Trans Mount May Be Shot

Started by Dochka · Mar 24, 2009 · 30postsSMF 2010–26

DochkaMar 24, 2009, 8:34 pm · #1

A noob question,is it the B or C trans in my 87 s12,when i was shorthening the shift knob there wasn't a ball in the end of the knob but it was narrow so it's the B i guess?

SlothMar 24, 2009, 10:11 pm · #2

I thought any 87 would be a C, not sure though. Either way, there'll be a plate on your firewall, it'll look something like this (examples is an s14):
posted image

Anyway, there should be an identifier for your engine which is where the KA24(DE) is in the picture, and under that should be the transmission, if it ends with a C, it's a C tranny, if it ends with a B, it's a B tranny. Hope that helps.

sideways_s12Mar 24, 2009, 11:00 pm · #3

It's a c trans 86 is where they made the transitionI have 2 86's and both are c trans and I also have an 85 which had a b trans in it

DochkaMar 27, 2009, 7:51 pm · #4

sideways_s12It's a c trans 86 is where they made the transitionI have 2 86's and both are c trans and I also have an 85 which had a b trans in it

Now and after i saw the b and c trans pics i remember when i was shortening my shifter,when i removed the stuff i saw that there was a fork type and not the circular hole,so now i'm sure it's the b,but how come,on the cars papers it's a 87 model?!!

David BMar 27, 2009, 7:54 pm · #5

DochkaNow and after i saw the b and c trans pics i remember when i was shortening my shifter,when i removed the stuff i saw that there was a fork type and not the circular hole,so now i'm sure it's the b,but how come,on the cars papers it's a 87 model?!!

well maybe it has a different trans on it...

DochkaMar 27, 2009, 7:58 pm · #6

David Bwell maybe it has a different trans on it...

No,it's moost likely to b the b,but maybe it's the 86model,and the jackasses confused that and wrote 87 on the pinkslip

sideways_s12Mar 27, 2009, 8:07 pm · #7

your also in the ukraine so maybe it's different there all 87's here in the states have c-trans' unless it swapped by somebody and if they swapped to a b-trans then they need to give up the car lol

DochkaMar 27, 2009, 8:15 pm · #8

sideways_s12your also in the ukraine so maybe it's different there all 87's here in the states have c-trans' unless it swapped by somebody and if they swapped to a b-trans then they need to give up the car lol

Na the car was in Lebanon,but i'm planning for the next month,a mechanic,a friend of mine told me that he can swap a s110 trans with the dog teeth,and said it was better than this one,so what you think?

datzenmikeApr 23, 2009, 10:38 pm · #9

DochkaNo,it's moost likely to b the b,but maybe it's the 86model,and the jackasses confused that and wrote 87 on the pinkslip

The FS5W71C was installed on cars with build date Jan '86 (correction) and on, making them '87 models.

Loquat15Jun 12, 2009, 6:32 am · #10

Hey Guys!

So i got this s12 from a friend who welded the diff and cut the springs (and other stuff...) It sounds like the differential bearings are shot, the oil appears to be fairly clean... it really sounds like i'm hearing a little coast/drive noise from the ring and pinion. I work at a shop that has a rack and it's not too difficult for me to replace these bearings...

just wondering what you guys would do??? I don't want to spend a whole lot of money on this car... i'm thinking about replacing the diff bearrings and seeing what happens...

Another thing, has anyone had any issues with a welded diff busting up? I don't care about the chatter from the tires moving... i know it cant be too great on the cv shafts... but... yeah.. has anyone broken anything??????????????

Thanks!

