Changing Gears in Transmission

[cygnusx1]

I have a Datsun 5-speed that came from an unknown vehicle. Supposedly it was pulled from a new Z under warranty in the early 70's. I got it from a retired Nissan mechanic who had it in his shed since it was pulled. It looked new. After I fixed the defect that caused it to get pulled, I put it into my 76Z. The problem was that the little "oil catch pan" which deilvers oil to the rear bushing was cracked. The lack of rear oil wiped out the tail bushing. To fit it to the back of my 76 motor, I had to swap the bell housing with my original 4-speed bell. I have been driving the trans for over 10 years. I remember trying to ID the tranny by using the ratio pattern but I never found out what vehicle it came from. The casting is a standard Nissan F#S### 5-speed number. However, it does not match ratio pattern with ANY Nissan 5-speed in any car or truck from 1968-1990. I never had any problems with it. It had a slghtly lower 1st and a good 5th for highway. 4th remains 1:1.

 

Now I have a hyper turbo motor in my 280Z. With the additional power, I find that 1st and 2nd are too quick. 3rd to 5th are very nice. Is it normally possible to change out gears from other FS series Nissan trans to custom taylor the ratios?

 

Thanks.

[JMortensen]

I know of no Nissan trans that has a countershaft with separate gears on it. They're all one piece that I've seen.

 

This means that even if you could locate a different 1st gear and 2nd gear cluster, you'd also have to have a countershaft that matched them. At that point, you might as well just get the transmission that has the ratios closest to what you want in the first place.

 

Sounds like you might have a truck trans. You can see if the ratios match anything listed here: http://www.geocities.com/z_design_studio/transmission.html

[cygnusx1]

DUH!! You are right! It's been that long since I had the trans opened up and I forgot the counter shaft was one cast part. Slap me silly!!

 

I looked at sooo many ratio charts from Nissanway back when and couldn't match anything up to mine. I'll check out that link Thanks alot.

 

Does the fact that I had to swap in my original 4 speed bell housing in place of this 5 speed bell help identify the trans?

[260DET]

Some of the 80's era five speed Nissan gearboxes have a couple of separate gears on the countershaft cluster. But yeh, best to buy a box with the ratios you want rather than chase after bits and pieces, keep the old one as a spare.