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What is wrong with my gearbox? 90 Sierra 5spd

Posted: Mon Feb 09, 2009 7:26 pm
by mike_nofx
Just noticed on saturday when i went for a wheel that when changing gears into 3rd that i could keep pushing the shifter up further than it should go (far enough to touch the CD Player). I can feel it 'locate' into gear and it will stay where it should when driving, but if i keep pushing it will keep going.

It was fine like this for a whole day of wheeling, until at the end of the day i shifted from 3rd to 2nd and the gearbox got stuck in 2nd. Im thinking i probably pushed it up too far in 3rd then moved it across before pulling it down into 2nd. (if you get what im saying!)

The way i fixed it was to pull out the gear stick, and re-align the gear selector rods with a screwdriver, then put the stick back in.

At first it seemed to only go 'too far' in 3rd, but now it does it in 3rd and 4th.

What could the problem be? and is it easy to fix?

Also, the gearbox has a crunch when going from 1st to 2nd, or 2nd to 1st unless you match the revs really well (which i can now) which i would guess is worn sinchros? Am i best off just finding a good 2nd hand one?

Thanks
Mike

Posted: Mon Feb 09, 2009 9:37 pm
by Gwagensteve
time for a new (2nd had) box methinks., or a rebuild on yours.

Problem A might be shifter sheet, but from what I've seen by the time the shift sheet is gone, the locating bolt and slot in the shifter ball is also hogged out so it will never feel great again.

the crunching is syncros.

My 660 box has a slow syncro into 5th even running redline heavyweight shockproof, but it's livable. in the main gears it would be a pita.

Posted: Mon Feb 09, 2009 10:05 pm
by Turbo Tonka
whats a rebuild on one of these boxes roughly cost??or is it a pretty simple rebuild?

Posted: Mon Feb 09, 2009 10:07 pm
by Gwagensteve
no idea.

I've only ever fitted replacement 2nd hand boxes.

There's got be near a day in it plus parts - more than a 2nd hand box.

Steve.

Posted: Tue Feb 10, 2009 5:52 am
by 11_evl
sounds like shifter bush is gone and 1st gear syncro is no good

Posted: Tue Feb 10, 2009 7:51 am
by weaves
mine does that in third aswell. it has since the day i got it.

i had never had an issue with it myself untill i let a mate drive it and he didnt know about it. kept pushing the stick up and it got bound up.

and since then on a stockton trip over my christmas holidays i was comming out of lavis lane where it opens up to the beach. hit a bump pretty hard and the shifter dropped as if it was in 4th but it stayed in 3rd.

it doesn't worry me. it doesnt affect me at the moment when i'm on dirt and mud.

Posted: Tue Feb 10, 2009 12:07 pm
by Guy
Mine did this ages ago, but I belive I rebulit it. (Rebuilds happened a few times :oops: for various reasons) was a worn something, I may have just swapped the "tower bit" ...

Is about a days work and depending on parts could be upward of $300. (especially if you need new synchro's\gears)

Posted: Thu Feb 19, 2009 4:15 pm
by mike_nofx
could there be any other reason why the selector rods are moving too far? Possibly a locating ball moving or something?

Its happened a couple of times now where it will jam into 2nd. I've learnt how to change without it happening now, i have to follow the exact H Pattern, especially when going from 2 to 3.

when it does jam into 2nd, i remove the shifter stick, and have to move the right rod down (towards the rear of car)
So im thinking if there is anyway i can open the box and somehow stop the right rod from moving forward too far forward?

Mike