Crunching gears - Synchro Questions

**kraiye** · 05-08-2009 11:46 PM

Hi all,
My EM1 box has just started crunching when changing from 2nd to 3rd. It's fine when I double clutch or am shifting down from 4th.
Just wanted to know how hard is this to fix and what's involved? Do I have to pull the whole box apart?

**mr180sx** · 06-08-2009 10:50 AM

try changing gearbox fluid first

**I heart the SSS** · 06-08-2009 11:24 AM

As above, try a lightweight box oil

VMX80 works well in tired nissan/toyota Boxes.

You could also add a tube or two of Nulon G70 to your box with fresh fluid.

**90LAN** · 06-08-2009 03:54 PM

Originally Posted by I heart the SSS

As above, try a lightweight box oil

VMX80 works well in tired nissan/toyota Boxes.

You could also add a tube or two of Nulon G70 to your box with fresh fluid.

probraly diff weight justin
hondas rev a bit more so they need a bit more protection
check out my eg6 thread
i had to change my gears
shows you whats involved

**Benson** · 06-08-2009 04:05 PM

We used VMX80 in all our gearbox's, even for racing! Very good quality oil

Heaps better than OEM

**kraiye** · 06-08-2009 05:45 PM

thnx but no thnx guys.
box fluid was changed not long ago and i'm not after a temp fix.
maybe if it was a gradual thing i could stretch it out but it came on suddenly, like one day the box was flawless and the next day 3rd is fked on up-shifts.

**delsol9000rpms** · 06-08-2009 09:26 PM

*Change your gearbox oil (Castrol VMX80 is good.. its cheap too)
*bleed your clutch...

Expensive but propper fix would be to pull the gearbox out and apart and rebuild it...

**Benson** · 06-08-2009 09:38 PM

Go to Castrol Syntrax

Doesnt hurt trying! Can always reuse the fluid later on

**MRK20CRX** · 06-08-2009 10:13 PM

none of the suggestions will work, it will only be a band-aid fix, until it screws up again, my advice is rebuild the box

**kraiye** · 07-08-2009 09:19 AM

thanks everyone
i'll do the fluid for now anyway and see if that helps until i can rebuild the box

2 more questions:
any idea what parts would be required? or would that need to be worked out when the box is apart?
and is there anything i should upgrade while the box is out? (possibly looking to boost it in the future)

**fatboyz39** · 07-08-2009 12:29 PM

changing @ low rev or high revs?

Most likely worn synros. I would replace bearings and seals. Upgrade to a 4.7 or 4.9FD.

**Lukezen27** · 07-08-2009 07:39 PM

I've tried all the diff oils and even automatic oil

Nothing works that well but half OEM and automatic oil seems to be OK.

Only really crunches down from fourth to third but not to bad going up gears..

One thing though

At the Creek last week hit'n it hard not one crunch changing at high RPMs \

What's with that?