I want bigger valves for this setup, right?

[datzenmike]

Hey

I just got the 2 Datsun L engine books - and for some reasons I thought the gearbox will be covered by them as well.

 

So now I have more gearbox questions - 1. the 71C is stronger right?

2. How do i identify the gearbox and gearing?

3. how complicated is it to change the bellhousing? open the screws In the bellhouse and in the middle and extract? ;)

 

Generally the C is much 'stronger' than the B

 

The largest outside difference between a B and a C box is the shifter. This is a C type gear box...

 

This is a B...

 

If the C is about 30" long it's from a Hardbody. If about about 34" it's from a car. I think the ratios are about the same with a large over drive.

 

Either long or short transmissions will require the drive shaft to be modified for length.

 

 

 

To put an L series front case on a C, you need to remove the front cover plate, remove the snap ring (keep the shims) remove the center bolts and split the front case from the adapter plate and rear tail.

 

The C case uses a 62mm counter bearing (the lower one at the front) that won't fit the B case's 56mm hole, so either have a machine shop mill the case out to 62mm, or remove the 62mm bearing and put a 56mm bearing on. The front inside of the B case needs to be milled thinner around the counter bearing hole for about 1/2" around it for clearance. Without this the counter shaft will bind against the case when assembled.

 

The C transmission uses a 16mm first/second shift rod and won't fit the 14mm hole in the earlier B case. Just drill it out.

[sneax]

Ok thanks Mike

 

Will do that today!

So the 56mm bearing from my 71B will do the job? (if its in good shape)

Anf the two other things can be done with a grinder and a drill?

Ok... Lets see... ;)

[sneax]

Hm

I opened the screws in the bellhousing, the circlip and the screws around the middle! Then hung it from the bellhouse and tapped it everywhere with a rubber hammer.

And now the rear casing came off!

 

How do i get off the front?

 

[Stoffregen Motorsports]

You want both halves to come off, so you can re-seal them both. The front half should just pop right off. You did get the circlip around the front input bearing, right?

 

Maybe hit it with a gasket scraper and a hammer in between the mid plate and the front half of the trans case. Be sure to file any edges smooth caused by the gasket scraper before reassembly though.

[sneax]

You want both halves to come off, so you can re-seal them both. The front half should just pop right off. You did get the circlip around the front input bearing, right?

 

Maybe hit it with a gasket scraper and a hammer in between the mid plate and the front half of the trans case. Be sure to file any edges smooth caused by the gasket scraper before reassembly though.

The SECOND circlip! Just discovered that one! Haha

Thanks

Got it!

[sneax]

The front inside of the B case needs to be milled thinner around the counter bearing hole for about 1/2" around it for clearance. Without this the counter shaft will bind against the case when assembled.

The smaller bearing is clear! Will take the one from the B box!

The 16mm shift rod hole is clear... Will drill it out!

 

But I am not sure about that 1/2" aroynd the counter shaft bearing!

Do yoy mean in the lid that sits inside the bellhouse? because i would just take the old one! Or where?? Thanks!

 

EDIT:

I think i understand!

The thickness of the case around the two bearings is less in the C gearbox. Therefor i meed to mill off the surface inside the front cover of the gearbox!

 

Right?

 

And i found inside that part of the bellhouse two other changes! There is one more hole - and then there is a little hook castet into it!

???

I upp a pic in a bit! :)

[sneax]

so there are the 3 difference Mike mentioned!

drill 16mm hole for the shifter bar - Understood!

bigger hole for the bigger bearing - got it!

and now i have to lower the surface around the counter shaft bearing (you can see on the two pics) to be the same distance to the middle gasket surface like in the C bellhouse! 

RIGHT? 

 

but there are the 2 other difference ive  seen inside.

first the oil catch hook thats casted in! and 2nd the additional hole!

do i have to reproduce them???

hole = easy

oil hook = not easy!!!

