Tutorial: FS5W71C Gearbox onto L-series engine

Answer to most of the common technical questions

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nzeder
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Tutorial: FS5W71C Gearbox onto L-series engine

Post by nzeder » Wed Jun 21, 2006 8:19 pm

With Dave's permission I am posting this tutorial. A SR gearbox = FS5W71C which Nissan have used in a number of cars over the years from 300zx Z31 non-turbo's, to Skylines and even the Holden RB30E powered Commodore. However not all FS5W71C are created equal. I can't confirm but I have heard that some have alloy selector forks other steel. Some have dual cone sycnro on 2nd and 3rd others only on 2nd. At the end of this tutorial you will find a ratio table I found that relates to the Skyline R32 gearbox's. I have done this as we have a lot of JDM Skyline imports so they should be easier to find. If I find info on the Silvia/200sx ratios I will post also. Also a number of manufactures make replacement gearsets of these boxes again I will post links as I find them :)
[font=Verdana]SR gearbox onto L tutorial

Parts Required:
L6 gearbox
SR gearbox
New L6 gearbox countershaft bearing (optional) Part Numbers: 63/22C3, TMB3/22C3, or 22BC0655X. Call CBC (www.conbear.com).

Specific Tools Required:
16mm drill bit
Dremel with a small grinding disc.
Optionals: 16mm H7 reamer bit, 41/64ths drill bit.

Step 1:

Remove L6 bell housing from gearbox. To do this unbolt the bolts halfway on the gearbox that go from the extension housing through the sandwich plate to the bell. Also unbolt the cover on the inside of the bell that the clutch arm sits on.
You will then need to remove the circlip on the front of the input shaft bearing. Use circlip pliers and a screw driver.

Put everything aside as you will be using some of it again.

Remove SR bell housing from gearbox following the same procedure.

Step 2:

Remove the SR countershaft front bearing using two chisel point screw drivers to get it started, then lever it off against the bearing (as opposed to the gear) so you don't ruin the gear.

Step 3:

Reinstall the 240Z countershaft bearing. Either reusing the one from the L6 box, or a new one. Gently knock it down with a rubber mallet.

Step 4:

Drill out the 1st/2nd selector shaft hole in the L6 bell housing using a 15 or 16mm drill bit then a 16mm H7 reaming bit. Or you could try a 41/64ths bit if you happen to have one lying around (thats what I ended up using).

Step 5:

Get a dremel/rotary tool and grind away 1mm or so from the countershaft casting on the inside side of the gearbox bell housing. This is necessary as the casting has been modified between the 71B and the 71C to accommodate the wider gears assumedly.

You also need to put a chamfer on the edge which is square standard. I made this chamfer between 1 and 2mm big.

Step 6:

Trial fit this bell onto the SR gearbox being careful of the oil supply cup on the upper passenger side just above the 1st mainshaft gear. Rotate the input shaft by hand. If it is very difficult to turn you need to die grind some more off the countershaft casting in the bell.

Step 7:

When you can bolt the gearbox up and rotate the input shaft easily you are just about ready to bolt the box together.
You could possibly have trouble with the 1st/2nd input shaft not wanting to go into the bell housing because this metal doesn't have any oil sitting on it, I suggest you squirt a dab in there. If the selector doesn't go in it can slide backwards (engaging 1st gear).

If this happens and the gearbox shifter is not in the 1st position you won't be able to select any gears (except 5th/Rev) from then on. If putting some oil in the 1st/2nd selector shaft hole doesn't solve the problem, you can put the gearbox in the 1st position before you bolt it up and it will be fine. Worked for me atleast.

Step 8:

Reassemble the gearbox as you took it apart and you're ready to go. Don't forget the circlip on the mainshaft bearing. Use the L6 front gearbox cover, clutch arm and throw out bearing carrier.


Additional issues:

The SR gearbox has the bolts for the gearbox x-member around 35mm further back than the 71B box. Depends on your car what you do to fix this. Here is what I did, tad dogey, but it works.
This gearbox is also 50mm longer at the end of the tailshaft. I took a tailshaft that was used on a 71B box and had it shortened by 50mm and it fits just fine (after you remove the cover for the front spline as it doesn't fit into the gearbox).

Big thanks to Mad1600 for helping me and motivation.

Pics to follow.


