[Spridgets] Motor Oil in the Gear Box

[rrengineer @dslextreme.com]

Rivergate probably used the same after market synchros that Paul did on my
rebuilt transmission.  When I told him it would crunch going into 3rd gear,
he said the synchros had the wrong angle machined into them.  He sent me a
set of the best used Datsun synchros he could pick out.  He offered to
rebuild it with the used synchros, but I did not want to go through the
hassle of shipping it from Southern California back up to him.  I decided to
have a trans shop or some knowledgeable Spridget list member help me swap
them out.  Interesting though, I had Castrol synthetic GL-5 85w-90 oil in it
when it was crunching in 3rd (hot or cold).  I recently bought regular
Sta-Lube Hypoid GL-4 85W-90 gear oil and drained out all the old oil and
replaced it.  Now it crunches in 2nd sometimes!?!  WTF?  Now I am wondering
what Redline MT-90 will do to the shifting?  In any case I have to baby it
when shifting and cross my fingers when I downshift in ANY gear.  There is
some improvement when it warms up as you are experiencing Dean, but I don't
think that is good enough.  I am quite sure it never crunched in any gear
when it was in a Datsun 210 and only had regular GL-4 gear oil in it.  I
believe the synchros are yours and my problem.
Mike MacLean

On Sun, Mar 21, 2010 at 10:05 PM, Dean Hedin <dlh2001 at comcast.net> wrote:

> Interesting.  I was worried that I initialy put in 85w (I recently switched
> Mobil synthetic 75w)
>
> I have two issues with my 5-speed.
>
> The first issue is the tendency of the 1st to 2nd shift crunch.  This is
> worse when the tranny is cold and goes away as it warms up.
> I can avoid it when the tranny is cold by gently performing the shift,
> which I do religously now.
>
> Putting in the 75w made the situation a little better.  I would also say
> that over time this tendency to crunch appears to be on the
> decline.  Maybe as a result of the synchos breaking in?   All other gears
> shift wonderfully.
>
> The second item is that the tranny is a little noisy when idling and in
> neutral.   It's a clattering noise. kinda like the tank tread noise
> you hear in old WWII movies.  It's not very loud but it's louder than I
> expect.
>
> If  I depress the clutch the noise goes away.
>
> I should mention that this tranny was rebuilt by Rivergate when I bought
> the kit a little over a year ago.
>
> ----- Original Message ----- From: rrengineer @dslextreme.com
> Subject: Re: [Spridgets] Motor Oil in the Gear Box
>
>
> Dean,
>    I just happen to have a 1980 Datsun 210 service manual.  The type of
> gear oil required in the manual is API GL-4.  The viscosity according to the
> viscosity chart for temp range of 100 degrees F down to -20 and beyond is
> 80W-90.  If you are going to operate in temps above 100 degrees F straight
> 140 wt.
> Mike MacLean
> 60 Sprite
> 56 BN2