200SX / S12 FS5w71b

[Matthew Abate]

I've found tons of info about adapting a FS5w71c into a 240z, but I can't find anything about using the 200SX / S12 version of the FS5w71b 5-speed in an S30 other than a little comment on this page:

'83-10/'84 200sx w/CA20 and the truck # 3 use same ratios. This is often touted as the best gearsets for a 4-cylinder 510. Very low 1st gear for fast starting acceleration and smooth progression of jumps between ratios. For use with an L-series, a 280Z/ZX style bellhousing must be swapped onto the CA20 tranny case and bellhousing modified to match with larger diameter CA20 shifter rods, and use smaller OD 280zx jackshaft bearing.

I'm interested in this transmission because of the ratios (3.592, 2.057, 1.361, 1.000, and 0.813) being so similar to the FS4w71b ratios that came with the car, and that 5th gear having longer legs for highway driving. It really seems like the optimal ratio spread.

My question really is, presuming I were able to get my hands on one, how hard is it to do the work described above. I can't seem to find an example of anyone having done it.

[Matthew Abate]

Someone on Hybridz.org pointed me to this: http://www.atlanticz.ca/zclub/techtips/240sxtransmissioninstall/

Not sure how much of that is applicable, since we're talking about the B transmission. I already see a couple of details on that link that might be wrong (i.e. Didn't the C transmission start coming with the 200x in '84?)

I'm pretty sure I could find a bell housing from a Z to bolt on, and the jackshaft bearing from a ZX is straight forward. The thing giving me pause is modifying the bell housing to accommodate the CA20 shifter rods. Would it not be better to use shifter rods off a Z/ZX? Is that even possible? This is foreign territory for me.

 

Another open question is whether or not this transmission is strong enough to work with a ZX engine. I've read the 200x B is weak (not sure why). The ratios might be right for me, but is this as good as or better than a ZX transmission as far as reliability goes?

 

I'd love to find a bolt in solution that down't need any modification, and the '83-84 ratios seem ideal, but the T5 sounds like it could be an even better option because the ratios aren't that far off, parts availability is better, and it might be stronger, but getting that into the car sounds like way more work than getting the 200sx B transmission in.

Edited February 23, 2016 by Matthew Abate

[Zed Head]

I agree with EuroDat from your other post (too many posts spread around on the same subject!) that unless you get the right "71C' tranmssion, there's not much benefit to the work.  The guys that did this swap originally did it for wider stronger gears, more better synchros (reverse synchro for example and a double cone 2nd and 3rd), and the stronger bearing.  Plus, apparently, the shifting mechanism is better.  Along with just general newerness and maybe some small fixes that come with most redesigns.

I mentioned in one of your other threads that I did this with a 1985 300ZX transmission.  But I got the transmission for $20 from a young guy on Craigslist whose mother told him it had to go (he listed it for $100, but when I paused on the phone he dropped to $20 - it had to go now!  I almost felt bad.).  And the bellhousing for $50 (blown up mystery ZX 5 speed).  So now I have a part that can be swapped to a 1994 240SX unit, but the 85 300ZX trans itself just offers the new shifting mechanism.  Gear widths are the same, I swapped the bearing, not much true benefit, except a good condition $70 transmission.  Plus it was a good reason to buy a drill press. 

The hole for the shift rod only needs slight enlargement.  Almost like a reaming operation.  The right tool will self-center itself, it's almost impossible to mess up.  

Get on to the Nismo site and find the car your transmission came from.  The MT chapter will have an exploded diagram showing the synchros, and will have the gear ratios (to be sure).

[Matthew Abate]

Thanks! This is super valuable info.

i don't actually own it yet, and it's two states away, so I can't tear it open. The guy who has it can't tell me which car it is, and it hasn't been rebuilt or anything. I have a feeling that I might be able to get it for under $100, which is why I'm interested. No idea what a bell housing will cost me, so I'm trying to evaluate the merits of the project.

To your other point, I started this thread before I found the active one. I'll switch to the other one.

Edited February 23, 2016 by Matthew Abate

[Zed Head]

I said Nismo, but I meant nicoclub.  And they only have 1986 on their site.  It shows not much different from a 280Z trans, except the gear ratios.  Still uses the old shifter style too so it might not even need the shift rod hole drilled.  Who knows, it might not need any work done, just a straight front case swap.

http://www.nicoclub.com/FSM/200sx/1986/1986-s12_manual.pdf

The truck transmissions have a shorter tail shaft and rear case, apparently, which might be another fly in the ointment (has anyone ever actually had a fly in their ointment?).  Although some say it actually gives a final unit that's the same length as a 71B.

If it were me, I might get it just to know some more stuff and have a project.  It might be a straight bolt-off, bolt-on swap.  There are so few of those cars around though that the 200SX info might be of little general use (probably why you can't find much on it).  In the long run though, this swap will probably get more and more popular as the Z car transmissions fall apart.  If the drifters don't blow up all of the 240SX's.