Osg 5 Speed Issue

[ShadowGTR]

I've got a similar issue in 3rd with my os box on my R33 gtr. It vibrates only in 3rd but I don't notice it unless you keep your hand on the stick. I've also got a brand new os giken set in my 32 gtr and it doesn't do this at all - totally vibration free in all gears. My old man who's a gun mechanic assembled both os boxes. He is putting it down to the 3rd/4th selector fork being a bit worn on the 3rd side in my 33 os box, making it vibrate when it's trying to hold it in gear. If it were a shafts, it wouldn't vibrate in only one gear.

Thinking of going back to a stock box for the 33 anyway as I don't like the ratios of 1st,2nd,3rd on my GT-SS turbos gtr. I think they are way too tall. Seems a good match for my T51 on the 32 though.

What are the ratios of the os box? thinking of getting one

[Piggaz]

What are the ratios of the os box? thinking of getting one

IIRC all at 8000 RPM

1st = 87

2nd = 138

3rd = 190

4th = 235 or whatever it is (stock)

and the OS 5th gear is 290

[elrodeo666]

Had a drive on the weekend of 2 GTR34's one with OS box and other with the Auto Gallery Yokohama SS690 and gotta say the later was smooth as silk to drive. Super smooth changes, real quick and real slick engagement compared to the OS box.

Definitely made my mind up to go the AGYSS690 !!

They are supposedly strong as the OS box and more popular here...

[Mr. Keets]

Who's car are we talking about now ? Mr. Keets seems to have a R32 GTR so he would've needed all the same parts I needed for my R32 GTR, which would include a new selector on

Yeah I don't recall a selector fork being on the bill. I looks like the box is coming out...any idea of the effort required to change it out?

[Piggaz]

Who you getting to redo the box man?

[Mr. Keets]

I'll put that call in the hand's of my Tuna...the guys who did the original job. I'm a bit pissed at them for this as we've had the "do it right first time and don't skimp" conversation before.

Is this going to be a major operation you think?

[Beer Baron]

well it's certainly not minor! to replace the selector it means box out and apart.

[Mr. Keets]

yeah I thought as much...I was hoping for some kind of miracle lol

[Piggaz]

Better not get it back and have the same problem!!

I wonder why OS Giken dont warn us of this issue or is it that they dont know about it themselves?

[Mr. Keets]

...it's not a CF tailshaft so it should be ok lol

[Piggaz]

lol. Yeah that stupid thing. Hopefully next wednesday night at the drags will snap it in half at the start line. stupid POS!

[Mr. Keets]

I've been speaking with one of my engineers at work about this and he has offered the following. It may be the natural frequency of the driveline, exaggerated due to the inclusion of the CF shaft

So my plan may be to put a new bearing in the old shaft(s) and try it out before rebuilding the box *fargen box fargen GT-R fargen lol*

Discuss

[Piggaz]

Been there done that. New shaft, stock shaft it doesnt matter. Same F*^&CJEN shit!

Dont waste your time man.

[Mr. Keets]

Bah!!!

Box out, selector fork R&R

[Piggaz]

After driving it tonight to wisemans ferry and back i think i might just leave it. Having said that, i might jump into it next week and want to rip it out there and then. What to do? ARGH!

[Mr. Keets]

I have put or is that poured a fair chunk of change into this car in preparation for the stroker kit and the inevitable defect that will head me towards a full strip down for the track...so I want it right. These cars are such a weapon when they're tight and smooth, so it's box out.

[elrodeo666]

Been having discussions with guys at HKS here in Japan and other tuning shops and we have come up with a slight different build plan for my box.

Original reccomendation was dont use the OS gearset and go the yokohama Auto Gallery 690 set but after many discussions with crew that are using this box the prognosis is the best box you can do for street is a combo of the 2 brands.

Run the OS gear set with strengthened input shaft and have Auto Gallery Yokohama build the box with their double con synchro system. what you get is a strong box plus super smooth shifts and a box with no vibration. This setup is supposed to be a killer box for the street.

Everyone here in japan says the same on the OS box ..around the 80kph mark a natural harmonic vibration occurs. I heard it reffered to from anything here as shudd shudda to a cat meow sound!! Japanese sound affects are hysterical.

My box will be pulled out next sat and rebuild will start. I'll keep you updated on the cost etc as may look at getting some made to send to oz if anyones interested.

[BK]

Try new 3rd/4th fork Mr keets ? Mine don't make noises at all as mentioned they do above. To repeat I have a brand new os box with uprated input on my 32. Done 5000km. Absolutely no vibration or noise in any gear what so ever at any rpm at all. Me and my old man built it. This has the series 3 synchros which needs a different selector fork for the 3rd-4th setup. The box in my R33 has an 'OLD' OS gearset which uses the older 32/33 synchros and uses the original selector fork for 3rd/4th. This box is the one that vibrates in 3rd. Maybe some people haven't got the RIGHT fork ? I'm going to put up with it though as I don't consider it bad enough to change on the 33. Is it really that bad MR keets ? I recall a list of parts you put down in another thread when you were building it. If you used all the parts on your list, the 3rd/4th selector fork was definitely on it. I remember comparing parts lists to mine.

Edited July 12, 2009 by BK

[Piggaz]

where do you get one of these different selector forks from? How much are they?

[BK]

I can't remember the cost for just the fork - maybe $100, $150 ? I got my stuff for the OS boxes from Darron at Just Jap. To do the whole new synchro + fork setup in parts was around $900 for me. I supplied part # though. Ah here it is -

I'm pretty sure it's 32811 - 05U10 for the Selector Fork.