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Gtr Decided It Suddenly Doesn't Like Staying In Gears....

Goombeh
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Goombeh Collaborator

Goombeh

Posted
Posted

Looking for some tech advice from all you Sky boffs out there.

I was heading home just now and the car has been absolutely fine, I arrived at a set of lights, shifted to second and before I stopped, depressed the clutch.

Now, as I went to shift to Neutral, (clutch depressed, car stationary) it was very difficult to take out of gear. I took the clutch to friction point again and it was engaging normally so depressed it again and gave the stick a little tug until it popped out. All good I thought, however now, there is no resistance changing into any gear at all. And driving requires I hold it in gear as it will pop out from transition from on to off throttle.

It does this in every gear now. All gears were fine before. So I'm thinking it can't be synchos or gears as it is suddenly on all gears.

Does anyone know what the mechanism is like for the shifter linkage enabling it to lock into gear.

Any help would be brilliant.

doo doo Proficient

doo doo

Posted
Posted

ok, the mechanism to keep gears engaged is not the synchros (if it still goes into gear fine, they're fine) but a check ball and spring. I think that the checkball has jammed (maybe some foreign piece of gunk floating around has jammed it) the fact it was difficult to push out of gear would support this- this would have been the jamming action on the checkball. I've included some pics to show you where this is located on the box and what it looks like inside. It's accessible without taking the box out and you shouldn't need to drain the gear oil either.

Firstly take the larger bolt out (17mm) and if you look inside you'll see a spring- there is a ball on the other side of this. Pull the spring out with a relevant tool and then the ball (you might need a magnetic tipped tool)- if it's jammed then leave it. If you take the whole assembly out (by undoing the smaller 14mm bolt) and the spring is loose, it will drop into the case and you will have to take the gearbox of and disassemble to retrieve it. Don't go there. However as the ball is probably jammed you should be OK, but do check. You will need to take the whole assembly out if the ball is jammed to unjam it anyway (you will have to pry it out as it has sealant on the mating surfaces)

If the ball is scored get another one and clean the assembly from any potential crap.

Reassemble with new sealant on clean surfaces and then pop in the ball and spring.

Any queries or probs post them up.

post-48345-1274683743_thumb.jpg

post-48345-1274683781_thumb.jpg

doo doo Proficient

doo doo

Posted
Posted

Quick edit- where taking the assembly piece out I've said if the spring is loose it will drop into the box, I mean if the ball is loose and still in the assembly it will drop into the box, take it out first. However, I imagine this is what is stuck so if it is you won't be able to take it out and it also shouldn't be able to drop into the box. sorry to be pedantic but dropping the ball into the box would really, really suck.

Goombeh Collaborator

Goombeh

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That sounds right on the money! One minute it's perfect, and the next it's sloppy through all gears. Just wasn't sure how it works on these but there was no way it was gears.

Thanks so much, I haven't even got in there but this is it, no question. You're a legend.

I'll let you know when I get a chance to get in there.

Cheers bud and thanks for the pics, that really helps.

Goombeh Collaborator

Goombeh

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Cheers again buddy,

It looks to me that the entire assembly retains the ball and spring, so if I take the entire assembly out and get the ball and spring moving again, it should be right, does that sound right?

thanks again mate.

doo doo Proficient

doo doo

Posted
Posted

Don't take the assembly out until you've tried to take the ball out. The ball is not retained in the assembly on the inner side, as it pushes against indents in the striking rod (which moves back and forward as you move the gear stick back and forward). You should still have side to side resistance in the gear shift lever as this is a different spring. If the ball isn't stuck and you don't take it (the ball) out before taking out the assembly it (the ball) will fall into the gear box case. And then it requires disassembly to retrieve. Yuk. If the ball is stuck you won't be able to get it out so it shouldn't fall in. You'll then need to remove it (the ball) from the assembly and clean it all up to work properly again. I know I'm repeating myself but as I can't be absolutely sure the ball is actually stuck, take this precaution as you don't want it to turn into a gearbox-out-of-the-car scenario.

Goombeh Collaborator

Goombeh

Posted
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That's a great explanation thanks, I can picture it now with your description.

So I can see now how if there was something caught where the ball would normally be pushed back into the assembly, it may have given me resistance. Then as I forced it out of gear (the ball into the assembly), it became jambed inside the assembly and now has no contact with the rod as the spring cannot push it back out on its own hence the gear selection feeling very loose.

