So I'm going through my 56 series U/C 4 speed and while checking my spare parts I noticed two styles of brass syncros; one has 12 teeth ( 3 groups of 4 set every 90 degrees) the other syncros are from my mid-close 4 speed parts and they have teeth all the way around.

So why the difference and what if any advantages are there to each style?

Tom

56-series 4-speed has teeth all around (H10)
60L has 12 teeth (3 groups of 4 set every 90 degrees) (H90)


H90 superseded H10 at some point, so they are also used in 56-series 4-speed gearboxes

60A uses yet another type

This is a synchro that came with the rebuild kit for my FS5W60A. As you assemble all the gears should you use any gear oil or grease? I planned to pack the roller bearings with lithium grease during assembly.

Attach file:

---

  60A.synchro.jpg (62.91 KB)

Lithium grease is OK, but it will be flushed out by the 90W. So using gear oil is fine for assembly. The lithium grease is easier to assemble as it won't drip while you're working with the parts

Yes, the H97 (60A) synchros and some H10 synchros are both all-teeth. Not sure how to ID the differences

Also the H10 synchros are either all-round teeth or 6-tooth type. Nissan says H90 replaced H10, but synchro manufacturers say they are different thickness and O.D. so maybe Nissan means they have to be used with updated synchro hubs?

DD as you are the oracle can you tell me what I have - a box labelled 32604-H7300 which contains 4 synchro rings which appear to be same dimensions as the synchros in my 60A box, but these have only 6 teeth, 3 set of 2 teeth.

And BTW, 360 degrees divided by 3 is 120 degrees, so all these synchros have their teeth every 120 degrees.

Good catch

H73 is the Applied Model Code for B210 of some kind (H50 is base 1973 B210). It probably applies to the 56A gearbox, as the 60 gearbox debuted with H74

If that is a Nissan genuine box, can you post a photo of the ring with the box?

CORRECTION: "H90 superseded H10 at some point, so they are also used in 56-series 4-speed gearboxes"

Per Nissan Parts, H90 "replaced" H10 (see this message for example at http://www.nissanpartsdeal.com/parts/ ... ng-baulk~32604-h1000.html)

HOWEVER, all dimensions are different. May be close enough to work?
. . . . . . . . . H1000 H9000
. . . . Thickness   7.8  9 mm
 Outside Diameter  69.6  68
cone part min dia    51  51.6
cone part max dia    53  53.6

Datsun factory catalogs show 3 styles for 56-series 4-speeds -- but none are 12-tooth
* 32604-18000
* 32604-H1000 (0.2 mm thicker than 180)
* 6-tooth 32604-H7300 (same dimensions as H10)

Attach file:

---

  H10.jpg (10.35 KB)

@denuto Oi me math ez #OOPS#e...........or is it my Geo-met-ree

Dave the 12 point ones came out, namely 2nd and 3rd only had a gap of .030 and those two gears were slow shift (read I had to pause on the upshift to 3rd and downshift to 2nd had to be very deliberate). I replaced them with new/newish 12 point type that had a gap of .040-.043, when I tried some of the 360 type on the ultra close gears (including the good ones from the mid close 4 speed) those had a gap of .025 despite the gaps being in spec on the mid close gears.

Tom

Quote:

Does this mean that all three part numbers are interchangeable?

Quote:Partially
* the Datsun factory parts catalog for the B10 says the first two are interchangeable
* The B210 JDM catalog says H73 is only backward compatible with H10

Attach file:

---

  32604_B210.jpg (26.28 KB)