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SovXietday -> Transmission FAQ - READ BEFORE YOU POST! (12/17/2007 9:31:30 PM)
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Certainly time that I write one of these. Things that I'm going to cover in this thread are frequently asked questions and frequently seen problems in our beloved Honda transmissions, but before I do.
If you are considering boosting or highly modifying an engine that is connected to an automatic honda transmission I urge you not to bother. The transmission WILL go, it is not an if or may, it is a will. These transmission barely hold their own power, let alone more! I will not be covering anything more on these. They are a pain in the ass to work on, I hate them, and I will not buy them. Also, because I have no experience with it, I will not be covering auto to manual swaps. We already have good information for that anyway. Now, onto the good stuff.
1. How a transmission works
2. Best stock transmission.
3. Differentials
4. Common problems
5. Clutch/Flywheel
1. How a Transmission Works
[image]http://www.nsxflorida.com/BaschAcura/DSCN2377.JPG[/image]
A transmission although confusing at first look is very simple. Essentially there are two shafts that hold the gears. The mainshaft and the countershaft. The mainshaft is just that, the main shaft (furthest shaft in picture). It is the shaft that is driven directly by the engine. The countershaft is the 2nd part to each gear and it also makes sure that the differential spins in the correct direction (closer shaft in picture).
The driveline is pretty simple. When the engine is fired the crankshaft rotates around in a circle. In neutral gear no gears are engaged so the car will not move. When you step on the clutch the throwout bearing pushes on a diaphram on the pressure plate and pulls the clutch off of the flywheel. This allows you to shift. When you shift, you are pushing what's called a "shift fork" in the trans case. These are the large metal shafts next to the gear stacks. Say you put the car in first gear, the shift fork will push a "synchro sleeve" that has a "synchro" inside of it.
[image]http://www.transmission-rebuild-kits.co.uk/images/18.JPG[/image]
This is a synchro, you can see the teeth. The gears on the gearstacks have matching slots for these teeth, and when the sleeve is pushed it uses the synchro to initially slow down or speed up the gear and match before the sleeve moves into the teeth. Once the gear is engaged you let the clutch "out" which allows the clutch disk to grip the flywheel again, essentially connecting the crankshaft of the engine to the mainshaft in the transmission. The mainshaft turns in the forward direction, which pushes the countershaft 1st gear to rotate the opposite way. The final drive at the end of the countershaft spins the ring gear and thusly the differential in the same direction as the mainshaft. Your axles are in your differential, so they will rotate in the same direction and thus your tires. Basically, it's the long way of saying that you're going forward! Now, a little more info about the transmission itself.
Each "gear" is actually two gears, and a "gear ratio" is found by dividing the number of teeth on the countershaft gear by the number of teeth on the mainshaft gear. So say you have 20 teeth on the countershaft gear and 10 teeth on the mainshaft gear. Your gear ratio for this would be 2.000. The larger the ratio, the shorter the gear. Most transmissions have 5 gears, a final drive gear, and a reverse gear. The 5 gears are the gears your grandmother is familiar with. Each gear is longer than the other in consecutive order (1 short, 5 long). The Final drive is a small gear on the end of the countershaft that turns the very large ring gear that is bolted to the differential. This is easily seen in the picture, the ring gear is the large diameter gear positioned under and infront of the countershaft. The reverse gear (cannot be seen in the picture) is almost always a straight cut gear that when shifted is dropped between the mainshaft and countershaft causing an extra rotation.
That is essentially how a transmission works. It's a simple concept once you get familiar with it and they're fairly simple to work with.
2. Best Stock Transmissions for Your Car
Bseries:
JDM ITR - Overall shortest gearing and comes with a factory LSD (Limited Slip Differential).
USDM ITR - Similar to the JDM ITR only with small changes in gearing. Has factory LSD
B16A2 (YS1) - Same thing as the USDM ITR with a slightly longer final drive and no LSD.
USDM GSR - IMO the best daily driver transmission out there. Short enough to be fun, but long enough to not be at 4800RPMs at 80mph. This is a GREAT low RPM engine transmission, the YS1 transmissions are better for the rev happy engines.
Dseries:
JDM DOHC ZC - Only will fit in EF chassis and extremely hard to find. Also has LSD. This is basically the Dseries equivalent to the USDM GSR. Although the case cannot fit into hydro chassis, the 3, 4, and 5 gears can be put onto the hydro shafts *with modification to the 4th gear*. If you don't want to modify, you can use a 1.033 3rd gear from a CRX HF or 1.066 3rd from a VX.
D16ZC(SOHC)/D16Z6/D16Y8 - These are the shortest stock hydro transmissions. Pretty much an LS Bseries transmission. The Y8 is slightly better due to having steel shift forks, otherwise they're arguably the same transmission. Will bolt up to any engine but case will not work in an EF chassis.
D16A6 - Cable trans guys, the transmission from the 88-91 Si will be your easiest swap in.
Hseries/Fseries
VTEC Hseries transmissions - Best geared but really nothing to scream about either. Your best alternative is a H2B/F2B swap in which you get rid of the crappy Hseries transmission and use a Bseries transmission.
3. Differentials
Differentials are probably one of the best mods you can do to any car. However, they are not cheap and they are not easy to install. Essentially what an LSD (Limited Slip Differential) does is help put down equal power to both wheels. Open differentials are a path of least resistance differential, so if one tire loses traction most of the power your engine makes is going to go to that spinning tire. The LSD on the other hand will keep power to the non spinning wheel to try and get traction back.
There are quite a few different uses for differentials, but the most common two differentials are the Quaife LSD and the OBX LSD. These are helical LSDs that use spider gears, other less popular LSDs like the Kaaz LSD are clutch type which is pretty self explanatory. For FWD vehicles IMO helical is the best and they last longer. The Quaife is lifetime warranty and very expensive ($1000+). The OBX is no warranty and much less expensive (~$400-450). The Quaife drops right in, the OBX needs to be shimmed correctly and is overall a pain in the ass to install. However, I have beaten the crap out of my OBX and it has held wonderfully and many many people have had the same results.
4. Common Problems
Almost always I read this issue and it is true for just about ANY manual vehicle you will ever own. If you are hearing a dull grinding/sliding sound while in gear your mainshaft bearing is going (aka the ISB or Input Shaft Bearing). This bearing is located on the opposite end of the mainshaft and gets worn quickly because of the clutch pushing it in and out. This bearing also takes the brunt of the torque from your engine. When you replace this bearing it's best to just replace all of the bearings at once, and always use OEM Honda bearings. The install itself is not bad but if you've never pulled apart a transmission I'd suggest against doing it yourself unless you have someone who knows what they're doing to help.
Strange noise when you push the clutch in and let it out. Generally doesn't happen too much when the car is in gear. This is usually the throwout bearing. MUCH easier to replace than the mainshaft bearing. Fairly cheap too, you can do this with a friend in abou
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