Best transmission

[datzenmike]

You have the infamous A series, AKA the "Monkey Motion" shifter. It's fault is it is rubber mounted and the supporting bushings small and easily worn out. With mechanical advantage a small amount of wear at the bottom translates to a huge amount of wobble at the top of the shift lever.

 

 

 

There are two 'cone' rubber  mounts (#8) squashed between slotted washers. When the rubber wears the washers can't hold the shifter in position and it  can actually rotate around in a circle. Some extra washers might remove the slack.

 

Bushing (#15) can wear and increase the forward/backward motion. Though not usually a large amount. There is also a thrust washer (#13) so slipping another in beside it may help. Keep in mind that everything has to be able to move, it can't be solidly tight.

 

The washers marked (#33) can't be got at without removing the striking rod... BUT you may be able to slip a thin shim down from above to remove some of the slop. See top picture. The #37 part has to be able to rotate from side to side. This would remove forward and backward motion.

 

 

The biggest wear spot is the (#19) pin and (#18) clip area at the bottom. This is where side to side motion of the shift lever is transferred to the striking rod. (#20) You may be able to slip a thin washer on the pin between the 'fork' and the striking rod. I did this on my 521 truck with same shifter. You could move the shifter in a circle the size of a basketball before. Others have replaced the pin and clips with a nut and bolt and tightened the forks against the striking rod to remove slack. Again they can't be tight the fork actually rotates slightly on the rod. There is also the risk of snapping one of the forks.

 

 

5 Speed

The Roadster's bigger brother 2000 had a 5 speed but finding one is very unlikely. Most were reclaimed for racing use and all rebuild parts exhausted. Five speed parts are usually labeled 'Unobtainium'.

 

Alternatively a 720 truck diesel FS5W71B 5 speed can be modified to fit the R16 or U20 engines. The diesel front case has the same bolt pattern and the starter on the left just like the Roadster. A few of the bolt holes may need to be drilled out larger.

 

Diesel front case bolt pattern...

 

Roadster front case...

 

The bottom picture was from PPeters? who cut this off a Roadster transmission in order to weld to a 71C 5 speed. Then he heard about a diesel transmission. I gave or traded the diesel front. I don't know what happened to this project.

 

Here's a picture of the FS5W71C transmission fitted with a diesel front case...

 

Here's another using a 71B 5 speed.

 

[russaroll]

5spd

?

[G-Duax]

I'm just about finished with my conversion to stick an HPI close ratio S15R 6-speed into my Toyota, just needs welding of the new front adaptor plate to the shortened FS6R92A front case. It will be off to a welding shop Monday.

The adaptor plate simply bolts to a Toyota auto bell housing.

 

The S15 6-speed is known to not take the abuse of a 2-liter turbo engine, but HPI builds them with the Nismo close ratio gear set, and other internal mods to take over 400 HP. (more than the Nismo version of the same trans, and way more than the Toyota W58, which I was going to stick in the car.

I would have no qualm about putting a stock S15 trans behind an L4, what so ever.

 

One of the reasons I went with this trans was that people have stuck it behind an L6 successfully, with minor internal improvements.

Somewhere I have links to those conversions.

 

So now that this swap is coming to an end, I will be looking at locating a 71C for my 620.

Mike has posted about the L-series to 71C conversion many times, and I've been saving all that info  :)

Or....

I may just put the Toyota W58 into the truck, since I have a freshly rebuilt unit taking up space in my shop.

 

Edited August 12, 2018 by G-Duax

[datzenmike]

Both 71B and 71C steel adapter plates have the same bolt pattern so all L series (and more, SD, CA, Z,) will bolt up to it, with a few mods to the front of the case. The 71C rear cases are different lengths and different shifter but same spline for the driveshaft. The 71C is at least twice as strong as the 71B, and although Nissan only used it to handle just over 160 hp on the VG30E (300zx and S12 200sx) it has been used to replace the 300zx turbo T-5 at just over 200 hp without problems. Claims of 300-400 hp on turbo KA engines have been made.