Cunching Syncros At High Rpm

[Pauly33GTS-t]

what a head f**k now I got this. I'm gonan put in good redline oils and pay 150 for a "short term" fix. I think the best way to combat the problem would be getting a full rebuild and replacing the synchros and then sticking with 1 good oil the whole way and change it prematurely everytime. I had my oil changed from a service recently which revealed the crunching, they didnt put redline oil back in obviously so Redline oil is great but its not a fix.

Redline 75/150 i think it is.

[tigr33]

i noticed this problem wen i was running the car at the track, from 3rd to 4th only at high RPM...

so u guys rekon use the redline oil?

[Pauly33GTS-t]

ok

my problem was the oil wasnt good enough when it was changed. most of you dont fret, it may be a simple oil change and you are back to smooth changes.

I'm gonna be using Redline Lightweight Shockproof (125 dollars for 3.5L) what do you think about this oil?

[Waldo]

The best option is to buy a 350z gearbox and just get the bellhousing modded for $400 these gearboxes are pretty cheap and are six speed and they weigh a tonne...but when u see the size of the gears in them compared to your rb boxes they look like they are meant to hold 1000hp.

[mattymagoo22]

I don't know about you guys but there is nothing at all wrong with the R33 box, NOTHING.

This box is good for 500 -600 hp.

Who knows how the cars were driven when in japan. The box does not strip gears, has dual synchros on first 3 gears. So with new synchros and a mineral oil to let the synchros bed in and a good run in period there shouldn't be a problem.

IF you build half a box and not all bearings and synchros then don't expect the whole thing to last.

And remember the synchros are wearing out it could be a clutch issue as well.

thats my input.

Cheers Matt.

[tom23q]

i have the same problem but only on a high rpm from 3rd to 4th, and from 4th to 5th, double clutching does help from 3rd to fourth but havent tried thats from 4th to 5th as it was just way too fast.

this started happening after i installed a 5puk extreme button clutch kit, any ideas??

[Trex101]

ok

my problem was the oil wasnt good enough when it was changed. most of you dont fret, it may be a simple oil change and you are back to smooth changes.

I'm gonna be using Redline Lightweight Shockproof (125 dollars for 3.5L) what do you think about this oil?

What! $125 for 3.5L..... that's freaking expensive you got there. Do a search in ebay, you'll surprise how much cheaper you can get.

[Pauly33GTS-t]

i bought mine from a store because who knows what the ebay sellers do with the oil, might be switching the shit who knows.

[Trust33]

perhaps they smoke it..

[Trust33]

Is this oil any good for both the the gearbox and diff??Does it come in a red container.

How much oil to fill the gearbox?i filled it once ages ago but cant remember how much i put in.

[Pax-Ottomanica]

The best option is to buy a 350z gearbox and just get the bellhousing modded for $400 these gearboxes are pretty cheap and are six speed and they weigh a tonne...but when u see the size of the gears in them compared to your rb boxes they look like they are meant to hold 1000hp.

What you've sudgested sounds good, but the question is..

- Do these boxes have a higher or lower gear ratios?

- Would the box fit in without the need of extensive mods?

Here's one for $700 on yahoo auctions, say $1,200 after shipping etc..

http://page6.auctions.yahoo.co.jp/jp/auction/f47489786

[LBR33]

Is it possible to get stronger then the factory synchros for the RB25 box

[Trex101]

i bought mine from a store because who knows what the ebay sellers do with the oil, might be switching the shit who knows.

Well, it's your money. Whatever makes you feel good.

[Risking]

The Z33 box is actually a POS compared to the R33 box. There is little to any doubt that the R33 box is the best gear set nissan have ever used and is identical to that used in the GTR. Look closer at the Z33 box when its stripped down and pick the weak points. The RB25 has offset baulk ring teeth 1st-3rd, The Z33 does not. The R33 has a very simple selector arangement, the Z33 has a barstard thing thats prooving to be difficult. The R33 has a much courser set of splines on the main shaft which the Z33 box is also going to struggle with come to decent HP engines.

Putting the Z33 box in is not an easy task anyways. It has an external and remote shift selector which is way to short for the R33/R32. the gear box mounting positions are extremely different and not to mention the fact that the Z33 flywheel won't fit the back of an RB without fouling the block.

There is NOTHING wrong with the RB25 box besides the fact that they WEAR like anything does.

Ive re-built hundreds of them and they will last another 15 years without any dramas when treated right and looked after. Broken selectors ARE NOT THE BOXES FAULT. Thats just drive abuse!!!!!!!

My advise is to try decent oil in it and if need be pull it out wack a set of baulk rings and bearings into it (no real need to do selector sleeves etc unless really worn) and then enjoy what is a truely superiour gear box.

[Pauly33GTS-t]

Redline recommends the oil I have just put in the car (and subsequently have no more issues), is it possible that clicking and nicking from changing gears is directly related to how good the oil operates at higher temps and pressures? Redline recommend Lightweight Shockproof for "Added advantage in racing applications" application.

[tom23q]

today i purchased "royal purple max gear" gear oil for my car today, apparently its better than the redline products... im going to put this in sometime this week if i get a chance. i will update the results once i have put the oil into the gear box

Edited April 3, 2007 by tom23q

[PJ.]

today i purchased "royal purple max gear" gear oil for my car today, apparently its better than the redline products... im going to put this in sometime this week if i get a chance. i will update the results once i have put the oil into the gear box

Sure the oil does help, but have you ever dropped the oil out of it to find little broken clips on the inside of the gearbox plug which is magnetic?

This is a common occurance with them too. I'm not a mechanic and far from a gearbox genius but this has happened to me twice. If 4th is crunching consistantly, pull the plug off and check whether these syncro clips have broken off. The parts are only worth $25 in total, there are three clips.

If the box is out you don't have to strip it to put these clips back in either.

[tom23q]

well im not crunching constantly only after ive been driving hard for a bit, so i think my problem might be that im due for an oil change or the oil that is in my gearbox right now isnt the right one... so hopefully this week i will post an update

[Risking]

Ah who told you that!! I think the "clips: you may be refering to are the syncro Paws and there is stuff all you can do with 4th gear without stripping the box to nothing as 4th gear IS the input shaft.

[MANWHORE]

My theory is that the r33 box and gearset is very strong. Like everything else though (and the way the skylines get driven), the synchros wear out.

about 1/2 skylines has worn synchros it would seem.

Maybe the synchros are a bit soft. I think driving plays a big part in how quickly they wear too.