5th Gear Crunch !!

[Gizmo73]

hi Guys (and Gals)..

just started happening on my R33 GTST, changing gears from 4 to 5 and it crunches, like the clutch isnt actually engaged..

It only happens with this gear change, but it doesnt happen all the time, just most of the time - if i do a low rev change (say at 80km/hr) and REEEEALLY change slowly (ie push in clutch, sit for about 2 secs and then change gears slowly) it sometimes doesnt do it.

However, everytime ive tried this method (and any others !!) over 100km/hr, its always crunched - man i hate that sound !

Being a daily driver on the freeway, i dont want to see this develop into a big issue.

In about a month im planning on getting the clutch replaced, lightened flysheel installed and i was going to get the thrust bearing replaced as well.

Can anyone think of what this could be, and what i should get looked at while the gearbox is out/being looked at ? (my suspicion is maybe the syncro - thoughts ?)

[Shaggs]

Not really offering any solutions but my r33 gtst does a similar thing but only if i'm changing from 4th to 5th at high revs in 4th. so i'd certainly be interested in any learned posts.

[Guest Robo's]

Yep i get the same in my 33

[Gizmo73]

hmm...but if this is the case, why would my car just start to do this now ??

i do a fair few freeway k's (about 450/week), so its not like i havent noticed it before...

[Timd]

If you end up handing it over to a workshop, make sure you give it to someone who knows what theyre doing. Ive recently had the 5sp on my rb20det reconditioned and it still crunches I took it back and complained. They picked it up, took it away. Didnt here from them for a week. Got the car back and was told i owed them 300(what it cost them) for a new set of gears! so i showed them my warranty and told em to stick it. Stupid cods, the problem isnt fixed. replacing the gears is the last thing youd think would be wrong with it. I think its the thrust bearing so ill be doing it myself when i can. seems like i have to travel up the cost to QLD to get any sort of respectable work done

[GTRsean]

My 92 R32 GTR crunches when changing to 4th and 5th gears, but nearly always at high revs when shifting.

The r33 GTST has the same gearbox as the 32GTR so maybe it's the nissan synchro's saying 'i don't like it anymore'. I changed my g box oil with castol and it's not so bad now, but it only does it at high rev changes.

I've heard that REDLINE SHOCKPROOF gear oil would be something else to try before pulling out the box.

Thrust bearings are not always the cause of crunching, it's you're clutch pedal height from the floor that can affect cear changes too(clutch not fully disengaged from engine).

[Zahos]

start off by changing the oil in your gearbox.

Try either:

- redline: a lot of people swear by it.. but at $100 to fill the gearbox, I dont bother. You problem seems to be pretty bad though, so maybe you would benefit from it...

- Castrol VMX80 + roil (what I used and I cant even make it crunch now, no matter how hard i try)

I had a small crunch, so thats why I dont feel a thing now. In your case, it may just reduce it, so that maybe you can double clutch to get into 5th and not ever crunch.

[Gizmo73]

oil-wise i just did a full change with the Castrol about 10,000kms ago....

[Zahos]

then it's not looking too good for that synchro.....

does it crunch when you double clutch?

[PTR33]

Just to add to the pile, mine does it sometimes and I know of another 33 that has the same "problem".

[CerealKiller]

Zahos what's roil?

[JimX]

Worn synchros. I used Redline oil to reduce it, but now it's slowly getting worse again. But still not anywhere near as bad as when I got the car, maybe 30-40% of the time now instead of 100% of the time when I got it.

It's been 30000km since I changed it, so I will soon drain the oil and put in VMX80 plus an additive. I have been warned that it's bad to go from a synthetic oil back to a mineral oil as I think VMX80 is, so I'm going to change the oil to VMX, drive slowly around the block a few times, then change it again with a fresh bottle and add the additive. Should be a good enough flush.

[Gizmo73]

then it's not looking too good for that synchro.....

does it crunch when you double clutch?

Hi Zahos...

Yep - even double clutch (sometimes)...

How much to rewplace a synchro - assuming ill already have the gearbox out ??

Hi Nathan...

http://www.skylinesaustralia.com/forums/sh...ead.php?t=37992

[GTRsean]

Anyone got any tips for pulling out my gearbox?

My clutch fork has cracked and I cannot disengage the clutch.

Bought another fork($45) and a new thrust bearing ($50).

I planned to do it myself to save some bucks and while the box is out I might pull it apart rebuild and put in new synchros. Got the manual so I've got an idea of how hard it's going to be.

[nismo33]

same here mostly on the 4th gear...but problem solved by double clutching...i dunno what it is really.. but perhaps over reving ? take it to the shop,.maybe not a big thing ,.you might not have to change clutch afterall...but if you're changing your clutch..then worry about it when it does the same with your new clutch.