Synchro conversion

[Alan Stanyon]

Ok i think i have worked it out the upper case is the same apart from some "relieving" (thanks Bill) the shafts are the same dimensions it's the position of the selectors on the shaft that makes them different would i be right? that would alter the "gate" on the selector plates which makes them different  i know the crown wheel is hobbed at a reduced angle to save on side thrust maybe? am i on the right lines To: 2cylinderhondas@yahoogroups.com From: dontranspac@...
Date: Mon, 17 Mar 2014 20:13:15 -0700 Subject: Re: [2cylinderhondas] Re: Synchro conversion
Interesting, the parts book only shows one set of cases for both types. Unless, my late book might only list a later common lower case. Should have checked to see how close the Honda codes are. (Honda codes are not entirely useless.) Sent from my iPhone

On Mar 17, 2014, at 7:51 PM, "Bill" wrote:
Don;
I
have made the change over to full synchro trans in a number of constant transmission Honda 600 using the early case.  The lower case is almost the same, but in order to have the full synchro counter shaft to fit, the center fin (rear section) must be cut.  Or the shaft will not fit.
Bill
From:
2cylinderhondas@yahoogroups.com
[
mailto:2cylinderhondas@yahoogroups.com
]
On Behalf Of
Don B
Laughton
Sent:
Monday, March 17, 2014 1:36 PM
To:
2cylinderhondas@yahoogroups.com
Subject:
Re: [2cylinderhondas] Re:
Synchro conversion
Good
news, almost, The upper and lower crankcases are the same for synchro and non synchro.  If you have the synchro main and counter shafts, final drive gear assy, shift forks and plates, you should be good to go.  Do you have the parts book?  It should answer any other questions.
Best wishes,
Don
On Monday, March 17, 2014 2:23 AM, Alan
Stanyon wrote:
Thanks Miles perhaps the two i owned previously i thought were synchro boxes (it was 35 years ago) one i drove and the other came to me in wooden apple boxes, UK cars were different we have the heater drawing air through the cylinders to heat the interior for instance thanks for the input.
Regards Alan
To:
2cylinderhondas@yahoogroups.com
From:
z600miles@...
Date: Sun, 16 Mar 2014 20:51:52 -0700
Subject:
[2cylinderhondas] Re: Synchro conversion
Back in 1985 I drove a Honda Z600 from Fehmarn
Germany to Hamburg on the Autobahn.
Then from Hamburg to the top of England. That
coupe was purchased in England by my
friend Martin and it did not have synchromesh.
Miles

[Bill]

The shafts are the same length, yes.  However the dimensions are different in that the lash configuration is different on the full synchro trans from the Constant.
The bearing keepers are the same but there is much more wear on the large bearing keeper where the oil pump rod thrust bearing rides against it.  If you are using used transmission internals then remove the large bearing keeper from the reverse gear side and use it on the oil pump side.  The thrust washers are the same on both transmissions which is good if there is some lash issues.  They are all brass so sanding them down to remove grooves is easy and if you need to add one to make things tight, sanding them smaller to make them fit is easy to do.  See chapter 6 in the Coupe supplement shop manual for more information on how tight they are supposed to be.
Bill