Datsun Roadster Forum-311s.org

Hello 311 experts:

I recently got my hands on a diesel 5 speed that I'm considering for converting in my '70 R16 4 speed.

I see lots of threads, but many are older. I wanted to see 8f anyone had and recommendations or suggestions for the conversion. Below are some of my high level questions

Do I need a new/resized driveshaft?
Are the gears from the 720 ok to use, or should I get the gearset from a 280z? Or gear recommendations?
Standard r16/u20 clutch work in it?
Can I use the bellhousing spacer from the 4 speed?
Does the shifter come out the same place in Floorpan as 4 speed?
Does the cross member need to be modified? If so, does this require removal of body?
Any other thoughts?

Sorry for all the questions, any help is appreciated

AC

I'm sure my Canadian friend Daryl will be along shortly and probably has answers...

It's a granny /Crawler gear 1st can't swap gears
Plus steel case
it's a 2 men finger smasher R&R

It's an aluminum case

I never saw a aluminum 720 diesel trans , helped put many in & out so it's a swapped reg truck trans the parts diesels were from Japan and expensive & were a paint shaker alum would not last

I'm currently converting my '65 SP310 to a 5 speed using the diesel front cover mated to the gear set in a FS5W71B short body trans.
See: -
https://311s.org/phpBB3/viewtopic.php?f ... on#p325195

Thanks for the comments, fairly confident it is aluminum housing on front and rear sections as magnets not stick, except for center plate. Looks like I will have to find a short back half to get length and suggested gear ratios. Any suggestions on models /years of short back half?

Yes, it is an aluminum case. I can't help with the gear ratios.

I have seen 3 diesel 5 spds, all were aluminum cases.

I think if you look in the 5 spd transmission thread I started many years ago you will find a bunch of gear ratios listed.
As I recall the gas truck versions had similar 1st-4th to the roadster with a slightly higher 5th (lower numerically) than the roadster 5 spd.
About 1980 280z 1st to 4th is very close to the roadster 5 spd with a .773(?) 5th vs the .852 of the roadster.
No idea about the short/long versions....

I installed the FS5W71C version from a 240SX....which is likely on the long side....

I would advise putting the transmissions (roadster/71B or C) side by side to make sure the shifter position will work. I had to reverse the shifter in mine to get it to work....it's in the thread...

I'll need to put a pair of 90deg bends in my shifter.
The difference in location to the stock shifter is about 60mm forward.
I don't consider it a deal breaker to the proposed conversion

Nissanman wrote: Mon Aug 23, 2021 2:14 am I'll need to put a pair of 90deg bends in my shifter.
The difference in location to the stock shifter is about 60mm forward.
I don't consider it a deal breaker to the proposed conversion

There are a variety of different configurations of shift levers that came in the different cars that came with "B" transmissions. If you ask around you might find one that works better than the truck shift lever.

Mike