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GTR 4th gear crunch !!!!

West

By West,
in Engines & Forced Induction

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wylie Mentor

wylie

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my 33 gts-t is the same, if your givin it some stick in 3rd and go for 4th like over 5000 rpm u get some crunchyness - still gets into gear fine just the noise, all other gears are fine

i think a saw some other threads on this that were talking about fast syncro wear and the box being naturally notchy ?

ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

time to change the synchro's in the gearbox.......if you keep going you will also need to replace the gear as well......thats if its not rooted already.....people....put the genuine oil in them and save your selves heart ache.....

SteveL Mentor

SteveL

Posted
Posted
I still buy them thru Nissan and 4th synchro is very common on GTRs and GTSs.

Give me the name of your parts guy and a contact number, I'll get my parts guy to talk direct to him. I've been through all this with Nissan (local parts, central parts distribution and all the way back to Japan) and my own investigation using FAST software has confirmed. The original type R32 GTR 4th (and 3rd) gear synchro has been superseded BUT the new part does not fit without replacing a bunch of other associated parts (eg engagement ring, hub, input gear, etc)

West Grand Master

West

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my 33 gts-t is the same, if your givin it some stick in 3rd and go for 4th like over 5000 rpm u get some crunchyness - still gets into gear fine just the noise, all other gears are fine

Funny but my seem to be THE OTHER WAY AROUND, at high RPM, no problems but like under 4000rpm it crunch very easy :headspin: .

I agree with ylwgtr2, it's probably time for a synchro refresh. But I would try an oil change first, we use Castrol Syntrax 75W-90

Will definately give that a go first, worse come to worses how much would the whole job cost for syncros replacements? How much is a good condition R32GTR box and labour?

Thanks

ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

the way to Fix the infamous earlier gearbox problem is to convert it into a double cone synchro...this requires a bit of machining but fixes the problem for good....i will have a hunt around and see if i can find my pics on machining them

ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

here people.....this fixes it....1st pic is what the untouched gear looks like......2nd pic in the lathe and machine the single cone off......3rd pic mill 4 slots in it for the double cone synchro boss hub to latch onto the gear....

ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

and you get the double synchro hubs and sh1t from this guy 0453510421.....its a japan number so you will need someone that speaks japanese to order the parts.......you could mod it to use a getrag 6 speed double cone assembly....but thats uncharted waters for me....but if i have to do another one....id be sizing it up that way as i now have plenty of getrag V160/161 parts here now

SteveL Mentor

SteveL

Posted
Posted

To be clear, those pics aren't of 4th gear, but of the 1st mainshaft gear - I can make out the sub-gear used on the 1st MS gear in one of the photos. The 4th gear synchro is also of the single cone type, but is actually part of the main input gear (ie the shaft that sticks out of the front of the gearbox and is what the clutch plate is attached to).

here people.....this fixes it....1st pic is what the untouched gear looks like......2nd pic in the lathe and machine the single cone off......3rd pic mill 4 slots in it for the double cone synchro boss hub to latch onto the gear....
ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

yes but the same mod is done to 4th aswell.......the part your saying is part of the gear is the dogs that the synchro ring mates the shift drum too....these dogs are prone to shearing off if the synchro ring is eitheir rooted,the incorrect oil is used or continued abuse of the transmission

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