelible ink. Keep any gears, bearings, shims, etc that were on shafts tied together or on dowels oriented in the position that you took them off. This is very important. You cannot pull junk apart and throw things in a box, hoping that in 2, 3, 4 or 6 weeks from now you'll remember what parts go where. Some parts are in fact similar, but they are NOT interchangeable.

Warning Lecture Coming -> If you don't keep your parts straight and have to pay someone to finish the job I can pretty much assure you that a very unhappy technician will be giving you a piece of their mind. Plus you'll pay accordingly. This bears repeating. Keep sub-assemblies together in big, re-sealable plastic bags (or on wooden dowels) and mark the bag with an indelible pen where the parts came from. Special kudos and bonus points for putting a description of the parts on the bag along with where the parts came from. For example, one bag would have "3&4 Shift fork", "roll pin", and "3/4 shift rod circlip". There's no question 4 weeks from now, THAT bag has the shift fork for 3rd & 4th gear-set, along with its roll pin and circlip! If a subassembly has 8 bolts associated with it, put the eight bolts in a bag, indicate where the bolts are from and indicate that there are in fact EIGHT of them! Make sure you use an indelible ink pen. Some marker's marks will rub off the bag when it gets oily.

Mark everything. Even big parts that you wrap in newspaper and tape up. For example, there are 3 shift rods of differing length and construction. Did I mix them up? No, and neither should you. Sorry for the lecture, but trust me on this, you can mix things up, so bag 'em, tag 'em, mark 'em.

8. Make sure you have snap ring pliers and circlip pliers. If you don't have these tools and don't want to buy them (or can't borrow them), then don't even bother trying to do this job. You can spend lots of frustrating time trying to slide snap rings off with screwdrivers, or use the correct tool and be done in 5 seconds. Please don't ask me how I know this.

9. Get proprietary parts from Mazda but get your bearings from a bearing supply house.

I felt that some of my bearings needed replacement. I learned a lot about bearings. The biggest thing I found out is that unless your bearing(s) are absolutely shot to the point they visibly wobble, make crunching sounds, or have discernible flat spots, there's no way to easily measure wear. A bearing professional told me that sophisticated devices are used to measure bearing wear and often a bearing must be destroyed (taken apart) to measure its wear. Sorry for the segway. I took advice from the manual, the few people who replied to my pleas for help here on Miata.net, and a bearing professional, and replaced the three major bearings on the input/main shaft.

I was able to buy higher quality, EXACT replacements, at about 1/2 dealer's price by going to a bearing supply house. I bought my bearings for $20-25, whereas dealers and the Internet wanted $50-75 apiece. Some bearing houses will not sell retail to an individual, but my 2nd phone call to a store listed in a Business to Business directory, found someone within 15 miles of my home. I brought the suspected 'bad' bearings with me and the professionals at the bearing house matched higher quality replacements (German bearings) within minutes. If you are trying to buy bearings over the phone you need to supply the seller with the bearing maker (most of my bearings were Koyo) and the bearing number stamped on face of the bearing. Mazda parts numbers won't help a bearing supply house. My recommendation? Take bearing(s) in hand to the bearing house. As you can see my cost was less than 1/2 of what my local dealer wanted and my local dealer was going to have to special order them for me.

10. Assembling the roll pins. Roll pins are used to hold the shift forks and shift selector arms onto the shift shafts. (Say THAT 3 times quickly!). These must be tapped out with a 4mm drift. To reinstall try this. With the fork or selector arm on the workbench, tap the roll pin in, just getting it started. Note, you have to have the cut of the roll pin facing the front (or rear) of the tranny. Put the fork or selector arm on the shaft, line up the hole, and use big channel pliers to squeeze and 'press' the pin in. As it goes in a bit adjust the channel pliers and take another 'bite' on the roll pin. You can squeeze the roll in place without hammering away at it.

Road bumps/pot holes

This section reviews the problems/delays I experienced in pulling the tranny apart and putting it back together. If you can avoid thse problems/mistakes/screw ups, etc then I'm VERY confident that you'll get through the job a whole lot faster than I did.

1. Removing the 1st snap ring from the input shaft. One of the 1st disassembly steps is to remove the input shaft snout on which the throw out bearing rides. Note, there might be a thin bearing spacer in the back of the snout, about 3" in diameter, perhaps .004 or so thick, don't loose this! Once you remove the snout there's a snap ring to remove from the input shaft before you attempt to push the input shaft and gear train out the back of the tranny.

I tried using screwdrivers like Rod's manual said, plus pliers, plus all sorts of other probe/ catch/ grab things I have, but nothing worked. I supposed I could have just twisted or bent or broke the snap ring but that just didn't seem right. So after the better part of an hour I stopped and went on a tool hunt. At a local Pep Boys I bought good set of snap ring pliers and returned. In 5 seconds the dam* thing was off, ergo my suggestion that you get one. Plus there are several more snap rings to remove.

2. Pushing the input shaft / gear train out the back of the bell housing. This too was an early step. Rod's manual suggests you use a hub puller, along with the long bolts removed from the tranny's mid-section. I HAD a harmonic balance puller but it was flat. The input shaft is about 8" long but the bolts removed from the tranny's mid-section were only slightly longer. When I used the bolts with my puller I could only grab 1/2 or 1 thread of the bell housing casing. There's no way I could crank on those bolts without stripping them from the case. I tried also sort of things like using shorter bolts and sections of chain to the hub puller, etc. but nothing worked. I tried to find longer bolts but couldn't.

