NA Trans Failure- common?
12-03-02, 10:51 AM
#26
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I just finished doing this!
Big thanks to Mazdaspeed 7 for his advice!
The FB into FC is easier than you might imagine, once it's out and on the bench. The tranny is made up of three major sections: bellhousing, maincase (containing all the gears), and extension housing off the rear with the shifter turret. The FB and FC trannies share most details, like bellhousing bolt pattern, overall length, 5th & neutral switch locations, etc.; and differ in details like rear crossmember mount, shifter location, vents in bellhousing. Here is an (ahem) 'abbreviated' description of what you want to do:
Use the FB maincase, with the FC extension housing, incl. tranny mount, and shifter. The FC control rod will fit the shifter fork rods without problem. Note when separating the extension housing - remove the speedo gear, 5th and neutral switches first, and don't reinstall them until the housing is back together.
The bellhousing you use is a matter of choice - my FB was from a 12A and did not have the vents that the 13B has, so I figured the increased heat and power of the 13B warranted the switch to the FC bellhousing. At any rate, you'll need to break all the sections apart anyway, because once you pull the extension housing, the forward seals will relax enough to start leaking / weeping (speaking from experience here). Note that special tools are required to separate the bellhousing from the maincase. You'll need to rent / borrow a 'FWD hub puller' (it's got a deep cup shape to it) and using a couple of the extension housing (long) bolts threaded into the front cover holes, pull and hammer on it until they separate. Note you will be pulling the mainshaft bearing off the input shaft when you do this, you have to remove the snap ring for it first (another tool you'll need - snap ring pliers). You can drive it back on with a hammer and block of wood. You'll need some replacement parts to reassemble as well - plan on replacing the front cover gasket and input shaft oil seal, the rear oil seal (tailshaft), new speedo gear O-ring, and you'll have to re-seal with RTV the case sections and shifter inspection plate. I forgot to change over the FC speedo drive gear, and so I had to use the FB gear housing. The shaft gear for FB is coarse tooth, and the FC is fine tooth. Anyway, the gear ratio of the speedo gears relates to rear end ratio and tire size - and in my case the FB and FC are within 2% of each other anyway.
I've only put about 50 miles on mine so far, and now it's in storage for the winter, so can't comment much on the differences. Certainly it revs faster - the gearing is shorter. My FB tranny ('84 12A) is equivalent to a 4.3 rear gear in first, 4.5 in second, 4.3 in third, 4th is still 1:1, and 5th is way shorter (.807 vs. .697). 5th is 3800 rpm @ 80 mph!
Good luck
Curtis
'86 gxl autox'r
Big thanks to Mazdaspeed 7 for his advice!
The FB into FC is easier than you might imagine, once it's out and on the bench. The tranny is made up of three major sections: bellhousing, maincase (containing all the gears), and extension housing off the rear with the shifter turret. The FB and FC trannies share most details, like bellhousing bolt pattern, overall length, 5th & neutral switch locations, etc.; and differ in details like rear crossmember mount, shifter location, vents in bellhousing. Here is an (ahem) 'abbreviated' description of what you want to do:
Use the FB maincase, with the FC extension housing, incl. tranny mount, and shifter. The FC control rod will fit the shifter fork rods without problem. Note when separating the extension housing - remove the speedo gear, 5th and neutral switches first, and don't reinstall them until the housing is back together.
The bellhousing you use is a matter of choice - my FB was from a 12A and did not have the vents that the 13B has, so I figured the increased heat and power of the 13B warranted the switch to the FC bellhousing. At any rate, you'll need to break all the sections apart anyway, because once you pull the extension housing, the forward seals will relax enough to start leaking / weeping (speaking from experience here). Note that special tools are required to separate the bellhousing from the maincase. You'll need to rent / borrow a 'FWD hub puller' (it's got a deep cup shape to it) and using a couple of the extension housing (long) bolts threaded into the front cover holes, pull and hammer on it until they separate. Note you will be pulling the mainshaft bearing off the input shaft when you do this, you have to remove the snap ring for it first (another tool you'll need - snap ring pliers). You can drive it back on with a hammer and block of wood. You'll need some replacement parts to reassemble as well - plan on replacing the front cover gasket and input shaft oil seal, the rear oil seal (tailshaft), new speedo gear O-ring, and you'll have to re-seal with RTV the case sections and shifter inspection plate. I forgot to change over the FC speedo drive gear, and so I had to use the FB gear housing. The shaft gear for FB is coarse tooth, and the FC is fine tooth. Anyway, the gear ratio of the speedo gears relates to rear end ratio and tire size - and in my case the FB and FC are within 2% of each other anyway.
I've only put about 50 miles on mine so far, and now it's in storage for the winter, so can't comment much on the differences. Certainly it revs faster - the gearing is shorter. My FB tranny ('84 12A) is equivalent to a 4.3 rear gear in first, 4.5 in second, 4.3 in third, 4th is still 1:1, and 5th is way shorter (.807 vs. .697). 5th is 3800 rpm @ 80 mph!
Good luck
Curtis
'86 gxl autox'r
12-03-02, 11:24 AM
#27
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Rebuilding is not that bad. The N/A does not have a dynamic damper (only the turbo).
What makes people think the cheap used trannies forsale are better than the ones in the car they have. Only driven to church by grandma?? Nahh....
Rebuild it and you know what you have.
What makes people think the cheap used trannies forsale are better than the ones in the car they have. Only driven to church by grandma?? Nahh....
Rebuild it and you know what you have.
12-03-02, 09:31 PM
#29
mad scientist
Calculated top speed is 175 mph at 8600 rpm. 5th gear is not a highway gear. Works good in the city, but I dont really going long distances at 4K rpm.
Gabe, if my cars running this weekend, Ill take you for a ride.
Gabe, if my cars running this weekend, Ill take you for a ride.
12-06-02, 08:31 PM
#30
I wish I was driving!
Thread Starter
Originally posted by Capn' Wankel
If your tranny was fine <snip>
BUT I had the same exact problem as you did and after replacing the pilot bearing I was golden.
Good luck and PM me if you want n e more details.
If your tranny was fine <snip>
BUT I had the same exact problem as you did and after replacing the pilot bearing I was golden.
Good luck and PM me if you want n e more details.
In neutral, transmissions out of the car, the input shaft will spin 720 degrees in either direction, and that's it. In gear or not makes no difference. Gonna open 'er up when exams are done and take pics for all to see the horror.
FB trans it is.
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