Bad synchro

[Lawrence]

Hi guys, I am having a problem with my fourth gear (its a four speed box) on my gq. It refuses to go in without a lot of fuss. I find that if i give it a lot of revs before i change it will go in with minimal fuss. I am familiar in double clutching when downshifting, but how does one do so when upshifting?

[howsie]

My cruiser does this when cold I take it out of gear foot off clutch rev to 2200 a few times then pop it in.

Sounds to me like some thinner oil in the box might help will flow out of the syncros easier.

[tehekho]

Double clutch is same as when down shifting, although generally you don't need to blip the throttle to get the reve where you need them, just pop the clutch at the right time as the revs drop. Next option would be to not use the clutch at all if you want to be hard bad ass

[ISUZUROVER]

Sounds like switching to a fully synth oil would help. Not sure what the nissota boxes normally run??? I had a worn 2nd gear synchro in my landie 5 speed. I switched to castrol syntrans. It took about 6 months to bed in, but now the box shifts like it has a new synchro.

[thehanko]

for upshifts just do the same thing as mentioned and dont blip the throttle as your trying to get it to match to lower revs not higher revs.

[Lawrence]

Thanks for the replies, guys. I figured that it will only go in at a specific rev. Just havent perfected it. The change of oil seems like a good idea though, as the oil that was put in it last year was a gl1 oil, which was what was at our disposal at the time.

[howsie]

My 80 pops in at about 2100 but as for oil best I've found is Mobil agrifluid 424. Similar stuff that they use in tractors. Dads 75 had worn syncros when he brought it with 400000km on the clock put this stuff in and it drives like its got a brand new box.

[chunks]

Give it a few a few thousands kays with a straight 80 oil (VMX80, RX80, MP80 etc) and see how you go.

[jemmos]

iv used that castrol, vmx 80, and didnt do much. iv got a 4.2td gu patrol thats done 335000 dont no bout the gear box, and i reckon my sycros between 4th 5 th, and 1st, 2nd r on the way, can anyone recomend a oil for me, not a new gear box? thanks!!

[ISUZUROVER]

iv used that castrol, vmx 80, and didnt do much. iv got a 4.2td gu patrol thats done 335000 dont no bout the gear box, and i reckon my sycros between 4th 5 th, and 1st, 2nd r on the way, can anyone recomend a oil for me, not a new gear box? thanks!!

SYNTRANS

It costs a packet, but is a lot better than the other oils mentioned.

[hulsty]

Sounds like switching to a fully synth oil would help. Not sure what the nissota boxes normally run??? I had a worn 2nd gear synchro in my landie 5 speed. I switched to castrol syntrans. It took about 6 months to bed in, but now the box shifts like it has a new synchro.

Which grade do you use? The M or 75W/85 I am changing my cruiser gearbox oil this weekend from Castrol VMX-M to something else, either going back to VMX80 or?


http://www.castrol.com/liveassets/bp_in ... B13127.pdf

[ISUZUROVER]

Sounds like switching to a fully synth oil would help. Not sure what the nissota boxes normally run??? I had a worn 2nd gear synchro in my landie 5 speed. I switched to castrol syntrans. It took about 6 months to bed in, but now the box shifts like it has a new synchro.

Which grade do you use? The M or 75W/85 I am changing my cruiser gearbox oil this weekend from Castrol VMX-M to something else, either going back to VMX80 or?


http://www.castrol.com/liveassets/bp_in ... B13127.pdf

Pretty sure I use the 75W85 - but would need to check.

The syntrans M looks slightly heavier - so I guess it depends whether your OEM spec is a 75W85 or 80W90.

[hulsty]

Factroy spec is Manual transmission (model H55F): API GL-4 or GL-5, SAE 90, 4.9L

[howsie]

iv used that castrol, vmx 80, and didnt do much. iv got a 4.2td gu patrol thats done 335000 dont no bout the gear box, and i reckon my sycros between 4th 5 th, and 1st, 2nd r on the way, can anyone recomend a oil for me, not a new gear box? thanks!!

SYNTRANS

It costs a packet, but is a lot better than the other oils mentioned.

FYI Mobil agrifluid and syntrans are the same stuff basically vmx80 is what I'm currently using and is too thin to offer enough protection you need to use an additive with it. Syntrans and agrifluid are basically vmx80 with that additive already in it.

[ISUZUROVER]

iv used that castrol, vmx 80, and didnt do much. iv got a 4.2td gu patrol thats done 335000 dont no bout the gear box, and i reckon my sycros between 4th 5 th, and 1st, 2nd r on the way, can anyone recomend a oil for me, not a new gear box? thanks!!

SYNTRANS

It costs a packet, but is a lot better than the other oils mentioned.

FYI Mobil agrifluid and syntrans are the same stuff basically vmx80 is what I'm currently using and is too thin to offer enough protection you need to use an additive with it. Syntrans and agrifluid are basically vmx80 with that additive already in it.

ROFL - you must be smoking some good stuff.

Syntrans is fully synthetic. Mobil agrifluid is not - neither is VMX80.

"too thin to offer enough protection" - lol - don't know where to start responding to that.

Additives are not needed if you use a quality oil of the right viscosity rating for the application.

[hulsty]

its not cheap $35 Per L for the 75W/80 Syntrans

[ISUZUROVER]

its not cheap $35 Per L for the 75W/80 Syntrans

No - certainly not cheap. However IME you can extend the change intervals as long as there is no water contamination. I last changed my gearbox oil 12 months and over 35000km ago. I have done the canning, gibb river, nullarbor plain, etc, etc, and the oil still lookd and smells like new.

There are other comparable synth oils which may be cheaper - e.g. Redline.