The style of hub puller needed is a cupped or humped puller, where the pulling flanges reach DOWN toward the hub by 1 or 2 inches. I did find this style of hub puller in the Internet, but rather than ordering and waiting, I fabricated the 2x4 instead. If you have a hub puller (or can rent or borrow one) you'll be hours ahead of where I was.

3. Separating the tranny mid-sections - There's a step early on where after you remove the 8 long through bolts holding the tranny together you have to 'split' the cases. You have to use a wood block and hammer on the case edges (without much grab) to separate the cases. This is not hard, just be aware that you really have to hammer away! Don't be shy.

4. Prying up the flanges on the countershaft and mainshaft bolts - This cost me a bunch of time. I wound up fabricating the tools I listed above. See if you can get a narrow chisel, or buy one and grind it down. Maybe your manly screwdrivers are better than mine. You'll save tons of time if you can pry those flanges up quickly.

5. Loosening the bolts on the countershaft and mainshaft - The countershaft bolt is 32 mm. You have to use your vise with jaw protectors to hold the gear in order to exert the appropriate leverage to free the bolt. I didn't have my vice mounted, nor did I have jaw protectors. So I had to fabricate jaw protectors and then position my vise, grabbing 5th gear, and then cranked away on the bolt.

The mainshaft bolt is down about halfway of the mainshaft and is 44mm, so you can't use a socket. Mazda has a special tool for this. I suppose you could buy or fabricate a tube wrench. The bolt is shielded by the synchro clutch hub so you can't get a big adjustable wrench on it. You have to use a drift and hammer it off. The manual calls for 125 lb/ft of torque to tighten so presumably there's 125 lb/ft of torque holding it on. Hammering away definitely takes time. There's no short cut here, but eventually you'll free this bolt.

6. Pulling the bearing from the mainshaft - As noted this bearing is about 1/2 down the shaft. I tried fabricating a puller with flat metal, instead of angle iron and it didn't work. I bought angle iron and it did, so get the angle iron, fabricate the tool and then get on with it!

7. Mating the center of the tranny to the bell housing - You are basically blindly putting the major pieces together. It's easy to mate up the input shaft into its bearing and the countershaft bearing into its carrier but there are two shift shafts that must also go into blind holes. Then you have to pound like he## on a block of wood and the tranny to get it to mate up. It just takes time and lots of hard, sweaty work.

Final recommendations:

There are two things that come to mind besides my opinions I've shared with you and they regard the final assembly and checkout of your tranny.

1. In one of the last steps in the assembly the tranny you're supposed to turn the bell housing upside down, in order to insert the gear train into. Not mentioned was the step that you need to temporarily install the input shaft 'snout' (someone told me it's called it a 'quill'). This sits in the front of the tranny and prevents the input shaft bearing from backing out of the bell housing as you lower the gear train into it and then have to pound away to push the input shaft (and gear train) into the bell housing.

Rods' manual made it seem like the input shaft slides pretty easily through the bell housing bearing and only taps with a plastic or rubber mallet are needed to mate the cases. For my '93 not so. I had to wail away with a block of 2x4 and my hammer to get it to mate up. This did not surprise me, since it took so much force to PUSH the input shaft BACK through the bell housing during DISASSEMBLY!

2. Once the tranny bell housing, mid-carrier, mid-section, and tail shaft are together (basically the tranny is assembled except for installing the input shaft snout), you need to test the tranny.

Make sure the tranny spins freely (not having the snout installed allows you grab the input shaft and easily give it a twist) So twist it. The tranny should spins freely in your hand. If it doesn't don't panic. Make sure the bell housing bearing is completely seated. Take a drift and drive the inner race of the bearing all the way home. At first my tranny seemed 'stuck' and difficult to turn. I gave the inner race a few taps all the way around its circumference and whoola! smooth turning tranny.

You'll need to temporarily install the shifter and go through the gears. Now since the tranny isn't doing any spinning don't expect perfect shifts, but you should be able to get through all gears.

The bad news? If the tranny won't turn or is binding badly, or just won't shift all gears then there's a probably a big problem requiring disassembly to find the culprit. If it happens, well once again you've got options, like going to a salvage yard or having someone else repair it, but don't be too hard on yourself, I've talked to a few professional Mazda mechanics and it happens to them too. Occasionally they'll fix a tranny, assemble it, find that something isn't right, then will have to go back in to fix the culprit! It happens.

Finally, the end!!

Well, that's pretty much it for my advice. You need to take your time, think, look, and mark your parts. Having done the job once I can honestly say it wasn't all that bad. If I had to do it again, I think I could disassembly the tranny in a few hours. I basically enjoyed the process (once I solved the 'puzzles') but then I had lots of time in which to do the job. There were some moments when I was talking to myself and some moments when I doubted the wisdom of deciding to do this job! I did this job because my tranny was starting to make some noise it hadn't made before AND I wanted to see the inside of my Miata's tranny. Trust me on this, your Miata's tranny is a thing of beauty. It's hard, industrial, kinetic art. I wouldn't have missed the opportunity of seeing the insides and working of that wonderful contraption we all take for granted, our Miata's manual transmission.

I hope this 'article' has been of assistance to you, either if you do the job OR after reading (and perhaps consulting the repair manual) have decided on an alternate route. Good luck and many happy Miata miles! Oh a few last things…

The tranny is now working perfectly, better than new. I spent about $135 in parts for bearings, oil seal, gasket, and thrust washer and my reverse gear set is NOT straight cut!

Back to the Garage

27 April, 2001