Dave
__________________
Standard Disclaimer: Its almost certainly more complicated than what I just said.

Dave Andrews

Race Car: 1973 240Z, L28ET, Autronic, GT35R.
Project: 1972 1600, 3200km old S15 SR20DET, ground up rebuild.[/font]
Skyline R32 gearbox specs:
Image

R32 GTS-T Type M gearboxes are good for about 400ps (390HP) this is the HCR32 listed above. If you car will have more HP you should look at the R33 GTS-T Type M gearbox (a R33 GTS-T is powered by the RB25DET) however most know these as the strongest Nissan box = expect to pay big $$ for one ie $2000+ these are not as easy to install as the output shaft is different = different yoke/drive shaft required etc + they are much bigger.
Last edited by nzeder on Mon Jan 15, 2007 10:29 am, edited 3 times in total.

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Different Gear Sets

Post by nzeder » Thu Jun 22, 2006 2:47 pm

As one would expect these are not cheap. But here are few companies in Japan that make different gear sets for the FS5W71C boxes. For those who's Japanese is as good as mine this is what I can make out - cost will be somewhere between $1600-$2200 NSD for the gear set (the type that change only the first 3 gears. To get the units which change 5th gear you can expect to pay cost to $4000 wow - you can kill a lot of boxes for that amount of coin)

First Kameari Engine Works (long time L6 modifier)
[web]http://kameariengineworks.co.jp/catalogue-P47-2%20.pdf[/web]

Next is OS Giken (the maker of the very rare TC24-B1 DOHC head that was fitted to a L28 bottom end - and before you ask no you can't get them anymore :()
[web]http://www.osgiken.co.jp/pro_gear/nissan.html[/web]

Next is Magic (not sure of the companies name, but if you have deep pockets you can purchase a new. Yes brand new FS5W71C with your choice of ratios, and if you have really deep pockets you could also pick up a LD28 crank that is modified to a 85mm stroke = 3.2l, or purchase a complete L3.0 or L3.1 with big cam etc)
[web]http://www.ny.airnet.ne.jp/~magic/cross-71c/index.htm[/web]
Last edited by nzeder on Tue Dec 14, 2010 2:54 pm, edited 2 times in total.

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djz
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Post by djz » Mon Jul 30, 2007 5:27 pm

When you got your box done did you reuse the smaller counter shaft bearing or have the bellhousing machined out to take the bigger one? If you had it machined did they have to do anything else to where the bearing goes, like grinding down the casting?
Nissan 280ZX 2 seater RB26 powered.

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Post by nzeder » Mon Jul 30, 2007 11:19 pm

djz wrote:When you got your box done did you reuse the smaller counter shaft bearing or have the bellhousing machined out to take the bigger one? If you had it machined did they have to do anything else to where the bearing goes, like grinding down the casting?
Yes I had the bellhousing machined out to take the larger bearing, they removed 2-3mm for the gear clearance as required (milled out using a milling machine) and also drilled an extra oiling hole that my doner RB box bellhousing had.

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Post by bernjean » Fri Oct 16, 2015 7:49 am

Can anyone tell me what happens with the speed drive when fitting the SR gearbox?
Bernie Kant

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Andy
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Post by Andy » Fri Oct 16, 2015 10:05 am

Stick a speed sensor in it, or they will take the Z speedo drive.... I think. I use the SR speed sensor as a bung as I run a wheel sensor.

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Post by bernjean » Fri Oct 16, 2015 8:34 pm

Had a look at RB conversion on internet and the L series cable fitted straight in. So my guess is that it would fit straight in.
Bernie Kant

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old_datto_fan
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Post by old_datto_fan » Fri Oct 16, 2015 9:11 pm

When I swapped to my RB box, the cable just went straight in so you should be fine.

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Post by Baker93 » Sun Oct 18, 2015 2:07 pm

Hi
There are quite a few different speedo drives ( ratios ) I have a load here if you need to adjust the gearing/ratio. From what I have seen they are all the same between the boxes.

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Post by bernjean » Sun Oct 18, 2015 3:58 pm

Yep lines up with all the info I have got
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71C internals into 71B box

Post by mikec(nz) » Wed Jun 22, 2016 1:22 pm

Just wondering if it possible to fit the 71C internals into a 71B casing. The problem I have is with the T & C rules which appear to limit to the period correct gearbox (the 1970's 71B) and preclude the 71C (1980's) but ratios etc are free.

