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Hey guys,

Lately when i cold start my R34GT I am not able to put it into 1st gear or reverse for a good 6-8 minutes.

Over all my gearbox seems to be a little bit notchy but some of my mates with skylines say they dont notice anything out of the ordinary, so I guess its just me being paranoid.

I have tried pumping the clutch continuously but it makes little difference, is it possible my transmission needs a good flush and new oil?

Thanks for any opinions! rolleyes.gif

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how do you mean 'not able to'? and this is pretty extreme in variation to your mates commenting that it is behaving in a way that is 'nothing out of the ordinary'.... also auto or manual? i cant imagine it being an auto with these symptoms but then again i wouldnt be caught with a skyline auto so wouldnt know...

Anyway, sounds like it could be one of 2 things in the simple side of things.

1- yes you do need to change the oil in the gearbox. I do every 20-40,000km and with the best stuff available. Iv also found that skylines love fresh good grearbox oil and work alot better with this.

2- your synchros are f*kd. Iv noticed that the RB25 gearbox can easily get bad synchros due to their age and the abuse they may have experienced in their life (use and mainentence wise.) Also i know alot of skyline owners who think this is normal RB25 box behaviour when in fact their synchos are not in the best of nick. But alot or Rb's have this issue and so many think it is normal behaviour (it isnt...)

its weird you cant put itto gear though as although when cold the oil is thicker and all that. if you not moving the gearset will just stop eventually once the clutch is depressed so you should still be able to put it in, and reverse is not synchronised im pretty sure so depending on where the mainshaft stops it might not go in...

plus if you have done synchros i would doubt 1st... from what i have seen mainly 2nd and 3rd gear synchros go due to ppl shifting real quick putting more stress on the synchros...

does it have a short shifter or anything.. i had one for about a week and box got notchy... took it out, put standard one back in and is perfect again...

+1 on oil i have also noticed that 25 boxes love new oil.. wat do you use jjman?

I believe mine is the same. 2nd gear synchro isn't great. 3rd has a notch. Both get better when warm. 1st is the worst though. I can't shift form 2nd down to 1st. I woul dhave to really push hard, and then probably grind it to get it in. So I just don't ...

I believe mine is the same. 2nd gear synchro isn't great. 3rd has a notch. Both get better when warm. 1st is the worst though. I can't shift form 2nd down to 1st. I woul dhave to really push hard, and then probably grind it to get it in. So I just don't ...

i should have added that.... when 1st gear synchro is worn it would be difficult or impossible to downshift into first without grinding..

Edited by PaulosECR33

edit i doubt it would only be first gear

new oil is the first thing i would do.. see how that goes. i uae that redline shockproof stuff its great but its pretty pricey.

be careful not to mix synthetic and mineral.. very bad things happen when u do that....

how do you mean 'not able to'? and this is pretty extreme in variation to your mates commenting that it is behaving in a way that is 'nothing out of the ordinary'.... also auto or manual? i cant imagine it being an auto with these symptoms but then again i wouldnt be caught with a skyline auto so wouldnt know...

Anyway, sounds like it could be one of 2 things in the simple side of things.

1- yes you do need to change the oil in the gearbox. I do every 20-40,000km and with the best stuff available. Iv also found that skylines love fresh good grearbox oil and work alot better with this.

2- your synchros are f*kd. Iv noticed that the RB25 gearbox can easily get bad synchros due to their age and the abuse they may have experienced in their life (use and mainentence wise.) Also i know alot of skyline owners who think this is normal RB25 box behaviour when in fact their synchos are not in the best of nick. But alot or Rb's have this issue and so many think it is normal behaviour (it isnt...)

Yes it is a manual, and when I say 'not able to'... i mean I literally dare to pull no harder until it warms up..

its weird you cant put itto gear though as although when cold the oil is thicker and all that. if you not moving the gearset will just stop eventually once the clutch is depressed so you should still be able to put it in, and reverse is not synchronised im pretty sure so depending on where the mainshaft stops it might not go in...

plus if you have done synchros i would doubt 1st... from what i have seen mainly 2nd and 3rd gear synchros go due to ppl shifting real quick putting more stress on the synchros...

does it have a short shifter or anything.. i had one for about a week and box got notchy... took it out, put standard one back in and is perfect again...

+1 on oil i have also noticed that 25 boxes love new oil.. wat do you use jjman?

Nope, no short shift.

I dont believe it is the synchro's as first gear does tend to go in a lot easier and sooner then reverse, and afaik (as you said) the reverse gear isnt synchro'd so it must be something else.

Also i should mention i usually can shift down to 1st gear quite easily without grinding, although i do have to be basically stopped or going very slowly ( i know this is somewhat normal ... I say this because my friend appears to be able to shift down to 1st when he is going alot quicker then if it was in my own car.)

Can you get it into 1st with the car turned off and clutch in?

I will check first thing in the morning :), pointless checking now as my car is warm.

yeah im using redline shockproof.

Bottom line is that the RB25 are good but older boxes now so you really need to look after them. So why use anything less than the best?. My R33 with 225kwatw has a box that feels like brand new and i plan to keep it that way. Fully synthetic and changed every10-20,000 kms and i absolutely baby it when cold and then i still only do i hard shift if im murdering someone ;) Otherwise i give it a nice gentle change every time so it goes in with no resistance and doesnt stress the synchros.

I used to have a Suzuki Swift GTi and the synchros went on that big time n i just ended up hating driving it. rrrrrrmmm, chkkkk, clunk, rrrrmmmm= NOT FUN OR COOL. Good thing i rolled it, would have been impossible to sell like that.... :P

Sorry to say Josh but that kind of behaviour from the box is not normal at all and sounds like the synchros are getting pretty f*kd. Change the oil to a really good fully synth (do you even know the lst time it was changed??).

otherwise perhaps things like a selector for or some shit might be the issue, but i doubt it based on the whole 'when it is cold' thing- which is textbook synchros...

Edited by jjman

yeh shockproof is the bomb.. i hate notchy and heavy shifting and that stuff is magic to a gearbox.. well worth the price..

i worked on a truck today that was really hard to shift into 1st and second and slight grinding.. (a synchronised box).... actually the boss made put a new exchange box as its under contract warranty...

any way when that failed to fix it and we had an argument as i thohught the clutch was dragging and gbox was fine he let me diagnose it..

first off i checked the master and slave cylingers for bypassing fluid... all good, holds pressure, returns good.. etc

then went on to check the clutch.. found that it was indeed clutch drag from besicly a defect in the clutch disc,

anyway im not saying that is your problem but clutch dragging could cause your issues and it will take longer disengage drive and mesh the gear so maybe look into that, and if its all good at least you can be confident it is a gearbox issue

first of all put some good oil in like jjman said. new oil works wonders on 25 boxes

Adjust the clutch pedal pushrod up the top of the clutch pedal. U need to adjust it towards the master cylinder so that it disengages the clutch more.

A quick how to do it

I think its a 12mm lock nut, loosen this then with ur fingers or long nose pliers turn the pushrod clockwise so it moves closer to the master cylinder. Keeping in mind if u over adjust it or u dont have any freeplay in the clutch pedal the clutch might slip. So u need to find the best spot for max travel(disengagement of clutch) with some freeplay

half inch rachet for filler... think its 17 or 19mm socket for drain plug (dont quote me though) and a lil oil pump or a hose with funnel... you can also fill it through the shifter hole if you can be bothered taking the shifter out...

make sure plugs are tight but not too tights as its alloy case.. let us know how it goes

  • 3 years later...

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