 

the new C bellhouse with hook and hole:

 

 

the old B bellhouse i will use:

[datzenmike]

If using the 56mm bearing I wouldn't worry about it. It would be a very good Idea to replace the 56mm bearing with a new one. These take a beating and one of the reasons the C went to a larger stronger bearing. If getting the case milled make it worth while and have the hole enlarged to 62mm for the larger bearing.

 

 

Check the shift rod hole size, I think it's 16mm, but match whatever the C is.

[sneax]

Great!

 

Bellhouse is at the machineshop! $50 and 2hours... Worth it! :)

Yes - its 16mm!

Thanks

[sneax]

Oh... And whats with the aditional hole? Gets oil on tje other side of the bearings because they are sealed bearings or what? And that other hook thing?

[datzenmike]

The J thing just catches thrown oil and gravity feeds it out into the front cover. If running the larger bearing (I would advise this) you can use the C front cover and drill out a lubrication hole to match.

[sneax]

The J thing just catches thrown oil and gravity feeds it out into the front cover. If running the larger bearing (I would advise this) you can use the C front cover and drill out a lubrication hole to match.

Ok... Thanks

 

I am using the big bearing!

Will drill the holes! :)

[sneax]

Clutch question:

Dave Rebello told me to use a 280z clutch!

Now i was looking around on ebay and there are plenty diffrrent once - with or without flywheel!

 

I planed to lighten my original flywheel here - cheep and easy!

Will the OEM 280z cluch do the job for a 3300km rally? (I know - depends on the driver

[Stoffregen Motorsports]

Nice work on the trans stuff. You jumped right in. I love that.

 

The L20B flywheel will work with the 280Z clutch, as long as it's the 225mm variety. Clutch discs came in 200, 225 and 240 mm diameter and you need to use the corresponding parts...obviously.

 

Will the 280Z clutch be enough? Sure. I would be more worried about having a race clutch with the type of racing you're doing. Race clutches overheat and wear out very quickly. If you're worried about the 280Z clutch, look around for a high performance 280Z clutch kit. Maybe with upgraded friction materials or harder clamping. Here's a link showing different types of clutches - https://whiteheadperformance.com/performance-parts/datsun-240z-260z-280z-1970-78/240z-260z-280z-clutch-flywheel-transmission/I'm just using this link as an example. I've never even heard of these guys before.

 

Per the flywheel. Yes, you should have yours lightened. It's the cheap way to do it. You could buy an expensive aluminum flywheel, or even a steel one, but again...you don't need that for what you're doing.

[distributorguy]

You can also have your flywheel step-ground to add a little more clamping pressure.  An extra .010" step can add quite a bit of additional clamping pressure, with no change in pedal feel or clutch disengagement when you apply the pedal.  Just put the step at the outside edge of the disc.  

[sneax]

You can also have your flywheel step-ground to add a little more clamping pressure.  An extra .010" step can add quite a bit of additional clamping pressure, with no change in pedal feel or clutch disengagement when you apply the pedal.  Just put the step at the outside edge of the disc.  

 

that sound like something I will definitely do!

To get that right... I will turn down the flywheel on the surface where the clutch plate is touching it??? about  0.010inch... and how exactly has the step to be at the outer edge of the clutch?

just making the space for the clutch to move more into the flywheel while the clutch is mounted on the upper part of the step, right?  

[sneax]

so Ive taken both casings off the gearbox to inspect and clean! the screws looked like they had been never opened!

 

Quick question: that tube for a hose at the top... what is it and how is it used originally? 

 

 

 

I ve counted all the tooth:

 

first:          14  33

second:    19  28

third:         28  26

fourth:       32  21

fifth:          39  21

 

any thoughts on that?

the fifth gear cogs are definitive not as wide as the other 4... so I have to be careful with pedal-to-the-metal in 5th!!!  

 

 

The machinework turned out like this... eem to be a decent job! ... I will drill the two oil holes by hand! 

 

now this oil rail for the end-shaft bushing was only sticking in there! 

 

normal it seemed to be attached by this tiny rivet, I think!?!?!?

inside:

 

outside:

 

 

should I drill it out and re-attache it with a rivet? or a crew with locktide? or...?

