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is my gearbox going to self destruct casue i lost 5th?

Posted: Wed Jan 27, 2010 5:13 pm
by pongo
I was coming back from wagga on the weekend in plus 40 temp, loaded to the hilt with camping gear, trailer, boat,etc. and my 5th gear started to play up. Its a MQ patrol and i recently rebuilt the box myself.

The problem started up a hill under load about 100km/hr , it developed a ticking noise, so i quickly put it in 4th and the tick dissapeared. now, whenever the box gets put into 5th it ticks straight away as soon as the clutch half engages. Does not happen in any other gear.

Im about to drop the oil and remove the pto cover plate to have a look. I know one of the 5th gear shaft surfaces wasnt the best and had to be sorted out for the new bearing to spin freely. All bearings are new, it still shifts into 5th fine, every thing else works fine except for 5th.

5th runs off the back of the lay shaft as the 5th gear on these boxes was a modification to the original 4th.

Opinions? im supposed to be heading out west for a new job and would love to take my car as long as it will hold together as long as i keep it out of 5th. Much rather drive out with fuel supplied than fly. would be nice to stop and see lightning ridge,etc on the way home in a couple months.

Posted: Wed Jan 27, 2010 7:07 pm
by pongo
dropped the oil and doesnt look too bad at all. still nice and clean with no strange smells. has the usual fair bit of metal filings on the sump bolt magnet, but nothing id call excessive at all.

also does it but not as load when transfer is in neutral and the car is stationary

Posted: Thu Jan 28, 2010 6:58 am
by bazzle
As long as its clean I would trust driving in 4th all day.

Bazzle

Posted: Thu Jan 28, 2010 7:14 am
by nerida67
4 th gear in the 5 speed is the same ratio as 4th(top)on a 4 speed
so driving in 4th all day wont hurt
its not reccomended to LOAD up 5th gear when towing,thats why u got dramas,its an overdrive
seems to be a fairly common thing with these 5 speeds

Posted: Thu Jan 28, 2010 9:24 am
by oldmate
nerida67 wrote:4 th gear in the 5 speed is the same ratio as 4th(top)on a 4 speed
so driving in 4th all day wont hurt
its not reccomended to LOAD up 5th gear when towing,thats why u got dramas,its an overdrive
seems to be a fairly common thing with these 5 speeds
a fairly common NISSAN thing :)


and old toyotas

if 1st to third are fine you should be right.

Posted: Thu Jan 28, 2010 9:33 am
by flyology
I have had zip to do with these gearboxes, but it sounds like a bearing on fifth gear or fith gear itself may have a chip or slight bit of damage on it.......

Posted: Thu Jan 28, 2010 2:24 pm
by GQ Bear
My 5th gear went on my GQ a few years ago. Just cruising down the highway on way back from 4wd trip, couldn't put it into 5th without it crunching like hell.

If i double clutch it engages fine, so that's just what i do now. Been like that a few years now, no probs.