That's brilliant! I just went out and got under there and i just can't get to it easily with the car just on stands. Your pics were very helpful as you can't see it from below, but going by your pics, I know exactly where it is. But I can't get my arms at the right angle.

i'm going to have to get the thing on a hoist I'm thinking.

thanks again, if you have any tips on accessing this, throw 'em at me.

thanks again.

doo doo Proficient

doo doo

Posted
Posted (edited)

So I've popped the car up and had a look under and I reckon you'll need to d the following to get decent access. Remove clutch slave cylinder, remove front drive shaft. Then you might like to drop the box down by doing the following- undo the driveshaft at the end of the transfer case (you can leave hydraulic line attached, just don't let it bear any weight of gearbox), undo exhaust at cat, with a jack or similar support under and of box undo the g'box crossmember then gently lower it down. You should check the fan clearance on the radiator shroud when you do this, but it's the only potential issue I can recall. If you have an aftermarket front pipe and need more room for drop then you can undo the steering plate cover that is directly under the front pipe, this gives a bit more room.

You'll probably have a small issue getting the assembly out (after getting the spring and possibly the ball out). Having taken the smaller bolt out put the larger one back in but leave enough of it sticking out to use a screw driver or similar behind it to pry it out- use the box case as a leverage point.

A hoist will make this far easier, but if you like a challenge it's possible to do on jack stands. Just have your swear jar within easy reach.

Edited by doo doo
Goombeh Collaborator

Goombeh

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haha.... thanks mate.

Swear jar's already full and I haven't started yet.

Great description and thanks so much for having a look.

You're right, front shaft and slave will have to come out as a min. I have a mate with a workshop so I'll try to get it on the hoist as I can see me becoming very loud trying to do this when i can barely fit my face under the car.

Thanks again, I'll let you know how I go.

Goombeh Collaborator

Goombeh

Posted
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haha.... thanks mate.

Swear jar's already full and I haven't started yet.

Great description and thanks so much for having a look.

You're right, front shaft and slave will have to come out as a min. I have a mate with a workshop so I'll try to get it on the hoist as I can see me becoming very loud trying to do this when i can barely fit my face under the car.

Thanks again, I'll let you know how I go.

  • 2 weeks later...
Goombeh Collaborator

Goombeh

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Well, cheers for all the info Doo Doo.

Got to the part, was frightened as hell that the ball was going to drop into the box, didn't make sense that it would though.

Came out, ball was jambed inside the cylinder, looked like the ball had worn a flat spot and that last time, it turned and the flat area helped jamb it in the assembly. So it came out together.. brilliant!!

Replaced the ball with a new one and she's wonderfull again.

Cheers for the help again.

  • 2 months later...
doo doo Proficient

doo doo

Posted
Posted

if the ball is stuck then yes it shouldn't drop into the box, but best to be absolutely certain first. It might not roll out as it's sitting flat, but using a magnetic tipped tool or similar to try to draw it out should tell you whether it's stuck enough not to drop. I imagine a gearbox shop or nissan will have a replacement ball.

doo doo Proficient

doo doo

Posted
Posted

The ball runs into indents in the single shaft that moves back and forward for all gears, so yep, a stuck ball or spring will affect all gears in the forward/back (ie 1-2, 2-1, 3-4, 4-3) by letting them slip out of gear (The stick will still move from side to side no probs as this is a separate pair of springs)

Birds Grand Master

Birds

Posted
Posted

If it's only happening in a single gear it is more likely a synchro hub issue than a selector issue. Synchro hub issues are highly symptomatic on deceleration or going downhill.

DVS JEZ Grand Master

DVS JEZ

Posted
Posted
If it's only happening in a single gear it is more likely a synchro hub issue than a selector issue. Synchro hub issues are highly symptomatic on deceleration or going downhill.

Doo Doo said in the 2nd post that the synchros dont hold gears in?

i thought the detents (little balls) held the selector fork rod in place once fully engaged.

so it might be possible as doo doo said,that the detent as shown in his pics might be getting stuck at certain sections of the selector rod.

doo doo Proficient

doo doo

Posted
Posted (edited)

Does it also happen in 2nd gear? You won't usually produce the same condition in normal driving of backing off in 2nd but try it and see if it's the same deal. The indent on the striking rod for 2nd is the same one for 4th and reverse. If you get the same sort of result then it might be related to the ball not locking into that indent properly. You can still take the ball mechanism out (with the previously mentioned precautions as the ball is probably not stuck) check it and clean it up and then see if the problem persists.

Edited by doo doo

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