 

thanks 

[datzenmike]

Quick question: that tube for a hose at the top... what is it and how is it used originally? 

Breather. Air gets hot inside a transmission and expands, shrinks when cooled down.

[sneax]

aaaand bevor I go to bed for today my lat quetion:

 

Can it be, that the bushing in the neck i in the wrong tilt / angle?

 

 

 

 

the rail from my last post ends in the upper hole on the left side of the neck. Id say thats where should be the outlet for the oil on the bushing. I got it on the opposite side without a channel behind.
anyone a trans-neck without bushing? :)

 

Has to come out... ?!?!

[datzenmike]

Why is that oil trough off? Was it loose? I'd get that securely in place before assembling the transmission. It's to lubricate the rear most part of the main shaft that can't get splash oiling from the turning gears.

 

Just replace that output seal with a new one. Easier now thnt when it starts leaking in a couple of months.

[Stoffregen Motorsports]

I think he's asking about the rear tailshaft slip yoke bushing. They do wear out.

 

It's hard for me to see the condition of the bushing in your pics, but if it is relatively smooth with no chunks or scoring, I'd leave it. Unless you think it spun. Is it loose?

 

Defintely get that oil trough back in place. You need that.

 

5th gear is definitely a weak point for these transmissions. Are you going to disassemble the cluster to install synchros and such? If so, be sure to check all of the thrust bearings (I think there are two) for wear. If there is wear in them (usually a step) and you install them backwards from the way they came out, you could loose all of the gear end play, which is bad. And definitely use red loctite on the tailshaft nut. Get it good and tight.

 

One more mod that racers like is to replace all the shift rail roll pins with a "dual" roll pin, where a small roll pin is stuffed inside the existing roll pin. It's extra insurance against breaking them during hard shifting. If you are getting parts from Rebello, see if he has a line on those. If not, you can make your own. Order the small pins from somewhere like here -  https://www.mcmaster.com/#roll-pins/=18gb4ls

 

I just saw these, but I've never tried them. Probably do the trick -  https://www.mcmaster.com/#roll-pins/=18gb5oc

[G-Duax]

Here are the 'coiled' metric roll pins from that page: https://www.mcmaster.com/#roll-pins/=18gc4nw

[datzenmike]

If that oil trough was off, you just may have some wear in the tail shaft. Early tails (not the 71C but early 4 speeds and maybe the 71B had removable bushings but I guess they wore so little they started just reaming the case for size and going with that..

[sneax]

Hey

 

Its been a while... I am working every day up to 12 hours to get shit done!

-Engine mounts are new

-trans mount new

-tumel new

Crossmember cut for half the hight and reenforced

-Tubular upper control arms

-4 piston brakes with vented rotors

-Rebello got the head done and its on the way down to Mexico!

-Almost all parts are on the way or here

I will post pictures when i have time and patience

[Stoffregen Motorsports]

Good news. Can't wait to see your progress.

 

I am not sure which one is the reverse light, but yes, I think it's the one at the rear (someone correct me if I'm wrong.) The cable drive is for a speedometer.

 

You don't need any of these to use the trans, but if you want reverse lights, it's easy enough to figure out which one is the reverse light switch. Use a multimeter (or even a test light) and shift into reverse and check that it closes the circuit.

 

If you want to use your speedo, and the threads aren't right (not sure if the MG uses the same thread as the Datsun, but I doubt it) you can have a custom cable made with any end you like. If the speedo needs correcting, then have the new threads built into the speedo correction box.  - https://www.google.com/search?q=speedometer+correction+box&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiK47HawvPVAhVKNSYKHb8CBoEQ_AUICygC&biw=1680&bih=910

 

You could also run an electronic speedo and get a signal generator that threads into the trans. Probably better for what you are doing anyway, as they are easily adjustable if you change your tire size or change your differential ratio. They make remote mounted ones too with a short cable to mount on the frame or body. - https://www.google.com/search?q=electronic+speedometer++signal+generator&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjc5sGLw_PVAhXFZCYKHcBVB80Q_AUIDCgD&biw=1680&bih=910