Ben

rageJun 12, 2009, 6:33 am · #11

i havent broken anything on my welded r180 yet. i would just buy another diff and wait for taht one to blow up, haha

EternalSwapJun 13, 2009, 7:31 am · #12

backlash is probably fucked

silvia loveJun 13, 2009, 7:41 pm · #13

EternalSwapbacklash is probably fucked

yup...i guess some people forget heating metal will warp it if not done right.

my bet...ring gear got warped while welding.

other possibility, your trans is making the sound.

jack the rear of you car up and spin the tires. see if they spin freely completely around. if it gets hard to rotate at any point your ring gears probably messed. you wont be able to shim it back cause it most likely wobbles now.

you didnt try to cool it down right away after welding it did you?

iggy just broke his diff. axle snapped inside the diff. nothing major but is more money spent. cause and effect type of deal. u kinda have to pay to play. our parts are getting older and weaker everyday.

Phisherman09Jun 13, 2009, 11:33 pm · #14

id just turn the radio up .

if it makes a big enough noise to be heard over the radio, then you probably should replace it.

mines been whining for two years and has been through 10+ drift events and it still hasnt exploded. yet.

David BJun 14, 2009, 1:13 am · #15

yea i swapped a welded diff into a r200 on a s13 it started to whine.. but has been fine for 3 months

Loquat15Jun 23, 2009, 1:54 am · #16

EternalSwapbacklash is probably fucked

Backlash feels to be between 1/4" to 1/2"

I think that's a bit much... I know a typical domestic diff goes anywhere between what... .06-.16 of course depending on what dif it is and yadda yadda yadda or was that .006 and .016...

Loquat15Jun 23, 2009, 2:55 am · #17

Anyone know if the r200 uses a screw style shim or the good ole bunch o shims?

IggyEGuanaJun 23, 2009, 3:01 am · #18

lol wow thats some serious backlash

exessive backlash is usually pinion depth. Hows the pinion bearing?

the diff original to the car or swapped from another car? No two diffs or cases are truely the same.

I yanked mine, popped off the ring, welded the diff, put the ring back on and slapped it back together. Everything has been tits for bout 2 years. Broke and axle a lil bit ago. It sheared off at the edge of the spline in the diff. Swapped in a junkyard axle and everythings fine.

Loquat15Jun 23, 2009, 3:55 am · #19

IggyEGuanaexessive backlash is usually pinion depth. Hows the pinion bearing?

I've never taken any measurements from a diff that had known excessive backlash. Whenever dealing with backlash it's always a fight between moving the carrier over a hair and hoping that pinion depth was just right.

I'm not sure how the pinion bearing is... i'll bust out the stethoscope as soon as i get my car back up on the rack (too frequent) All i know is... there is LOTS of noise... blah... I figure i may as well get a new(used) differential due to bearing price.

IggyEGuanaJun 23, 2009, 4:17 am · #20

I said that wrong but anywho did you take a contact pattern? You can use the fancy blue transfer paint/goo or you can just use grease it works.

Loquat15Jun 23, 2009, 5:23 am · #21

IggyEGuanaI said that wrong but anywho did you take a contact pattern? You can use the fancy blue transfer paint/goo or you can just use grease it works.

Well, it could be pinion depth :-) that's the best way to say it... i mean, it would make sense afterall. I'm pretty damn sure that enough material has worn away on the pinion and ring gear that it might be too far away now... that or the bearings are too shot... ugh, gotta pull that thing apart...

I'll put some good ole yellow grease on there and run a pattern. I've got plenty of it :-)

EightySix200SXJun 25, 2009, 5:32 am · #22

datzenmikeThe FS5W71C was installed on cars with build date May '86 and on, making them '87 models.

wrong. august is the cutoff year 08/86 makes it an 87.

86s12sr20detJun 25, 2009, 7:53 am · #23

thats funny cuz i got a 3/86 and its the c trans never looked at the engine code but looked at the diff picks and its deff the c trans

86s12sr20detJun 25, 2009, 8:17 am · #24

so does the trans mount go out like motor mounts do? its an 86 ca20 with the c trans, starting off from a dead stop the trans makes this horible clanging sound, almost like its jumping back and fourth i know the trans isnt shot it shifts perfect, what could the noise be,any ideas?

