Gearbox Issue

My 1996 Integra DC4 GSI has had a crunch from 2nd to 3rd for a while now when I shift above 3.5k RPM, or shift too quickly. But today I noticed while I was driving at around 1am when the temperature was around 6º C (Very cold!) that the crunching was gone, 2nd to 3rd gear shift was smooth at any rev change, even 7000. But after a few minutes of hard driving, the crunching began again.

The car had not been driven since around 5pm so it had been sitting for around 8 hours and the engine/gearbox would have been very cold.

My question is, if I replace the gearbox oil with a thicker oil could it possibly stop the crunching all together? Thoughts and opinions on what I can do, best oil to use, etc.

Thanks :)

Your logic is correct , but that would be a bandaid solution and under certain situations the synchro will catch n grind anyway.
There is some brand like redline shock proof or similar made for this result.

Personally I would be dropping the box and just fixing it. Depending on your location our trader Chez00 has some good drive in drive out packages

I got a perfect condition gsi gearbox sitting on my garage floor...
pm me if ur keen, il sell it cheap

Changing the oil wouldnt hurt, had it happen in my old r34 skyline, new oil fixed the grinds

I picked up a cheap B16 driven car and had standard JDM J1 box which had a serious crunch anything over 3k rpm 2nd to 3rd. Had to really baby it to get it into gear with no grinding. Swapped out the oil for some Honda MTF and since then have done a couple of hillclimbs and car gets revved out (not thrashed) with no issues at all. Can't believe it made such a difference.

Try that.

Did the same with my turbo (Y1 box) which has a slight crunch, same gear over 7k rpm and made no difference at all. Worth a shot for how much it costs though.
Have a new custom set up with Type R internals etc in a cable box ready to install from Chez00 (Neat Gearboxes), can vouch for his work if the oil swap doesn't fix it.

Sorry for the noob question, but what could be the issue? Is it just the clutch on it's way out or the flywheel??
I've noticed mine (s80 LSD) grinds if I change too quick, but I've been putting it down as user error. Am I wrong to??

If the clutch is operating correctly (master cylinder and slave operating, fresh fluid, bled properly etc.) and you're still crunching, it's almost always a synchro issue. These are damper rings that assist the transition from one gear to the next by slowing the rotating assembly down. As the synchro rings wear out from friction (they have a very hard job in a high revving car like a Honda), it allows the gears to collide with another metal part called the "sleeve" or "slider". This creates the crunch. Once you have a crunch, the more you drive it the more damage you will do internally. Often sleeves and gears need replacement in a gearbox that has crunched for too long.

Modern oil is so good that it can temporarily disguise the fact that the synchro rings have worn beyond their service limit. It will slow down the inevitable but it is not a "fix" per se, unless you had the wrong oil in from the start.

Ok thanks alot! I'll change the oil with Honda MTF (original oil) and see how it goes.

Not worth changing a synchro on that GBox. The labour alone will be at least $750 + new synchro.

Replacing the GBox will be at least $500 + replacement GBox.


Change the oil and see if it helps. Otherwise just deal with it IMO, and remember to go into 3rd gently around 2,500-3,000RPM which should be fine anyway given how long those damned ratios are...

Hi Flyson - check out this thread - there is a no cost method to try before going and dropping out the box check it out Natey has had no issues since and I've got about 10000 on my box now since I did this and no issues/crunches.

http://www.ozhonda.com/forum/showthr...rbox-crunching

Read page 3 near the end of the thread.

I've tried something like this before, but not for 2 minutes only a few seconds. Ill give this a go. Thanks

Usually the bseries suffer in those synchros 2nd and 3rd . I would follow Sam's advice for starters and if not then a gearbox rebuilt will be needed . I would suggest to rebuilt the gearbox instead of buying a new one due to warranty issues . For example when we rebuilt a gearbox both Sam (Neat gearboxes and me Extreme Project World) give 1 year warranty. In that one year everything that we do is covered , so it turns out to be cheaper in the long term . If you are in Sydney , you are more than welcome to come by and we can see it for you and go from there and on .