While the 71C internals/box seem to 50mm longer even after changing the bellhousing - I have read that the 71C kameari gear kit might be to be purchased/modified so that it fits the 71B box with only some bellhousing modification. I read that this the variation is achieved by using different spacer rings on the mainshaft cluster.

Anyone know if this is possible have any more info?

Cheers Mike

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Re: 71C internals into 71B box

Post by Andy » Wed Jun 22, 2016 3:21 pm

mikec(nz) wrote:While the 71C internals/box seem to 50mm longer even after changing the bellhousing
Mike, there are kinda two lengths of the C, firstly the box appears in lower powered Skylines, Cefiro etc and is shorter, like the B and secondly in 5 speed Silvias which is the 50mm longer version.

These guys are probably worth talking to http://www.wellingtonautomotive.co.nz/s ... boxes-grid as they have a dog engagement option that seems reasonably priced here www.GOTBOX.co.nz.

They may have done the experiment with the B casing or can help you regarding both a 50mm shorter box or fitting the gear set into a B casing.

I would be interested to hear how you get on.

Just as an aside the C type Silvia box places the gearstick in a better spot, more like the original A boxes in the Z's.

Just as a thought cannot the rules be interpreted as meaning any FS5W71 box whether A,B,C,D,E,F or G?

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Post by mikec(nz) » Wed Jun 22, 2016 4:00 pm

Thanks Andy did not know about the two length 71C, that's worth investigating and matches something else I heard from my Japanese agent.

Dog box - I was tempted by Anthony's one - but really prefer the easy life and want to keep syncros.

The rules in T & C are very vague, I am trying to keep it as original as possible irrelevant of the rules. But if I can get a 71C that bolts in with only a bell housing change then I am interested. Did not want to modify the rear mounting as that is an obvious change.

I however did find out how to fit the R180 crown and pinion out of a Subbie into the stock R180 diff housing with the Quaife LSD (after my little incident launching off the line in thelast race, at the Festival of Motor racing) .

It was not a straight bolt in as the bolts were bigger, but we drilled it out and made a thin spacer plate and it all worked. So now have a 4.4 final drive. Will post detailed pics in due course.

Does anyone have a short 71C available?

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Post by Andy » Thu Jun 23, 2016 12:34 pm

mikec(nz) wrote: But if I can get a 71C that bolts in with only a bell housing change then I am interested. Did not want to modify the rear mounting as that is an obvious change.
Not sure of your mounts on the 240K but on the earlier Z for the C type there was around a 20-30mm offset for the rear mount points which was handled by elongating the mount holes on the bracket and using a small offset plate. That is the rear mounts on both the long and short version of the C type are a little further back. Later S30's used a different mount system and a bracket customisation was necessary.

You should still be ok with your driveshaft length on the shorter version.

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Post by Andy » Wed Jul 06, 2016 1:58 pm

I had a pm from a member regarding this conversion with silvia vs skyline, so I thought I'd post my small amount of experience on this sticky which also reflects that of another club member who has done a similar conversion.

Hi Andy,
Curious about your advice to ConnorAnderson. (in the classifieds)
According to nzeder a 71c from a Skyline R20det does not require the driveshaft shortening.


Correct


If correct ,why would you advise S13/14, rather than the Skyline one ?

1. The gearshift on the longer S13/14 box falls to hand easier in the longer box, I had to modify the gearlever on the skyline(shorter) box to have it in the right place.
2. It is easier to find full upgrade gearsets for the S13/S14 box.
3. If you are upgrading the engine and using the standard driveshaft you are going to break the driveshaft eventually, so while fitting new bigger universals to the driveshaft it is no more expensive to shorten it. All of the original driveshaft is too weak, everyone breaks universals and many racers have buckled their tubes as well. For a road car the tube is probably ok but the universals are the same size as a 105E Anglia and seriously undersize. I actually replaced the tube with a bigger one as well so ended up with a complete new driveshaft.

The only downside to the longer box is that it seems gearbox angle and difff angle become just a little more critical so pack the gearbox angle to suit the diff angle or vice versa or both, they should both be the same but not inline i.e. the uj's should have around 1deg angle in them but definitely not 0 degree. Just to verify, the lines extended from the input shaft of the diff and the output shaft of the gearbox should be parallel but not the same.

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