NY200sxJun 25, 2009, 8:51 am · #25

whats better? b or c? i have an 85 turbo i think its a b.. iono lol

EightySix200SXJun 25, 2009, 2:02 pm · #26

NY200sxwhats better? b or c? i have an 85 turbo i think its a b.. iono lol

internaly trans are the same.

b trans= external shift linkage
-(have to cut or use 720 pickup or s130 shiter from 280zx)
-uses 19 tooth speedo pinion
-weaker *i hear*

c trans= internal shift linkage
-(cool shifter options can use b&m and ebay s13 shifters)
-uses 21 tooth speedo pinion
-stonger supposedly

MK1.5 BREAKDOWN..... AS A OWNER OF 2 MK1.5 CARS HERE'S SOME INFO

ive seen mark1.5 cars with mark1 and mark 2 interior guts and components..

my auto mk1.5 has the chassis of a mark 2 i.e tranny crossmember and shifter like the later cars but retains a full mark 1 interior and exterior. its also a silvertop ca20 not black my production date is 02/86 which would be a mid year model change all the way until 08/86. my car uses ECCS like an 87 ca20 or ca18et of any year. its wired like a mark 2. no vacum advance ignition and such.

ive seen mark1.5s with full mark 2 attributes also. it all depend on what nissan had left to put in the cars. the later mark1.5s have more mk2 interior and chassis attributes than an earlier mk1.5... i.e earlier mk1.5's have alot of mk1 shit cuz nissan had to use that shit up. ive seen mark 2 interiored cars with blacktop ca20es and vacum advanced ignition. its weird nissan used a vast array of leftover items from previous years

like WAYLON said though body panels were not mixmatched. it would be cool to have mk2 tails on a mk1 car though from factory. but thats asking for too much! u wont find a mk2 with solid axle here in teh u.s but jdm mk.2 base models had solid axle on some of there cars mostly on their ca18s powered cars

Drft-s12Jun 25, 2009, 8:21 pm · #27

Yeah i had the same problem my trans mount was gone...i just picked up a Nismo one for a 240sx cause it was the same damn price as a stock one lol

If not check your carrier bearing.....

rageJun 25, 2009, 9:17 pm · #28

yea prolly is the trans mount. for a cheap, easy fix, you can use windo weld polyurethane adhesive

datzenmikeJun 29, 2009, 1:06 am · #29

EightySix200SXwrong. august is the cutoff year 08/86 makes it an 87.

Yes, sorry. This means that from about '86.5 on would have the C type trans.

EightySix200SXinternaly trans are the same.

b trans= external shift linkage
-(have to cut or use 720 pickup or s130 shiter from 280zx)
-uses 19 tooth speedo pinion
-weaker *i hear*

c trans= internal shift linkage
-(cool shifter options can use b&m and ebay s13 shifters)
-uses 21 tooth speedo pinion
-stonger supposedly

Internally they are SIMILAR, but not the same. The C type have a much improved shifter mechanism internally. The shift forks are massive compared to the tiny thin B type. Counter bearings in the B type are only 56mm diameter, the C type are up-graded to 62mm for strength. Also the oiling for these bearings are improved due to internal passages in the cover plate and an 'oil thrower' just behind the front counter bearing. All C type gears are wider than the B type though they are the same diameter. C type synchro rings are improved and the C type 1st/2nd shift rod is 16mm diameter compared to the Bs 14mm.

The pinion teeth number only reflects the rear gear ratio that it's mated to. However the 10mm bolt that secures the pinion drive cog is at the 12 o'clock position on the B type and at 6 o'clock on the C type. B and C type pinion drives cannot be swapped.

B and C trannys are mostly identified by what shifter is on them and when they were introduced in mid '86. Some FS5W71B types made from about '84 contain some of the internal modifications such as gear width, shift rod size and larger counter bearing but are still a 'B' type. FS5W71B are 31.5" long and there is a 26.3" model as well. FS5W71C type are at least 33.5". The 'B' type was used on at least 5 different series of Nissan motors.

RedneckJun 29, 2009, 4:01 am · #30

Wow informative post about the B and C tranny differences Mike. Good info for reference.