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Discussion Starter · #1 ·
Hi guys and girls

I have a problem. The gearbox in my GQ 2.8T jumps out of 1st, 3rd and 4th gear. Usually when backing off the throttle and back on again.

Does anyone know what could be the culprit? I'm thinking something to do with the selector, but not 100%.

Thanks in advance
 

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Discussion Starter · #5 ·
Worn bearings. Either way I would suggest it needs a rebuild, or get another one.
What bearings do you suggest it is?

Synchros has come to mind, but it would be hard to believe that all (but 5th) the synchros are gone. We've not long bought the car, and it's fine to change gears when cold.

It only jumps out of gear when your cruising along, and you back off the throttle completely.
 

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Hi mate,
In the top of your box you have a 3 selector rails , when you put it in a gear there is a cutout in each one of the rails , there is also a detent ball and spring in the housing when the gear is engaged the cutout meets the ball and spring when the gear is engaged and the pressure of the ball caused by the spring on the side of the cutout is what holds it into gear until you pull it out of gear by hand. The reason it jumps out when you back off is because when your under power the drive line is loaded and thats what is holding it in gear but when u back off there is no load holding it into gear. Worn syncros will cause grinding but wont cause it to jump out of gear. You will find that You may have worn selector rails, or cross your fingers it may be worn or broken springs, you can check the springs and rails out pretty easily but you need to know what youre doing, let me know how you go mate. cheers
 

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Detent location

Have same problem with mine popping to neautral in 3rd under no load will accelerate fine in 3rd.just looking for detent spring.found 1 to the left of gear leaver on top of gear box is there more
 

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I'm not really into the RD 28 box,it is similar to the skyline GTR/GTS4 box,I have asked and

been told "get a workshop manual" by a skyline guy,apparently there is a possibility of a

detent ball dropping into the box while the spring tension is off :shock:.the TD?TB box is

entirely different,Google an exploded view of the box,

Cheers,G.
 

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I overhauled a GQ Patrol RB30 transmission a while back with same gearbox (FS5R30A) The top rear large output shaft ball race was completely shot allowing the mainshaft to pump backwards & forwards.
The gearbox is also in a D22 Navara & VL turbo Commodores (RB30ET) but these have different gear ratio's.
They are a beautiful changing gearbox & well made but unfortunately showing their age now.
Cheers - Leigh
 
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