Troubleshooting and Repair - OS Giken OS88 Transmission

OS88 sequential transmission internals

A Skyline GT-R should be your fun car. A sequential transmission makes it even funner.  Streetable, yes, but most people that don't know cars, will think something is broken. Pull that shifter into first gear, and the whole car clunks as the dogs in the transmission engage. 

OS88. You can see the wires into the bellhousing for shift position. Then the next cable with the 90 is for the shift lockout. This is very, very close or maybe touching the body on a car. You may need some percussive maintenance to clear. 

Unlike a true manual, a H-pattern, a sequential lets you just pull the lever back and forth to shift gears. Its much harder to miss a gear in a sequential, but not impossible. Especially if the trans get old, or you don't tell it that you want the next gear. 

There is no "please give me the next gear" kind of slow shift you might do with a street car. Every time you want to shift you "tell it" you want the next year. Pull it hard and firm, it will give you that next gear, otherwise it may just make nasty sounds, other than the normal nasty sounds. 

Some in car action of the Stagea 260RS, when it had an OS88 installed.   I do really recommend running a catch can on the OS88. They seem to move a bit of oil. The two we have will about coat the underside of the car in a day.  For R's Day 2024 we ran lines from the transfer vent, and OS88 vent to a catch can in front of the battery. 

Under the bellhousing. Front of trans. The shift indicator contact is on the first gear. The 2nd gear is off. Under it are the spring loaded pawls that are part of the shift system. 

Reverse gear. This is partially disassembled. Missing the main shaft gear in this pic

Reverse gear or counter gear really. It slides between these gears to engage reverse. 

Reverse

Reverse

So we had two different issues with reverse and the OS88. The first one was the c-clip that holds the shaft to engage the reverse gear. 

Some more in car action of the other OS88.

OS88 catch can . This cheap catch can even has a dipstick. Around $35, saves a lot of mess.  I put this in front of the battery, all the way in the front. I just hooked the transfer vent, and the transmission vent together. It's really not going to mix the two fluids, and honestly even if it does, its not that big of a deal.  I ran it sealed, no atmospheric vent, but you might want to try some different ways for your own car.  I did have to empty it once at Laguna Seca during R's Day. 

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